Smoking: valves or rimgs........?
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New User
Joined: Aug 2004
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Smoking: valves or rimgs........?
I just bought a 1990 F250 5.8 with 240,000 miles. I just did a compression check and all cylinders are 140-145lbs after a short warm up period. It does however, smoke at idle and when a friend drove behind me he mentioned the "smoke/oil" smell. This truck will be used to tow a 6500lb boat/trailer combo from CA to Alaska in June and will then be used for only 5 weeks or so every summer when I'm in Alaska. The rest of the year it will sit parked at at friends house up on blocks.
How do I tell if its rings or valves that are letting oil by? If its rings, I might be inclined to do a valve job. If rings I'd rather not pay the 2000.00 that the Ford dealer wants for a new motor.... Would there be any other options? I've rebuilt 6 SBC's but really don't have the time/$$ to spring for a rebuild at this time.
Any suggestions?
Lance
How do I tell if its rings or valves that are letting oil by? If its rings, I might be inclined to do a valve job. If rings I'd rather not pay the 2000.00 that the Ford dealer wants for a new motor.... Would there be any other options? I've rebuilt 6 SBC's but really don't have the time/$$ to spring for a rebuild at this time.
Any suggestions?
Lance
Elder User
Joined: Oct 2004
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From: Fleming Ga
If it is valve stem seals, they usually show up worse when first starting up after sitting because the oil runs down the valve stem past the seals and pools on the piston. Normally after the engine cranks and runs a few seconds the pooled oil burns off and the smoke decreases or goes away.
Freshman User
Joined: Aug 2004
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From: St Cloud/Orlando area, FL
OK. Checking the rings, pull the plugs, do a dry compression check. Then, squirt a couple squirts of engine oil in the plug holes and do it again. A significant increase indicates rings worn (which goes w/o saying at 200k plus miles. Valves/stem leakage is usually indicated by smoke right after start-up or after idling for awhile. Clears when you run the engine. Sounds like you've just got a tired 5.8. Just for laughs and giggles, try a product called "Restore" in a silver can. Run this for a couple dozen miles and retake the dry compression readings. Let me know what you find, OK?
Posting Guru
Joined: Dec 2003
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From: Centerville, Iowa
Restore does nothing that a higher viscosity oil couldn't do. That is the primary benefit to using such products, the uprate in the viscosity of the oil. Rather than go that route, he'd be better off to go with a good 15W40 diesel rated oil to give those rings a bit more chance.
Freshman User
Joined: Aug 2004
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From: St Cloud/Orlando area, FL
Originally Posted by Saurian
Restore does nothing that a higher viscosity oil couldn't do. That is the primary benefit to using such products, the uprate in the viscosity of the oil. Rather than go that route, he'd be better off to go with a good 15W40 diesel rated oil to give those rings a bit more chance.
