Board index Flathead Power-Technical Questions, Answers, and Suggestions Evo's Thru 99 Engine oil filling up primary, when running

Engine oil filling up primary, when running

Chuck Sumner

Working on a 84&1/2 evo, FXR. The primary oiling system has been eliminated, but the primary fills with oil after about 50 miles. I have replaced the motor sprocket seal, and pulled off the cam cover to check the breather. It has a steel breather that is in time. I cant figure out why it fills with oil. It also has very low oil pressure when warm(5-8 psi) at 2500 rpm, I supect a stuck relief valve in oil pump for low pressure. Would it have anything to do with primary filling with oil? Also, it has a 41 up clutch. I thought evos had the diaphram style clutch. The guy paid $3500 for this bike. I think it is a bunch of mis-matched parts thrown together. HELP!!!!

Posts: 152
Location: Carver, MN

Certain Evos had issues with the "cast - in during manufacture" insert that the timken presses into, coming loose. The first symptom was oil transfer between engine and primary. If that is what you have, the fix is to replace the cases or send them to STD to have them repaired. They machine out the insert and install their own. May be a long lead time, but cheaper than cases.

Posts: 903
Location: Hill City, Ks. USA

I've got a customer with a 85 FXR. At first I thought it was a mismatch of parts, but he's had the bike from new. This might be a bit basic, but are you sure you put the main seal in the right direction?
The case race problem is correct. Nice to know STD will repair the race. I was unaware of that.
Other than a crack in the case, I see no other alternatives.

Posts: 2688
Location: Los Angeles, CA
My cases have the leak in them. I have just keep draining the oil since 1982. :mrgreen:

Posts: 113
Location: Plattsburgh, NY, USA

HD did away with cast in LH "grey metal insert" around 1989. Too many problems coming loose. Instead HD pressed the Timken race right into the aluminum bore. You didn't get too many chances to change LH Timken race before they galled the bore & you lost your interference fit. Heat up the case to 300 degrees [bolted together] and they come out easier. Zippers also does this repair- maybe quicker??

Posts: 1538
Chuck- $3500. doesn't buy much these days.

To find where the oil is exiting from, try just doing a 'leak-down' test.

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