Engine Oil Temp
 

I'm replacing my oil temp gauge and I'm running Gaffrig red line gauges. My oil temp gauge that is presently in the boat starts at 180 and max at 350. Not sure when the red light alarm comes on on the gauge. Usually when I'm running the boat it seems as the gauge is two high of a range for the boat temp that it normally run's at. I have purchased another Gaffrig red line oil temp which starts at 140 and max at 320, I think that this one sets the alarm off at about 250 degrees. I have recently purchased the boat and have not had an opportunity to really pound the boat in hot conditions.
I'm running a 500 hp and I'm wondering what is normal oil temp for this engine on a hot summer day?
I don't want to put this lower temp gauge in the boat and have it going off when the water and air temp gets warm.
Thanks
Active Mike

If your oil temp ever gets to 350* or for that matter 320*, its COOKED. 250* is a good spot for the alarm. It will tell you to back off before you hurt something.

I took the mains out on a perfectly good lower end this summer after exceeding 280f with dino oil. Been fighting oil temp problems with my closed cooling for some time now. I ran sythetic after rebuilding that engine for the rest of the season, backing off in the 250-260f range. I agree with Griff... 250 is approaching trouble. If I had my way, which I will, my oil temps would run around 200f cruising and go to no more than 220 after a flogging.

Dave

Thanks guys for the info. My two other boats ran around the 180 to 200.
Thanks again,
Active Mike

Where are you fellows measuring your oil temp...in the oil passage, or in the pan?

My temp sensor is in the passage port.

I would imagine that the oil temp is higher in the pan as opposed to in the passage. Right?
In the Chevy performance book it says 300 degrees max, in the pan. Do you guys agree with this? When running hard, I get up to the 250 to 270 range, in the pan.

Mine is in the remote filter pad spare port. I believe this is similar to reading in the pan. First stop after the pan is the oil filter if I remember correctly. From my bad experience, dino oil cannot take 300F no matter where it is measured. Synthetic a little better. We make large quantities of adhesives where I work. These are dino oil based (30 wgt basically). If we heat that to over 300f we get charring and clogged pump filters... basically the oil breaking down into it's fundemental components. Not sure of the correlation

Blue thunder, are you noticing your pressure dropping as it heats up? I never had a problem with pressure drop until I ran on a big lake - lots of WOT time. Typically on a small lake and only holding open for 1-2 minutes at a time. I purchased a HD cooler to try to minimize the temps.

It drops some John after a 260f romp, but rebounds after a short cruise or idle.

Dave

My pressure would drop allmost 10 PSI when I hit it hard and the temp elevated from200 to 260. I then switched to synthetic oil and the pressure drop under the same conditions is only a few PSI.

Are you guys using engine oil coolers?

Yes, stock merc stuff for me. Working on upgrading to higher cooling capacity units.

Dave

Yes, a 4" x 24" cooler.