The Buda

First day out since i installed the rebuilt motors and the oil temp are running much higher than when the motors were pulled in the fall to be freshened up. This is a twin seup with Gen 5 454's bored 60 over with standard size rod and main bearings with a B&M 250 with dual carbs running 5 psi boost, 32 degree total timing.
Last year the oil temps would be about 190 and climb to 220/230 after extended runs, water temps are low, not running thermostats.
This year the oil temps are running 210/220 after running 5 to ten minutes (3500 rpm) and level off but climb rapidly over 250 when running full throttle.

The cooling system is exactly the same as last year and it ran with no issues.

Both motors are reacting exactly the same way.

Any suggestions?

minxguy

Does the temp top out at 250 or slightly above (260)?
If it does I wouldn't worry, when you start getting to 300, then worry. Run a high quality product and it should be able to handle 250 no problem. If you can get the temp to 300 or over, look for a larger oil cooler.

Ken

stevesxm

nonsense. yes... a hi quality oil will survive at 250/260 but the notion that you want it there is ridiculous. the temps need to be stable not above 240. as for the problem, the good news is that both motors do it. the bad news is that both motors do it

you would like to believe that the motors aren't both built that tight as to cause this issue. i hope youre right.

lots of people here have written of experiences with relief valves and hi volume oil pumps doing bizzare things and making hi oil temps ... i haven't seen this but its possible i suppose.

so what's changed other than the rebuild ? engine compartment ventalation ? on mine, the difference between cracking the engine hatch open and not was 40 degrees of oil temp.

oil thermostats ? did you add some or take them out ?

if what you say is true... that this is a straight rebuild with no material changes then your combination that was stable before should be so now....

so logic says simply that its either the motors are built WAY too tight and headed towards failure or something in the infrastructure was changed while they were out that is now causing a big change in engine compartment temps or the oil cooling system itself.

either way... ( stating the obvious) you need to get the temps down to where they are stable at 220 or 235 for as long and as hard as you care to run the boat.

so ask yourself and make a simple written list...

EXACTLY what was changed and is now different from when you started ?

your answer is on that list