Convince me that I don’t need to

[ECR]

First proper trackday for 3(?) years at Loheac on Friday. I installed my spare engine for the day after I had skimmed the block to eliminate frequent head gasket problems. The only other work that I did on it was to replace one oil control ring which I managed to break during reassembly (oh, and all new bearings of course) The car ran very well and I genuinely surprised myself with my eventual speed after such a long layoff. A really enjoyable day.

However, the day ended when my oil pressure soared ( nearly 100 psi at one point). It flickered back to normal and was obviously the pressure relief valve sticking. I'm told that this occasionally happens with vx engines but I've never experienced it before. To add to that, my low pressure warning light flickered on occasion (there are some very tight corners). Pressure returned to normal and no nasty noises. I did have to top up the oil more than I expected although I could have underfilled it at home ....not sure ....

Taking the car off the trailer revealed a significant (engine) oil patch on the floor. Changing the oil pump is a no brainier which I can do with the engine in the car, but to check/replace rear crank seal is engine out.

Convince me that it's not necessary ..... (if you can)

 

[SM25T]

Guessing the leak was from the rear of the engine then ?

[ECR]

Yes. Presumably dripped down from the bell housing

[Wrightpayne]

Might have been the short term high pressure that caused the leak somehow? ;-)

[ECR]

Yes,but has it damaged the seal, or did it just blow by?

[SM25T]

You probably know the answer to your question.

[revilla]

OK this is from my understanding of K Series engines. I'd expect it to apply to the VX but I may be wrong and I'm happy to be corrected!

The oil oressue you are measuring on the gauge is the pressure of oil in the oilways feeding the bearings. The oil in the crankcase is NOT under pressure. So a sticking OPRV will not apply any additional pressure to the crank rear oil seal.

Any pressure applied to the crank rear oil seal will be from blowby combustion gases pressuring the crankcase, but if it is properly ventilated this shouldn't be significant. I think it's also more likely to dislodge, rather than damage the seal (in the case of a K) which would lead to a rather large leak.

So I really don't think the short term high oil pressure incident will have damaged the crank rear oil seal.

However ... That's doesn't mean it hasn't failed for one reason or another, and you're getting a leak .. 

[rj]

What Andrew said

[revilla]

Are you absolutely sure it's coming from the bellhousing? No chance oil could have got thrown out elsewhere and run down to the bottom of the engine? In thinking breather hoses, catch tank etc. (What breather/ventilation arrangements do you have?

On a VX can you see inside the bellhousing at all to see if it is oily? Can you carefully poke anything in through the clutch fork hole down to the bottom to use as a sort of dipstick, see if it comes up oily?

[ECR]

Thanks Andrew,that's obvious now I come to think about it.. I haven't looked under the car yet but high pressure would affect the front seal I think and if that leaked and blew back along the sump ....I can see into the bellhousing with a camera so I'll check later and as the oil pump and it's seal are going to be replaced that should sort out any problems at the front end. Engine breaths into the dry sump tank and that goes to a catch tank which was dry. Gearbox also breaths into a catch tank as does the diff

[ECR]

Front crank seal looks fine, no sign of oil.it's definitely not blowing backwards as the sump is dry. I fear a poor seal on an old crank( it did have witness mark where the old seal had rubbed)

A new crank is not preferred , does anyone know of a way of reclaiming a crank (metal spray, sleeveing )

[ECR]

[revilla]

I've managed to polish oil seal witness marks out of crank palms by hand before and ended up with a reliable seal. I've usually just uses abrasive Scotch Brite pads (dark red grade). It's hard going, the crank metal is hard. I use small pieces and work with thumbs. Be ready for sore thumbs! If you work around just until the mark disappears you can be fairly sure you're taking off about the same amount all round. Not had one leak after doing this (so far). Again ... K Series experience, may not be applicable!

[ECR]

The rear crank bearing cap is sealed in place to prevent leakage into the bellhousing. It could be that this seal has failed. It's an awkward job to do, sealing vertical and horizontal faces at the same time so perhaps I didn't do the job well enough. In any event, the engine is going to have to come out again.I have the time and the tools, the enthusiasm seems to be faltering though It'll be fine once I get going....