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silky13

C20xe fresh rebuild rear crank seal leak

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Guys, looking for a bit of advice, just dropped newly rebuilt red top into the westy and it has a serious oil leak between engine and bellhousing. Have checked sump and cam cover bolts to rule those out, but it really is pointing towards rear crank.

Since engine has been built by a third party (including a new crank seal) should it being going back to them to sort, or is there something I've potentially done dropping engine back in motor? Any advice much appreciated!

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The problem will be that the seal between the rear bearing housing and the block has not been done well enough. This seal is made with silicone type sealants and if they are not applied properly (and of the right type) then you will get a leak.

 

Most people assume that it is the huge crank oil seal that leaks but in my experience it very rarely is.

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I agree with crash test - that rear crank bearing and sealant has to be scrupulously clean - and of course the crank seal has to be the right way round !  :suspect:

 

There are a number of sealants around - "RTV" type but I read so much about leaks on the C20XE when I was rebuilding mine I used the proper stuff from Vauxhall http://www.autovaux.co.uk/product/90485251-sealing-compound-1503295.aspx   

 

I think there are also a number of discussions about the best type of seals to use on the sump and I think the consensus is the cork type (Elring do a good bottom end set with one of these) - the cork one has a rubberised face and metal inserts to stop it being crushed too much and there is one either side of the windage tray - cheaper versions are often just synthetic material with no inserts and slip over the windage tray and I think they then get squeezed out.

 

If the leak is really bad and it's not obviously the sump gasket then yes, I would suspect the rear crank bearing sealant or oil seal and would get back to the engine builder for their comments. I would doubt installing the engine would dislodge anything unless you banged the sump really hard somewhere. 

 

p.s if the oil is flooding out they may have left the rear oil way bung out !!(it's behind the flywheel) :down:

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The GM sealant as above is the correct one to use, doesn't dissolve in contact with oil  like the  usual silicone RTV's.  You need to remove the engine and flywheel again to fix this, :( Searching Migweb forum should find photos on how to seal the rear bearing cap correctly   I also use the old style double cork sump gaskets and they don't leak at all.

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It happens. The rear sealing can be a complete PITA; I know highly respected XE builders that occasionally get a leak when they test run up the engine for the first time after it's been apart.

As said, the original Vauxhall sealant will give you a guaranteed product to use, though there are a few from other sealant makers that do the job as well, (you'd have to do a bit of digging on here and Mig Web for the brand names, 'fraid I can't remember them!)

As said, sealing round the rear bearing cap is critical. Though I've also noticed over the years that the rear cap seems a devil of a thing to get absolutely square to the block, which does make me wonder if it causes the odd tiny gap between the block/cap and the rear seal. A few advise putting a smear of sealant around the outer edge of the rear crank oil seal before installing it. I never got as far as trying that myself, but certainly would have done the next time around, if I'd stuck with XE's.

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It happens. The rear sealing can be a complete PITA; I know highly respected XE builders that occasionally get a leak when they test run up the engine for the first time after it's been apart.

As said, the original Vauxhall sealant will give you a guaranteed product to use, though there are a few from other sealant makers that do the job as well, (you'd have to do a bit of digging on here and Mig Web for the brand names, 'fraid I can't remember them!)

As said, sealing round the rear bearing cap is critical. Though I've also noticed over the years that the rear cap seems a devil of a thing to get absolutely square to the block, which does make me wonder if it causes the odd tiny gap between the block/cap and the rear seal. A few advise putting a smear of sealant around the outer edge of the rear crank oil seal before installing it. I never got as far as trying that myself, but certainly would have done the next time around, if I'd stuck with XE's.

As Dave says, the mating surface is not going to be dead square after the engine as been dis-assembled a few times for re-builds.

 If you remove the bearing cap, degrease the surface with a solvent or thinners, then run a continuous bead of sealant from under the bearing cap mating surface, around the groove to the other side of the bearing cap and screw down the bearing cap nuts, that is a sure fire way to stop leaks.  Start of with just a thin bead of sealant under the bearing cap, increasing the thickness of the bead around the cap groove and finish under the other side of the cap with the thin bead.  Worked for me.

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