/6 & the mysterious oil disappearance

[rmrod]

I've got 39K on the Super 225/6 in a 78 Aspen Coupe(w/AT PS) that sat in a garage a lot and was used less than 2K miles/year. Now, being the second owner, I manage just under 500 miles a week. No oil leaks, anywhere! The engine is loosing a quart of oil in just under 1K miles. The EGR system is working well and has passed Illinois emisions. No blue smoke visable from the tail pipe and it runs like a Swiss watch. If this engine has a weakness, is this it or could it be something else? What is causing the oil to disappear? Any Ideas?

[Stoga]

Just to be sure, check the valve cover on the lower rear passenger side. If they have a leak there, a slant will use a lot of oil.
The problem is with that location is it is low and often the oil can run and spread out on the floorpan of the car, without hitting the ground. Another thing you may want to check is the PCV if it has never been changed. If neither of these make any difference, you may want to look at the valve seals. Even on a low mileage car, it's been a fair amount of time since 1978, and the valve seals could have hardened and allow oil to pass down the valve guides. Have someone drive your Aspen, and you follow, and if you see blue smoke, even if just a puff, when the driver lets off the gas, that is a pretty good indication the seals have went bad.
Also, check the oil pressure sending unit too, these have also been known to leak on occasion, and can pump quite a bit of oil out because they are hooked directly to an oil gallery. The oil has to be going somewhere, just gotta find where it's escaping at!

[rmrod]

Stoga

Thanks for confirming some of my suspicions. First, I did replace the rocker arm cover gasket with a new Fel Pro piece. Great pains were taken to make sure that the gasket seated well especialy at the lower rear corner. Secondly, the PVC valve was changed out when I did the tune up about 6K miles ago.

I also had suspected that the valve seals could be the culprit given the age of the engine. The engine is cosmetically clean and free of external oil seapage. If they are made out of a materail simular to that of the cover gasket, then they're toast!
(The gasket was hard and brittle and fell apart in my hand. I am well aware that machines that sit for long periods of time without use is can cause lots of problems. ) This could be it. I'll have to wait for better weather before I can do any probing.

Can the seals be changed out without taking the head off? Would it have to go into a machine shop?

Rmrod

[Stoga]

Can the valve seals be replaced without pulling the head?Definetly Yes on not taking off the head, and no machine work is necessary.
You'll need a valve spring compressor and a fitting to pump compressed air into the cylinder. Remove the rocker shaft and pushrods and spark plugs. Fit the air fitting, they make special ones that will replace a spark plug, available at most parts stores, or make one yourself out of an old fitting that fits your air line and break the porceline out of an old spark plug that fits your engine, and weld the two together. When you pump the air into the cylinder, this will hold the valves in place when you remove the valve spring. Give the top of the retainer a sharp whack with a brass drift or hammer to shock loose the valve stem locks, compress spring, remove locks, remove spring. Then remove the old seal, probably in pieces, then re-assemble. A bucks down method of keeping the valves up is to feed a coil of cord or small rope thru the plug hole, then rotate the piston up to hold that against the valves. Remove rope when valve springs are reassembled. If you'd rather not mess with it, this is a fairly standard job that most auto shops can handle, call around and see who'll give you a good price and changing the seals on a slant is a lot easier than most engines, should be relatively inexpensive. Definetly sounds like you got a nice lil Aspen!
Everytime I find an old one, the odometer has been turned over twice and the car beat with an ugly stick!

[mrdodg]

Check the oil pressure sending unit as mentioned earlier. Returning from AmeriCruise '98 in Snowmass, CO, my /6 powered '63 Dodge p/u dumped ALL its oil through the cracked plastic insert in the sending unit. It won't leak with the motor off but when it is running there is pressure on the sending unit. The part is only about $3.00 and it's easy to get to.

[rmrod]

Mrdodg
Your idea just landed on an unstruck cord. The oil pressure sender could be the culprit. It functions well, so I have no reason to look. Now, I'll check it and advise. Thanks.
RmRod

[71dart666]

Sounds alot like my slant 6, I just assumed the rings were shot on mine. Didnt know it was an oil burner when i first got it till i changed the oil and was pretty surprised when only 2 quarts drained out. Good thing these engines are bullet proof, if it was a chevy or ford I would have probably been calling a tow truck.