I have noticed a small amount of foam on the oil dip stick. In addition, I have been getting a Check Engine Light (4-3-6, Fuel Mixture Lean). The engine tends to miss slightly at highways speeds and I don't have smooth acceleration. I took it to a local shop and they suggest to replace the oxygen sensor and mass-air sensor. I'd really hate to drop $500 on these parts just to find out that ain't it and I need to drop another $1500 for a head gasket.

I plan on getting the exhaust checked for coolant and I'm going to do a compression test. Anybody have compression numbers for what I should be expecting? Also, it there any other way of getting foaming oil other than a head gasket problem?

Thanks,

Phil
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'86 740T Sedan 235k (RIP), '96 850T Wagon 80k (sold), '95 850T Wagon 103k (current)

We'll I checked the oil dipstick after driving home tonight and there was no foam, but she still had poor acceleration and was kinda missing at highway speeds. I was thinking about repolacing the front O2 sensor and tried to get the old on off. Question. How the #GF#) is someone supposed to disconnect that connector if they have astandard size human hand? Do you need to remove the input conduit to the turbo?

Anyhow, needless to say I didn;t replace the O2 sensor. However, I did locate a piece of crappy tubing joining some vacuum lines which looked more like a Home Depot Special than a vacuum line. I replaced the hose witha "real" vacuum fitting and drove her for about 15 miles. It seemed like she ran a lot smoother, better acceleration an no missing. Then again, that's what happaned after I replaced the plugs the first time the CEL came on, and it reverted back after a day or so, to poor drivability.

Anyhow, any suggestions on front O2 replacement would be greatly appreciated.

Phil
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'86 740T Sedan 235k (RIP), '96 850T Wagon 80k (sold), '95 850T Wagon 103k (current)

Driving Style:

I drive the car daily ~13 miles each way to work and back. Nothing more.

I have noticed that the foam is not consistent. Somtimes, the stick is 50% full, but like last night, there was almost nothing. The oil was changed about 200 miles ago and I still get small amount of foam on occasion.

Compression numbers are: 160, 135, 150, 130, 160

The antifreeze was changed last winter and it is still perfectly green. I have a hairline crack in the radiator which only leaks during winter when it gets below ~20°. As a result, I have an aversion to fixing it. It leaks about 5 drops a night if the temp drops below 20°. But until this last week, it hasn't been cold enough to leak and the level is for all intents an purposes fixed.

I was planning on taking the car to a shop and have them check the exhaust for coolant. They can do thay right?

I just bought a front O2 sensor, the original has 125k miles on it, but I was afraid to replace it in case the coolant could cause it damage.

Klaus, I did clean th MAF sensor connection and put di-electric grease on it. Didn't help unfortunately, still getting code 4-3-6. I also got 4-1-4 once.

I'll keep you all appraised of the situation as it manifests itself.

Phil

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'86 740T Sedan 235k (RIP), '96 850T Wagon 80k (sold), '95 850T Wagon 103k (current)

Time for an oil change. In your damp, cold climate, you aren't getting the engine hot enough to burn off the condensed water. I would not worry too much.

You should try cleaning the electrical connection to the mass air sensor befor replacing it. An O2 sensor usually causes a rich condition when it fails.

Klaus
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1975 164 w/174,800mi (Sold) 1995 850T w/91,000mi, 1998 V70R w/129,000mi

Foaming in the oil could be from short trips and the engine not getting hot.

Compression numbers can be anywhere from 120 - 190...what you are really looking for is any one cylinder being 20% above or below the highest or lowest reading you get.

If you had a head gasket leak, you should be missing at lower speeds more likely. Are you losing coolant slowly? are your temps running higher than normal? Either one or both could indicate if you have a head gasket leak.

What kind of driving do you do?

It is not unusual to see a bit of foamy deposit on the dipstick if you do a lot of short haul trips during cold weather. That means that the engine isn't getting hot long enough to drive off the moisture.

I recommend sending an oil sample to a lab and finding out if you have antifreeze getting into the oil. A shop can also check quickly to find out if there are hydrocarbonds getting into the coolant.