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[albitz]

My Diesel Cavalier has the vac pump on the rear ofthe alternator which has an oil feed for the vac pump bearings.
It sprung an oil leak a week or so ago so I have just fitted a new oil seal which I thought would cure it. Just fitted the new seal and put it all back together but its still leaking as bad as ever.
Having looked closely at the leak it looks like it could be coming from the body of the alternator itself rather than the join between the vac pump and alternator.This doesnt really make sense to me as I would have thought oil would be able to get into the alternator.
Im a tad confused and frustrated as its a bit of a pita to take it all back off again,so dont want to do that unless Im pretty sure I know how to cure the problem this time.
Anyone got any previous experience of this please ?

[andyc]

Albitz

Have you checked the feed banjo seals and the return pipe. If the oil is coming out of the alternator then you have big problems as there shouldn't be anyway for the oil to get in there

Andy

[albitz]

Checked them Andy,it isnt coming from there.Its definitely coming from near the join between vac pump and alternator,but the join between the two looks dry.
I suspect Im going to have to take the alternator off the car again (3rd time) and inspect things very closely.
Got painting & decorating to do today  ......so will have to wait until tomorrow.

[Darth Loo-knee]

I know they are expensive as I had to change mine Albs.
At the time we had a Classic Range Rover too that a replacement alternator cost £50. My Cavalier TD £175 at the time

[Kevin Wood]

Is it not possible that the vac pump is sucking in oil from somewhere?

Just thinking. There'll be an air outlet on the pump. If oil is getting into the vacuum lines, it'll come out there. Not sure where the oil will be coming from. Not losing brake fluid into the servo, I suppose?

[albitz]

The vac pump has its own oil feed & return Kevin,so that where the oil source is.

[Marks DTM Calib]

Hmmm, dependent on the vac pump type (e.g. rotary vane) then the oil supply is required in order for the vanes to make an effective seal and produce the vaccum. So when the vanes and rotar wear the oil expelled out of the vent (as there will be vent to atmosphere) will increase quite a bit. could it be this?

If its a basic diaphram setup then things are very different (but it would not need an oil feed)

[albitz]

Will have a closer look when I remove it again,but it has an oil feed and a larger pipe which is apparently the oil drian back into the sump.No vent to atmosphere as such that Im aware off,but another pipe goes out the top to the servo to provide the vacuum. Splined shaft comes out the rear of alternator and inserts into the pump to drive it.Dont know any more than that tbh.
Could feasibly be wear as you suggest,although it seemed to start suddenly and leaks from one particular spot,which is difficult to see with it on the car and the engine running.
Im thinking when I remove it this time to resist the temptation to clean the oil off first,but leave it as is and hope the oil trail will provide a clue.
Guessing drain back to sump could also provide vent to the atmosphere via breathing system ? If so,it isnt leaking from there,but coming out from somewhere alse close to the join between pumpand alternator,but doesnt appear to be actually coming from the join. Need it off the car again I think and then have a very close look.

[Kevin Wood]

Oh, OK. If the pump has its' own oil feed then that's probably the source.

[albitz]

Well Ive found where the oil is leaking from but dont know why.Theres a little hole in the alternator visible in the pics,and that is where its coming from. Im wondering if there shoud be a little grubscrew or similar in this hole and it has fallen out.
I suppose it will need info from someone fimiliar with these units.



Piece of red wire poking i to the hole

[Kevin Wood]

Is that the face of the alternator where the pump bolts on?

If so, I'd say it's leaking out of the front face of the pump and that hole is there to drain any leakage so it doesn't end up in the alternator.

[albitz]

The machined face visible just above the hole is where the vac pump sits (attached by 3 bolts to the rear of the alternator) the oil seal ive just replaced (O-ring) is visible in the pic too.Then there is the splined shaft which comes from the alternator and drives the vac pump. I had assumed the O ring seal would prevent oil from leaking into the alternator as well as escaping to the outside world.
I have just been and had another look however and the seal wouldnt prevent oil from getting into the alternator.I would assume theres another seal inside the body which is supposed to do that job,so that is probably where the problem lies and I very much doubt its a service item.
So,I have a feeling the alternator may just be inside its warranty in which case I will try and get a replacement.If not,a new one would be more than the car is worth so I might rig up some sort of catch tank arrangement to catch the leaking oil.
The car had about 9 months MOT left and then it will probably be going down the scrappy (hopefully to be replaced by a Merc 190D) so Im not going to throw money at it.

[albitz]

Having said all that,the hole isnt at the lowest point of the alternator when its on the car,its actually almost at the midway point between the highest & lowest points,so maybe it isnt a drain hole ? 

[Lazydocker]

ISTR that's where mine leaked from, but it's a long time ago

[albitz]

I would be interested to know why it leaks from there,but I may never know.