Paging Sfdon -- Still Have Questions on Pulley Size

thehackmechanic

thehackmechanic

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Pursuant to this thread (http://www.e9coupe.com/forum/showthread.php?t=10468), I have a M30B32 engine with a flat-faced water pump, the nose extension, a single pulley, and the 9-bladed fan. I'm upgrading the radiator and thought I'd update the pump, pulley, and fan to the newer style. Sfdon recommended, as part of this upgrade, replacing the original 124mm crankshaft pulley with the 142mm pulley to clock everything faster.

I was about to remove the pulleys and belts in preparation to order and install new parts, but when I look at it, what I see is the water pump being driven not off the replaceable part of the crankshaft pulley, but off the grove that's part of the harmonic balancer. I can see that changing the crankshaft pulley will clock the power steering pump and a/c compressor faster, but it won't have any effect on the water pump.

Is there something I'm missing?

Also, you recommend "Use the Napa fan clutch [rebuilt] with the old style spring rather than the poly-metallic strip. Cheap and they work great." Is there some source for these? All I can find is the new NAPA TEM 271366 clutch at $125 a pop (yikes!).
 
Do you have the original balancer (the grey disk) or do you have a later balancer, such as the kind used on M1.3 setups?
 
Harmonic Balancer

I have what came on the M30B32 engine, which was out of a 533i. There is a grooved pulley integrated with the balancer that runs the water pump and the alternator. There is a bolt-on two-groove pulley that runs the power steering pump and the a/c compressor. I haven't measured it, but it looks like it's the same setup that's on my '85 635CSi. That is, the harmonic balancer/pulley look the same. The 635 obviously has the later-style water pump and pulley with the asymmetric bolt holes, and the spin-on fan clutch.
 
M5 Pulley

I have the early M5 pulley mounted on the water pump and use the standard harmonic balancer. This speeds up the water pump and fan while leaving other items changed.
I am sure you could figure out the part numbers from realoem or just call Metric Mechanic. The recommended and supplied mine.
 
The first two pics are from the M30B35 engine on my '85 635CSi, but the harmonic balancer and crankshaft pulley arrangement on my E9 look the same. The water pump and alternator are driven off the innermost groove which looks to me like it is on the harmonic balancer, not on the pulley. The power steering pump and compressor are driven off the pulley. The last two pics are from the M30B32 engine in my E9. It looks the same. From here, you can see unequivocally that the two-groove pulley is bolted onto the harmonic balancer, which has a pulley groove for the water pump and alternator belt.

All the diagrams in Realoem also show the harmonic balancer as having a pulley groove, and the bolt-on pulley as having two grooves.

So my question: How can changing the crankshaft pulley make a difference when the water pump is driven not off the crankshaft pulley but off the harmonic balancer? What am I missing?
 

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Hello- Am in LA using a iphone for a computer.
Unless your engine was swapped- your e28 has a
B34. Iwill get to a computer tonight and get you more
Info.

Don
 
1 55 0401

1 152 172 391 8


Fan clutch from napa

I will post pics latter
 
Clarification

Thanks Don. To clarify,

--The engine in my E9 came out of an '84 533i. The block says "3.0/3.3" so I believe it's a M30B32.

--You're correct that I misidentified the engine in my '85 635CSi. I believe you're correct that it's a M30B34, not a B35 as I said.

But this doesn't change my pulley question... :^)
 
I can see that changing the crankshaft pulley will clock the power steering pump and a/c compressor faster, but it won't have any effect on the water pump.
Click to expand...

That makes sense. But why would you want to increase the speed of any of these? With the larger fan/clutch and upgraded radiator, cooling is not an issue.

Attached is photo of what I think the configuration you described is. Originally the 72 CS had the PS pump driven off the second (outer water pump pulley). The only "upgrade" I have heard about is changing the PS to be driven off the crank pulley. Could this be the pulley upgrade he is referring to? I am not sure if it just happens to be a larger diameter (It didn't seem larger from my memory).
 

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Yes, that is what my current E9 belt and pulley setup looks like (right down to the nose piece on the flat-faced water pump), except I don't have the toothed harmonic balancer.
 
New water pump pulley is smaller -- need different fan belt

Just to follow up on this for those who come after me, the parts for the cooling system upgrade (new Mark Preisendorf radiator, new water pump, used water pump pulley with asymmetrical holes, 11-blade 410mm fan, spin-on Napa fan clutch, thermostat) all arrived, and I began to put things together. When I started assembling the belts, though, I found that the 13x1060 belt that the car had used for the alternator and water pump would no longer fit -- there was so much slack that the alternator hit the end of the adjustment track. When I compared the new (well, used) water pump pulley with the asymmetrical bolt holes to the original one with the symmetric bolt holes, the new one was slightly smaller. I had a 13x1055 belt lying around, and that fit, but the alternator was literally at the end of the track with no further room for adjustment for the belt stretching, so I still needed a slightly smaller belt. Turns out Bavauto has a closeout on 13x1050 belts for three bucks. I snagged two of them.

As per the earlier part of this thread, I never changed the pulley on the crankshaft to the larger one to make the water pump spin faster, because that belt doesn't run on the removable pulley; it runs on the pulley that's integral with the harmonic balancer. But as I think about the fact that the new water pump pulley is slightly smaller than the old one, it should serve the same purpose. It should make the water pump spin faster. On a 10-speed bike, a larger chainwheel (the gears at the pedals) gives you a higher gear; shift from 5th to 10th and, for the same RPM, you go faster. That's analogous to putting a larger pulley on the crankshaft. But similarly, selecting a smaller gear at the rear wheel has the same effect; shift from 9th to 10th and, for the same RPM, you go faster. That's analogous to using a smaller pulley at the water pump.

So by luck, I stumbled into the same effect.
 
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