Grandma's '92 745 w/ 150k. I had been experiencing high crankcase pressure last year and wrote here about finding a clogged air box and then having the replacement blow apart. At that time, I did the dancing oil cap and tried to access if I had excessive pressure in the crankcase. It seemed better after the second air box and drilled out flame trap. Fast forward 1 year of not driving the car much and fighting a couple other problems. Recently, I noticed the o-ring on my dip stick was broken so I wrapped it with teflon tape. Yesterday, after getting home from an 80 mile round trip, coolant and steam was leaking from the rear passenger corner of the head-block seam. My oil cap does a little more than a dance when you loosen it and observe the crankcase pressure. No water in the oil or oil in the water but there is a little bit of a black film inside the coolant reservoir.
So... fixing the dipstick may have increased the crankcase pressure enough to pass the problem on to the head gasket but I have a question.

What's causing my present high crankcase pressure? Could I have had a blown head gasket for the last 1-2 years causing my new breather box to blow apart, my dipstick to blow out of its tube and now a coolant passage leak on an outside corner of the head gasket and NOT seen oil in the water or water in the oil?
Or... With 150k, could my rings be so gone that the pressure is this high?

This car was Grandma's and has always been in the family. It's had good service and sat more that it was driven. Oil changes have been neglected a little in the last 10 years but it doesn't get driven much.

If it's rings, I'll probably junk it but I don't want to. I'm thinking I should replace the head gasket and access but I don't want to waste time and $.

Could I have had a blown head gasket just enough to have a good running car but high crankcase pressure with no other head gasket symptoms like contaminated water or oil?

Thanks in advance, C.

 

If you have steam coming from the head gasket then it is most likely blown. The black film in the coolant reservoir is another symptom. With the engine running, do you see bubbles in the coolant reservoir? If so, then definitely the HG.

As far as the HG causing backpressure in the crankcase, the only way I could see it is if the HG fails and leaks into an oil passage that runs between the block and the head. So I guess it is possible.

 

If you have a blown head gasket, you will develop much more coolant pressure then normal. Most cars will have a coolant cap or reservoir cap pressure of about 12-15 lbs. if it's blowing off coolant, good chance it's a hg.

Many times it's difficult to detect water in the oil. Take a drop off your dipstick and put it on your hot exhaust manifold. It will slightly bubble if water is there, it won't if only oil.

Also, pull each of your spark plugs. If you have one particular cylinder affected by the hg, the plug will be much whiter and cleaner then the other after the mix of fuel and water had cleaned it.

 

HG can be complicated as the gasket separates coolant from oil from compression... In your case though, looks like you do have a bad HG and no, it was not caused by the teflon tape.

I'd take a compression test to be sure, then do a headgasket, EASY!!! Non turbo, right? Even easier...

 

Thanks. Yes, it's a NA B230F. My friend at work said that area is a known blown HG area; passenger rear corner. He also thought I could be getting the extra pressure from a blown HG and not see a lot of other signs. Also, I caught this within about the first 10-15 minutes of leaking from the head/block so prob didn't have time to contaminate the oil. My friend warned me to look carefully at that corner of the head and maybe have the head surfaced. I've read about corrosion and acid pitting. At 22 years old, it could even be corroded from the outside at that corner. I've ordered a head set even though my wife is ready to retire the Brick. I say no no no. C.

R2millers- I love the oil on the manifold trick, that's a good one.

 

No need to retire it! Surfacing the head is your biggest expense, and I wouldn't even do that if the car was not overheated but that's me... These HG just let go due to age, nothing more. And super easy to do!

 

I blew the radiator about 1 year ago and it did get pretty hot. I was in the country and limped it home hot; start coast start coast.... That's why I was asking if this pressure in the crankcase could have been the HG without the other signs. When I get the head off, I will look closely at that area. Thanks, C.

 

You can check the head to see if it is warped. Just use a straight edge and a feeler gauge. I don't remember the specs off the top of my head but you lay the straight edge along the head and measure the gap with the feeler gauge. If it is out of spec, then have it resurfaced.

 

Overheating and blown head gaskets go hand in hand. If it gets hot, even driving it a short distance is fatal in most cases.

I've been lucky but I drive, watching the temp gauge before anything else and every 10-15 seconds at best guess.

I've had three of these plastic radiators split and if not careful, watching the temps, I could have been in the same place.