Last week, I wrote about replacing the Bavaria’s hood brackets to get the hood to stay up without a broomstick, and increasing the main jet size from 135 to 145 to lessen the buffetting at low to mid RPMs. This week I thought I’d pull the belts off so I could thoroughly inspect them. This would also allow me to spin the engine accessories by hand and listen to them individually with a mechanic’s stethoscope to see if any of them were the source of an annoying chirp I was hearing. I wound up going down the slippery slope of tackling the water pump and fan.
BMW’s legendary M30 “Big Six” engine had a longer life than any other BMW motor; it was used in cars from 1968 through 1995. During that span, it had three different water pump/clutch/fan arrangements. The earliest one had a water pump with a flat nose, an antique fan clutch that bolted to it, and a 2002-style fan and front plate that bolted to that. That was followed by the “nose”-style arrangement that had a piece that bolted to the front of the water pump, and a conventional viscous fan clutch and fan that bolted to the nose piece with a single bolt. With the E28 and E30-era cars came the modern arrangement with a fan and clutch that had a spin-on nut that threaded directly onto the front of the water pump. I was familiar with all of these because my 3.0CSi originally had the earliest one, the Bavaria had the middle one, and everything from the FrankenThirty to the newer cars has the later one. In addition, my Euro 635CSi had the middle one until the fan cracked multiple blades coming home from The Vintage in 2019 and needed to be replaced with the later configuration because no old-style parts could be procured quickly. Upgrading to the new configuration also requires changing the water pump pulley because the hole spacing isn’t the same as it is on the old pulley.
When I bought the Bavaria in 2014 and immediately road-tripped it to what was then called still Vintage at the Vineyard, I didn’t find anything crucially wrong with the crucially wrong with the cooling system, so I bought a new Graf water pump to have as a spare and put it in the trunk. The trip was successful, but the engine ran hotter than I liked due to an old radiator, and the car’s a/c wasn’t working, so when I got back, I resurrected the a/c with a modern Sanden-type compressor and parallel-flow condenser, and installed a triple-core radiator. The spare unused old-style water pump was still in the trunk. Now that I was looking at selling the car to two friends who are flying up on July 9th from Birmingham, Alabama, to drive it home in the summer heat, I wanted to be certain they had no cooling system issues. So I wondered if I should just upgrade everything to the new-style water pump and spin-on-fan-clutch configuration. I figured I’d start by looking at the car and see what condition it was in, beginning with the belts. I slackened the alternator, allowing me to slip the belt off, twist it around, and examine it. On the underside I saw cracks and dry-rot.
As I began doing what was necessary to replace the fan belt, I was surprised by several things. The first was that I’d completely forgotten how archaic the belt arrangement is on the Bavaria. Even the fan-belt-tensioning adjustment bolt on the alternator’s sliding track is a pain, quite difficult to reach from either topside or from beneath the car. And the power steering pump doesn’t run off the crank pulley—it runs off the water pump pulley, which has an additional groove to the one that runs the alternator. In addition, the power steering belt is the outer-most belt, so it must come off to remove the fan belt. I did remember that the a/c compressor belt is also on the outside, so it too must be removed. But I was stunned to find that, with the triple-core radiator, the bolt attaching fan/clutch to the nose piece was so close to the radiator that there wasn’t enough room for even the skinny power steering pump belt to pass between them.
Sorry for the out-of-focus photo. The arrows point to the belt and the bolt holding the fan and clutch to the nose piece.
So to replace the belts, the radiator needed to come out.
I didn’t seem to have much choice, so out it came. It’s bigger and heavier than a 2002 radiator, and more difficult for me to handle these days with my fragile back, but I got it out. Off came all three belts. In addition to the cracked fan belt, the power steering belt looked ancient and hard. I went upstairs to the laptop, dug into E9coupe.com, found the original belt lengths, found the belts on a combination of FCPEuro and eBay, and put all three on order.
With the belts off, I spun the accessories. The goal was to see if the water pump, alternator, or power steering pump were the source of the chirp I was hearing (they weren’t), but in doing so, I immediately saw a new issue—the fan was wobbling by a non-trivial amount. You can see it in this video. The two-groove pulley on the water pump itself was also wobbling slightly.
I undid the bolt holding the fan/clutch to the water pump and pulled it off, exposing the nose piece on the front of the pump. I then removed that and spun the water pump to verify that its front flange was flat and wasn’t the source of the wobble (it wasn’t). The water pump bearings felt a little dry and scratchy, but there was no play or rumble. I had little doubt the car could safely make the trip to Birmingham without replacing the pump. Still, with the radiator out and the pump exposed, even in this age where one needs to be careful about replacing functional old parts with new ones that may well be of lesser quality and may not last as long, replacing it seemed like a slam-dunk.
The question was whether I should simply install the replacement old-style water pump that had been in the trunk for a decade, or update the whole system with a new-style pump and spin-on clutch that didn’t require the freaking radiator to be removed in order to replace the belts. Since the fan also needed to be replaced due to its wobble, upgrading the system seemed to be the obvious choice.
With the fan off, you can see the water pump’s archaic nose piece.
As I said, I’d done this upgrade twice before—decades ago when I installed the M30B32 533i engine into my E9, and in 2019 when the fan on my 635CSi exploded. I knew I needed the new-style water pump with the threads on the flange, its matching spin-on clutch and fan, and a new water pump pulley. I also recalled that there was some issue of which pulley—that the trick was to buy a smaller one that caused the water pump to spin faster. I went on E9coupe.com and looked at posts. I also saw that the guy on E9coupe who knows the most about this was now recommending a special Euro-only thin-profile fan.
And then I realized that I had a big problem—the Bavaria’s power steering pump was still being run off the two-groove water pump pulley, and this was incompatible with the new spin-on water pump configuration, as that configuration required a single-groove pulley with a different hole spacing.
How had I never had to deal with this before? I had a dim memory of, when I dropped the M30B32 engine from the 533i into the E9, needing to do some level of mixing and matching of engine accessories, but I couldn’t recall exactly what I did with the power steering pump. Since I had the E9 in the garage right next to the Bavaria, I opened up the hood and had a look. Yup, three belts running off the crank. I assume that, on the 635CSi, the PS pump was already running off the crankshaft pulley, making its water pump upgrade easier.
From outer to inner: compressor belt, power steering pump, fan belt.
I looked on E9coupe, and the answer was a bit more nuanced—that what you need isn’t a three-groove pulley, but a harmonic balancer with a pulley groove integrated into it, and bolt the two-groove pulley bolted onto that. Further, this post on E9coupe said that you needed to use the later power steering pump mounting brackets that had a dogleg in them to move the PS pump further out so it aligns with the outer groove in the pulley. This was also apparently what I’d done on my E9 decades ago and had no recollection of.
Faced with finding and ordering all of these parts and installing them in a less-than-two-week timeframe for when the buyers are flying up to drive the car home to Alabama (what if the parts don’t arrive in time? what if they don’t fit? what if there are fan-to-radiator clearance issues?), I made a decision: No. Although it seemed like “it would never be easier than now” to do the water pump/fan/clutch upgrade, it wasn’t at all “easy” now. Plus, the car had been running and cooling perfectly well for eleven years with the old configuration in it. I decided to install the old-style water pump I already had, stop the fan from wobbling by replacing it, and if possible, find a two-groove pulley without the slight wobble that mine had. This would give me ample time to drive the car around and be certain there were no issues.
The old water pump came out without a fight. I was surprised to find that there was no sealant on the back side of the gasket. It’s a wonder that it wasn’t leaking. I was also surprised that it had zero corrosion on its metal impeller. This pump can be used as a spare. It did, however, have a “95” date code, so it was a 30-year-old water pump, and replacement was the responsible thing to do.
Thank you for your service.
The new eleven-year-old Graf pump finally moves from the trunk into the engine compartment. You can see the that the Bavaria apparently already has a harmonic balancer with a pulley groove in it, and a crank pulley with one groove, so what I’d need to do the upgrade is a two-groove crank pulley. As I said, nuanced.
For the second issue (the bent fan), I undid the four 10mm fasteners connecting the fan and clutch, and to my surprise, a hail of washers fell onto my workbench. What the? It turned out that whoever installed the fan and clutch was concerned enough about fan-to-radiator clearance that they backspaced the fan a quarter inch. I first tried to straighten the bend in the fan plate. Then, wondering if maybe uneven height of the four washer stacks was contributing to the wobble, I went to my local Ace Hardware store and bought four 1/4-inch metal spacers. I test-fit the reconfigured fan and clutch and spun it, and the wobble was better, but not gone. It was silly to nickel-and-dime this problem any further, so for $30 I ordered a new fan from FCPEuro, and am waiting for it to arrive.
For the slightly-bent water pump pulley, I looked online, and could not find anything that was click-and-buy. Then I had a light-bulb moment: My numbers-matching boat anchor of an original engine from my E9 probably had this pulley on it, and was sitting under a tarp at the end of my driveway. I pulled off the tarp and spun the fan.
I’m sure the 3.0CSi’s numbers-matching boat anchor I mean engine was surprised to be awoken from its slumber.
One of the few photos you’ll ever find of the original-style fan clutch.
The pulley looked straight, so I yanked it off and wire-brushed it. I test-fit it onto the water pump and stretched the PS belt to it, and it wasn’t even close to fitting. I then held it next to the original pulley, and could see that they were different, with the power steering groove on the Bavaria pulley being substantially smaller than the one from my 3,0CSi. Why? Don’t know.
3.0CSi pulley left, and Bavaria pulley right. No spare pulley for you.
So. In the time frame I have, the Bavaria is getting a new-old-stock original-style water pump, a new mid-configuration fan with spacers to keep it back-spaced from the radiator, and new belts. I feel like I’m doing the responsible thing.
The new fan is scheduled to arrive today. I planned to submit this article once I’d buttoned the system up, but I just discovered that the new Continental 1075mm fan belt I’d ordered is cracked and dry-rotted nearly as bad as the one I took off. 1075 is not a commonly-used size anymore (FCP doesn’t appear to carry them), so you’re at the mercy of either off-brand belts, or finding Continental belts on eBay that might be dried-out old stock. D’oh! I put another one on order from a different eBay vendor. We’ll see if it’s any better.
This is why I have trust issues.
Everyone, please, remember this article, so when the buyers have to deal with a broken belt at some point and ask “Why the hell didn’t Rob just upgrade the water pump when he had the radiator out so we don’t have to remove it again now,” they understand.
—Rob Siegel
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Rob’s newest book, The Best of The Hack Mechanic, is available here on Amazon, as are his seven other books. Signed copies can be ordered directly from Rob here.
Tags: finding parts water pump
