Charley B

This is on the '83 4.7 Euro 5 spd. with GTS oil baffle, auxiliary oil cooler, and Devek oil breather control baffle.

Car runs great normally but at RPMs above 5400 the dreaded blue cloud strikes. In an attempt to isolate the problem to the breather system I pulled the hose from the oil fill cap and plumbed it to an empty plastic 1 quart oil bottle.

I took it out and ran it up to 6000 RPM with no sign of the oil cloud, but upon smelling the hot oil I pulled over and the bottle had blown a hole in it's side and oil was all over that side of the car.

I understand the need for a catch can or tank, but what I'm concerned about is whether or not the amount of force to pump out that much oil in a few minutes is an indication of some sort of pressure issue in the crankcase.

Mrmerlin

what does a compression test show? do it hot.
It sounds like worn rings,

OR the vent hose is filling with oil and you need a different oil separator

Charley B

Thanks Stan, I haven't run a compression test yet. I'll do that next.

Where is the oil seperator and vent hose?

Charley B

If it were worn rings wouldn't it tend to smoke under normal hard exceleration, like between 4k and 5k?

Lizard928

It is ring float, or the rings being lifted off the walls.

I have the same problem on my car (87 S4), I plan to plumb in a vacuum pump and that should sort the problem. I dont see the point to going to drysump on a street car.

Charley B

I'm dealing with it at the moment because I have someone interested in it to use as a race car.

I don't want to let him buy it if there's a problem other than the normal high RPM blowby issue.

Would a dry sump solve the problem or would there still be an issue with crankcase pressure?

Lizard928

a drysump system would solve this problem entirely.

Speedtoys

..drysump my bank account that is..

Charley B

Would an accusump have the same affect?

Lizard928

No, an accusump will not generate a vacuum in the sump which is what is required to help "pull" down the rings and improve their seal.

Charley B

I did a cold engine compression test.
1 = 165
2 = 163
3 = 135
4 = 140
5 = 163
6 = 150
7 = 155
8 = 145

IcemanG17

How about a hot compression test as a comparison? Cylinder 3-4-8 are a bit low....the others are fine since its cold..... I remember my $300 engine had every cylinder around 150-160psi with one spiked to 175psi.....but its a USA engine too...so .7 CR less than the euro....

Charley B

I reran the compression test hot and got exactly the same result.

After running some Rislone 'unstick your rings' goop through it I can now run it up to redline without the blue cloud, although by the top of third gear I still get a little blue smoke.

Lizard928

The problem with a compression test is that most don't understand how to do it right and it lacks a great deal of information. A leakdow test would be a far far better test to perform and see as to how good or bad the rings seals etc may be.

BC

Be careful. That much blow by can create massive seal problems. Such as main seals being blown out and pushing 8 quarts out in several seconds. And then an under car fire which other people on the highway point feverishly at.

Ask me how I know.