My brother has 502 efi's in his 32 fountain fever and was seeing high oil temps on one engine.
250 degrees or so.
other engine was 170 deg.
At the same time his water temp gauge had failed but water pressure was normal.
any suggestions?

Have you lost any impellers on the sea water pump on the motor that is showing high oil temp? When the blades come off the impeller they can get caught in the oil cooler. You can try back flushing the system to clean it out, or take the ends off the oil cooler and look inside of it.

Thanks, I will check it out.

Sounds like a good possibility. He bought the boat last year and it has always had higher than normal oil temps on that one side. Seems to have gotten worse lately though.
Maybe had a blade in there and now it turned to cover more area or something.

Thanks for the input.
Very much appreciated.

changed water pump, changed sea water pump impeller (it was fine)
Didn't find anything in cooler.
fixed the gauge its running 10 degrees hotter than other engine, Oil pressure is 40 psi at 2500 rpm

Water pressure is slightly lower than other engine even with new impeller.
Exhaust manifolds and risers are hotter on this engine as well?

Any other Ideas?
tests?
etc.

nm

I once trashed an impeller and overheated a 502 efi. I replaced the impeller and backflushed the system. It still ran hotter than it used to. Talked to a Merc tech and he told me to replace the thermostat. It worked! Temps were back to normal. Aparently an overheat can damage the thermostat and it wont open properly.

Also a clogged oil filter will make the oil bypass the filter and oil cooler system.

Ron

We changed the filter, oil, thermostat removed.

cleaned and backflushed the cooler.
Just in case.

water temps down to 120 to 140 now.
oil temps are still 200 or above.

water pressure has dropped but thats to be expected with no thermostat I would expect.

Any one have any other possiblities. were running out of things to check.

Thanks again for any posts.
They are very much appreciated.

Guys, can you tell me what your oil temps are on your fountain fevers?

I talked to my engine builder who does my race cars and he says thet 200 is normal, 170 is low, and anything over 270 is time to worry.

Whats the general consensus on regular oil temps?

I was told not to delete the thermostats on EFI motors. Something about needing to be a certain temp to run correctly, computer sensors and all.

Thanks for the input on the thermostats.

I will look into that and see if we should replace them, in the mean time if anyone can tell me thier oil temps that would be a big help?