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| Oil in the air cleaner--another puking, farting Geo, yet my compression is good; check valve, maybe? | |
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| Tweet Topic Started: Aug 13 2013, 07:02 PM (2,237 Views) | |
| bbowens | Aug 13 2013, 07:02 PM Post #1 |
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Hi gang, I know that this topic has been discussed to death, but my compression is good (210), yet I get a lot of oil up there in the air cleaner, occasionally a fart if I push it, but also pretty stinky around the air cleaner--enough to give me a headache sometimes if I have to sit a stoplights a lot. Anyway, I've been reading up on this, and I'm wondering if maybe this engine doesn't have that check valve in the top of the block? I can tell that the head and block are not matched, and neither is original to the car, but I haven't had the head off. I did put on the updated valve cover, pcv valve is new, and hose is clear. So, the question is--any way to check for the presence of this valve without removing the head? PS--I've done the compression test three times; the first time, my mechanic didn't do it the "Geo Way," and got 155; the second time, I did it with a Harbor Freight gauge and got 190; the third time, I took it back to same mechanic as the first time, instructed him on the "Geo Way," and he got 210 across all three cyl's (he's a certified BMW mechanic using Snap-on gear). |
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| Old Man | Aug 13 2013, 08:09 PM Post #2 |
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good compression indicated that the compression rings are good. It says nothing about the oil rings. You can have good compression rings and bad oil rings which can produce blowby.......... |
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| bbowens | Aug 13 2013, 08:51 PM Post #3 |
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is that very common? if I were to change just the oil rings only, would I need to de-glaze the cylinders like for the compression rings? |
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| cwatkin | Aug 13 2013, 09:06 PM Post #4 |
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The oil rings can get dirty and stuck from using cheap oil or not changing it enough. You might try some good synthetic oil with like 8 ounces of Marvel Mystery Oil mixed in. I recently helped a neighbor with a new one they got that runs well but had some pretty good lifter noise, especially at startup. The engine now pretty much sounds like any other decent G10 out there. On the other hand, I had an engine that was puking and farting BAD! Much worse than anything you describe and 1 quart per 100 miles oil burning or worse! I tried this and other treatments on this one and nothing helped. My compression was marginal on this one (150-160 psi). You probably have better odds. Conor |
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| Old Man | Aug 13 2013, 10:43 PM Post #5 |
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I should have said bad OR STUCK oil rings----before you go crazy throwing parts at it try some Marvel Mystery oil. --- 8 oz in an oil change and top it off with MMO each gas tank full for at least 3 tanks. In those 3 tanks also put 8 oz of MMO in the gas tank. maybe your rings are stuck and this will unstick them |
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| cwatkin | Aug 13 2013, 11:25 PM Post #6 |
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I also recently saw a post about someone swapping valve covers from a newer model to the older ones. The 1991's come with the older more "square" style valve covers. The newer ones have the lines in the top and are supposed to have a better baffle for separating the oil from the air. I have seen plenty of the older style valve covers never cause an issue so I suspect something else is up. Could you have a bad PCV valve? If so, definitely clean or replace it. Make sure the hose isn't filled with goo. What kind of oil do you run? Conor |
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| bbowens | Aug 14 2013, 05:10 PM Post #7 |
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I'll give it a shot, but when I had the pan off, things were looking pretty clean. I've only put 1,000 miles on this engine; don't have much history on it before that, although plenty of signs of neglect and poor mechanicship.
Edited by bbowens, Aug 15 2013, 12:09 AM.
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| bbowens | Aug 14 2013, 05:12 PM Post #8 |
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I do have the newer valve cover installed, new pcv valve, and cleaned out hose. I use regular oil, currently 10w-30, which I'm about to replace with 5w-30 Edited by bbowens, Aug 15 2013, 12:07 AM.
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| v8440 | Aug 14 2013, 07:39 PM Post #9 |
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Advanced Member
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I second the marvel mystery oil. Another trick you could try is to drain about 1/4 of the oil and replace it with diesel fuel. Then, IDLE the engine for about 5 minutes or so. Change oil an filter. That'll clean just about anything out that hasn't been totally baked on. |
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| Cobrajet25 | Aug 16 2013, 05:43 AM Post #10 |
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You seeing a lot of blow-by with the oil cap removed and the engine running? Maybe a plugged oil return hole in the head?
Edited by Cobrajet25, Aug 16 2013, 05:46 AM.
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| geostang | Aug 17 2013, 09:43 PM Post #11 |
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If the oil ring is causing blow by aren't the plugs going to indicate oil burning and be fouled and not clean ? ? |
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| clarkdw | Aug 18 2013, 12:46 AM Post #12 |
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Plugs may have no oil on them . The blowby gases, if there are any, are going the other way from the cylinder to the crankcase. The oil farts are caused by either blowby or excess oil in the top end. If your compression is as good as you say I am very strongly voting for a missing oil check/restrictor valve putting too much oil up top. If you want proof do a leakdown test. You're going to find very little % leakage to the crankcase with 200+psi compression. If your oil rings were bad/stuck you would be burning oil but not necessarily blowing it out the PCV system. That requires blowby pressure in the crankcase and as I said with the very high compression you have that is very, very unlikely. Unfortunately the proof of the check being there, or not there, is going to cost a new head gasket and bolts if you didn't use reusable ones but the up side of that is it will be a relatively easy fix. Edited by clarkdw, Aug 18 2013, 12:47 AM.
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| Johnny Mullet | Aug 18 2013, 08:32 AM Post #13 |
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Fear the Mullet
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Coyote X has a 91 that had this problem and compression was good. When he came to GeoPalooza the engine started knocking. We tore it down and found this..........![]() All fixed now and no oil farts. |
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| bbowens | Aug 19 2013, 07:51 PM Post #14 |
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you found a piston laying on his radiator support?
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| Mythstae | Aug 19 2013, 08:01 PM Post #15 |
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What is going on in the left of your picture? Looks... scraped... |
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