The Stovebolt Site Forums The Shop Area Engine Shop Oil leak on a straight 6....

It's probably the rear main seal, but there's so much oil down there right now I can't tell for sure.

One of my Chevy dealer's people recommended putting a half quart of trans fluid in with the oil. The theory is that trans fluid has more detergents than the current formulations of oil and this detergent helps prevent leaks (I think by expanding the seals). Does that make any sense?

I have no faith about trans fluid in oil expanding seals. I have for many years added 1 qt. of transfluid to oil before oil change and let idle for 10 minutes for the detergent effect. I seriously doubt that this wouild have any effect on any seal, let alone a rear main. Take it to the car wash and hose it off.

If anything the tranny fluid would clean the crud out from around the seal and make it leak more. I doubt if anything short of replacing the seal will cure it. Drop the pan and pull the rear main housing and replace the seal. If the crank has a big groove cut in it, it will leak again.

There are two probs with using tranny fluid in motor oil:

1. If the engine has a bunch of sludge from running non-detergent oil, the tranny fluid could break some of that loose and clog the pickup screen or get drawn into the oiling system.

2: Rubber & some neoprenes and vinyls expand when chemicals attack them. If a rubber seal is expanding due to chemical contamination, its failing.

While tranny fluid is an excellent lubricant, it belongs in the transmission.

good luck

chip

There's fixing the problem, then there's covering it up. It may be a pain, but it's less of a pain than any damage that might be caused by doing the wrong thing. Pull the engine and replace the rear main seal to fix the leak, would be my advice.

Here's a $15,000 example of why transmission fluid isn't supposed to be used as engine oil: http://forums.pelicanparts.com/showthread.php?s=&threadid=83967

Gives weight to the old addage, "more money than sense"... :o

-Boyo

Whew! You guys are brutal!!!



I'm capable of doing a tune-up and brakes, but I haven't pulled an engine in 30 years....

::::grumble grumble grumble::::



P.S. Thanks for all the advice on trans fluid. It didn't sound like the best idea in the world. I appreciate all the years of experience you are willing to share.

I have ran atf (ONLY 1 QUART) occaisionally with oil changes on my 72 Chevy 4X4 for more than 6 years now.
I have hauled many vehicles(cars,trucks,equipment and BIG trucks).Way over weight on the load being hauled several times and the engine is still running well.
The engine was usedwhen I got it and was a rebuilt engine from a smaller school bus.Then it was thrashed out in the sand dunes by my brother-in-law when he had it in his 74 suburban.He gave the suburban to his son who also thrashed it out in the sand dunes until the tranny went out.
-Like I have said, I have ran it hard for about 6 years now.
-
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As for the ,,D.A. who ownes the Porche, all I can say is 5 QUARTS of ATF!!!!!!!! :confused: :rolleyes:

JunkYardFrog,, what year is the engine you are referring to?
-Does it have a plugged PCV valve?

If you haven't pulled an engine in 30 years, its definetly YOUR TURN!!!
Absolutely check the PCV valve, and never add anything to motor oil, except more oil All that other snake-oil junk just causes more problems/poverty than its worth.
When you get the engine out, if you do, always check rear cam plugs, freeze plugs and anything else that may leak between engine and trans.
Keep in mind, it could just be a VC gasket leaking, or even trans fluid working its way up the input shaft (overfilled?)

Ooops!!!

Did I say 30 years? I meant, um, well, how about 30 minutes?

1962.

I don't think so. I don't think it has one. This baby is real basic.

Fascinating.

I had not heard about mixing ATF with oil before, so I only put in 6 ounces as a small test. It's been in just a few days, but I must say that the amount of oil on the ground is about half of what it was before. I haven't had a chance to crawl back under it, or steam clean it yet.

This engine was also thrashed, or at least very poorly maintained. They were running it without an air cleaner! I've changed the oil twice already, so when we change it tomorrow that will make three changes in roughly 300 miles. The oil gets black after only a few miles of driving. I can't imagine what the inside of this engine looks like.

Does your engine(I am guessing it is a 235)have an oil filter on it?
-It should hang off the intake manifold.

Yep. I've never seen one like that before (this is my first truck). You unscrew the lid and remove the oil filter cartridge.

I've never heard of ATF in the oil, it seems like it would foam as soon as the engine got up to temp. I used to have a '71 New Yorker (Jesus H. Chrysler, the notorious open header fourdoor, long story ) with a power steering pump that would empty itself daily. I started pouring ATF into the pump and (eventually) it only needed monthly fill-ups. I sold the car before those swollen seals came apart entirely.

I have been adding ATF to oil for over twenty years with nothing but good results (cleaner engine internally) I agree that you should not do it to engines that have been running non-detergent oil. I also stated that I let it idle for 10 minutes before I drain. I do not nor do I recommend driving with this additive. ATF is 10 weight oil with a highly detergent additive. I use it every 3rd oil change if the oil is looking black and dirty before I change (3000) miles. Since I do not buy new vehicles I see this gradualy cleaning up engines that have not been maintained correctly. This really only applies to modern cars. I do not advocate this in old vehicles. Just what I do. I'm comfortable, it works for me!

ATF has an acid in it for the friction clutches in the "slushbucket" so they don't slip all the time and burn up.
While it is highly detergent, I wouldn't run it in an engine as a lubricant; unless only for a very short period, like 30 mins.
It's just too hard on seals..........Ever see an Auto trans. that doesn't leak or have a "weeping" seal?
If the inside of your engine is that dirty, try a quart of Diesel when you change the oil. Run for half an hour, then change the oil. You will have to change the filter too (if so equipped).
Change it again in a couple of hundred miles to make sure you get all the diesel out.
This worked for me on an old 283 that had been out in the rain with no intake on it.
It ran 40k and 5 years after........

No air filter?.........Bad deal

Good luck!

JYF,, Glad I come and check on where you guys are hiding out once in a while. WOW!! When they say "different strokes for different folks"- I now know what they mean. There are hundreds of ways to "shade tree mechanic" fixes on these old I6 235s but that is all they are. I will admit that I am probably the laziest guy you ever saw but the other thing is- I just plain have to "do it right" and do it ONLY once. I wouldn't advise nor suggest using ATF in an old 235, especially if it is something you wish to keep. If you are wanting to pretty it up for a potential buyer, then it will make your oil "look good" but sure isn't gonna help the engine much. Same goes for using Diesel, it is only a "shade tree" trick. These 235s are really simple engines and if you follow some simple rules working on them is easy. When I rebuild an engine I always advise changing the oil every 1,500 miles. Most would say you don't need to do it that often, but it doesn't allow impurities to build up and usually your oil is old anyways because you aren't getting to many miles in a short time. Don't use detergent oil in an old 235, (unless it is a newly rebuilt) and when you use ATF or diesel be aware that you may dislodge deposits that could plug a vital oil line and then give you really big problems.

Now, as to your rear main seal leak. There is a "tech tip" that I wrote that is really "Blonde" proof. If you run into any problems or confusion with it just email me and I will assist you.

Rear main seal replace

Thank you very much Oly,

You are a true gentleman and a saint!



The ATF seems to have knocked out about 90% of the problem, for now. We are going to put in the Mobil 1 oil today and then watch to see how everything goes.