I have a rebuilt Ford 289 engine (do not know how long ago it was rebuilt) that takes a quart of oil in about 250 to 300 miles. It does not smoke or leak, runs fine and has good compression. A friend has a 350 Chevy engine with the same issue. What can the reason for this oil consumption without smoking or leaking?
The oil consumption is too high and assuming no leaks, that oil consumption is due to valve seals, piston rings, or both. There’s rebuilt and there’s rebuilt correctly.
Regarding “good” compression, what numbers are you talking about? Dry and wet compression test? Leakdown test?
When you say that the engine was rebuilt, what was involved in the rebuild? If the rebuild consisted of just putting in expansion rings and grinding the valves, the cylinder walls may be worn causing your oil consumption problem. I don’t think blue smoke will show up at the rate of 1 quart per 300 miles.
The other issue may be the valve guides or valve stem seals. I had this problem with a 6 cylinder cubic inch Ford engine in a Maverick I owned. It took a quart of oil every 300 miles and there was no blue smoke. When the valve stem seals were replaced, the consumption was reduced to a quart every 1250 miles.
Thanks for the input on oil consumption. I tend to agree with the diagnosis.
Valve stem seal problems will usually produce a big puff of smoke on a cold start-up…Bad rings will belch smoke if you engine-brake in second gear then tromp on it, a big puff of smoke usually results…Synthetic oil or a catalytic converter can mask exhaust smoke…
Is the PCV system working properly? A 289 is quite an old engine, must be an old car. I’ve seen some of those that someone installed a set of cheap “Go-Fast Chrome” valve covers that didn’t have the right baffles in the valve cover. The PCV valve was just sucking oil in from around the valve springs.
The term “good” in regards to compression numbers was never clarified although the numbers don’t always tell the whole story.