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Author Topic:   Alcohol Washed Bearings
OKC9
Dirt Roller

Total posts: 16
posted March 16, 2003 07:24 AM
Open show 383 roller, Shaeffers 20w-50 synthetic oil, MSD chipped at 7200. After about 15 nights, oil pressure dropped. Engine builder disassembled and found rod and main bearings shot with no other measured wear. Sent bearings to Clevite. Engine builder now says the bearings got alcohol washed because of rich jetting. Jetting was set on exhaust monitored full car dyno. Right now we are not sure what to make of the engine builders assessment. Anyone have thoughts on synthetics losing lubrication qualities in alky engines?

sdhnc29
Dirt Freak

Total posts: 467
posted March 16, 2003 04:20 PM
If I am understanding correctly , you ran 15 night's on the same oil ?? I'm not too familiar with Shaeffers 20w-50 synthetic oil , but if it is not compatible with alky , then you could definitely have a build up of alky in the oil .

Another possibility could be , if your oil was changed regularly , and you don't have or use a fuel shut off valve , is that you had fuel leaking by the needle and seat in the carb , down into the cylinder's and by the ring's into the pan at one time or another after your car was parked . This would contaminate the oil regardless of how rich you may or may not be . Which would also account for the sudden oil pressure drop . This sound's a little far fetched , but I've seen it happen .

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

OKC9
Dirt Roller

Total posts: 16
posted March 18, 2003 05:19 PM
We did change the oil every race or two. We use a KSE pump, but do not have a fuel cut-off. The oil does get that milky look, but it goes away when the oil heats up. We have used Torco and get the same milky look, also Kendall. You may be right about the leak by. Thanks

Slam_Shifter
Dirt Full Roller

Total posts: 53
posted March 19, 2003 10:07 PM
We lost the mains and rods in a motor we had done and almost lost another and the problem wasn't fuel wash down. Our oil would get the comes and goes milky look and then had a sudden pressure drop that took the bearings. Our problem was a bad head. It was a porous casting and when we had the seat job done everything checked and spec'ed ok but when you put the head under pressure it had a pinhole water leak that only occured when you brought the car in off the track and it was hot. We run pure water so the plugs were never fouled and had no signs of water leak other than what looked like condensation in the oil. It took 2 different shops checking the heads to find the pinhole around the seat. Odd and unusual circumstance but just something to look into if you are not sure the problem is fuel wash down.

Slam_Shifter

yankie
Dirt Roller

Total posts: 10
posted March 23, 2003 07:22 AM
how much fuel pressure do you run


oops, hit enter. Too much fuel pressure will push past the needle and seats in carb
causing flooding 6 lbs of pressure is plenty


OKC9
Dirt Roller

Total posts: 16
posted March 24, 2003 05:42 PM
Yankie, I can't find the dyno sheet right now, but the engine builder did change the KSE pill to increase the pressure. I think it tops out at around 9 p.s.i. at 5500 to 7000 rpm. I remember that we had the floats too high for a while. Do you think this may have caused it?

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