Oil Temp Question
 

I have a Revolution Marine Oil cooler 3" x 18 that I bought used from a member on this form. The front part is the power steering and the rest is the oil cooler. I have #10 stainless steal braided line for all the oil lines. Temps are still reaching 300 degrees according to the gauge the sender is mounted in the block above the oil filter adaptor. I'm sure that it should lower than that with that size cooler. I think the oil cool might be clogged not sure I tried calling them but get no answer any info would be great thanks.

Don't play around buy a new oil cooler, check all plumbing lines. Make sure water line from the water pump goes right into cooler first then engine. Check gauges and sender as well. You should never run oil temp over 275.

Before you go nutty, get it up to temp and shoot the filter with a infrared gun. Make sure you're gauge/sender are telling a true story.

Secondly, make sure you're engine is not LEAN. If truly getting up to 300*, that's friggin hot.

ok thx ill check it out

is the 300 temp after a hard run or just up cruising around? if after a hard run does it drop down quickly? 300 is way too hot but as Mild said you need to shoot it to make sure it is a real number. most of the ones I have built and run would get up to around 230-240 on a hard run at WOT but as soon as you ease off they would drop to 200 or so within a minute or so.

just cruising it will get up to around 240 after awhile. At wot for a bit it hits 300 and it does come down back to 240 ish pretty quick. 300 is as high as my gauge goes not sure if its getting hotter than that.

also my engine temp is between 150 and 175 never gone past 175. not sure if that matter or not.

Definately !

Your block is a cooler, not just a heater. Temps on both sides try to equalize themselves.

Merc mainly uses 140F thermostats for many different reasons.

300F way too hot. Hope you have high quality synthetic in there now until you figure it out.

2nd that, my engine oil I thought was running hot, hit it with no touch heat gun , bingo : 30* cooler

I don't have a oil temp gauge. Does hitting a part of the engine with an infrared thermometer work?

No. The oil filter can will give you a decent reading, not the block.

How close of a reading are we talking?

Pretty close. The factory oil temp sensor is mounted to the remote oil filter housing on my Fountain. I read abt 10 degs cooler with the IR gun compared to the oil temp indicator, but who knows how accurate the 24 year old factory gauge is.

tell us more about the engine..also are you using stock merc cooler lines etc ? stuff is pretty much junk from the lower HP engines, best to re-do with larger lines, better non restrictive fittings, cooler, adapters...

+1 on everything SB said. I had a ZZ502 with 300* oil temps after a WOT romp. Changed to bigger lines and bigger cooler. And to lower the engine/block temp I drilled three 3/16 in. holes in the 140* thermostat. Lowering the block temp helped allot!! Used the same set up on my NA 557 with good results. Oil was always Mobil 1 V-Twin 20/50

Sounds like the oil pressure relief valve (located in the block oil filter pad) is bypassing the cooler. Many plug this valve so all oil is run through the cooler

While it could be what you say Kurt, however remote, There may be another possibility here. Here is a lesson I learned a few years back. I had been using 3x18" coolers for years in my old engines and always ran between 210-260 degrees maybe even 270 after a long hard run. When I built the new engines for the phantom I bought the same 3x18 coolers. But the oil ran so cold ( 100-120 ) the oil condensated. I really had no experience at the time with oil thermostats because I never needed them . The reason for the difference , my original coolers, which I got through a diesel supply company, were very different. They had a bundle of 12 tubes while my new ones bought from a offshore company has a bundle of 32-35 in them. Just a thought.

I'm guessing that the actual tube length for your oil cooler is somewhere around 12". Still, 12" x 3" diameter is a fair amount of cooler unless you have a high H.P. big block (over 425 horsepower).
#10 lines should also be plenty. It is easy to sight through the tubes to see if they are blocked (impeller pieces sometimes).

I would not want to see 300º oil temps under any condition, even WOT for brief periods. I would ensure you gauge is reading correctly and then
follow the many great suggestions given. I too use Mobile 1 V-Twin 20-50 oil.

My first thought was a lean condition as well, could also be timing. So those items need scrutiny asap. Also along the same lines as kidnova mentions, I'd remove the coolant stat and try to get coolant temps as low as possible until you get a handle on the issue. Oil temp will track along with coolant temp so any improvement in coolant temp should translate to the oil as well. Plus of course high quality synthentic oil is a must until you get the temps under control. Anything over about 270 calls for throttle back and crack hatch.

If your engine is computer controlled it may not like the switch from a 160º to a 140º thermostat...just something to consider.

Captain Yarrr, with your pumped up 6.2s I would recommend oil temp gauges. You might be surprised at how hot your oil is getting.

EXACTLY what I was going to say. This happened to me. After $1090.00 later (two new coolers), the builder found the sending units were a mismatch in ohms to the Gaffrig gauge. BIG waste of money. Heat gun is the answer. Home Depot for $40.

Yes I think I'm adding that to my list. I put the IR thermometer in my boat this weekend so I can get a rough idea. I have coolers but I would feel better if I check on it.

An oil temp gauge is one of the most important gauges on the dash. It is also, the one that is most overlooked when installing gauges. Most people would be extremely surprised (unpleasantly) at what their oil temp climbs to.
Eddie

Where is the temp sensor on most boat engines ?