Manual transmission input seal-worth changing?

[disco stu]

Just wondering if it's worth changing the input seal to the gear box while I've got it all apart? NL 3.5 petrol engine with 5spd manual. Not sure if the input seal goes often in the transmissions

Thought just occurred to me while I'm in the engine bay scrubbing away. It's really really dirty in the bell housing. I'm not sure if it's engine oil or what, but it seems to be a lot blacker than baked on engine oil normally is, which seems to be a really dark brown color in comparison to this.

Anyone changed them on these transmissions? I'm assuming you take off the bell housing to access the seal

Would appreciate any thoughts

Cheers, Stu

[disco stu]

Made the call to change it. There is a lot of oil in the bellhousing, and none on the clutch/coverplate, so it seems the oil has come from behind the clutch rather than just the rear main seal. $9 seal so not a big expense

I've taken all the bolts out of the bellhousing, but having trouble getting it off the gearbox itself. I'm assuming its the sealant that is holding it on, but nothing I've done so far can get it to shift.

Anyone got any clues to help me out?

[brw0513]

I have a manual that may help.

Here are a few pics to whet your appetite.

If this is of interest then send me your email address. Or let me now how to transfer a big file to you somehow (old-ish dog here looking to learn new tricks).

[disco stu]

Thanks Ian. I actually already have that manual, but really appreciate the offer

So, uuum, I'm guessing it helps if you remove all the bolts?? There was one hiding in a pool of water covered in grease right at the bottom. Might have to give it another go tomorrow night

[brw0513]

I am following your progress with interest.

I'd really like to replace the clutch and overhaul the gearbox in my NL and do all the work myself. Not just to save a few $$$ on labour, but to learn more about the car. I still love it

The challenge of gearbox removal is my hold off point at the moment.

[disco stu]

It certainly sounds painful to remove while engine is in the car. I'm working with engine out and gearbox in. I've always shied away from things like gearboxes, but I'm starting to think that if needed in give it a go. I've done lots of other jobs that would be as technical/fiddly, just never an actually gearbox

[disco stu]

Bell housing off. Crazy how easy it is when you remove all the bolts! There was water inside from me washing, so the seal really must be screwed.

When draining a bit of oil there seemed to be a lot of metal particles in it. Also oil behind the rear of the bell housing which was black dirty. Oil I drained was just darkish brown oil color, nothing to bad I thought. My suspicion is the oil was left for a long time, got really dirty black. Was changed since then given the not overly bad color.

Given the amount of metal particles, I'm pondering doing a flush of transmission before refilling. For this I was thinking a lighter weight oil, maybe a full fill or just topping up, probably just engine oil. Drained really well afterwards.

What are the thoughts on this-bad idea?

[Kaldek]

Got any pictures of the metal? Is it particles or "glitter" and what colour is it.

[disco stu]

Haven't got pictures. Can try later, but difficult taking photos with oil covered hands!

Was silver colored. Some at least appears to be aluminium, that gray color. I should have been clearer on size-very fine, not large, way smaller than glitter. Silt sized or finer if you know your geology! What seems to be general wear, but just not something I think is good to be floating around in there

[erad]

Probably the most important thing with this contamination is "What is it?" Get a magnet and see how much sticks to it, If most of it doesn't stick, you probably have no worries. If most of it sticks, maybe.... Even then, some ferritic contamination is normal, but it would be a minor amount.

[disco stu]

Good point. I'll drop a bit more tonight into a glass jar and try it out with a magnet. The drain pan I used is pretty scungey, so I'm not going to bother trying to get some out off there. I'm not really in a position to go changing the box based on that sort of wear particles in there, but nice to know what sort of condition it might be in

Any other thoughts on the worth of flushing it out? I figured a thinner oil would drain out the old stuff a bit better

[erad]

You could probably flush it out with kerosene. That would get the loose stuff mobilised and then you could drain it, reflush to get the dregs and then you should be OK to fill with real oil. I am talking about doing it on the bench, not in the car itself, bit I guess you could do it in-car as long as you didn't drive it too far and only at light loads.

You could use some light engine oil. The recommended oil for my first car was SAE30 engine oil, and the 80 gear oils actually have a similar viscosity to engine oils anyway.

[disco stu]

Thanks Erad. My thinking goes that there isn't anything in a normal gearbox that could be harmed by incorrect oil for flushing, just wear faster, but I still like to hear the opinion of others.

Box is in the car, so flushing like that is a little harder. I could even do something like half gear oil half diesel. Diesel a lot cheaper than oil at least to waste

[erad]

Diesel will do the same job. I often wonder why they put magnetic drain plugs on differentials bu not on gearboxes. Probably because you are more likely to get scared by the crap you get from a gearbox.

[disco stu]

The schematics said there is a magnet in this box, but it's buried somewhere up the back and I'm not about to strip the whole thing apart just to get to that.

Cheers for the help. Might try clearing it it once the car is running. Got the seal this afternoon but it's too big I the inside-gave me the wrong size it seems