My son and I have been building a 261 for one of his projects. Yesterday, we installed the gauges and plumbed the lines, and basically buttoned up the motor in terms of oil. Dropped my pre oiler in place to pre oil the motor before I dropped in the Langdon HEI I have for the motor, spun with drill, and promptly had 3/4 quart of oil dump out from what looks like the rear main seal.
The block is a Canadian Pontiac block, 59. Now I have to go back and double check that.
In the meantime, I am starting to second guess myself as to whether I put the seal in backwards, or this block is going to need a rope seal. First time I have ever had this issue and it is either my fault, or it’s my fault, lol.
At any rate, can anyone tell me if I have this seal in backwards?
I did. I think I am going to have to pull the newly installed trans, flywheel, pull the motor, then the bell housing, and then preoil it again and sort out what this is doing. Maybe it’s not the rear main seal. Maybe I did something else dumb. It was a lot of oil.
It’s possible. I had not thought of that possibility. Now that you say that, I think what I am going to have to do maybe is Take out the trans, pressure plate and flywheel and the sheet metal baffle. Then use the preoiler and pressurize the system. Might be able to sort out whether the oil is actually coming from the rear main or someplace else. If it’s the main, then I will have to pull the motor. If it’s not the rear main, I will block up the rear of the motor and remove the bellhousing and see if the oil is coming from one of the new oil galley plugs or the rear cam plug.
The rear seal is possible I suppose, but I'd say unlikely, Mike. I say that because except for the area I already mentioned...where the cap connects to the block, there is no pressurized oil going to the rear seal area. It is hard for me to see most of a quart flying out through the rear seal even if you forgot to install the cap bearing. (we can see the bearing for the block is in place). Gravity would be your friend there and the oil would just dribble off, anyhow. Oil galley plug, camshaft plug...yes, a failure there would pour a lot of oil out, but I think you would have seen a problem when you put those in.
One thing I did notice is the top rear bearing sits more below the surface of the block than I'd expect. Could you post a picture of the cap with its bearing installed?
Depending on the clearance you left at the rear main bearing (hopefully .001" or so), not much oil will squirt out of there normally. A lot of blow-by will force more than normal oil past the rear main seal, but your engine wasn't running.
And you already installed the flywheel, so I'm assuming you put thread locker on those threads. You can get a bunch of oil through those holes if you try this before putting on the flywheel, but I'm certain you know that.
Did you feel the back side of the head?
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Jon, thanks for the questions. Bearing clearances all came within specification. End clearance within specification. Flywheel was installed. No oil on back of head, coil bracket was installed. Oil pan dry. It looks like it was between the flywheel and the bellhousing. At first glance anyhow.
I kinda threw in the towel at that point. At one time in my youth I could lift a four speed on and off, but no longer, lol. So I have to arrange for some help to get the trans down. Then I can pull the pressure plate and flywheel off.
One more question. Did you check the clearance between the rubber seal and the crankshaft end piece? I usually do that when I have the block on the stand upside down. I use a common piece of copy paper about 1/2 inch wide. Lift up the crank (no caps on it yet), set the paper in across the rubber seal about 1/2 inch and set the crank down. Then try to slip the piece of paper out the back end. It ought to be tight...the copy paper is .004" thick. If you have something less thick (maybe .001" shim stock) you can use that. At any rate even .001" thickness should have perceptible resistance. You don't want too much but you want some. Hard to put into words.
Yeah, I have those memories about laying transmissions on my chest and scooting out from under, also. Plus some others that have nothing to do with engines, transmissions, etc.
Good luck. I'll be curious about what you find, Mike.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
Jon, you were right. Not the rear main seal. My son and I took the trans, flywheel, clutch and bellhousing off. Dummy over here forgot to install both of the rear oil galley plugs.
We installed the plugs with a little anaerobic sealer, then a little rtv on the outside edges after the install. Will let that stuff set up until tomorrow and will pre oil the motor again. If no leaks, put it all back together again.
Thanks for the update, Mike. I've been wondering. Sorry you had to do all the extra work but the puzzle looks solved now. Hopefully it isn't as summer-like in PA as it is here in sunny TX.
That independent front suspension looks nice there!
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
That's great when a rear main seal leak turns out to be something easier to fix.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
