The Stovebolt Site Forums The Shop Area Engine Shop Let's get all that oil out....pulling the pan

Second of some questions -

The oil that is in this thing looks to have been there for at least 10 years. Black and very thick. So it needs to go.

In fact I am thinking of dropping the pan off and cleaning it, fill up with oil, run, and drop the pan again before one final fill up.

This is a C-30 with a 292 that doesn't match the year of the truck...engine is a '70's model. How hard with this be and am I headed in the right direction? Anything I need to look out for?

Dave

It,s a good idea to pull the pan in a situation like that but it,s a pretty tough job on that model. You have to take the engine mounts loose & raise the engine way up. You certainly wouldn,t have to pull it a second time.

Had a '60 Chevy 235 and I would change the oil and within 100 miles the oil was black. Stuck a stick in the engine and found a sea of muck in the pan. Something I tried and it worked great. Get the engine hot. Drain the oil and fill the crankcase to the full mark on the dipstick with a 50/50 mix of fuel oil and transmission fluid. Run for 2-3 minutes and drain. Only let the engine idle! Don't drive it! On the 2nd flush, I had the valve cover off and poured the mixture over the rockers while the engine was running. After about 3-4 flushes the stuff started staying clean when I drained the pan. Gave it an extra shot for good measure. Problem solved.

I had an uncle who did this on his Chevrolets back in the late 40's and 50's. Only he used kerosene. He would drain the engine, fill it with kerosene, run it for about ten minutes and drain the pan. He would do that twice and he would swear that he maintained the cleanest engine in town.

Joe

My dad talks about doing the kerosene wash during the 50's, and of course it cleans the oil out pretty good. Working in a garage in the 80's we had a fellow bring in a Pontiac where for whatever reason gas had drained into the oilpan. Luckily we drained that out before the roof blew off. In any event, in both cases, afterwards the engines were both so clean that the oily gunk which had been plugging up all the old seals had washed away, and both engines used way too much oil. Just a thought, an old clean engine might draw a bit more oil.
Karl

A problem you may run into is what is called "false seals". As gaskets and seals go bad due to age and abuse they would normally start leaking/seeping. The grunge you want to remove has "packed" the bad seals so when you remove the grunge, your false seals goes with it. All of a sudden you've got a clean engine leaking all over the place. Gaskets and seals can be replaced much easier than a hard to find engine, It's par for the course and a good reason to spend time in our shops breathing fire into these old iron horses.

Just my opinion...but a flush on an engine that has been setting up for years, is not going to do much to rid the ole girl of that heavy sludge that cakes up the lower sump. If you've got the skills, pull the pan, use a putty knife (because that's what it's going to take) and dig out the grung. If the rockers are caked, it wouldn't hurt to carefully remove them, and off the vehicle, give them a good cleaning and flush. I wouldn't break a lot of stuff loose on the top of the head. You don't need that cascading down into the pan after you add the new oil. Just bolt the rockers back on, check her valve adjustment, replace the pan, stick in a new filter and oil'er up.

While you've got the pan off, it's a good time to check out the overall condition of the guts. I've found that a really gunked up engine may still give you some good service, but if it's cruddy on top and down below, you're probably at, or getting close to a rebuild. The thick crud is moisture, remnants of fuel from blow-by, and solid particles that are a result of the combustion process. The engine probably wasn't running that good when she was taken out of service. It's also a good time to knock out any dents or dings and square up the gasket surface.

A heavily gunked engine, to me, is indicative of
one that is reaching the end of it's service life before a rebuild. A clean top, clean rods and a little hard sludge in the lower pan aren't going to raise that much concern. Popping a rod cap or two can give you even a little more info.
If she's running, and the oil pressure is stable, you might be able to stretch a few more miles out of the engine.

Beltfed, hit it on the button about the old seals and gaskets. Even a 10 year old rear main that has been sitting idle, has the potential to cause you much grief. As the weakest component in an engine, you will probably wind up having problems with it even if everything else is clean and looks good. You may get lucky for a while!!!

If you plan on hitting the highway and running your little engine hard, you'd be better served, to do your overhaul before you bust something and wind up with a pile of useless junk.

One more thing to watch with flushing old engines, chunks of crud can break loose and clog the pick up on the oil pump. I think Fla 54 make a very good point. Just my 2 cents.

Sean

I think it's a good idea to pull it once to give it a good cleaning. Pulling it again isn't necessary because the drain plug is at the lowest part of the pan. Anything that is flushed by the fresh oil should exit the pan when you pull the plug.