vacuum pump oil leak !
 

hi all
discovered ive got a slight oil leak on my 940 TDI vacuum pump around the bottom nut . take it the rubber gasket has failed pump only been on 2 years i have ordered a new rubber gasket and the 2 flanged nuts .is there anything to look out for when i do the job ?

Yes make sure the leak is not actually from the headgasket right there in the middle. Common place for headgasket to leak oil out right there, looks like it is coming from the lower mounting ear of the vacuum pump.

But if you can verify it is actually leaking from the vacuum pump, then likely the new o-ring will seal it up.

NOTE: When removing the vacuum pump do not let the plunger rod slip out. It's two ends are different enough (can be hard to tell by eye) that the wrong side against the cam lobe will quickly wear it out. If it keeps wanting to slide out, take it out and set it aside in a way that you can reinstall it in the same orientation when reattaching the vacuum pump.

vacuum pump oil leak
 

thank you for your valued comments Ngoma . there is oil around the thread on bottom nut so as head gasket is below this im just hoping that its not head gasket as that could be a disaster for me !
regards jim

A trick for making removal and reinstallation of the vacuum pump easier:

Before loosening the vacuum pump mounting nuts, first rotate the engine (either with wrench on front of crankshaft or by "bumping" the starter motor) until the small V-notch in the injection pump pulley is close to aligning with the TDC mark on the pump bracket. It does not have to be dead on, just near it. This will put the camshaft in a position where the cam lobe that drives the vacuum pump is close to minimum lift, taking the heavy spring pressure off the pump. This way you are not fighting that spring while you remove the pump and try to put it back on, makes it much easier and limits the risk of damage to the parts.

It is common to find that someone in the past has spread a large amount of RTV sealant on the pump to seal it to the head. That is not necessary and eventually leaks. The best way to get it to seal up is to NOT use any gasket sealer, ONLY use the rubber O-ring, which tends to last a very long time. Try to clean off any remnants from past use of sealer to remove all of it. New o-rings available from Volvo dealer or aftermarket.

A little bit of vaseline or grease can help hold the O-ring in the pump recess as you reinstall it, otherwise it sometimes wants to jump out of position and then get sliced when you try to tighten the pump down.

thanks for the valuable info V8VOLVO i will keep you informed when i get the gasket and new flanged nuts from my volvo dealer .

vacuum pump
 

hi
latest i have the gasket and nuts i have replaced the bottom nut thats all and all is dry at moment early days yet . i can see the notch on the injection pump pully but i cant understand . do you mean the notch on the fly wheel housing should match up to the mark on the flywheel . sorry im a carpenter so a bit limited in the details here .. also im keeping a close eye on the head gasket spot under the vac pump for oil leaks there just hope its not leaking there !
all comments most welcome .

vacuum pump
 

hi V8VOLVO
is there a notch then on the rear injection pump cog then i understand the cog notch and the notch on the injection pump bracket need to be near each other
regards jim

vacuum pump slight leak
 

hi all
i had a look at vacum pump tonight and there is a misty oil around the pump
i may be wrong on this but i fitted a Febi pump this may have a different size gasket groove than the original pier burg pump which is causing the oil mist in that area as the engine block is designed for pier burg pump there can be very little tolerance with a bolt on part !
what do you think ?

Never seen a Febi version so no idea on that.

Did you study the fit when you mated it up to the cylinder head?

Did you

Tighten the fastening nuts evenly and in stages?

Make sure the o-ring sealing gasket was in good condition and in the proper position? Sometimes they like to spring out of the groove when fitting the pump into position.

Clean well the whole area to pinpoint exactly where the leak is originating?

hi NGOMA and all
if i put my finger at the bottom edge of vacuum pump there is a tiny bit of oil there .as i can see a tinny line of oil on the edge of the head gasket about 30 mm each way its tiny but shows up with a very bright LED lamp .
so till i get the chance to remove the vacuum pump and fit a new gasket i just keep every thing dry as possible im loosing no oil so the leak is very tiny but its coming from somewhere , it woud be bad for me if its the head gasket as its a job i don't know where i could get it fixed . as the car has 279000. now and i have just bought all front end bushes ready for a guy to fit .