High oil temperature ?
 

I have a 1997 35' fountain with twin 500hp carb motors. The oil temp on my port motor runs about 215 at normal running and the water temp is at 130 degrees. Starboard motor oil temp runs about 180 and the water temp is 130. Last year it was fine. Today is the first time I had it in the water this year. Is this a gauge problem or a sending unit problem. Where would the sending unit be ?

Switch gauges or sending units, and if the elevated temp follows it, you have found your problem. I would also check to make sure there is not a restriction in the oil cooler on the one that is running hot. Is it running oil T-stats? If so, one could be sticking closed.

Also, I think the sending units are mounted in the remote oil filter pad on the HP 500's.

Sounds like you may have a issue with the internal oil thermostat on the HP500. Your port one may not be opening properly

215 is not high, several oil garu's say 240-250 is where it should be under 200 is way to cold. Check with Chachi on the Dnet he is very knowledgeable he has worked for Specto Oil for man years, they make some very good racing oils.

Called Ken Chachi the temps I posted and run my stoker at are correct and are far more beneficial to the life of your engine, cold oil makes for the white goo in your valve covers which over time leads to broken springs we know where that leads!

I was assuming that the 215 degrees on the port motor was high but after reading other post about oil temperature, it seems that 215 is ok and it is the 180 that is to low. I swapped the gauges and the problem followed. I bought 2 new gauges and will install this weekend and see what happens. I also swapped the sending units and nothing changed.

The problem w/ hp boat engines often is if you start at 240f oil temps cruising, after a wot extended blast you will be 280f or more. That is why they need to run cooler, like 200f cruise to give room for the wot blast.

That, from the high oil temp king LOL

You got that right old buddy. I'm a legend in my own mind :o)

Not sure who Ken Chachi is.

I do know, most big HP MARINE engine builders, wouldn't care for oil temps continuously at 250*. One of the biggest builders, Mercury Marine, and Mercury racing, do not set their engines up to run those kind of oil temps.

In automotive, oil temperatures normally remain consistent with coolant temp. Also why some vehicles have engine oil coolers built into the radiator, and still have a external cooler in front of radiator to keep things cool. Mainly you see that in trucks, setup for towing.

OMG you Dont know who ken chachi is??:eekdrop:

Am I supposed to ?

No comprendo here as well, who is ken chachi?

BTW, that chart is exactly right. You should run 180f cruise and let the temp rise for a wot blast. This idea of running above 212f on the gage to eliminate condensation is falicy. The oil cycling gets much hotter than the gage will ever read.

I never used to have oil stats. At wot, maybe i'd see 140* at most. Never had condensation issues, and when engines tore down after 6-7 seasons, bearings looked great.

I did however install the Merc HP500 style oil stats and plate style coolers when rebuilding last year. Couldn't be happier with the setup. My temp gauges will sit at 180* all day long cruising, and have had it WFO for 6-7 miles straight at 5600-5800RPM, sits at 210 and no hotter.

The problem ended up to be faulty gauges. I installed 2 new gauges and my temperatures on both engines are running about 180, 190 at cruise and go up to 215, at wot blast.