Rear Main Seal - DIY replacement?

[davidr]

My SN's engine is leaking oil at the rear main seal (RMS) (mild but persistent slick under the engine and a trail down the vertical face of the bell housing).

How difficult is replacing the rear main seal, on a difficulty scale of 1-10, easy-hard?

I'd need to remove the transmission to access the RMS, also the bell housing and flywheel - will I have to rig up a sling or some such to support the rear of the engine when the transmission is removed?

Since the engine-transmission assembly is supported with two mounts near the front of the engine and two mounts at the transmission, my concern is what happens when the engine is separated from the transmission - are the two front mounts alone sufficient to support the engine without damaging anything?

Any insights would be appreciated.

Thanks
-Dave

[Texas88]

Dave,

New rear main seal ... $29, while your at it, an oil pan gasket ... $49, a chain engine hoist ... $99, a 40 year old Oak tree in your driveway used to pull the motor ... Priceless.

I did the exact same thing on my 88 SN last year. The scale of 1-10 is not real accurate because some folks think changing an oil filter is a 9, but each persons expierence and abilities are unique. It can be done, and it is not rocket science. I found it easier to pull the whole motor and trans together and rent an engine stand to work on it outside the boat. If you have the motor out do a pan gasket at the same time and check your oil dipstick tube seal and your drain plug seal for leaks. If you leave your motor mounts alone and not change any settings you should not have to re-align anything.

BIG ADVICE, DOUBLE STAR ** The rear main journal on the crank can and does get small pits and a small groove in it over time and a new seal alone WILL NOT FIX the leak. (Trust me, I did this job twice ... although the second one went faster than the first). The expensive fix is to remove your crank have it welded, ground and polished, a lot of work. I talked to a very experiencd motor guy and he said he knew right away just what to do. He said in a Very "Southern" type drawl with a bit of chew in his mouth, "Ya need a Shpeed Shleeve". I said pardon me and he repeated a little louder "A Shpeed Shleeve, boy, a Shpeed Shleeve". I asked politely "A Speed Sleeve?" and he said "Thats what I said, a Shpeed Shleeve". He was very knowledgeable and directed my to a high-end speed shop where I got a Speed Sleeve, which is a thin sleeve that you tap onto the end of the crank with a hammer and wood block that covers the pits and grooves making the new seal have a smooth surface for a good seal.

MOER BIG ADVICE, Make sure you get a seal for a correct craft that has a reverse engine. You want a seal that directs the oil to the inside as the crank turns.

So there you have it, the job can be done and it is about a 6 on my scale. Take alot of dig pics and label things so you remember where it all should go. All in all all the work is better than nasty oil in the bilge.

Good luck,

Bryan A.
Austin TX

[davidr]

Brian,

First off, that's a great picture!

Thanks for the tips and the run-through - first I've heard of a "shpeed shleeve", but it sounds like a good idea. I found an online source, rockauto.com that sells speed sleeves for about $10 (they call it a "main bearing repair sleeve").

I have an LH motor, I'll be sure to get the correct seal.

This looks like a significant project that can be broken down into bite-size chunks (like most things).

Thanks again
-Dave

[M3Fan]

Texas88- If you can, please post more pics of the process! I'm sure this could help numerous people if it is well-documented. Looks like you really have a handle on it.

[davidr]

Follow-up question for anyone who knows:

aside from the rotation issue (left hand vs. right hand), is there any difference between an automotive rear main seal and a "marine-grade" rear main seal?

Thanks
-Dave

[83sn2001]

If the oil pan is not leaking I would not replace it because you do not need to remove the engine for the rear main seal.Unhook your coupling from the rear of the tranny,take your tranny mount loose from the engine rail, lift up on the tranny output yoke and place a block of wood under the oil pan.Remove the tranny, bellhousing, Damper plate, and flywheel.There is your seal. Takes the job from a6 or 7 to about a 3 or 4.I have replaced them with automotive seals and have not had a problem.

[Texas88]

83sn2001,

You may be right about not pulling the engine, but if you have the space and equipment to do so it is easier to work on an engine on a stand in the garage than in a space restricted motor cavity. Also if there is anything else you want to do it is out in the open for you to work on. Either way with some time and proper planning and not being in a rush, the job can be done at home saving some (alot) of money and giving one a healthy pride in accomplishment.

Bryan

[davidr]

83sn2001,

Thanks for the comments, I'll try first without removing the engine (wish I had an oak tree).

Bryan,

I've ordered the parts, including a speed sleeve.

[nautiquesonly]

Can anyone tell me the part number for the "Speed Sleeve" I would like to order one.

Thanks for the assistance.

Nautiquesonly

[davidr]

FelPro 16251 "Main Bearing Repair Sleeve"
FelPro 16301 installation tool

I got them from Rockauto.com, I just looked up Ford trucks (F-150, F-250) the same year as my boat and with a 351 engine.

The installation tool is a high-density plastic cup/plate that cradles the sleeve, whack the back of the cup with a mallet/hammer to install the sleeve onto the crankshaft end. Not essential (Bryan A. used a piece of wood instead), I liked it though. About $9 for the sleeve, about $25 for the tool.

I doublechecked on Rockauto.com and they list the same sleeve (and tool) for '82 and '96 engines, so if you've got a 351 Windsor that sleeve should work.

[nautiquesonly]

Thanks Dave appreciate the quick answer. Mine leaks a little and this will be a winter project. We ski about 5-7 days a week and it was only a matter of time until this needed to be done.


Thanks,

Nautiquesonly

Living Life one bouy at a time behind my Nautique.