Guest mattrp Posted April 14, 2000 Share Posted April 14, 2000 My 305 in my 72 datsun burns oil horribly, but only during engine braking. I went autocrossing, which never uses engine braking, but revs high, didn't suck down a drop of oil. But on normal streets where you shift down a gear and let the engine slow you down, the engine just pumps the blue smoke out the tailpipe, and I am quickly a quart down. At no other time does it act this way. I have tried the restore stuff, and the heads are rebuilt, but the rings have many miles. Is this just a characteristic of old rings? Matt 72 500Z Quote Link to comment Share on other sites More sharing options...
John Scott Posted April 14, 2000 Share Posted April 14, 2000 My old rule of thumb is when it smokes under load its usually the rings. Under coasting conditions, engine drag, the valve guides/ and or seals. Leaky guides/ valve stem seals will also give a puff of blue when you start after sitting a while. John Scott Quote Link to comment Share on other sites More sharing options...
MYRON Posted April 15, 2000 Share Posted April 15, 2000 I agree with John on this one. When braking all the oil that is pumped to the top side of your motor may be flowing heavy to the # 1 and 2 cylders and a large volume of oil is running down the valve guides... Do a compression test, if it is good the it is positively the guides... Pull your heads and get them re-worked or replaced and you should be ok... Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 16, 2000 Share Posted April 16, 2000 BTW, Engine braking is not a good idea. I did this for years until I went to a drivers training school. They had some real good examples of parts failure due to engine braking a car. Driving instructor chewed me a new one every time he saw me doing it on the road course and it eventually broke me from doing it. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted April 17, 2000 Share Posted April 17, 2000 I,d have to agree with John,Myron and Mike.Just throwing in my 2 cents. Quote Link to comment Share on other sites More sharing options...
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