Cord

iTrader: (2)

The other week when I was running the boat, I was concerned about the oil temps. After about a 5 mile cruise I was showing 160 degrees and slowly rising. I was also showing 120 degrees water temp which was also slowly rising. The water temps don't concern me as much as the oil temps as they are proably the result of the crossover.

The oil system consists of a permacool thermostat on a 3x12 oil cooler and a remote filter. At first I feared that I had the oil lines on the cooler reversed, but last night I confirmed that they are correct. I do have a milky foam in the valve cover, but the oil is clear. My feeling is that the condensation is a result of the oil not getting hot enough and is not a result of reversion.

Here is how the system is plumbed:
block (outside of adapter) to thermostat to oil filter (center) to block (center of adapter)

WETTE VETTE

You are probably right about the milky film on your valve covers being a result of not enough oil temp. I do not run a thermostat and use a 3" x 25" cooler, but that includes the power steering cooler. It is kinda a good / bad situation because the oil stays cool and it is difficult to get the temps up. I just make sure that every time out I run it hard enough to get the oil to 212 and I never see the milky film. Because my oil temps stay low I run 10W40 Amsoil which is a pretty lite oil compared to a 15W50 or a 20W50 and pressures stay down around 60 PSI at 6000 + RPM with the oil at about 140 to 175, which is where it is normally at. Try cruising at 5000 RPM for a long stretch and it should come up. I normally make 3 or 4 6200 RPM blasts across our small lake and the temp in the pan is at around 212. It is fun warming up the oil.

Cord

iTrader: (2)

I agree, I should have run the boat longer, but at the moment the wheels were falling off and I just wanted to get into port. Unfortinatly, I don't think I'll be able to run the boat any more this year due to the fact that WE'VE SKIPPED FALL!

blue thunder

I don't believe you ran long enough for the oil temp to plateua (sp?). Mine take a good ten miles in the summer to reach normal range. Wait for Indian summer and go for another rip. If nothing else, it will make a good excuse to justify.

BT

MIKEHTMSR24

I don't have a thermostat in the oil line and it takes forever to get the oil temps up in the summer time. I do have a water stat and I see about 140 when I am running.
I was told by a very good marine mechanic in Atlanta (Gary Grimes) not to run the engine hard until I see 180 on the oil and after 230 get out of it. My sensor is mounted after the oil cooler.
I think after a 5 mile cruise your temps should be up to 180+. No matter how cold the water is. I have read the posts on perma cool. Good or bad I haven't voted yet.
Gary told me the merc oil stat was the best to use and easy to install. The other good ones require a lot of pluming.

Anybody got a Merc oil stat for sale!!!!

MACDAD260

Here is something to ponder on oil temps. When I switched from the stock 7.4L to a 502 last spring I decided to try running with the stock accessories first just to see what would happen. I also installed a Gaffrig oil temp gauge with the sender in the remote oil filter housing. This measures oil temp right out of the pan. Running the stock dual oil cooler on the 502 caused the oil temps to get to 230 at a 3000 rpm cruise. At a 4000 rpm cruise the temps would climb above 260. I never did much running above 4000 rpm until I installed a 12 X 2 engine oil only cooler and a pema-cool t-stat. Even with that the temps would see the high side of 260 on moderately long runs at 4500 rpm. At 3000 rpm the temp was 215. I was told by my engine builder and a Merc Mechanic that that was Ok and nothing to worry about. In August I seized a piston on the 502 due to too lean of a mixture in the carb. I pulled out the 502 and put the 7.4L back in, leaving the larger oil cooler in place. On a moderate cruise of about 3000 rpm the oil temps would get above 200. At 4500 or higher the temp would get about 240.

My point to this long story is that even with an oil cooler 3 times larger than stock, the oil was getting above 240*. I never had a gauge in the boat when I had the stock motor and the stock cooler so I can only imagine how high the temps get that way. I have run the motor for 15 to 20 minutes at WOT that way in years past and I never had any problems. The engine is just as clean inside as a new one. No signs of oil overheating, no moisture. My conclusion is it is better to have the oil too hot rather than too cold.

Another thing to ponder. Gaffrig makes a series of gauges with built in idiot lights. The light goes on at 270*. I have to believe that anything up to that temp is OK.

Do a search on oil temps. Lots of differing opinions as always. You'll just have to settle on something you're comfortable with and go with it.

Se ya, Doug

blue thunder

I feel comfortable between 220 and 260*. When above or below I back off the throttles. I like to see the oil stay below 270 max for sure during an entended wot blast. To me most of it depends on what it takes to get it to different temps. In my boat, if I was cruising at 3k and the temp went to 260*, I would shut it down because this would be an abnormal deviation.

My 02

BT

MIKEHTMSR24

But please remember one thing. Were is your sensor located?
Yours is at the hottest point. Mine use to be mounted in the oil pan. The pan is a 14 qt. I saw the same temps you are seeing. I ran for 125 hours this way and thought I was doing fine on the low end. It didn't take long to see the 180 I was looking for. On the high end is what scared me. I saw 230 fairly easy. I would back out if I got to 240. Then I talked to Gary and he said those temps are fine when you read in the pan and he advised me to change the sensor to after the oil cooler. He said he would rather see what is going into the pan. So I change the sensor location.

MACDAD260

Ya mike, I noticed that you are reading after the cooler. I think I will put in another sender this winter and wire it up with a toggle switch so I can read the temps on both sides of the cooler. I agree, about 230 is max back into the bearings. That's what the airplane guys say too.

blue thunder

Good point Mikehtmsr24. My sender is in the remote filter adapter. Big difference.

BT