Topic: 59AB engine oil leak on 40 Ford Coup


Dick    -- 08-13-2021 @ 5:34 PM
  My 59 AB engine performs and runs great after solving the condensor issue.
Now I want to tackle the usual oil leak that I have been told is probably caused from the car sitting too long prior to me obtaining it. I have driven it over8,000 miles and tried a lot of things including running Rotella and Lucas oil stabilizer. We think it is the rear main seal. I have heard there may be a way to install a new seal without pulling the engine. Any advice and tips will be appreciated.
I run the diaper and it works well but my leak is just worse than it should be.
Dick McSpadden


ford38v8    -- 08-13-2021 @ 7:29 PM
  Dick, to help determine if your engine’s oil leakage is normal or abnormal, please answer the following questions:
What oil weight are you using now, and how long have you been using it?
Do you have an oil filter installed?
Exactly how much oil do you put in, including the oil in your oil filter if you do have one?
Is the car normally parked on level ground, and if not, is it parked uphill or downhill?
Is the leakage measurable, is there a catch pan underneath?
Do you add oil between changes?
Is all the leakage from the hole with the hanging cotterpin at the bottom of the clutch cover?

Alan


Dick    -- 08-14-2021 @ 12:06 PM
  Reply to Alan:
She’ll Rotello 15-40 Lucas stabilizer
No oil filter
4 quarts to fill line on dipstick
Always parked level ground
Leak could be measurable, at present Iuse the “diaper” but I will put a bucket under and measure it.
Mostly dripping from cotter pin.
Change oil at 2000 and due mostly to leak add 1qt est ever 600 miles.
Not smoking or fouling plugs.


ford38v8    -- 08-14-2021 @ 1:11 PM
  Dick, I was hoping for a clue to indicate something other than the seal. Not. Can't help you on the seal, but about the lack of smoke, any smoke from oil burning would be white, contrary to what one would think to be black, which is from a rich mixture. 600 miles/quart is a lot. Have you done a compression test? How about blowby? How many miles on the engine? If you go to the trouble of changing the rear seal, you might also consider a ring/valve job while you're at it. These old engines are not like the modern in that they rarely get up to 100k miles before needing a rebuild. If you have the space and the mechanical aptitude, a ring/valve job can be done at home.

Alan


carcrazy    -- 08-14-2021 @ 3:35 PM
  I would not change the rear oil seal for a leak of 1 quart per 600 miles. Many old engines with some miles on them will use that much oil or more. I know the leak is an annoyance. If you just place a cookie pan under the engine when the car is parked in the garage it will minimize complaints from your lady.
For oil try using a conventional straight SAE 30 Weight Detergent oil with a ZDDP additive to reduce valvetrain wear. The 30 weight has greater viscosity than the multi-grade you are currently using and should considerably reduce the amount of oil leaked.


Dick    -- 08-14-2021 @ 4:26 PM
  Thanks for the advice guys. The engine had 231 miles on it when I got the car..
It has 8,785 miles on it now. The fine old fellow who did a good amateur restoration on the Coup passed away and the Car sat in a barn for 3 years. It has leaked ever since I
Acquired it and after flying my 1950 Navion for 40 years , I just can’t stand oil leaks.
Also leaking a quart every 600 miles is just too much as Alan said. I had to be a little handy to fly that Navion for all those years but at 83, just don’t trust my mechanical skills so much anymore but I still fly.
It is not a “Dearborn candidate by any means but I drive it and it is a crowd pleaser.
I was hoping to be able to have a seal installed without pulling the engine, if I have to do that, I will take the advice to do the other work mentioned. Thanks for the advice



JayChicago    -- 08-16-2021 @ 7:52 AM
  Carcrazy, I don’t understand this:
“The 30 weight has greater viscosity than the multi-grade you are currently using and should considerably reduce the amount of oil leaked. “

He is using 15-40 with stabilizer added. I would think straight 30 weight oil would have greater viscosity only when cold, which is a small fraction of the running/leaking time.


len47merc    -- 08-16-2021 @ 11:18 AM
  Bob, if I placed a cookie pan under the cotter pin on the '47 I can absolutely assure you that would not minimize complaints from my Lady! The opposite maybe!

Steve


carcrazy    -- 08-16-2021 @ 12:15 PM
  A multi-grade oil does not get thicker as the temperature increases! It thins out less than a single weight motor oil would as it heats up. The base weight oil for a 15-40 weight oil is SAE 15. The straight SAE 30 oil will not leak from the engine as readily as will a multi-grade.


ford38v8    -- 08-16-2021 @ 1:01 PM
  Dick, with only a couple hundred miles on the engine, it would have been you to break it in. If not fully broken in with a break in oil, the rings would not seat. Do a compression check to verify ring seating. A warm engine with oil squirted in the plug holes will test higher compression than dry if rings are faulty. Compare readings wet/dry on all cylinders.

Alan


TomO    -- 08-17-2021 @ 7:35 AM
  Carcrazy, I think that you have the viscosity change of oil backward. The 15-40 oil has the viscosity of 15 weight oil when the 15 weight is cold and the viscosity of 40 weight when the 40 weight oil would be hot. The 30 weight oil will thin out at operating temperatures and have a lower viscosity than the 15w-40 oil at operating temperatures.

Oil viscosity does not seem to be a contributing factor in leaks. A 5W-20 oil seems to leak just as fast as a 20w-50 oil.

Dick, I would follow Alan's advice about the compression check. If the engine sat for a number of years, it is possible that the rings could be stuck and not controlling the oil consumption. I seriously doubt that you are leaking a quart every 600 miles. My Lincoln drips oil from the drain plug and the oil consumption is about 0.5 quarts in 2,000 miles. There are 45,000 miles on the car and engine. ( I wish that I could find a fix for it, but new drain plug gaskets do not seem to have an effect on it. It is too hard for me to crawl under to see the source of the leak and I have had to leave it up to others to diagnose the leak source)

To replace the rear seal, you will have to drop the pan, and I have found it easier to pull the engine to get all of the seals on the pan and crankshaft seated correctly. If you do replace the seal, use a modern replacement for the rope seal. They seem to seal better.

Tom


JayChicago    -- 08-17-2021 @ 7:55 AM
  “The base weight oil for a 15-40 weight oil is SAE 15. The straight SAE 30 oil will not leak from the engine as readily as will a multi-grade. “

But we are talking here about leakage past the rear main seal. I thought that seal will only be seeing oil and leaking while engine is running, while oil is warm. Shouldn’t see any oil when engine is sitting, when oil is cold. Am I wrong about that?



37RAGTOPMAN    -- 08-17-2021 @ 12:59 PM
  hi
I would check the oil breather, it might be clogged and causing pressure in the crankcase causing the oil leak
also do a leak down test and a compression test,
do the compression test dry and wet, see if the compression rises,
check for blow by, take the oil breather pipe off and see if it puffs,out fumes
let hear how you made out,
my 2 cents 37Ragtopman
also check your OIL PRESSURE SWITCH on the back of engine for oil drips, seen it before

This message was edited by 37RAGTOPMAN on 8-17-21 @ 3:44 PM


carcrazy    -- 08-17-2021 @ 3:05 PM
  Dick, Do you know if the original oil pump was replaced with a later, higher pressure/higher volume pump when the engine was overhauled? If so, this could be causing an oil leak past the rear main bearing oil seal.


missouriron    -- 11-09-2021 @ 4:33 PM
  I'm having the same experience with my 40 4dr. It was restored 12 years ago and parked. I run the engine 7 to 8 minutes and was able to loosen the valves so that the engine doesn't snap, krackle and pop any more. But I collect a little over 2 ounces of 30 weight. It doesn't drip, it pours.

I was hoping that you would get some info about replacing the seal without pulling the engine.

Ron


TomO    -- 11-10-2021 @ 5:05 PM
  Ron,

Ford used 2 different styles of rear main seals. The most common on a 1940 engine would be the "slinger type". This is a thin disc that rotates with the crankshaft. It fits in a potmetal piece V groove and deflects the oil that come from the rear main bearing back into the oil pan. This type of seal is not replaceable. It works very well when the rear main bearing does not have excessive clearance, the original 50# oil pump is still in the car and the pipe on the rear main bearing cap is in place. On steep hills, some oil will leak past the slinger into the clutch housing. That is why the cotter pin is there.

The other type of rear main seal used is the rope type seal. These work very well until they dry out and become hard. This type can handle the 80# oil pump better than the slinger seal. This seal can be replaced. The normal way to replace this type of seal is to remove and clean the pot metal pieces that hold the seal, replace the pot metal parts back in the block and then replace the seal. I have never done this without disassembling the engine, but there are people who claim to have replaced the upper seal by using a piece of wire to remove the old seal and pull in a new seal.

The reason that I have never tried to replace the rope type seal in the car on a 37-48 Ford is that dropping the oil pan is a bigger hassle to me than pulling the engine. To pull the oil pan, you must unbolt the wishbone at the ball joint, brace it to give you clearance for the oil pan, remove the engine side pans, remove the exhaust cross over pipe, jack up the engine and support it so you can get at the front bolts on the pan and have enough clearance to get the oil pan clear of the front cross member. Then you have turn the engine over to find the sweet spot where the front crankshaft counter weight will allow enough clearance to slide the pan back to clear the front cross member. When you reinstall the pan, you must be careful to not disturb the cork oil pan seal on the rear main. It is much easier to do this on an engine stand or with the engine laying on the floor top down, than lying on your back fighting the counterweights, wish bone and frame while you are trying to line up the bolt holes.

I hope that I have been able to help you make a decision on which way to go to fix your oil leak. If you need more help, or a better explanation, I suggest that you start a new topic devoted to your circumstances. The people on this Forum will help you any way that they can.

Tom


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