Crack in bell housing

[Adam]

I have noticed a reasonable amount of oil under the haf after each drive. I think it is transmission oil, and after closer inspection looks like it is coming out of a crack in bell housing. Had engine out not long ago to replace clutch and think the only place oil can come from is seal where engine shaft goes through?? Didn’t replace seal when engine was out but may have damaged it trying to line up engine and clutch when putting back in?? The crack in the bell housing is a concern, looks like a weld line where it has cracked? Is this normal or has casing already had damage and been repaired??
Very vague info sorry, guess I’ll have to take engine out again and look inside casing!
I still have the bung in bell housing, maybe I should take that out first as I may have overfilled transmission oil, therefore leaking through seal into bellhousing, then leaking out crack in side of bell housing??
Can the bell housing be repaired with welding easily?? Looks like one casing for whole transmission??
Any help would be greatly appreciated, and I could be way off the mark with my ideas!!

[heinkeljb]

Hi Adam,

Sorry to hear of your troubles. Bell housings don't usually get broken unless they get "thumped" rather hard. First thing to do would be to take out the bolt in the bottom of the bell housing as if you have a build up of oil in there, it will end up on the clutch plate and you will get clutch slip from a contaminated clutch plate.

Try getting some of the oil between your fingers to see if you can work out if it is gearbox oil or engine oil. Either seal could be leaking.
Bellhousing "could" be welded but it will require someone who has experience in welding "old" Aluminium castings as it will need warming up before being welded and then being wrapped up to cool very slowly or it will just crack along side the weld as Aluminum cools.

As you have seen, the Bell housing and the Differential / Gearbox casing are all one piece. Is your Haf a four speed, or a four speed with Krawler or a five speed? I wonder how difficult it would be to find another Diff / gearbox in Australia?

John

[Adam]

Haf is a 5 speed, and transmission seems to be in very good condition, so it would be very sad to have to remove everything to put into a new casing as that might be a job a little out of my league. Do the casings normally have a weld mark vertically up the bellhousing? Or would this be a previous repair??
Exhaust is tight under the drain plug so will have to remove to release plug.
I would have thought seal from engine shaft into transmission would have been at a higher level than the oil level in transmission???? So even if seal was damaged very little oil would leak through?
Is that a correct assumption??
Thanks for your help John. I am about 90% sure the oil is transmission and are hoping that I over filled transmission oil, and can get casing weldid up and seal replaced and be all good.

[AustHaflinger]

The crack in the bell housing is a concern, looks like a weld line where it has cracked? Is this normal or has casing already had damage and been repaired??

There is definitely no welding on the gearbox case/bell housing. I assume the old weld is on the bottom where it has taken a whack in the past and been welded up. Do you think the crack extends into the actual rear diff area letting oil to leak out there?

While there are no engine mounts and the engine hangs off the bell housing, I would not have thought there would have been enough stresses to crack a weld in the cast aluminium - I suspect that as John has alluded to the heating/cooling process when the weld was not done correctly and the crack actually started in the cooling process when the weld was done.

I am not able to offer much in the way of advice other than finding someone who can do a metal stitching repair something like this https://www.youtube.com/watch?v=5_doBwALJ5Q

I think to do a reweld correctly would be difficult with out dismantling the gearbox/diff.

The other possible way, as the area is not all that stressed would be to just drill a small hole at either end of the crack (assuming both ends are still in metal) to stop the crack progressing and leave the crack there. There is obviously some risk but if this did not work then you would have to look at other options anyway.

So some options to consider - but you do need to resolve the leak - is it a big leak that requires rectification or a small leak that has just built up in the bell housing and then leaked out.

Good luck with it.

Garry

[heinkeljb]

Post some pictures of the leak. The very first thing you should do is clean the whole area - Oil can move a long way from the source and give false impressions.

The pivot pins for the rear axles are known leak points so it is possible you are getting oil from there and it is showing up under the bell housing. I'll take some pictures later of an empty gearbox / diff casing and post them. Then you can see if yours is similar or not.

Engine oil is under pressure through the crank so if the rear oil seal is damaged, it will leak from there. It is also possible that the engine has been put back in badly at some point and has been allowed to rest on the gearbox input shaft. This can bend the shaft which then knackers the oil seal and could I suppose do other damage the casing, but far more likely a crack would be caused by the casing being hit. Probably whilst off roading.

John

[Adam]

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[Adam]

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[Adam]

Cracks are certainly not just paint cracks, fairly significant cracks almost half way around housing!!

[Adam]

Cracks are certainly not just paint cracks, fairly significant cracks almost half way around housing!! The cracks don’t seem to run towards transmission, just in a ring in line with clutch.

[AustHaflinger]

Wow - that is intriguing. From my limited knowledge that crack looks like it is a result of the welding process. As for why it was welded in the first place - where it is, and how long it is I very much doubt it is the result of a bash from under.

You said the crack is around the bell housing in line with the clutch and this is the clue for me - without other information I think the clutch/flywheel has disintegrated and damaged the bell housing resulting in the crack. When you have had the engine out is there evidence of damage on the inside etc.

Irrespective of the why for's etc - action is needed. It is hard to see but I would drill a hole at each end of the crack to stop it growing and then leave it and monitor it closely - yes there is a risk. If the crack continues then the engine and gearbox/bellhousing need to come out and the issue needs professional welding attention.

Please let us know what you do.

Garry

[Adam]

My clutch did recently let go, pressure plate fell to bits and caused some carnage inside!! Maybe this aggravated the existing weld?? Cracks are too major to leave, so out with the engine, again, get bell housing welded hopefully, work out which way oil is coming from, replace seal to transmission, cross my fingers and hope for best!!

[heinkeljb]

Hi Adam,

Your transmission has had some previous bad luck in no uncertain terms!

So this is a standard bell housing picture - it appears from the two pictures you posted and your comments that basically it has been welded all the way round the bell housing.
Given that the engine is suspended by only the four bolts to the bell housing. If the cracks are now more than a couple of inches long then you are in serious danger of your engine falling out of the back and it will take the gearbox input shaft with it!
I know it is not something you want to hear, but you will have to take the engine out again, so you can get a better look at exactly where and how long the cracks are.
Plenty of cleaning fluid and a brass wire brush to clean the areas up both inside and outside. It looks like it has been painted black on the outside, that will all have to come off so the cracks are clean.
Obviously a professional welder who has experience in welding old Aluminium crank cases would be the prefered choice to do the repair work, but I think they would want the casting out of the Haf AND emptied of all the internal gears etc.

As I wrote earlier, the casing would be heated prior to the welding (the cracks would be ground out to remove any oil that might be in the cracks which would contaminate the weld). Then the welding would be done and the whole casing wrapped up in asbestos (or what ever they use now) blankets so that it would take hours to cool down to the point you could handle it.

To be honest, I think you might find it more cost effective to source another casting. Then either use the new gearbox / differential (if you get one with internals) or transfer the internals from the one you have to the new casing. Yes, there are some parts of the operation which seem to be complicated, but possibly there is someone in Australia who could build it for you? It is definitely possible to do it yourself, the workshop manual for all that it is not detailed like a Hayne's manual should provide enough information to do the job.

John

[Adam]

Don’t you hate it when you get told the reality of a situation and you really don’t want to hear it!!!
I thought if I could get casing welded leaving all the internals in it wouldn’t be too bad a job, however if all the internals have to come out, I don’t think it would be worth the risk of using old housing!! Shame because gearbox and transmission seem in really good order, although I suppose you never really know. I think I would be up for stripping down gearbox with some help from friends, I have workshop manual . Would haflinger technic possibly have a casing, and maybe a seal and gasket kit????

[heinkeljb]

Adam,

I think if I were in your shoes I would take the engine off,clean up the inside and outside of the bell housing to try and find where the oil is coming from. As you say most likely the gearbox input shaft seal, but maybe the engine crank oil seal.

Then unfortunately, remove the differential / gearbox which will require you to do the following:-
Drain the oil from the gearbox.
Remove the rear wheels, jack and axle stand on the central tube (so you can adjust the height).
Loosen all four platform mounting bolts.
Disconnect the hand brake cables on the hubs.
Disconnect the clutch cable, AND slide the rubber sleeve under the drivers seat up the tube to expose the clutch cable.
Disconnect the brake lines to the hubs, remove the flexible hoses.
Disconnect the gear linkage - Make a straight line mark across the discs which provide the gear linkage adjustment so you have something you can line it all up again with when you put it back together.
Now you can remove the rear two platform mounting bolts
Start jacking the rear of the platform and check I haven't forgotten to tell you to undo / remove something!!!!

Keep checking the front two mounting bolts are loose but not removed - as you want to try and keep everything in line.
Keep checking that you haven't kinked the clutch cable too badly.

Eventually you will be able to get he platform up high enough to undo the 8 bolts that hold the central torque tube to the gearbox and slide the transmission out. You might have to lower the gearbox slightly but just remember that the rear end will go up slightly as you remove the weight of the platform so when putting things back together the gearbox will have to be tilted a bit to line up on the shaft properly.

See this also: http://www.haflingertechnik.com/ftp/tec ... dfs/10.pdf

Once you get the whole transmission out, you can remove the platform holding tower.
Then you can remove the differential side covers, make sure you remove the drain bolt as the magnet on it sticks up into the differential housing.
The workshop manual will tell you which side to remove first, I think it is the right hand side as looking from the bell housing.

Once you have the transmission down that far, you could take it to someone who professes to do Aluminium welding and see what they say about doing any repair work on the cracks.

What have you got to lose? You already don't have a useable transmission, so it if they say they can repair it, great. If it fails, then you have your transmission in the state you require to swap stuff over.
I would at this point also be on the look out for a replacement transmission - even if it is a 4 speed version, because at least then you can have a running Haflinger rather than a pile of bits!!

John

[Adam]

Awesome, thanks heaps for your help John, sounds relatively straightforward!!spoke to dale at Haflingertechnik, they have new and used casings but cost of shipping would obviously be big, and he also scared me talking about re shimming gears and selectors, I dare say well out of my pay grade!!!! Will start by removing transmission and go from there! I don’t have too much time on my side at the moment so will see how I go!!!!
Thanks again, Adam

[heinkeljb]

Yes, there is shimming involved, but like any jigsaw puzzle - one step at a time. The workshop manual and a competent gearbox company should be able to do it.

Hopefully, one of your countrymen has experience putting gearboxes together and will chime in. If you can afford to wait while things are shipped to you, then sea freight shouldn't break the bank...

Take pictures and post them, then we can watch your progress!

John

[Adam]

Cheers John, Dale from Haflingertechnik has seen this cracking before??
Like I said, perfect outcome would be to get casing welded with internals intact. If I have to remove internals I might as well have a new casing is my thoughts.

[Adam]

Engine out, bell housing had about 150ml of oil in it, pretty sure transmission oil. Seal to transmission was stuffed, but still can’t understand why oil coming out of that seal when seal is quite higher than high oil level. Can engine rear seal be changed without pulling engine apart??
Will start removing transmission tomorrow night hopefully.

[Julian B]

It can inasmuch as IIRC the seal is put in after the two engines halves are joined together.

[heinkeljb]

Check the input shaft to the gear box is straight! If it is bent it is scrap as it will wreck every oil seal you put in.

Gear fling oil around quite effectively so it is quite possible there is a ledge of valley into which the oil drains after being flung around inside the gearbox. It will then drain out via a knackered oil seal.
John