DIY Job or Not? Rear crank seal replacement

Matt11 · Sep 17, 2015

I think my rear crank seal has gone.

I have oil all over the gearbox housing, from where the wading plug fits and also dripping from the front edge of the sump. It's black oil so assuming its engine oil. It isn't too bad but it does seem to be getting a bit worse it its a nuisance more than anything.

I just wondered, is this a job I could do at home, bearing in mind that this will have to be done on my drive with axle stands, a few jacks etc and without a fancy 4 post lift? Is it something that can be done or is it best to get it done at a garage?

I've been quoted £250-300 to have it done but would prefer to have a go at doing it myself.

One garage said that changing it might not help as "if the engines damaged, it'll force oil out of it again or somewhere else". What could he mean? What damage would cause it to do that?

All advice appreciated.

Matt11 · Sep 17, 2015

sorry, forgot to say. It's a 1989 90 with a 300tdi and LT77 gear box.

blue beasty · Sep 17, 2015

Which engine?

Matt11 · Sep 17, 2015

blue beasty said:
Which engine?

Yeah, just added that after. Thought it'd probably help! It's a 300tdi with LT77 gearbox

big si · Sep 17, 2015

After doing mine on a 200tdi and replacing the gasket between the block and flywheel housing also which will give the same symptom i think id be happy to pay 250 to let some other person do it, advise a clutch while yer in there too seeing as it all has to come out anyway.

Matt11 · Sep 17, 2015

big si said:
After doing mine on a 200tdi and replacing the gasket between the block and flywheel housing also which will give the same symptom i think id be happy to pay 250 to let some other person do it, advise a clutch while yer in there too seeing as it all has to come out anyway.

That's what i was thinking to be fair. Just fancied having a crack at it if it was straightforward enough. I don't think there is a gasket on the 300tdi but wouldn't be the first time i was wrong!

big si · Sep 17, 2015

Its not complicated , just a lot to do for a wee little seal, if you do it yourself make sure you get a genuine seal too mate as its alot to do to find out a cheap seal has failed.

wammers · Sep 17, 2015

Easy mornings work in a garage on a ramp but a total ballache flat on your back.

big si · Sep 17, 2015

wammers said:
Easy mornings work in a garage on a ramp but a total ballache flat on your back.

Engine out when i did mine, i hate rolling around on the floor.

Matt11 · Sep 17, 2015

Alight cheers all. I'll get it booked in one of these days then.

blue beasty · Sep 17, 2015

I've always taken the gearbox out but there's not a lot in it either way.

As others have said it's straight forwards but laborious. Pressing the seal in square without twisting the fooker can be tricky by hand on yer knees in the driveway but doable.

+1 on the clutch and release bearing and check the clutch arm carefully at the pivot and slave rod dimple while yer there.

Matt11 · Sep 17, 2015

any ideas what the guy meant about engine damage causing oil to be forced out? Kind of got me worrying in case the seal is changed and its still leaking.

big si · Sep 17, 2015

I presume he means crankcase pressure build up, worn rings or blocked galleries, you would see evidence from oil filler i should think first though. Cap blowing off or oil seeping past it, breathing and chugging heavily when the caps off.

blue beasty · Sep 17, 2015

big si said:
I presume he means crankcase pressure build up, worn rings or blocked galleries, you would see evidence from oil filler i should think first though. Cap blowing off or oil seeping past it, breathing and chugging heavily when the caps off.

That or main bearings

Matt11 · Sep 17, 2015

big si said:
I presume he means crankcase pressure build up, worn rings or blocked galleries, you would see evidence from oil filler i should think first though. Cap blowing off or oil seeping past it, breathing and chugging heavily when the caps off.

What's the best way of checking for the above? What would i expect to see at the oil filter? what's the "cap"? Pretty new to all this so i generally need things in laymen's terms

blue beasty · Sep 17, 2015

The 710 cap

Matt11 · Sep 17, 2015

blue beasty said:
The 710 cap

ok. Stupid question but now i know!!

blue beasty · Sep 17, 2015

Matt11 said:
ok. Stupid question but now i know!!

Over pressurisation tends to push oil out of the top of the engine wherever it can, dipstick, filler cap, cyclone breather.

Tdis are heavy breathers anyway but if you think this might be a problem the first thing is to check the breather is clear because that might be all it is.

If main bearing are on their way youll hear knocking on cold start up.

How bad is the crank seal leak? Most Landies like to leave a mark

wammers · Sep 17, 2015

Matt11 said:
ok. Stupid question but now i know!!

If you turn it round it may say OIL.

Matt11 · Sep 17, 2015

It's not too bad to be honest but i do think its got slightly worse the last week or so. I leave it in the train station car park all day and there will be a 4cm diameter oil stain when i get back. Its more of a nuisance than anything and the wife goes nuts about the state of our block paved drive!

well theres no sign of any oil being pushed out of the cap or the filter, there is however oil leaking from the hose that goes to the radiator. I've just got a new rad today and am going to change all the oil and coolant hoses to it when i get around to ordering them. I think the leak is just because the hose is old and cracked near where it meets the pipe which fits to the rad.

DIY Job or Not? Rear crank seal replacement

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