I am currently working on a 47' Fountain with 502mag triples. The oil temp gauge on one the engines is reading about 225 degrees when we get going. It will cool down after we idle around for a while. The other two gauges are reading about150 degrees. Any ideas would be much appreciated. Thanks guys.

Several things can cause this problem. A lean condition can cause heat to build up in the oil. Worn rings and blow-by can cause excessive heat. There may be a problem in the oil thermostat/cooler rigging diverting the oil passage through the cooler. You could also have debris blocking the water passages in the oil cooler, although I would expect to see higher water temps with this as well.

I would worry about the 150 degree coolers. The oil needs to get over 212 to boil off any condinsation. 235 is normal. When you start going over 250-260 the oil will start to break down. Do a search, you will find hundreds of posts on this topic.

it sounds as if there is an issue with the oil thermostat housing malfunctionig. on the 525's the headers leak internally into the engines, then when they warm up the water evaporates and the salt chrystals stay behind and end up in the filer or getting lodged in the oil thermostat itself.

good luck.

We have that exact problem right now. CMI's are terrible!!!

I have a 1997 35 fountain with 525sc's cmi headers and mine is doing the same. I had changed the gauges, and the sending units, changed the t-stat in the filter housing and my port motor runs higher temp than the port. BUT when you put a infered temp tester on the pan and or filter the temp is 5 degs apart What is up ?

the temp in the pan is after it is cooled, so may not be correct in finding your problem. also depending on which guages you have and their sweep you may have the wrong sending units.
the sweep of the guage dictates what ohm impendance they operate at.they must be matched as a pair or you will in fact get different readings.
are your water pressure readings different? if so that may be an indication of a raw water system clog. typically the water pressurer reading is taken from the inlet side of the cooler on the right hand side of the engine on the oil cooleer itself. you may want to remove the caps from the ends of the cooler and check for debri. as well try back flushing the raw water system from the heat exchanger back. when you do this start at the inlet side of the exchanger, then make sure you remove the hose on the out let sidedof the engine oil cooler, this way if there is debri stuck in the power steering cooler which is in between the engine oil and heat exchanger you get it out.
once you know it is clear from the exchanger to the outlet of engine oil cooler than reconnect hose and remove hose from inlet side of engine oil cooler and repeat.

good luck. and sorry for the long winded reply

I have checked and cleaned out all strainers. Both oil and power steering.
I guess another question is what is the normal oil temp.
Could this be a sender problem? The gauge doesnt peg out either way. Or could this maybe be a center engine lugging behind the other two????
Where should the center drive be trimmed at when running. Either just getting up to plane or wot???

possible sender. ground it out and watch gauge. also does the gauge drop or move when the boat is ice cold and you first start it?
i might check for loose connections behind guage or even the type of sealant on the sender.