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Old 01-11-2017, 10:57 AM   #1
Dave_G
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Oil pressure too high?

The other day I started up my '91 iX and without warning blew most of the volume of the engine oil out in a big puddle under the car. A post-mortem revealed that the gasket on the oil filter had pushed out, allowing most of the oil to gush out.

It was a good-quality Wix filter, and I had oiled the filter gasket before putting it on, the same as I always do in the decades worth of oil changes that I've done. It had already gone about 2000 miles since the last oil change.

I'm wondering if I'm facing a problem with oil pressure too high. (Unfortunately we don't get oil pressure gauges in our E30s, just idiot lights. ) It was a reasonably cold day when this happened (10˚F/-12˚C), and I've read some reports that the oil pressure relief valve could fail, and if it does, it's more likely to happen when it's cold.

I've changed the oil and replaced the filter, and the car is running fine for now, but we've got lots of cold winter days left this year and I'm concerned that it's just going to happen again unless I can find the underlying cause.

Does the M20 have a oil pressure relief valve? Where is it? Is it part 7 in this diagram? http://www.realoem.com/bmw/enUS/show...diagId=11_4329
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Old 01-11-2017, 11:22 AM   #2
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I drilled a hole through the long hollow bolt that holds in the oil filter housing and cooler.

#6
http://www.realoem.com/bmw/enUS/show...diagId=11_4329

And put an oil pressure gauge there.
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Old 01-11-2017, 12:11 PM   #3
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Yeah, it's a common M10 problem, but the M20 has the same plunger- style relief.

For me, usually, it'd happen when I r3vved it too much stone cold- like, 4k or higher.

I DID also find, once that the Wix gaskets weren't seated all the way into the channel.
You had to REALLY shove, but then it'd go down another 1/8" or so...

I agree= start with the gauge, and see... I just replaced the idiot light sender with a mechanical gauge.

t
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Old 01-11-2017, 12:51 PM   #4
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I drilled a hole through the long hollow bolt....
You clever bugger !!!

How's the gauge holding up that close to the exhaust manifold ? Or did you remote it ?
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Old 01-11-2017, 01:28 PM   #5
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It's fine. I put an 90 degree elbow into the hole and the sender runs forward so it's not very close to the exhaust at all.

I'd get an electrical gauge though. I wasn't fond of the idea of piping hot high pressure oil into my cabin.
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Old 01-11-2017, 01:47 PM   #6
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I'm probably going to put in an (electrical) oil-pressure gauge just so I can see exactly what's going on.

But, assuming it confirms my suspicion of excessive oil pressure that blew out my oil filter on a cold day, what are the likely causes of that? Stuck relief valve? Clogged oil passages? Something else?
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Old 01-11-2017, 02:12 PM   #7
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firstly i would use an OEM oil filter.

what oil are you using? ultimately it shouldnt matter in normal conditions because the pressure should never go above the relief pressure which is approx 70psi (or is it 60 i dont remember) but if it gets stuck then the pressure will spike depending on the oil viscosity basically.
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Old 01-11-2017, 02:23 PM   #8
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I agree with digger. I only use Mann or Bosch. As far as the pressure relief, it should be about 60psi as that's all I ever seen with a stock setup and mechanical gauge.

If you didn't have the filter tightened proper, it may have just pushed out. One of the local Spec e30 racers blocked his relief completely and I saw 70+psi in his car on the dyno and it didn't blow out the oil filter seal. Don't remember what his was starting cold (well, cold for FL lol), but with the bypass delete, he would see whatever the pump was capable of.
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Old 01-11-2017, 07:07 PM   #9
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Galling of the steel relief plunger on the aluminum bore does it.

M10s with stuck reliefs typically see 150+ stone cold, but hot tend to
stay below 80 no matter how stuck they are.

t
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Old 01-12-2017, 04:15 AM   #10
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What weight oil do you use in the Vermont winters for the M20?
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Old 01-12-2017, 05:46 AM   #11
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This was with Castrol 10W-40, which is mostly what I use.

I suppose it's possible that the oil filter wasn't seated properly, though I doubt it because I didn't do anything different from what I've done hundreds of other times, i.e. oil the gasket and hand-tighten it 3/4 of a turn after the gasket touches the mount. Also, it had already gone 2000 miles before blowing.

I have a question about the pressure relief valve, though: where is it? People have been talking about the little $10 gasket thing in the oil filter mount, but I've also seen something that sits inside the oil pan, which makes more sense -- i.e. it makes more sense to dump oil into the pan than into the engine bay and onto the ground. Unfortunately, if it is inside the oil pan, that's going to mean major work. This is an iX, so separate the ball joints, pull both front axles, and lower the front subframe before even getting to the oil pan.
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Old 01-12-2017, 05:49 AM   #12
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Quote:
Originally Posted by tim88325is View Post
What weight oil do you use in the Vermont winters for the M20?
Rotella 5W40 works well in the winter. Keep in mind that this is synthetic oil and, if your engine has never seen synthetic, it might develop some leaks when switching over.
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Old 01-12-2017, 08:58 AM   #13
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The one time I experienced this the old filter left it's gasket on the car. With the double gasket the filter didn't seat properly and spewed oil everywhere.

Pic of the oil pressure gauge sender. Disregard cut AC line, blown headgasket oil drip, etc..
http://imgur.com/yt108R2.jpg
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Old 01-12-2017, 09:05 AM   #14
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Originally Posted by Kershaw View Post
The one time I experienced this the old filter left it's gasket on the car. With the double gasket the filter didn't seat properly and spewed oil everywhere.
I saw that happen once to a friend of mine, who always used Fram filters. Ever since then, I always check the filter mount to be sure it's clean and free of old gaskets. And I never use Fram filters.

I'm positive that's not what happened here.
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Old 01-12-2017, 10:49 AM   #15
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Quote:
Originally Posted by Kershaw View Post
Pic of the oil pressure gauge sender. Disregard cut AC line, blown headgasket oil drip, etc..
http://imgur.com/yt108R2.jpg
I have a stack of new bolts waiting for this very modification. One of the many, many, side projects I have laying around the shop
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