Rear main seal leak.

[Gordo]

Hi guys. No matter what I try, the rear main seal leaks, It's not the bearing cap, but the seal around the crank. Obviously when the engine is hot it leaks badly and runs under the car ,onto the exhaust and all over the back of the car. I have heard you can tighten the spring on the rubber seal but I have not try ed this yet as they say it could make the seal get hotter and wear more. Any one else have this problem, and what do you suggest I try next. Cheers Gordon.

[C.A.R.]

Try a speedy sleeve?

[peter mc]

hay gordo this is the problem with big hp l28s the seal will be out of round. the problem is the crank flexing the last two l28 that i have built i measured all the bearings after they had dune 25 hours and found the front top bearing had 3tho wear and the rear bottom bearing was the same and the rear mane was not good . the other problem with them is the crank can bend with big rpm as i have found out lately. 

[Gordo]

Thanks Peter, you have told me this before, I was also thinking about crank case pressure. I have the standard two, one in the rocker cover and the one in the block. I might try putting an extra breather in the front cover plate of the head, what do you think. How much pressure would build up in the crank case at high revs. Enough to force the seal out when the engine oil is hot and the rubber seal is soft ?

[peter mc]

no Nissan got this OK on the L-series the 2 breathers work just fine. The only way you can make it better is to run a vacuum pump and run negative pressure in the sump which will help to seal the rings and all the other seals and this is good because it helps to make a bit more HP. This is the reason why dry sumps are so good.

[peter mc]

The real fix would be to stiffen up the crank.

On my new motors i have been getting the crank de stressed and nitrided, and also i am running a girdle with studs to hold it all in place.

[Gordo]

Thanks Peter, I have a bit to think about then. Cheers.

[benny]

anyone had this problem with an L26 block?

seems the problem is the L28, breaking cranks ...etc........ :'(

 

maybe people tend to use the l28 in high performace applications due to the extra capacity

[peter mc]

l26 and l28 same crank and all of them have the same problem

[RB30X]

l26 and l28 same crank and all of them have the same problem

 

This must effect what sort of clutch material you can use won't it Peter? With that oil leaking out all the time. Most of the aftermarket clutch materials give up with the slightest hint of oil in the bell housing. I was talking to the bloke from Race Clutch and he wasn't even interested in selling a clutch to me due to the fact it was going to sit behind a dirty old alloy LS block which expand and contract as they heat up and cool down causing more rear main issues than L series engines.

[peter mc]

yer you would think the LS would have problems  but they don't There block and crank are nice and short and stiff mind you when i turbo them  and get 450kw they tend to leak.. and there is so Meany clutches out there for the LS you can get them at the milk bar. yer clutches for L series not so Meany good ones for big hp but they can be found if you are willing to pay.the AP racing one in my car was $3000 trade .you get wot you pay for some times...  as with most in line 6 cylinders the length of the crank is its down fall flex and torsional vibration are very hard to deal with at hi rpm for any lenth of time