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M60 Oil Pump bolt experience

I had previously read multiple accounts of people finding that the 3 fasteners that mount the oil pump (1 bolt and 2 nuts actually) have a habit of coming loose on the M60 engines. M60s are the V8 engines found in some of the mid 90's 5 and 7 series cars.

I knew that my 1994 540i has had the nikasil short block replaced with Alusil (based on the block part number). I therefore sort of expected that these oil pump fasteners would have been retorqued and lock-tited during reassembly and therefore would be OK on mine. But I also figured it was easy enough to drop the lower oil pan and take a gander at the next oil change just to be safe. That next oil change was last weekend...

Well, I'm very glad that I did check because the bolt was lying in the bottom of the pan and both of the nuts were considerably looser than the torque spec. I reinstalled the bolt and snugged everything down to spec using red loctite, so hopefully it won't come loose later.

A couple of things I found during this job:

One is that the drive chain to the pump was a bit loose. The spec is

10mm of slack and I measured 15mm. The adjustment is supposed to be the hex things between the pump and the block, but I could not budge them with an open end wrench but did not want to go crazy with cranking on them. Has anyone here ever done this adjustment? Maybe I should just not take chances and put a new chain on there since it has stretched so much.

The second thing was that the steel oil pan had been significantly deformed at each of the bolt holes. It seems that somebody cranked the bolts down (ostensibly to eliminate an oil leak?) and the old style cork gasket caused the pan to be bent up at each bolt. I was able to bend the pan back into shape pretty well by supporting the pan with 2x4 blocks and hammering/punching the dents down with a 1/2" x 1/2" x 6" block of pine. This was required due to the redesign of the gasket. It is now a steel plate with a neoprene lip on the inside edge. In the deformed condition the pan would not have even hit the lip and would have leaked like a sieve. Good thing too because a new pan looks like it runs a couple hundred bucks.

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-Fred W

Reply to
Fred W
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You have more faith in a dealer than me. ;-)

Reply to
Dave Plowman (News)

well, not any more...

Reply to
Fred W

My best one was having the cam sensor replaced under warranty. Later work (by me) showed they'd punched off the fan clutch by the damage to the nut, and had replaced the pop up rivets on the fan shroud with cable ties.

Reply to
Dave Plowman (News)

Luckily for you, you were unable to get that hex thing loose, because it's called a main cap bolt and loosening it could contribute to crankshaft failure.

The adjustment for the oil pump is actually done with an 8mm Allen key, through the hole that the forward bolt goes in. The adjustment is in the oil pump, against the head of that crank bolt, not the crank bolt itself.

This is very standard and was likely not just a case of someone trying to stop a leak. When we were doing the Nikasil block replacements back in the mid 90s, most pans would come off deformed, even on cars with less than 30K miles and no record of a leak. I think it was a case of overtightening at the production facility. We did the same thing as you, used a mandrel and hammer to straighten the lip.

Brett Anderson KMS

Reply to
KMS-Brett Anderson

Yeah, as I was working on it it just didn't look right to me, so I didn't really try very hard to loosen it. The procedure I was looking at in the Bentley manual showed their being an adjustment in only one corner, yet each of the corners of the oil pump had the hex thing.

Thanks. This was certainly not clear that this was the case either from the Bentley or the parts breakdown s that I looked at. I'll try to make the adjustment next oil change.

Reply to
Fred W

Brett,

OK I see the adjustment now. It's item #6 in the parts drawing (link below), right? I sure wish it had been spelled out so clearly in the Bentley or any of the other on-line references that I was looking at. I wonder if the adjusment moved (hence the chain's slackness) when the bolt loosened and dropped out, rather than the chain actually stretching.

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One further question for you: Mine did not have the plastic chain gaurd and there were no signs of remains of one in the pan. Am I correct that my '94 (manuf 9/93) did not come with that part. The parts breakdown seems to infer that.

TIA for your expertise,

Reply to
Fred W

Thanks for the verry acurate information! I have a 1994 530i m60 with 330,000 kilometers and my oil pressure has fallen to 4 psi at idle when warm running but cold it 10 psi, so I,m not going to chance it and I have ordered new pump. Your infowill help thank you. snipped-for-privacy@remaxcrown.ca

Fred W wrote:

Reply to
john via CarKB.com

Hi Fred.

Many of the early cars came with the chain guard and BMW had us remove them due to the risk of, of all things, an oil pump bolt falling out and getting caught by the gaurd, jamming the chain and exploding the motor.

So the short answer is that if your car came with one, a dealer removed it many years ago.

Brett Anderson KMS

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Reply to
KMS-Brett Anderson

Thanks again, Brett.

I'm wondering, have you ever heard the oil pump chains make any noise if they are loose?

The reason I ask is that mine is making a randomly intermittent "clicking" noise that seems to be coming from the lower front of the engine at idle and just above. The clicking happens sporadically but will usually reoccur within 10-15 seconds. It seems to increase in frequency when I rev the engine just above idle.

I'm not driving the car at all until I can get back in and adjust the chain tension with the hope that this will remedy that situation. Otherwise, I suppose one of the drive belt pulleys or driven accessories might have a bearing on the way out. I will have to remove the belts and see if the noise goes away (engine only run briefly)

Reply to
Fred W

Never mind Brett, I found the source of my noise. It turned out to be one of the two idler pulleys for the serpentine drive belt. The bearing was dry and was making the noise. I was able to pull off the seals, clean up the bearings (did the other idler pulley while I was at it) and and regrease them (and refit the original seals).

I don't know how long they would last like this, but I'll be ordering up some new ones and swapping them out preventively. Tossing a belt on the freeway is a bad deal...

Thanks again for your help with the oil pump chain adjuster.

Reply to
Fred W

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