Oil temps and closed cooling revilation
 

You guys have given me a lot of advice on this problem, so I thought I would share some of my recent findings. A little background:

Have had oil temp problems for 3 years with this boat. Have even changed both engines and still running 230F cruise and skyrocketing during WOT blasts. Took main bearings out on one engine last year when oil temps got excessively high 280F+ with dino oil. Made it my winter mission to fix this problem.

Over the winter I installed 3" EMI oil coolers, blocked the oil bypass valve, re-plumbed all oil lines to eliminate 90* elbows, changed out exhaust to KE headers and went to different oil filters with internal bypass. I figured I would be over cooling the oil now so I went from a 140F tstat to a 160 coolant tstat.

I was very disappointed to see after my first run that my cruise temps were still as high as 220f and wot still was getting to 250f+ in a hurry. Obviously I was missing something. So I decide to switch to a 120F coolant tstat, remember this is closed cooling here. Not able to find that tstat, I decide to take the guts out of the 160F coolant tstats I just installed. This weekend was my first real run with no tstats (kind of). The result is 200F cruise temps and after a extended WOT blast I am seeing 220F. When I back off to cruise the temps go right back to 200F. That is excactly what I have been trying to achieve!! All this time my oil temp problems may have been solved with a change is coolant water temp, I just never thought they (coolant and oil temps) were closely related. I know some of you battle the same issue, and think you may benefit from trying what I just did.

BT :cool:

Re: Oil temps and closed cooling revilation
 

Arizona Speed and Marine has 120 stats. 120 may be too cool unless you have a blower or some other need to keep the engine that cold.

Re: Oil temps and closed cooling revilation
 

Arizona Speed and Marine has 120 stats. 120 may be too cool unless you have a blower or some other need to keep the engine that cold.

Re: Oil temps and closed cooling revilation
 

Both engines are running at 130F water temp cruise and 150 max WOT. That works for me as long as oil temps are able to get above 212. We'll see how it goes and with get 120F stats if necessary, thanks.

BT :cool:

Re: Oil temps and closed cooling revilation
 

B.T.
I had the same problem with one engine last weekend :mad: . Long story short...I had a blockage in the flex hose thru the transom assy. I have a hard time getting to 200* oil temp even at WOT. I'm suprized at your temps with those gigundo coolers. I have the Merc HP500's on mine and they to one helluva job.You have water pressure guages?
Cal (mopower)

Re: Oil temps and closed cooling revilation
 

Blue Thunder,

Thanks for the thread. I switch to a drilled 140 tonight. I run full closed cooling with an alpha outdrive and a bravo engine mounted raw water pump. The bravo raw water pump is fed direct from an 1 1/4 scoop type thru fitting so I know no hoses are kinked. I have no oil cooler on my vortec sbc and I know my oil temps get hot.

The other problem this might help is that the engine might kick out less water before the t-stat opens. There is no room left for an overflow bottle.

Thanks

Re: Oil temps and closed cooling revilation
 

I was a little suprised too Cal. I can't explain why, but my closed cooling must have been the primary problem all along. For some reason the water temp is having a direct affect on oil temp. I don't have water pressure gages, maybe next go around I'll install some. How you making out with the spring debug?

Flyfast, you are welcome. I've been fighting this battle a long time and am happy to have finally made some progress. I thought about drilling holes but gutted them instead leaving the tstat carcass in place for some restriction. And now that you mention it, my coolant level in my overflow reservoirs did not go up this weekend even after some hard running, so you may be on to something there. You should definately spring for oil temp gage/sender at a minimum.

BT :cool:

Re: Oil temps and closed cooling revilation
 

Still have a slight drip from either the timing chain cover or crank seal :hothead:
Really burns me because this one was whooped on for two hours or better on the dyno and no leaks. Would also like to try 26 Bravos or 27 Mirages in leiu of the 28 Bravos I have presently. Gotta mess with some jetting too as I get a sooty stern and am using too much gas.ROTFALMAO

Re: Oil temps and closed cooling revilation
 

Don't overlook the keyway in the balancer in search of the oil leak. Sometimes they take a while to develop. I have 27p mirage plus' you can try if we meet up somewhere. I'll be at the Bay Saturday through Tues of next week. Curious what you are running for jets and what carbs. I am working that same issue. No soot on the transom, but plenty on the plugs. Trying to decide what my next rejet (Friday night) will be and am collecting opinions.

Dave

Re: Oil temps and closed cooling revilation
 

Dave , I get a drop on the lip of the oil pan below the crank. I have put an oil diaper under the front of the engine and it gets pretty messy. If it were the keyway it would be out the front of the balance and that's dry.
As to jets etc. totally different animals. 540 ci...1050 Dominators with custom billet metering plates and annullar boosters. Presently 92s around and no pv's.
Think I'm going back to 88's for starters.

Re: Oil temps and closed cooling revilation
 

Bluethunder,
You may still consider the 120 t-stat to help get your temps up sooner. The reason I switched to the 120 was the same as yours. After I added the blower I went from 210 to 225 on oil for cruise and 235 to 250 at WOT. The 120 brought it down to 215 and 240. Both before and after the water was temps were 140 and 150 at WOT. The lower block temps just acted as a cooler for the oil.

Re: Oil temps and closed cooling revilation
 

Also you may want to check for a collapsing main water inlet hose or air leak on the suction side.

Re: Oil temps and closed cooling revilation
 

We'll see how it goes with no tstat for now. For now I am really enjoying no air pocket at the top of the engine when trying to add antifreeze. It is a real ***** to add antifreeze with my closed cooling when a tstat is in place.

I have been working this problem for years, as I said earlier, everything has been replaced at least once and still had the problem. You are the first person Baddog, other than me, that I have heard state engine coolant temp has a direct impact on oil temp. I wish I'd known that three years ago, I'd have a lot more money in the bank from not replacing shot bearings :eureka:

BT :cool: