1940 Lasalle rear main seal leaking

jmscan06 · August 20, 2015, 02:46:26 AM

My engine back fired a couple of times and now my rear main seal is leaking a lot. Is it possible to replace with out pulling engine? I corrected the back firing problem. It was a bad wire in distributor.

John Scanlan
CLC # 28099

Bobby B · August 20, 2015, 07:12:05 AM

John,
Hi. They say it can be done, but I've always pulled any engine to do this job. It's SO critical to get the seal flush cuts on the cap/block (along with some sealant) perfect, in order to avoid future leaks. It's difficult enough when it's on the engine stand, never mind trying to do this either upside down or laying on your back. I also wouldn't use the factory style waxy rope seal. I used the graphite type seal made by "Best" on my Flathead. When you compare them, you'll see why the "Best" seal is far superior, and a smart upgrade to avoiding future leaks. While the engine's out, it's a good time to freshen up the engine bay, engine paint, gaskets, etc...

. Hope this helps!
Bobby

Steve Passmore · August 20, 2015, 08:47:52 AM

I dare say there are people who have done it but I personally agree with Bobby. I can't really see it being done effectively as the seal has to be really rammed in there. OK doing the cap but theres a special tool for driving it into the grove in the block and the crank shaft is in the way. When the crank is out I use an old crank to do this job. To remove the crank while in the car doesn't bear thinking about. Quicker to pull the motor.

harry s · August 20, 2015, 09:45:30 AM

Definitely good advice from Bob & Steve to remove the engine. I can't imagine anything worse than doing that job under the car. Getting the main seal and also the main cap cork seals right is very critical to a successful fix. Good Luck, Harry

robert G. smits · August 20, 2015, 01:01:19 PM

Planning on doing my 41 this winter, where do you obtain the "Best" seal. Thanks, Bob Smits #2426

JoeCeretti · August 20, 2015, 01:27:33 PM

It all depends where you live. They have a list of distributors/dealers on their site... http://www.bestgasket.com/

Bobby B · August 20, 2015, 08:04:45 PM

John,
Hi. I purchased it from Marx Parts LLC for $21.00 plus shipping. They had it in stock. Good people, and they carry the whole "Best" line of Gaskets. The Crank in the Flathead is a little tricky getting it in/out due to the physical size of the main counterweight. It can only be in one position. The first time I ever removed one I couldn't believe how much it weighs. I thought something was binding, but it's just so damn heavy! Lot's of Fun that Flathead isâ€¦â€¦.

. Good Luck,
Bobby
http://marxparts.com

Steve Passmore · August 21, 2015, 03:22:55 AM

Quote from: Bobby B on August 20, 2015, 08:04:45 PM
John,
The first time I ever removed one I couldn't believe how much it weighs. I thought something was binding, but it's just so damn heavy! Lot's of Fun that Flathead isâ€¦â€¦. . Good Luck,
Bobby

Second that Bobby.

camelot · August 21, 2015, 08:13:17 AM

Has anyone had luck with the "Chinese finger" tool? I looked at the seal on Marx parts and it looks like the same kit they used in the old FE series ford engines. If you lube the rope seal up and turn the crank shaft as you pull the seal around, it used to work. I would loosen the other Mains to allow the crank to drop just a bit.(also helps with clearance) After getting the seal around and reinstalling the main cap it should crush the upper seal up into the block. I know the Ford seals weren't easy but they were doable in the car. But in defense of pulling the engine it isn't like it is today with all the accessories and wiring. Its just these fenders are so wide. Long arms are a must!

Steve Passmore · August 21, 2015, 09:22:21 AM

A couple of problems doing that Alex is they have to be really rammed in there. I have always found them too tight to slide around. When I use an old crank to fit them one has to really beat on it to get them in. The special tool is also meant to be hammered. One must also leave a small amount protruding once they have been rammed in. Using the cap will pin the ends and prevent this and mess the ends up completely.

camelot · August 21, 2015, 11:45:09 AM

I know I'm gonna have to get to the seal on my Lasalle. I'll save it for a winter project also. Thanks for the advise.

Bobby B · August 21, 2015, 04:50:38 PM

Quote from: Steve Passmore on August 21, 2015, 09:22:21 AM
A couple of problems doing that Alex is they have to be really rammed in there. I have always found them too tight to slide around. When I use an old crank to fit them one has to really beat on it to get them in. The special tool is also meant to be hammered. One must also leave a small amount protruding once they have been rammed in. Using the cap will pin the ends and prevent this and mess the ends up completely.

Steve,
Hi. There was a major difference in the rotational force required to turn that crank once the rear main was in. I'm sure it'll eventually wear in and conform to the journal diameter. It sounds primitive, but it really does need to be finessed in, along with performing clean cuts of the seal ends and sides with just the correct amount protruding.
Last thing you want is to be taking that out again because you rushed it.
Bobby

Steve Passmore · August 21, 2015, 05:34:42 PM

You don't need to tell me Bobby. I couldn't turn the crank at all but it did turn on the starter.

sly37 · August 22, 2015, 09:30:51 PM

I've done many many "ropeseal" to modern rubber based seals. I remove rear main cap, loosens others slightly. Spark plugs out and with a 1/2 in socket and breaker bar. I use simple coat hanger and work the old rope seal out while turning the crankshaft just enough....DO NOT TURN THE OTHER WAY" Coat hanger is a very soft metal and won't damage sealing areas. After its out clean with a small bendable soft wire brush. Install new seal.
S schroeder

sly37 · August 22, 2015, 09:34:29 PM

The hardest part of that repair is getting an old hardened rope seal out. After that it's easy.
D schroeder

gary griffin · August 23, 2015, 09:52:05 AM

I have a tool kit called "Sneaky Pete" (Google it). It consists of a corkscrew with a handle to remove the old seal and a clamp on a cable designed to pull the new seal over the top of the bearing. Simply remove the bearing cap and loosen all of the other caps a couple of turns and use the corkscrew device to remove the old seal. Then push the clamp through the opening and it will come out the other side of the bearing housing, clamp the new lubricated seal and gently pull on the handle and the cable will pull it around. Trim the ends of the seal with a razor knife and put it back together.

Sneaky Pete kits are shown on Google and are less than $10 from several vendors.

The trick is to loosen all of the bearing caps equally allowing the crankshaft to lower a few thousands of an inch so there is enough clearance for it to work.

I have done this several times in the past. The most difficult thing is to get the pan off.

Tom Knoebel · August 23, 2015, 12:21:55 PM

Deon and Gary,
Have the process dialed in.
Only thing to add.
On a lift is Ideal. Some folks rent space by the hour at different club sites and shops. They do at our Local Air Force Base for retired military.
When removing the oil pan slowly rotate the crank to clear the crank weight.
Should rotate easy with ratchet provided plugs removed and in neutral. Block your wheels or be on four equal stands on solid ground.
This is a good opportunity to do the oil pump. Terrell Machine in Texas offers quality rebuilding.
New pan gasket is a must. Wash the oil pump pick up and splash plate. Make sure the oil pump floats and does not hold oil.
Also a dab of RTV sealant at the seams after flush trim helps new rear main.

Enjoy
Tom

jmscan06 · August 23, 2015, 08:25:50 PM

Thanks for all of the great advise. I'm concerned that I may have caused other damage. However the Engine appears to be Running fine. So my next step is to check compression. If it is bad I will pull engine if it is good I will drop the pan take a look and then consider what my next step is. Again thanks for all the great advise.

John Scanlan
1940 Lasalle 5227C

gary griffin · August 23, 2015, 08:43:10 PM

I think you had a flash fire in your pan, indicating leaking from the carburetor. I see no way for a cylinder backfire to blow out a seal but a small explosion (Limited by the amount of oxygen in the sump) could do what happened to you. Has your engine been using excessive gas and have you had gas smells coming up into the cab? Take a look at your carburetor and see if it is leaking and if the float is set properly.

jmscan06 · August 24, 2015, 09:16:01 PM

Gary I was having trouble with my distributor. Engine cut out when I was going down a steep hill going about 55 I did not realize that the engine had stalled. Engine and exhaust must have fulled up with gas and when it restarted there was a loud explosion which I thought came from the exhaust system. I pulled off of the highway and repaired the broken wire in the distributor and continue to Stowe VT. Prior to this happening rear main did no leak. Engine runs fine no problem with carburetor and oil is not diluted with gas. Regardless of the cause I now have a leak from the rear of the engine that is leaving puddles under the car.

John Scanlan
CLC # 28099

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1940 Lasalle rear main seal leaking