TR4/4A Rear Main Seal TR4A

[KVH]

I have rear main seal leak. It's not exactly just a few dribbles. It's a bit more than that. I need to check further, but it looks like a good two tablespoons after a long drive and then sitting for a few hours.

Can I just watch the oil and live with this, or do I need to set aside some time to take the engine out and apart?

Life wouldn't be fun if these cars were flawless.

Oh, and I guess I should ask. The PO put a "lightened flywheel" in the car. I can tell it's probably good for performance, but it seems a bit harsh. Could that put more stress and wear on the main seal?

thx

 

[Geo Hahn]

2 tablespoons would bother some folk, I would be more likely to live with it and watch & wait (for a bigger reason to pull the engine).

BTW - a little oil goes a long way so if you're judging by the puddle perhaps it is even less.

 

[Geo Hahn]

Okay, I don't do much in the kitchen so I had to look it up -- 2tbsp = 1oz.

An ounce of oil everytime you park the car does sound a bit much (and probably makes you wonder what you lose at speed). I suppose oil consumption would be a clue to the latter.

 

[Moseso]

There is no contact between the stock oil seal and the crankshaft. The "harshness" of the flywheel should have no effect on the seal. Even if you have one of the later replacement oil seals, the seal is right behind the main bearing. It would take some pretty ferocious shaking to cause early seal failure. I don't think the flywheel is to blame.

 

[RJS]

More than the rear main seal, see if you can check whether the crankcase is venting properly. Even the smallest pressurization in the crankcase will push oil out the rear main seal.

The original PCV system on the TR4A was marginal at best. If you still have it in place, take a test run without it. Remove PCV and rubber hoses, cap the port on the intake manifold with a little rubber cap, and just run a 1/2" hose off the valve cover vent. Test drive for 20+ mins.

I used to get the oil leak just like you. With better crankcase venting I now only get one tiny drop after an hour of hard driving (and I suspect it is from a bad gasket on my fuel pump or timing chain cover).

Bob

 

[KVH]

On my 4A, the prior owner removed the PCV and left the valve cover vent open. He also removed the block freeze plug and reinstalled the stock TR4 breather pipe.

So . . . it looks like I just have a bad main seal.

I rechecked the amount of oil. I suppose it's more like one tablespoon after 24 hours.

 

[HerronScott]

On my 4A, the prior owner removed the PCV and left the valve cover vent open. He also removed the block freeze plug and reinstalled the stock TR4 breather pipe.

I'd try to find a TR4 valve cover with the TR4 vented oil filler cap if you already have the TR4 road draft tube.

Scott

 

[KVH]

To replace the rear main seal, the crank must be removed? Correct? Aren't the bolts behind the flywheel?

 

[TR3driver]

Yup, it's definitely an "engine out of the car" project. On top of that, there is a special tool required, and the dimensions given in the shop manual are wrong (as is the tool being sold by at least one major vendor).

BTW, there will soon be a new "improved" seal available through (Joe) Alexander Racing Equipment. Too soon to say for certain, but it sounds like it should work significantly better than the "improved" seals currently on the market; plus it reportedly does not require having the crank machined (so you can go back to the original if you choose).

 

[MoHealey]

Randall,
Digging up this old thread to ask yet another question...
Can you tell me where I might source the locating mandrel?
..one that's the RIGHT size, that is, for a TR4?
Thanks
Bill

 

[TR3driver]

Can you tell me where I might source the locating mandrel?
..one that's the RIGHT size, that is, for a TR4?

Yes, Joe has those as well. Not listed on his web site, but the contact information should be correct:
https://www.the-vintage-racer.com/Contacts/default.asp

BTW, the new seals are now available too.

 

[TR4nut]

Roadster Factory is selling Joe's mandrel from the looks of it now...

 

[M_Pied_Lourd]

Yes was just going to mention it. Looks like the seal and the tool are in the special parts catalogue this week.

Cheers,
M. Pied Lourd

 

[MoHealey]

Found 'em. Thanks!

 

[eschneider]

A few links from the Morgan world (TR4 engines)

I'd love to hear Randall's input on the t-shirt and shellac idea. The concept is well-respected in Morgan circles, as is the guy who came up with it.

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https://www.gomog.com/allmorgan/allmorgan38.htm#MAIN

https://www.gomog.com/allmorgan/TRoilseal.html

https://www.gomog.com/allmorgan/plus4oilleaks.html

 

[TR3driver]

I'd love to hear Randall's input on the t-shirt and shellac idea.

Sorry, I don't have much to say, except that the felt seems to work for me.

One tip is to be sure you have enough felt. Easiest is to have an extra set on hand. You should not be able to get it all in, even beating on the drift with a hammer, so finish by cutting it off (leaving some sticking out to be compressed by the pan).

I cut the felt it into short sections (as per the book) and drop them into a shallow (disposable) dish of Permatex. When I tamp that into the hole, I can see the Permatex ooze slightly all along the joint ... no way is that going to leak.

But using T-shirt material should work just as well, and is a lot handier if there wasn't enough felt in the gasket set.

That's an interesting tip about cutting off the 'ears' ... I've changed the rear main bearing several times with the engine in the car and don't recall those ears being trimmed. But that may be differences in flywheels or something. I've not tried that with the project TR3 yet. In any case, I'll trim them next time.

I've not actually done many full rebuilds; been planning one for the past 20 years or so but never quite got a round tuit. It's amazing what you can do with the engine in the car! Don't tell anyone, but my previous engine actually has shims behind the rod bearing inserts, to close up the clearances with a worn crank. But the crank in the 'project' TR3 is surprisingly unworn (considering that the bearings were worn into the copper), so I left out the shims this time

 

[MoHealey]

Regarding the improved seal...
Any "complications" that I should expect with the one-piece design? Anyone actually ever installed one? I noticed that there is a core for the seal casting, so the mods to it can't be too severe.
It's pricey, and I would sure like to avoid ruining the thing in the process.

 

[TR4nut]

Regarding the improved seal...
Any "complications" that I should expect with the one-piece design? Anyone actually ever installed one? I noticed that there is a core for the seal casting, so the mods to it can't be too severe.
It's pricey, and I would sure like to avoid ruining the thing in the process.

I just finished installation of one of the new seals a few weeks ago. No more complicated than the other modern seals but without the need for modifying the crankshaft. And without the extra machine shop costs I think its pretty price competitive. Instructions were excellent too.