Is this blow by and what to do about it?

volvoQs · Post by **volvoQs** » 02 Dec 2010, 19:31

1990 740 turbo

Smell oil/fuel in car under hard acceleration.

Have replaced front camshaft seal, oil trap and oil cap gasket.

Have checked hoses and connections.

Have changed oil and filter.

Runs well otherwise.

Oil cap will float while running when removed.

At a loss. Could the long hose going into the block under the oil trap be blocked? It looked clear. Do I have a "check valve" in this system as it's a turbo?

Marvel Mystery Oil?
Kerosene in the oil?
Clean out/replace hose going into block under oil trap?
What other options do I have?
Anyway to vent these excess gases out some other way?

Post by **JDS60R** » 02 Dec 2010, 20:18

I willl et those who know the 740 better chime in. My approach would be to pinpoint any blockage in the system as it is common for the flame trap ,etc to clog up. If no blockage ( may just be a restriction) could be found then I would do a leakdown test and see how much flow is passing the rings and valves.

I am sure a 740 guru will chime in on where to look first.

Post by **billofdurham** » 03 Dec 2010, 11:46

I'm not a 740 guru but there is no flame trap on the turbo engine. Do not try to remove the pipe from the oil trap to the sump to check it as you will have to remove the oil sump to get it back into place. Usually this pipe doesn't cause problems as it should only be returning oil to the sump. If the oil trap were badly blocked then it is feasible that sludge has entered that pipe with the oil but gravity should have moved it on.

You have replaced the oil trap but did you check that the pipe from the oil trap are clear by blowing through them?

If they are all clear your next step would be a leakdown test as suggested by JDS60R.

Bill.

volvoQs · Post by **volvoQs** » 03 Dec 2010, 19:23

Taking it to a shop tomorrow morning...will see what they think

I did check the hoses and connections and they were all clear.

Basically looking for the best way out of a bad situation now I feel.

Post by **billofdurham** » 04 Dec 2010, 11:46

Keep us updated, please.

Bill.

volvoQs · Post by **volvoQs** » 04 Dec 2010, 15:55

Mechanic and I agree rings are probably shot.

If I keep out of the throttle it doesn't leak. Need to just behave and limp it along.

Tried some Rislone miracle stuff, planning on it not working, then I may rig up a PCV valve in the valve cover or oil cap and create my own vent/drain. I don't have money for rebuild or newer car. Need this thing to last about 6 months.

Retired MVS Contributor · Post by **Retired MVS Contributor** » 04 Dec 2010, 16:12

Check the hose nipples going into the intake manifold for restriction or blockage...

volvoQs · Post by **volvoQs** » 04 Dec 2010, 16:51

Already cleaned those out. Thanks though. I just don't know where else there could be a blockage. Feel like I'm missing a valve or something somewhere. Probably the rings are tore up or cylinder walls are.

Post by **JDS60R** » 05 Dec 2010, 15:20

Try this
It actually works if rings are the issue