I have a 1988 volvo 740 GLE, with 208,000 miles on it. The past few weeks it has been severly leaking oil from the oil fill cap. The vaccum system is working correctly and the seal on the oil cap is also in good condition. Is there any other problem that might cause this to happen? I apologize if this has already been discussed elswhere.

as I recall...it might be a clogged flame-trap that would cause this to occur...

Frank

Hi!

My 740 developed this problem. A flame trap replacement, while definitely in order, didn't halt the crankcase pressure. I had to replace my breather box - it was a long, dirty job under my oily, messy hood, but it fixed the problem.

Ari

Well the flame trap wasn't clogged. The breather box was a bit dirty, after cleaning it out the problem seems a little better. Still leaking some oil however.

The breather box (oil separator) is not easy to get clean; did you remove it and give it a complete cleaning? That would involve scraping at the openings (a 3/8" bit works well on the top opening), and hitting with a hammer to break the deposits loose. When you have removed all that you can a couple of soakings with solvent helps to finish up.

Also check to see that the small vacuum hose is open all the way to the nipple on the intake and use something to make sure that the nipple itself is open (a small drill bit makes a quick job of it).

When the system is open and breathing as it should you can use a piece of paper to check it. At idle simply lay the paper over the oil filler opening and it should be pulled down and held in place by a slight vacuum.

Randy

Perhaps it is a good time to change your oil. I have observed that old dino oil tends to promote crankcase pressure, I guess because it coagulates and mixes with the gunk already in the engine. Try that, and also make sure that your engine is not overfilled with oil... and check all your vacuum ports on the throttle body to see if you need to unclog them. A probe made out of wire should be fine for that.

Ari