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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 84ChevroletTruck on November 02, 2016, 08:28:26 pm
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Hi everyone, i'm pretty sure I know the answer to my question here but it is about an oil smell issue. I have a brand new GM 350 crate engine with 10k miles. I daily drive it and make sure that everything is maintained. I had one oil leak at the valve covers and stopped it so now nothing is leaking and it does not smoke upon start up or while driving. When i'm cruising down the road and let completely off of the throttle I get a strong smell of fresh oil. everything seems good and i'm suspecting the valve seals have failed. would this likely be the only cause considering it is new and that being a common issue? i'm sure it wouldn't be burning past the rings by now.
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When you let off the throttle, what you are doing is closing the throttle plate. Intake manifold vacuum goes way up. So it could be valve seals. But the other thing that happens when vacuum goes way up is the PCV valve opens. You could be sucking oil there, particularly if it is gummed up from closing all the way and you suck oil into the hose when the throttle is open, then when the throttle closes you suck the oil out of the hose.
I would put a new PCV valve on first. They're like 4, 5 bucks. And clean out the PCV hose while you're at it.
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In addition, when you pull the PCV valve out of the valve cover, look down through the grommet into the cover. There should be a baffle that prevents oil splash from directly entering the valve.
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ok awesome, ill check that now.
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alright, i went ahead and put a new PCV valve in. I noticed that there was a small amount of oil around the grommet and on the baffle inside of the valve cover. it was only a small amount of oil but i went ahead and wiped everything up. When i pulled the hose I smelled oil on the PCV side and fuel on the carburetor end. During my drive after replacing it I still received the burning oil smell. Any other suggestions? checked the plugs and all of them were oil fouled and had gummed up oil just below the threads.
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The previous PCV valve I had was still new as well and was not dirty or gummed up.
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...it does not smoke upon start up or while driving....
...checked the plugs and all of them were oil fouled....
These two statements are contradictory.
If the spark plugs are oil fouled, the engine is burning oil and should be anticipated to emit bluish gray smoke from its exhaust, though it might be slight and difficult to observe. A momentary bluish puff of smoke at cold startup indicates worn valve guides and/or valve guide seals - bluish smoke under acceleration and cruise is more consistent with piston ring wear/damage, cylinder glazing or oil dilution.
Allow a drop of engine oil to fall onto your clean fingertip from the dipstick. Does the oil hold together in a tight, well-defined circle or does it quickly track outward along your fingerprint? Tracking your fingerprint indicates fuel dilution of the oil that can easily pump past the piston rings. Fuel dilution can result from a faulty mechanical fuel pump or prolonged fuel leakage from the carburetor directly into the intake manifold. You can perform a dry/wet compression test, or better under the circumstances, a cylinder leak down test to determine cylinder condition.