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Oil burning during down shift


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The engine is a 3.0SC that has been completely rebuilt by a very reputable builder.. Every bearing replaced, new rings, cylinders prior to being reinstalled were checked for roundness, valve job 3 angle with new guides, etc. no expense spared. Running CIS, engine has about 4500 mls. Under load it is pinging while running 93 octane.

During initial start up blue smoke from oil in chambers, when it warms up and you down shift or come off gas large volume of blue burning oil smoke appears. Car pull well and idles smooth as silk. Can a vacuume leak cause sudden oil to go into chambers? I checked to see if to much oil in tank and seemed ok, let some out, still same problem. Any thoughts would be appreciated..

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When the valve job was done were the valve guides replaced and/or at least measured. Were the valves measured as well? And were the valve seals replaced?

Is the oil level proper?

Edited by logray
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Yes everything was done correctlY, tha only happened about 750 miles ago. The person that did the heads has done 6 other cars without any problems. I went on the forum as a last result prior to pulling the engine and doing a top tear down.. Any other suggestions?

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I trust that you are using the dip stick at operating temp and not the known unreliable dash gauge to check the oil level. Next step should probably be a leak down test before you drop the motor. I would also suggest posting your issue in the Pelican Parts engine rebuilding forum which has an extensive following by air cooled experts.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/

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To add to my previous post, because of the pinging, you should check the vacuum lines for inside blockage, kinks and that they have been connected to the right place.

The oil smoke could be caused by a blocked or kinked breather hose. It is located at the top back of the motor and goes to the top of the oil tank. Any left over rags in there from the rebuild?

After that and before you embark on a leak down test, I would pull all the valve covers and check that the valve guides are not partially unseated and that the valve clearances are still there.

Let us know how you make out.

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Ok ... Here is the long and short of the problem.. I had the distributor converted to a mechanical unit and the co. That did it said they put new parts in it! However it is old used parts. The magnets broke loose and caused an excessive amount of advance and caused pinging, thus caused the pistons to fail between the rings. Catastrophic running engine failure. We took the engine apart and found that 5 out of 6 pistons and cylinders have damage. Next on the addenda pistons and cylinders. I am deciding if to post this distributor rebuilders name on the web and also if I should place an action on him. Doing background info to see what if anything can be done.

Thanks for all your input..

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  • 8 months later...

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