Is this blow by and what to do about it?

  #1  
Old 12-02-2010, 08:31 PM
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Default Is this blow by and what to do about it?

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?
 
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Old 12-02-2010, 10:22 PM
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[
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?

The "oil trap" aka oil separator sits on top of the block directly under the hose. That has to be taken out and cleaned or replaced.
 
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Old 12-02-2010, 11:15 PM
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How many miles on the car? I have heard of using a "catch can" to prevent oil from getting into the intake. I believe that my car ('82 242 GLT) is also getting some blowby because under hard acceleration I can also smell oil. I haven't done the cap test yet. I was wondering if you couldn't somehow fit a PCV valve into the valve cover directly for added ventilation. You would probably need to somehow fit a grommet.
 
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Old 12-03-2010, 04:30 PM
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If you can smell oil under hard acceleration, you need to start saving for another engine. Anything else is a band aid. Once the bores are worn to that stage, there's no solution apart from an over bore.

Regards, Andrew.
 
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Old 12-03-2010, 08:23 PM
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Ouch! @ Typhoon's comment!

248,000 miles on engine coonman
 
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Old 12-03-2010, 08:24 PM
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Also, taking it to a shop tomorrow morning, will see what they think
 
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Old 12-03-2010, 10:14 PM
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If you smell it in the passenger compartment, is it also laying down a smoke screen from the tail pipe? When you come to a stop does smoke seep from under the hood? Where the smoke comes from is an indicator of what the issue might be. As Andrew suggests, perhaps your motor is toast. Then again, perhaps your engine is coated in 20 years and a quarter million miles of oil and dirt. Perhaps the feed line to your turbo seeps, valve covers, etc. Hard acceleration means boost and boost means heat...lots of it. My turbo glows in the dark occasionally. Heat will cook off that old oily dirt near the turbo. High rpm's will sling even more oil out of aging gaskets and seals.
 
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Old 12-04-2010, 01:27 AM
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I run full synthetic in my car so there is no smoke out of the tail pipe. However, under hard acceleration at night I can see "pseudo smoke" in the headlights of the person behind me. I am using quite a bit of oil at this point. Possibly a quart per week. But the old brick keeps going. Still I know that this is not good and the oil ending up in the intake is also a bad sign. 248k may be signaling a ring job. My motor is probably in that range as well. Damn Volvos are tough beasts!
 
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Old 12-04-2010, 06:42 AM
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^^So, full synthetic doesn't smoke when it burns? What is "pseudo" smoke? Why on earth would you use synthetic if you're running through a quart a week? How many miles do you drive a week?
 
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Old 12-04-2010, 10:26 AM
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a simple compression test will clear the mystery whether u need rings or not...
 
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Old 12-04-2010, 11:13 AM
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It's hard to explain what I mean by "pseudo smoke". If I really push it at night and look back in my rear view mirror, I can see something in the exhaust. Synthetic oil doesn't really burn like conventional oil does. I am sure that if I was running conventional oil there would be a bit of smoke. I have been running full synthetic for the past 90k miles so there is no plan to change back to anything else. I don't believe that my oil consumption is coming from oil being burned. Rather the engine getting worn is causing more blowby which in turn causes more oil in the intake and stresses the ventilation system as well. See this article...

http://www.pbase.com/stealthfti/pcv

I should probably get a compression test done as well. But I have dumped so much cash into this car already this year. It is getting to the point of no return frankly. I might just be looking for a cheap Toyota for doing my food deliveries. I probably drive 2000 miles per month but have no idea since the odometer is broken.

But volvoQs you should look at that article and do a compression test also.
 
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Old 12-04-2010, 04:53 PM
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No smoke from tailpipe. Talked to mechanic this morning. Think it is leaking from oil cap gasket now, but only under 1/2 or more throttle, also hear a slight hissing sound then. It must be burning off on the exhaust manifold. I tried some Rislone magic juice and am fully expecting it not to work. When it doesn't work, I am going to build the most unique invention ever for my volvo...going to drill a hole in the oil cap or valve cover (with it removed!) and install a rubber grommet and PCV valve, then run a hose to a collection device mounted in the engine compartment. See what happens! I can't afford an engine rebuild or a newer car, so need to limp this one along. Also going to simply try to behave and stay out of the throttle. Thanks for all of your help and comments!
 
  #13  
Old 12-04-2010, 10:41 PM
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That's what I was thinking. Use a PCV valve and a catch can. Why not? I am still thinking about doing this with my car as well.
 
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Old 12-05-2010, 03:53 PM
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Thanks for the article/site!
 
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Old 08-13-2017, 10:34 AM
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Hey, have a 1990 volvo 740 turbo as well and when i put the oil cap on top of motor when it's running it shakes a bit + the hoses seem to be oily etc.

When it idles it sounds a bit loud, so i think i might have blowby :l

What do i do is blowby fixable without having to rebuild the motor?
 
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Old 08-13-2017, 03:26 PM
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Originally Posted by volvoQ's View Post
No smoke from tailpipe. Talked to mechanic this morning. Think it is leaking from oil cap gasket now, but only under 1/2 or more throttle, also hear a slight hissing sound then. It must be burning off on the exhaust manifold. I tried some Rislone magic juice and am fully expecting it not to work. When it doesn't work, I am going to build the most unique invention ever for my volvo...going to drill a hole in the oil cap or valve cover (with it removed!) and install a rubber grommet and PCV valve, then run a hose to a collection device mounted in the engine compartment. See what happens! I can't afford an engine rebuild or a newer car, so need to limp this one along. Also going to simply try to behave and stay out of the throttle. Thanks for all of your help and comments!
I did that 100K miles ago and it works well. Now have 369K and still running.
 
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