| 240 Alternator Mod Page and my Mechman Installation |
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UPDATED: September 9, 2023 CONTACT |
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Send me an email if you have questions or can contribute to any info here.
CONTACT
For details on the development of this project, scroll down or CLICK HERE.
240 Alternator Idler Pulley Bracket for 240 red block B21/B23/B230 for use with a high-performance alternator. CLICK HERE for Alternator Idler Pulley Project Details
Questions? Please read this page or CONTACT me with any questions: CLICK HERE. |
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View Cart or Check Out please click below button: |
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| Here's a video of this idler pulley bracket in action during the early prototype testing phase.
I ran the prototype for 5,000 miles to fully test for any problems and I
have used the production bracket now for nearly 10,000 miles with great
results. https://www.youtube.com/watch?v=-O9fC3fR4ac |
| Some Basics: How does an Alternator Work? Here's an entertaining video https://www.youtube.com/watch?v=zfGm0gZhgCc |
| What to Do about your Old Under-Charging Volvo (Bosch) Alternator |
| Here's an interesting video of the complete restoration of an old Bosch external fan alternator. https://www.youtube.com/watch?v=eLgjyJBvYs4 |
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| And here's one that's show you a pretty good partial rebuild of a 1988 Volvo external fan alternator. https://www.youtube.com/watch?v=6o_OrF2S_UA |
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| How about a video showing how to remove your 240 Alternator? https://www.youtube.com/watch?v=A72pWPYm8yo |
| Improving the Charge with a BIGGER/BETTER Alternator |
| SO, WHY WOULD YOU WANT OR NEED A BETTER ALTERNATOR? My 1984 242 Turbo originally came with a modest Bosch 55 amp alternator. Can someone explain why such a non-significant alternator was used? A non-turbo 240 got a 70 amp alternator. In stock form, that tiny 55A alternator was barely adequate from the beginning. Like most light-duty Bosch alternators, it suffered from a significant voltage drop when a moderate load was placed on it, especially at idle (although raising the idle to about 1000 rpm did help). And it also suffered from an even larger voltage drop when it got hot (and of course it sits close to the turbo).  The Volvo B21 (red block) engine was not originally designed to have a turbocharger when it was designed in the early 1970s. The turbocharger was added much later. I guess the Volvo engineers did the best they could. Options are few if you have a flame thrower next to your alternator, unless you want to move the flame thrower or move the alternator. They did neither.
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| WHAT HAVE OTHER CARS MAKERS DONE TO ADDRESS HOT ALTERNATOR PROBLEMS? In the mid-1980's PORSCHE ran into a similar problem when they added a turbo to the 944 to make the 944 Turbo. There was not enough room on the exhaust side to add a turbo. There was barely enough room for a manifold. So where did the turbo go??? Have a closer look below. This 4 cylinder engine is similar to the Volvo engine in that the intake manifold is on the LEFT and the exhaust manifold is on the RIGHT. Unlike Volvo, the Porsche engineers found NO ROOM on the exhaust side to mount a turbo. Instead, they ran a pipe from the exhaust manifold, UNDER THE ENGINE, all the way to the intake side and put the turbo under the intake manifold just a few inches behind the alternator! Crazy stuff. You can feel fortunate there were no German engineers working on the Volvo turbo engine design.      I had a discussion with a Porsche 944 Turbo owner about heat-related voltage drops. Porsche engineers did some extra work to help reduce the heat by adding a LARGE COOL AIR DUCT to bring air into the back of the alternator. This likely helped during highway speeds, but heat was still always a big problem. I don't know if Volvo engineers thought about this, but they would have had a much more difficult time doing something similar, unless they moved the OIL FILTER first. |
| CAN COOLING DUCTS BE ADDED TO A VOLVO 240 ALTERNATOR? Yes, if you're determined enough . . . . But there isn't any room behind this 240 alternator below. Adding a shroud or duct would require relocating that oil filter first. |
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 So if the 240 oil filter was to be re-located, maybe there could be room for something like this low-profile cooling shroud. This shroud is Porsche PN 96410640302. I have not tried doing anything like this. If you're inspired to try it, please let me know. |
| Volvo (Bosch) 55 Amp versus 100 Amp Alternator Size Comparison    The above photos show a size comparison between a Bosch 55 amp (240 Turbo) and a Bosch 100 amp (740).
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Here's a good video from iPd on Volvo V-Belt Basics and Identification. https://www.youtube.com/watch?v=wsJ0ROAv6U4&t=138s |
SPACE FOR THE BIGGER OIL PRESSURE SENDER Since the Bosch 100 amp alternator case is physically a lot BIGGER than the old 55 amp alternator, it causes interference with the large 2-pole oil pressure sender found in a 240 Turbo. That brass 45 degree fitting came standard on a 240 Turbo, but the bigger alternator still hits the sender with that fitting unless you can swing the alternator outward farther.  |
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So generally the oil pressure sender needs to be re-positioned to make
room for a larger alternator. Sometimes finding the room for it needs some new ideas, but if the alternator can be swung out further from the engine (with longer belts) you can be successful. But this isn't always possible.
THESE PICS are from some other 240, not mine, but it shows how TIGHT THAT SPACE is for the oil pressure sender when a big Bosch alternator mounted. 
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 Ultimately, I dealt with the cramped space a bit differently as you can see in this image above. I mounted a "remote sender" after I had some bad experiences with other options, such as cracked adapters. There's a longer story to this, but the short version is that this remote method actually worked very well. Here's a thread that goes over the longer version of this story and this mod in more detail: https://forums.tbforums.com/showthread.php?t=192788 |
 If you can find enough room, the ultimate position for this sender is shown here, WITHOUT ANY BRASS ELBOW or ADAPTER, but this would require a way to move a BOSCH alternator EVEN FURTHER away from the engine. Or a physically SMALLER alternator might work (i.e: DENSO: Click Here). |
| Here's why I found there are serious limits to a longer belt. A longer belt MIGHT have helped this installation by swinging the alternator further from the engine, which would make extra room for that oil pressure sender. But then you find that swinging the alternator further out only moves the belts TOO CLOSE to the alternator mounting bracket below. A longer belt in this situation means the belt is going to hit that bracket. So the longest belt in this situation is probably going to be somewhere close to the 10 x 950 mm I used. That belt is about 25 mm longer than factory. 
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| What about a DENSO? |
| Here's the compact Nippon Denso alternator in a 240.
It has become popular to install this smaller case Denso alternator, which can be found in some later 700/900 models. It's physically smaller than the above 100 amp Bosch. These Densos can usually be found in 80 or 100 amp capacity. They perform pretty much the same as a large Bosch alternator at idle. The most positive benefit is that they do fit better. There is more room for the oil pressure sender with this more compact alternator. 
Denso alternators found in Volvos are usually either 80 Amp or 100 Amp. They look similar to each other, but you'll notice the 80 Amp units have a SMALL 6 mm lug for the fat red cable. 100 Amp units will have a LARGER 8 mm lug.   |
| SERVICING A DENSO Here's a page devoted to rebuilding a Denso alternator with more pics: https://www.volvoclub.org.uk/faq/ElectricalDensoRebuild.htm And a discussion thread on Servicing a Denso Alternator: https://forums.turbobricks.com/showthread.php?t=349853 |
| INCREASING THE VOLTAGE IN A DENSO What about increasing voltage output for a Denso alternator like this? It's not something I have tried personally, but there now seems to be some interesting videos on this subject. Here's one where the author increased output from 14 volts to 14.7 volts. The video is not in English, but following along is pretty easy. https://www.youtube.com/watch?v=HRgSHGhcolg&feature=youtu.be |
| Introduction of the MECHMAN ALTERNATOR #1 This installation of my first Mechman Alternator was back in 2010**. |
| **MECHMAN ALTERNATOR #2 was later installed in 2019 and CAN BE FOUND BY CLICKING HERE. |
| Back in 2010 I finally gave up on the 100 amp
Volvo Bosch alternator. It was not going to cut it.
The biggest problem for me was how it charged at idle. When running the air conditioning (with a big electric primary puller fan and dual condenser fans), voltage was suffering badly at idle and it became much worse after the alternator started getting HOT. I had begun using a big Ford electric puller fan, first trying a Ford T-bird fan from a salvage yard. I eventually changed to a Lincoln Mark VIII (Mark 8) fan, which is slightly more powerful than the T-Bird fan. A Mark VIII can pull up to 40 amps at full speed, but full speed isn't really need very often. But even a raised idle speed of about 1000 rpm couldn't bring voltage up enough for my happiness.
BOSCH VOLTAGE DROPS With the BOSCH 100 amp alternator, the voltage drop between COLD and HOT with a heavy load at IDLE was: 14.4 volts COLD to 12.4 volts HOT. A FULL 2 VOLT DROP! Also this situation was forcing me to set the idle speed higher than it should be to help keep voltage from going through the floor. Here's a temperature reading from my exhaust manifold (AT IDLE) a short distance from my alternator. 
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| My Intro to Mechman So, in 2010 I was introduced to Mechman high performance alternators by a Turbobricks member. I then talked with Mechman and I told them about my low idle voltage. I was assured that a custom unit they would send me would improve voltage at idle by offering more amps at idle. Mechman didn't really have a high-performance Volvo-specific alternator, so they custom tailored a GM Delco style alternator to fit a Volvo. Skipping ahead: The Mechman alternator did improve charging at idle and overall output was much better, but it STILL suffered from an annoying voltage drop when it got hot. The voltage drop was not as bad as the Bosch though, but I still had to resort to keeping my idle up a bit higher than normal to keep charging voltage from dropping off below 13V when everything was on. I began thinking there might NEVER be a real solution for a 240 Turbo with the alternator on the exhaust side and I thought I might have to eventually move the alternator to the other side of the engine like on the Volvo 740. |
| I began a discussion thread in Turbobricks in 2010 back
when I got my first Mechman. That thread is here: https://forums.turbobricks.com/showthread.php?t=215613. |
| SPOILER UPDATE: August 2019 I learned in 2019 that Mechman no longer offers CUSTOM FIT alternators like the one I bought below. It was customized (machined by Mechman) to properly fit a Volvo red block. BUT, I have since found there are STILL pretty simple solutions to make a universal high-output alternator fit your Volvo. I've added info that should help do this. CLICK HERE. |
FIRST MECHMAN 2010 DETAILS
| Here's the Mechman alternator from 2010 compared to the Bosch 100 amp I was using up to that time. The Mechman used a large case GM Delco style housing that has been slightly modified to correctly fit in the factory Volvo mounting location (while also using a few spacers). I was told this Mechman unit was a one-off 170 amp alternator based on the Delco AD230 (original to a 1996-2013 GM truck) with a little custom machining to its case so it would bolt up similar to the Volvo Bosch alternator.  Similar Volvo conversions have been done using GM AD244 and GM DR44 late model truck alternators. The reported benefit is better output at idle, which is something the old Volvo Bosch unit don't do well. More about the machining modifications Mechman did can be found HERE.     |
| GROUND CABLE When Using a Mechman Attaching a big ground was a bit different on this alternator. It didn't come with a ground stud on its case, so the solution (also suggested by Mechman) was pinching a ring terminal against the case underneath as shown here. It turned out to be a good solution as long as that long bolt doesn't tend to loosen over time. I used a good lock-nut on that long bolt to make sure it didn't vibrate loose. 
The best charging results with this new (2010 Mechman) alternator came after I added a dedicated 4 GAUGE ground cable and positive cable DIRECTLY from the alternator to the battery. You can see the results of numerous tests in the above mentioned installation thread. I still experienced a pretty significant COLD-to-HOT VOLTAGE DROP using this alternator, but ultimately adding these cables provided the best result so far for any alternator I had tried up to this time. |
| Using enhanced (LARGER) POSITIVE and NEGATIVE Cables. The latest version I did on my car uses large fine strand, high-flex WELDING CABLE. Welding cable uses very small wire strands, making a large, fat cable much more flexible. Why do you need flexible cable? I'll tell you why. My first version used large, fat normal strand cable. The vibration and flexing of the fat power cable to the alternator eventually broke the cable at the alternator lug after a number of years and many miles, leaving me stranded and calling for a tow truck. Plan ahead and get better cable. 
 This illustration ABOVE will give you an understanding of what is recommended with a high-amp alternator. You should consult the manufacturer of your alternator for a cable size recommendation, but be prepared to be told to make them very BIG. I made this illustration above to show the big dedicated cables (POWER AND GROUND) going directly from the alternator to the battery, so power and ground is as absolutely as direct as possible. The cable going between the alternator and the starter becomes completely optional, since you really no longer need that cable if you do this. Of course keep the cable from the battery to the starter, since you'll still need that to start the engine. |
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 <<< WARNING NOTE: I don't recommend using one
of these inexpensive disconnect devices on your battery
when using a high output alternator like this.
I had one of these on my
negative battery terminal back in 2010. After
installing the Mechman I began experiencing
some strange intermittent momentary voltage
drops when the alternator was under load,
such as when the AC was on. It took a
while to figure it out and it's detailed in
the Turbobricks thread mentioned above. It turned out
that this disconnect knob was creating higher resistance in the ground cable
circuit and the Mechman was sensitive to
it. I removed this devise so that my battery ground was solidly connected. |
| DEALING WITH BELT SLIP The Unintended Side Effect of a HIGH-PERFORMANCE ALTERNATOR |
| Back to this photo below: Have a good look at the belts wrapping around that pulley. There's just a little more than 90 degrees of belt wrap. The actual belt-to-pulley contact patch is pretty small. But that's how a 240 is designed. Why is this a problem? (keep reading) 
This
was not really a problem back when the weaker 55 amp original Bosch
alternator was there, but it became intolerable with a high
output alternator.
I found that I needed to tighten the
alternator belts much more and then they usually needed more tightening
later as they began to wear. I was putting a LOT of stress on my belts. That can cause problems. 
That bolt in the front of the block for the adjusting bracket has been known to break off (it happened to ME). I've also seen a few people with broken water pump pulleys (see thread here: https://www.forums.turbobricks.com/showthread.php?t=323223). Over-tightening a V-belt is just plain BAD. It can also prematurely wear water pump bearings and generally your belts don't last as long as they should. They just wear faster and then they begin slipping again sooner. |
| MORE ON THE BROKEN BOLT ISSUE WILL CONTINUE BELOW. |
| Belt Failure Concerns Some reasons why over-tightening is BAD, in case you're wondering. |
 This was NOT an alternator belt. This was a 240 crank pulley to AC belt. It failed on my 242 after about 300 miles of use because I goofed and adjusted it too tight. The belt didn't actually break, but it did jump off the pulleys after breaking those reinforcing cords. |
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That
long corded string stuff above was the embedded cord in the top-side of the
belt. The cord separated from the belt (or maybe snapped from too
much tension) and then eventually unraveled.
The belt eventually came off the pulleys and I found it sitting in my
belly pan. Most of that corded material ended up wrapped around my AC
pulley. Once that
corded part separated, the belt lost the ability to stay tight. After losing that corded material, the
belt became more like a big, soft, stretchy rubber band.  |
| MECHMAN #2 Updated 2019: I Got a New BIGGER/BETTER Mechman |
| In 2019 I installed a new Mechman #2 for the 242. This one is physically about the same size as the previous Mechman, but it's much "beefier" on the INSIDE. This alternator came with a 170 amp 6 phase HAIRPIN STATOR. According to the literature a bit further below, it's based on a GM Delco CS130D (original to a 1998-2002 GM F-body, i.e.: Camaro). This Mechman part number was B8206170M (PN B8206 with 170 amps).   |
| The alternator Mechman provided for me
was custom prepared by them for a VOLVO. This means they did some MINOR MACHINING to the case so it would easily bolt up in the Volvo red block mounting location similar to a normal Volvo Bosch alternator. And of course it also got a double V-belt pulley instead of that serpentine pulley, since the 240 uses V-belts. More on the custom modifications that were done to create this alternator can be found HERE. |
| UPDATE NOTE about custom Mechman availability: August 2019 In 2019 I learned that Mechman no longer offers CUSTOM FIT alternators to directly fit a Volvo. This customization was done to my alternator. More about this is further down in this page. So are the custom features really necessary? The answer is NO! There are great solutions to make a UNIVERSAL high-output alternator fit your Volvo. I have added info below that will help. CLICK HERE. |
| Before getting this alternator I had no clue what a 6 PHASE HAIRPIN STATOR
was. Now that I know, I'm here to say that if you upgrade to a
high-performance alternator, buy one with a hairpin stator. There's info below that will show you how different a 6 phase hairpin stator looks and performs compared to a normal 3-phase type. |
So, the 6-phase hairpin design looks pretty cool.
. . . but does it actually perform better?
YES IT DOES. Keep reading below.
| WIRING a Mechman I've added some information below on the WIRING for this alternator. Below you can see that this installation included an Adjustable Voltage Boost Module (AVBM). I was talked into buying this with the alternator order, mainly because I questioned whether this alternator could actually support the Voltage I wanted, without HOT voltage drops or simple overload voltage drops. I was coming from the perspective and experience that NOTHING (so far) had been fully successful at providing that. Not even the FIRST MECHMAN. So I was open to trying anything. As it turned out, the AVBM was NOT really necessary, but since I had installed it, I've kept it and used the voltage readout to keep track of voltage. I've never needed to adjust it. I leave it at the lowest setting. It's been useful because the voltage readout reflects accurate voltage taken directly from the alternator, not simply the voltage seen at the dash, like a normal volt meter would show. Anyway, the AVBM has been discontinued by Mechman, so it's NLA.  Eventually, I'll REMOVE THE AVBM and I'll install a simple digital voltage gauge or digital read-out for monitoring voltage. Simple alternator wiring methods are shown below. . Here are a couple ways to connect the Mechman (or any GM style CS130D). You have undoubtedly heard of 1-wire alternators. Forget what you heard. This is NOT a 1-wire alternator. A true 1-wire alternator is considered self-exciting and doesn't require an external circuit source to excite charging. The GM CS130D requires an external source. Note: P-L-F-S pin designations AKA: P-L-I-S.   Resistor. 470 Ohm 1/2 W Carbon Film Single Resistor. https://www.amazon.com/dp/B07QYRRX3L/ref=cm_sw_r_cp_api_glt_i_WWNKYZX7ES9QZMTDZ693 The polarity for a resistor is not important. If you're familiar with the old Bosch alternator, it used the red D+ wire from the dash charge warning lamp to excite charging. The CS130D is not very different. This method above usually works for this type of alternators using this 4-pole plug. With this method above the “L” (Lamp) terminal is connected to switched 12v, with a resistor in-line to reduce current to the regulator. The resistor will offer a similar effect as a warning bulb, except with this method you will not have a dash warning lamp that will illuminate if the alternator fails. Either way, the resistor is important. Many on-line sources say that if you do not use a resistor on this circuit, you may eventually burn up the voltage regulator. The 12 volt switched source needs to be powered when the key is in the "RUN" position. This will activate the alternator when the engine begins running. It must be a switched circuit, because if a constant 12v circuit was connected, it would eventually drain your battery after the engine was shut off.  An alternate method of exciting the alternator is shown above. This method offers two redundant ways to excite the alternator. Plus it offers an opportunity to have a dash warning lamp if you want one. The lamp used is normally a very low wattage incandescent bulb (1 or 2 watts). The bulb will offer a small amount of resistance, which will protect the regulator. The alternator doesn't need very much resistance. Some sources say the minimum trigger is as low as 1/4 watt. The only downside to using a bulb is if it burned out. That would cause your alternator to stop working with any warning. Fortunately, this above method also offers a redundant way to excite, using the 'F' terminal also connected to switched 12v. No resistor should be used with the 'F' terminal wire. More info: https://www.dirtydingo.com/shop/pages.php?CDpath=4&pID=108 Activation of a GM style alternator with a 4-pin plug. Here's a video that demonstrates use of a resistor. https://www.youtube.com/watch?v=a3pp448t0U4 Here's a method designed to bump up voltage output in a GM style alternator with a 4-pin plug. https://www.youtube.com/watch?v=qLX-RBcsNrU He is using the following parts: Resistor connected to the "L" wire: 470 Ohm 1/2 W Carbon Film Single Resistor. https://www.amazon.com/dp/B07QYRRX3L/ref=cm_sw_r_cp_api_glt_i_WWNKYZX7ES9QZMTDZ693 The polarity for a resistor is not important.  Diode connected to the "S" wire: 1N5404 Rectifier Diode 3A 400V. https://www.amazon.com/BOJACK-Rectifier-DO-201AD-Electronic-Silicon/dp/B07NWJ514L/ref=sr_1_6 The polarity for a diode is important. For this installation the silver band needs to be pointing toward the alternator. 4 POLE ALTERNATOR PLUG EXPLANATION This plug connects to the regulator and would be typically found in a 1998-2002 GM F-body (Camaro), 2004-2005 Buick or Pontiac, and 2001-2006 Cadillac. Fits alternator part numbers: Denso 104210-3060, 104210-3070, 104210-3300, 104210-4540; GM 15145637, 25697765, 25697766, 25758348, 25759776, 84009369. Note: The P-L-F-S pin designations below are also sometimes called P-L-I-S.  This connector can be found fully assembled with wire pigtails as PN 110-12046. If you need the connector housing only or the terminals and seals separately, search for: Metri-Pack 4-Way connector, Aptiv (Delphi) PN 12186568. Female terminal 17-20 AWG, Aptiv (Delphi) PN 12048074. Wire Seal Aptiv (Delphi) PN 15324976. Sealing Plug Aptiv (Delphi) PN 12059168.  More info: https://www.dirtydingo.com/shop/pages.php?CDpath=4&pID=108 DELCO VOLTAGE REGULATOR  If the voltage regulator ever needs to be replaced in this CS130D type Delco alternator, I thought I would add that info here, just in case it becomes useful to you (or me) in the future. 12 Volt, B-Circuit, S-F-L Terminals, 15.0 Voltage Set Point, w/ LRC For Denso Alternators. Part Numbers: Denso 126600-0030, 126600-0031, GL10031, 104210-330, 104210-454, Transpo IN6003. |
MORE MECHMAN INFO The Mechman I'm using is this one above, PN B8206170M. The '170' in the PN is the amps. The 'M' is a machined finish. This style alternator is also available in 240 amps and in a BLACK finish, such as the PN B8206240B pictured below.  Note about the alternator POWER OUTPUT lug: In this photo above you can see the output lug may be pointed to the rear or to the side. I'm using one that's pointed to the rear. If requested, Mechman offers the option of either configuration. |
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| HAIRPIN STATORS (Info taken from MECHMAN'S web pages) 6 Phase Advantage  Mechman Elite and S Series alternators employ cutting edge alternator technology not found in other aftermarket alternators. 6 phase hairpin stators make Mechman Elite and S Series alternators fundamentally more efficient than other aftermarket alternators. This new technology and increased efficiency equates to incredible output at extremely low engine RPM, less energy wasted in the form of heat, and more horsepower to the wheels. Also because less heat is being generated, the internal components of Mechman Elite and S Series alternators last longer. This is especially beneficial on turbocharged and/or endurance racing vehicles with high engine compartment temperatures. All Mechman Elite and S Series alternators feature soldered stator and rectifier connections, with epoxy re-enforced stator connections, reducing the chance of vibration failures. High Pole Count  Mechman Elite and S Series units are built exclusively with precision balanced low-mass rotors that allow them to operate safely at shaft speeds of 20,000+ rpm. This high RPM capability, combined with excellent output at idle, gives the user a much broader operating RPM range, and more flexibility in the size of the crankshaft pulley used. A properly selected Mechman Elite and S Series alternator can even fix low voltage problems caused by using small diameter, or "underdriven" pulley ratios. The higher pole count in the rotor also results in less electromagnetic interference to cause problems with radios and other electronics. Twin Rectifiers  As a final precaution, Mechman Elite and S Series alternators are constructed with twin high efficiency cooling fans, and twin internal rectifier plates. While other high performance alternators have only one rectifier with 6 diodes. Mechman Elite and S Series units boast 12 press fit diodes with 300% more surface area to dissipate heat. These considerations to cooling airflow and heat dissipation make Mechman Elite and S Series high performance alternators the most durable aftermarket alternators you can buy. If you are experiencing pre-mature alternator failure, intermittent electrical accessory problems, or low voltage at any engine RPM, a Mechman Elite or S Series alternator is the answer! |
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Here are the dyno specs for this 6 phase alternator, Mechman PN B8206170M. As you can see it puts out 145 amps at idle and 185 amps while cruising.  That sounds impressive but what does that mean in real life?
Impossible you say? I would have doubts too if I didn't see it for myself. So yes, if you can afford it, buy a 6 phase hairpin stator alternator. |
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| And this video shows the fully HOT alternator voltage when getting a full load: https://www.youtube.com/watch?v=T5c_6JGEplo |
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While the above reading may seem deceiving, the actual voltage drop measured at the battery is shown below. |
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| IDLE SPEED I've mentioned in a couple places in this page that I've had to increase my idle speed to improve charging. This was a must when I was using a BOSCH alternator and back then I had to keep idle at 1000 RPM. With a Mechman this can be a subject to pay attention to also, but it's not as big an issue. Every car is not the same. My 1984 240 Turbo factory idle speed is 900 RPM. I run my car at about 950. That's a bit higher than most normal 240s. Most non-turbos recommend 750 ±50 RPM. I know some MECHMAN users are running their idle below 700-800 RPM, but I think that 700 might be pretty much as low as I would go with a Volvo 4 cylinder and with an alternator like this. You'll find there's a certain RPM threshold where charging begins to drops off if you dip too low, so adjust accordingly. |
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INSTALLATION GUIDE
for the IDLER PULLEY BRACKET
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If you have ever experienced a sheered off bolt in the front of the engine block like this below, this section will concentrate on THAT PROBLEM.  A few customers have asked if they could use this idler pulley bracket to replace the adjuster mounting point where that bolt commonly breaks in the engine block. The below photos were sent by Tyler W., who experienced MULTIPLE broken bolts there. So he mounted the idler bracket with spacers for just the purpose of eliminating the need for a bolt in the block.   Tyler originally wanted to try to use the bracket without an idler pulley, because he wasn't using a high-amp alternator. Eliminating the idler pulley may be possible, but Tyler found that the 1130 mm long V-belts he used created some interference between the belts and part of the original bracket under the belt (near that lower bolt). I believe Tyler could have avoided the use of the idler by using a shorter belt, which I think would allow the alternator to tilt upward enough to gain belt clearance. |
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Here's a good selection of 2-groove pulleys, all machined from cold-rolled steel. https://store.alternatorparts.com/2-groove.aspx |
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This is the Super Start Platinum from O'Reilly Auto. The Volvo 240 uses Group Size 34, which uses the above specifications. An AGM battery means it's constructed using Absorbed Glass Mat, which is superior in design to an old school flooded lead acid battery. I picked this battery because it's made by East Penn Manufacturing, who has been known for making the revered Deka battery line. CHARGING VOLTAGE The Mechman alternator I use typically charges between 14.5 and 14.7 volts when things are good and hot and stable. This seems to be OK for this AGM Battery, certainly not excessive. Most high performance AGM battery manufactures will recommend charging between 13.8 and 14.8 volts, while some will recommend up to about 14.6 volts. Keep in mind these recommendations always come with temperature variables, so try not to take them as absolute. For example, you can see how recommended charging voltages will change dramatically depending on temperature in XS Power's AGM guidelines. Most guidelines will agree that charging below 14 volts is getting close to insufficient for a battery like this. |
