21 replies to this topic

[Crestside]

Hello, good folks!

 

I have yanked the 850 out of a '67 Moke in order to replace/strengthen a motor mount as well as try to pin down the perpetual notorious leaks.

 

The motor/gearbox seem to always be covered in a layer of fresh oil, so it's been difficult to pinpoint any one leak. Hence, I have/will be replacing diff output shaft seals, timing chain gasket, oil filter housing gasket, tappet cover gaskets, fuel pump gasket, speedo output gasket and crank pulley seal, as well as the main gear/clutch seal (also changing out the clutch disc while it's all off). 

 

I was not sure whether I am up to the latter task (clutch and main seal), but I think it's a reasonable job with a flywheel puller and the seal install tool? What is the recommended way to actually get a grip on the old seal and pull it out? This can all be done with the clutch housing in place, right?
 

I've read that the half-moon seal between the block and tranny housing is a typical leak culprit? Can this be replaced without having to take apart the whole backplate (is this typically a source of leaks?) and timing chain assembly? (I'd really hate to have to mess with cam timing). Is it an even more laborious job to separate the block from the tranny to slip in the new seal? What is the verdict on the semi-rigid vs. soft ones? (I have one of the latter laying around from the AJM804B kit).
 

Also, is it worth it to mess about with the chunk on the LHS of tranny (where the speedo gear sits)? I noticed there is a cap on this with a rod inside? 

Thanks in advance!

Edited by Crestside, 26 May 2020 - 01:23 PM.

[Crestside]

Any input on this?

 

Just went ahead and ordered 400 pounds worth of parts as well as a Haynes manual.

[nicklouse]

First you need to work out where the leak actually is from.

 

you can get some UV oil leak additive. Clean engine etc. Add trace run engine. Turn on a UV (black light) source then you will know where your leak is.

[Spider]

If it's never been apart or some time since it has, I'd suggest replacing all gaskets and seals. It's not a huge nor difficult job and about the only special tools you'll need (that comes to mind) is a flywheel puller and a Primary Gear Oil Seal installer.

 

If you buy gasket sets, just be aware that not all sets are 100% complete. I'm yet to see any that includes for example the speedo drive seal and distributor sleave seals.

[Crestside]

I am pretty much replacing the lot - I had a "complete" gasket kit (missing tapet cover and speedo gaskets) laying around, but I am still unsure of the process for replacing the half-moon seal (have ordered a rigid now as well) and whether it can be replaced without having to take apart the whole backplate and timing chain assembly? Also, not sure if the LHS "chunk" on the tranny is worth messing with (i.e. does it entail gears and bearings)?

[Crestside]

Anyone able to provide feedback on this? Input is greatly appreciated.

[GraemeC]

 whether it can be replaced without having to take apart the whole backplate and timing chain assembly? 

 

No it can't. Timing gear and backplate must be removed.

(and that is using the rigid seal, for the soft seal the gearbox must be removed too).

 

Don't know what you mean by the LHS 'chunk'

Edited by GraemeC, 27 June 2020 - 03:57 PM.

[Spider]

By 'Chunk' I think you mean the Speedo End Drive Cover ?

 

Item 24 in this diagram

 

http://www.minispare...ion.aspx?1~4~34

 

[Crestside]

My apologies! I had forgotten all about this thread. 

 

I believe #24 is the one - it's the bit below the main pulley which the LHS motor mount bolts to. I don't know if this is a common source of leaks and whether it's worth to mess around with?

 

Does anyone have a decent write-up of how to replace the half-moon seal? How do you make sure the timing doesn't unsync? I bought the rigid variety seal from Minispares. 

 

Thanks in advance!

[absx2]

Sorry it`s a bit late for you Crestside but I have found that quite often the oil leak on the timing gear side is caused by the tappet cover seals, either the bolt O ring or the orange rubber is deformed, misaligned or rotten and the oil finds its way to the lowest point and we blame the crank seal or half moon seal.

Same goes' for the rocker cover

 

It might be of use to someone reading this in the same position 

[Spider]

Wholly Cow,,,,, thread resurrection !

 

It's unlikely the Oil Leak is from the Speedo Drive Cover, often it's oil leaking higher up that accumulates on this cover (as it's the first horizontal surface on the way down) that can give the appearance that it's this that's leaking. All the same, it it very straightforward to remove and replace this cover. You will however likely find that the Speedo Drive Seal will need replacing. Item 36 in this drawing;-

 

http://www.minispare...riv.aspx?1~4~41

The source of your oil leak typically would be the half moon seal (as you originally set about doing), the timing chain cover gasket, though, not through any fault of the gasket, but distortion of the cover, the pulley seal, be aware the cover needs to be centralised when refitting. It may also be from the head gasket, as the pressure oil feed is above this end of the engine. It's a little rare, but definitely not unknown.

 

Be aware too, you'll need a 1-5/16" Socket to under take these tasks, but otherwise, it's just basic hand tools.

[croc7]

First you need to work out where the leak actually is from.

you can get some UV oil leak additive. Clean engine etc. Add trace run engine. Turn on a UV (black light) source then you will know where your leak is.

Agree with Nick on this one. Fluorescent dye into the oil, run the engine and have a look with the black light. Its amazing how well it works to pinpoint the source(s) of leaks.

[Crestside]

The fluorescent die is definitively a top tip for the next time around.

 

I believe I have a new speedo drive seal in the parts pile, but my speedo 'connector assembly' is plastic and not aluminium in the schematics that the seal seem to be intended for? 

 

I was able to tear down the timing chain assembly and uncovered what is likely the offender of most of the leaks on this side of the engine. The half-moon seal was the OEM cork variety (!), and probably never touched since 1967. Now that the cork leftovers have been picked out, the question remains how to proceed? I really want to avoid splitting engine/gearbox.

 

I have two different versions of the soft seal and one of the rigid variety - they all seem to differ slightly in terms of profile and length. The rigid variety is noticeably shorter and actually seem to leave a gap on each side, while the softies seem slightly too long and are difficult to push in all the way to the flat face. One of the soft versions was easier to get to seat inside the space, so I think that's my best chance (maybe just trim it slightly)?

 

Do you recommend combining the rubber seal with a certain sealant/silicon, and if so which (type)? Also, any tips on the reassembly? Is applying the gaskets dry the preferred method? Is it a bad idea to leave the old gasket (it's really fused on there) and just put a new on top, on the backing plate of the timing assembly?

[nicklouse]

The soft is for fitting when the engine is split.

 

the ridged is for fitting without splitting the engine.

 

I would split the engine.

[Crestside]

The rigid one is several millimetres undersized as it is, and I don't think splitting the engine would make s difference in that regard.

What kind of precautions must be taken if splitting the engine/gearbox? Any good guidelines? Kinda sucks that the whole clutch assembly that I just put together must come apart again.