Convince me that I don’t need to

14 posts / 0 new
Last post
ECR
ECR's picture
Offline
Last seen: 12 hours 52 min ago
Joined: 17/04/2014
Convince me that I don’t need to

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
SM25T's picture
Offline
Last seen: 15 min 6 sec ago
Joined: 17/04/2014
Guessing the leak was from the rear of the engine then ?
ECR
ECR's picture
Offline
Last seen: 12 hours 52 min ago
Joined: 17/04/2014

Yes. Presumably dripped down from the bell housing

Wrightpayne
Wrightpayne's picture
Offline
Last seen: 20 min 29 sec ago
Joined: 17/04/2014

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

ECR
ECR's picture
Offline
Last seen: 12 hours 52 min ago
Joined: 17/04/2014

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

SM25T
SM25T's picture
Offline
Last seen: 15 min 6 sec ago
Joined: 17/04/2014
You probably know the answer to your question.
revilla
Offline
Last seen: 30 min 46 sec ago
Joined: 17/04/2014

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 .. 

SV VVC 170 - 170.4 bhp @ 7100 rpm - 142.4 ft.lb. @ 4900 rpm

rj
rj's picture
Offline
Last seen: 6 hours 49 min ago
Joined: 17/04/2014

What Andrew said

tbirds search:

Blatchat Google Search

revilla
Offline
Last seen: 30 min 46 sec ago
Joined: 17/04/2014

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?

SV VVC 170 - 170.4 bhp @ 7100 rpm - 142.4 ft.lb. @ 4900 rpm

ECR
ECR's picture
Offline
Last seen: 12 hours 52 min ago
Joined: 17/04/2014

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
ECR's picture
Offline
Last seen: 12 hours 52 min ago
Joined: 17/04/2014

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 )