Oil usage

TERRYP

MEMBER
FORD MUSTANG

I have a 1967 Ford Mustang 289 2bbl. Engine. It uses excessive oil. I have replaced valve stem seals. I ran a vacuum test on it and I have 20.5 inches of vacuum and the pointer on the gauge does not move or bounce with the car idling. I can speed the engine up and vacuum goes up a couple inches, still the needle on the gauge does not bouncing and then when I let off the gas the vacuum drops to 17 inches momentarily and then returns and holds at 20.5 inches of vacuum. There are no external oil leaks on engine. Ran a compression test on it and the readings range from 137 to 161 pounds. The engine has to be burning it but I see no tell tell smoke from the exhaust. I know the engine is old but I do not see what could be wrong with good vacuum test and fairly good compression test. Any ideas out there? :(

1 Reply

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

There is only two ways the engine will use oil, burning & external leak. You say there is no external leak so you must be burning oil. Check the spark plugs, are there any deposits building up on them? Does is puff a little blue smoke on start up? This would be valve stem seals or worn valve guides. You say the comps are ok, but that won't give a good indication as to the condition of the oil control rings. Do a consumption test, This is best done with fresh oil and a new filter. Change oil and filter, have oil level spot on the mark. Note speedo, in one week of normal driving re chek oil and add if required, but messure excatly the amount added, use a plastic kitchen mesuring jug. Note speedo and you will have oil usage per miles/ Km's If plugs are fouled don't bother with a fix in a bottle, waste of time and money re buid as required will be the only answer. Depending on the type of oil you would not want to be using any more than 1/2 Litre per 5,000 Km's (sorry not on Miles and gallons in Aust)

Do the test first, good luck

Mark (mhpautos)