Hi all,


I have a '92 740 turbo that my wife has been driving. I travel a lot. When I got in it last week and saw the oil light come on. When I checked the oil level to my horror discovered it was 3 1/2 qts low. at least five years ago I had to clean out the flame trap (crankcase ventilator) because it was plugged and blew out my front cam seal. I check it once in a while, but this thime its not plugged. What else my be causing oil to blow out the oil cap and other places, (bad rings)?

 

a compression test would verify the condition of the rings and valves.

on the turbos. there is no 'flame trap' per say, just a oil separator box and a hose over to the intake air path between the AMM/MAF and the turbo... that fitting on the big air hose that this breather hose goes into is a heater circuit to keep it from gumming up in cold weather.

 

Ah yes oil separator. So what else my be causing oil to blow?

 

There is definitely positive air coming out of oil filler hole.

 

valve stem and/or piston blowby is the usual source of positive pressure in the engine. I'd guess the vent from the engine to the oil seperator box is clogged, or that heated connection to the air intake hose.

 

pierce,


I'm not sure what your referring to when you say "heated connection". My oil separator which I have already checked and can blow through in all directions from each whole to any other hole, has only two connections in the top. The main tube coming from the turbo and the little rubber tube coming from the intake. which is also open.

 

the big fat air hose that goes from the MAF near the air filter box to the turbo intake, it has a connection for that crankcase vent hose, and that connection has an electrical connector on the side. It took me a fair bit of digging to determine that electrical connection is power for a heater circuit, intended to keep the air vent from clogging up.

don't try and remove that small fitting from the big air hose, its sold as one piece.

here,


thats my 92 turbo... the 'big air hose' I'm talking about is to the picture's left of the engine, under the big air pipe that goes to the intercooler, and you can see the electrical connection to the immediate left of the timing belt cover on the front of the engine.

 

don't seem to have a clogged hose or separator. Can you steer me to compression check procedure here?

 

pull all 4 spark plugs, insert a compression tester into #1, have friend crank motor for a few seconds (I suggest removing the main fuel injection fuse (fuse #1) so the fuel pumps don't run), and read guage. then move compression gauge to next cylinder, repeat for all 4 cylinders.

ok, see here... Engine:Mechanical better, more complete compression test procedure...

 

Thanks pierce, my compression tester check valve is broke and will have to go get a new one. I have been dreading this day as I am in the middle of rebuilding a 1972 Honda too.

 

I did a compression check today and wasn't thrilled with results. First off I topped up the oil, took for a short drive to warm it up. I removed all plugs and depressed accelerator.
#4 read 117psi, #3 read 122psi, #2 read 140 psi, #1 read 130psi. While warming up the car I probably lost 1/4 quart of oil. It seems to be blowing out the crank seal in the front. I plan on doing a leak down test soon for further analysis.
I'm looking for suggestions as whether replacing the crank seal would enable me to keep this car on the road or would I be wasting my time? The car actually starts and runs fine. Ive had it for 15years and love this car. I not sure I'm prepared to rebuild it though.