TxHawk

iTrader: (2)

I had a 502/502 rebuilt for my 27 Flat Deck Resto. Nothing major, marine built by proven marine builder. Maybe 525HP.

8 quart pan, 3" Oil Cooler, -12 AN lines etc. I had a Hardin Marine thermostat remote oil filter on it for the first 2 runs running Straight 40W Oil. Oil PSI on block, Oil Temp at remote filter. Flowing through filter then cooler.

Runs great, good oil pressure, good water temp, not running hard. Made a minor pass and oil heated up to 225 on the gauge. The temp didn't want to stop there but I didn't let it get over 225. Oil line fittings on cooler were not hot at all, filter obviously was. Cut open filter and found nothing, clean.

After much thought and discussion, I removed the thermostat and went to a regular remote adapter. This time it didn't heat up as fast, but as soon as it started to get some heat it went to 225-235. This is running 3000-4000 rpm with a quick blast to 5k.

Next run, I changed the oil to Valvoline Racing 50W. My thought was having better oil in it if I am going to get it hot during break in. This time I let if get to 250 before I shut it down quickly and got out my IR Temp Gun. I couldn't find a reading over 190 at the pan, block, fittings, filter etc. Most were 175-185.

I can't imagine there being 60* difference in oil and the readings I can get with a gun.

I have a new set of Gaffrig Gauges and senders. I wasn't impressed with them but the price was right. I cannot get the tach to work right and now I am doubting the oil temp after all of this.

Funny enough, I had to add the Oil Temp and Water PSI to the set I bought. Had I not, I'd be out running the crap out of this thing not worried.

Any thoughts? Plan is mechanical gauge next trip.

BenPerfected

You might need a bigger oil cooler.

PARASAIL941

Try different brand oil filter. Any additives/heavy visc oil will slow flow through cooler.One of my parasail boats runs higher oil temp under load when we use a Wix filter , other boat doesnt care. Good luck!

mike tkach

iTrader: (3)

if your handheld showed 185 as the hotest i think you might have a faulty sending unit.did you use thread tape on the sending unit?

F-2 Speedy

iTrader: (6)

Maybe the sender is the wrong impedance for the gauge, how long is the cooler ?

TxHawk

iTrader: (2)

Cooler is 3x12. New sending units have a ground wire and came with the gauge. They do have thread sealer on them but I believe with the ground wire that won't hurt the reading.

Ran-Dom 32

I had a similar issue , one gauge would creep up anything over 4k.. changed senders & swapped gauges & the problem went away ... (I also change the oil thermostat) I was never able to find a hot spot with a temp gun (nothing over 180-190) I believe I had a bad ground somewhere , sounds like you may be dealing with same thing

mike tkach

iTrader: (3)

post a pic of the sending unit&wire if you can.

jmoore1225

iTrader: (1)

I have had same issue, have determined it has to be the gauge. I swapped sending units & it still did the same thing. I shot an IR gun all over on that engine & it was actually always cooler than the other motor. This engine was a fresh rebuild & has a larger oil cooler too.

F-2 Speedy

iTrader: (6)

Are you flowing the oil against the water flow, some will say it doesn't matter but I think it does

edit: what kind of block adapter are you using, three fittings on the adapter ?? hard to see