Another #8 bearing leak...

930gt-40r · 930gt-40r's Garage

On a rebuilt 930 motor, would could be the possible cause of a seemingly aligned #8 bearing (notch is pointing at 12 o'clock and ridge is aligned with case..)? I know the builder used loctite 574 on the outer surface of the bearing and a new o-ring. And it is leaking from the outer perimeter of the bearing. It also looks like the case didn't seat 100% around the bearing...
Any experience or thoughts appreciated...

lucittm · lucittm's Garage

Torque on the case thru-bolts in the area of #8 bearing?
Wrong bearing?
Pinched o-ring?
Tweaked engine case? (It IS a turbo...)

Good Luck,
Mark

930gt-40r · 930gt-40r's Garage

Im thinking about the pinched oring
If one were using sealant on that bearing (controversial) they wouldnt be hot to lube the oring before mating the two...
I didnt think of that.

MBruns · 04-14-2009, 06:00 AM

574 is the wrong product to use , "O" rings need to be able to move to seal and the 574 will set up and prevent that, not to mention create a measurable film between the case bore and the outside diameter of the bearing that in some engines I have seen on (mag cases) that the crank wouldn't turn with the 574 used there. For years I have used just oil and a detailed surface and no issues, however I did a 2.7 that had some corrosion in the "O" ring area and had to use a 3 bond product 1211 to help that situation, (it had to be torn down to figure out and reassembled and shipped back) but that took care of the problem.
Good luck, Mike Bruns JBRacing.com

930gt-40r · 930gt-40r's Garage

I agree on the 574 vs the oring- the oring is supposed to move and 574 negates that. I am just aggrivated that I have to split the case on a new motor that is otherwise perfect...

Eagledriver · 04-14-2009, 08:43 PM

As you know this is a chronic problem area on these engines. I use a little Dow 111 silicon paste on the o-ring and nothing else on the bearing itself. You must not get any silicon grease in the seam of the case or it will displace the case sealant and cause a leak. For this reason I leave the area of the o-ring that is near the seam dry. When you put the case halves to gether you have to watch the o-ring compress and make sure it doesn't pinch out into the case seams.

This is a big problem on Mag cases if you use the Performance Products "tech tip" of using a bigger o-ring.

There are many other schools of thought on sealing this area and you get to decide what has the best chance of success for you.

-Andy

T77911S · 04-15-2009, 03:49 AM

nice tip andy. so do you not recommend the bigger O ring?
i have seen an older mag case where the the Oring wore a groove in the case. is this a problem with the mag's, and what about the alum cases?

930gt-40r · 930gt-40r's Garage

yea Andy- that is a good idea
It is too bad that I got to take the motor down to bare @ss again- it was put together very well the first time save for the o-ring.

cstreit · cstreit's Garage

You can also use a non-hardening sealant on the o-ring. Know a guy who's used them successfully. Me? Just use a light coat of oil on the o-ring to help it seat. No locktite on the bearing because it could spooge up the o-ring, it's gotta be able to move a bit.

YTNUKLR · YTNUKLR's Garage

Kris,
sorry to hear, bummer!

+1 to MBruns and +1 for Henry Schmidt's sealing technique

I have had 100% success with a very light coat of Dow 111 or 55 on the o-ring, and a light coat of Threebond 1211 on the #8 bearing itself.

The Dow 55/111 allows the o-ring to un-bunch itself and "find its home" after you've installed it in the groove. The 1211 is a non-drying type silicone sealant that peels off very easily, and is very good at dealing with taking up any gaps and vibration.

574 is a hardening product; it's a really bad choice in this application, unfortunately..

afterburn 549 · 04-22-2009, 11:43 AM

I have herd of people jamming some goop in around it...I think I would try it
3m 5200 is tenacious....spray clean all oil off (brake cleaner amd or the like ,what can you loose ?

930gt-40r · 930gt-40r's Garage

Quote:

Originally Posted by afterburn 549

I have herd of people jamming some goop in around it...I think I would try it
3m 5200 is tenacious....spray clean all oil off (brake cleaner amd or the like ,what can you loose ?

I have thought about doing this in depth, I just can't bring myself to do it. I am looking at the bright side though- another $100 worth of goops and gaskets and another day of time is all it will take to pull the motor apart and correct the problem and throw it back in.
I actually am about to tackle another few projects on the car like wire up a Haltech and paint my new non-slant-nose fenders.... and then Ill pull the motor down and take care of the leak.

afterburn 549 · 04-22-2009, 04:11 PM

an other day ??? you are one fast person !!

930gt-40r · 930gt-40r's Garage

well figure all of your measurements are done and you start out at say... 7 in the am, motor is on stand at 9:30, engine is down and apart in around 11:30, clean it +prep through bolts 12:30, maybe another 3 hours for re assembly and cam timing, another 3 or so to get the motor in the car and fill with oil... its possible.Im also not taking apart the cam towers either- that right there is an assload of time saved. I could also pull the motor the night before and save some energy for the next day.