Ilmor m-10
 

New here so please bear with me,
Having troubles keeping it cool. After 3-4 min WOT runs, I heat up. My HTM has a big hood scoop but I think I need more?
I tried water wetter, but still get up to 230-235 ish, but will drop to 100 with a mild idle for 3-4 mins.
(Closed cooling, sea water system, in fresh water.) New impeller this spring, gadget shows 20 pounds of water pressure.)
If I lift the hatch cover 2" boat runs much cooler, just don't really want to rip it off the back of the boat.
Does this mean my water pump is weak?
Or is this temp. ok?

Ilmor MV-10, WOT RPS @ about 5600.
(I'm told 6000-6200 is red line, but honestly cannot afford to replace.)

Anyone know of a trust worthy shop in the mid west Chicago land / Southern Wi area for the top end rebuild at 500 hrs? Or to do general maintenance.

New and need my 10 posts, seen this short cut earlier.

Purchased an HTM sr-24 love the boat, has an awesome ilmor mv-10, but miss the arability of a good mechanic in town

Have had pretty good luck with Mastercraft of Chicago, but 1.5 hrs one way is a drive, just for an oil change.

This thread has info which could also be in your other one. I would suggest removing the end caps off the heat exchanger and clean out the tubes

I know this sounds goofy, But I have found some circulation pumps with the impellers rusted off. The pump commonly called the water pump on a car or truck. Even fresh water only engines. I am sharing because it was a hard lesson the first time I found it.

Back to the shop.
 

Charged up both batteries last night 100%, they were still good this am.
Went and had them both tested and there just fine.
So, we got a little more fresh gas and went out.

Boat ran Awesome for off and on about 3 hrs. Drove down river and it Ran Awesome again. Turned around and it started running like crap all over again. Pulled it out of the water, and she's going to the Dr Tomorrow am.

I will post what they find for anyone else in the future,
Thanks again for helping out to All!

More common than one thinks. One one the reason I went out and have all mine water circ pumps made here in the USA.https://cimg3.ibsrv.net/gimg/www.off...da7a6d1b51.png

Sounds like a fuel delivery issue or ignition issue(s)

Run engine on a remote fuel supply tank. This will take the boat side fuel end out of the mix or pin point were your issues are.

Next take a hand held temp gun with you - measure temps of the ignition coils when the engine is running good. When engine starts to run bad go back and see what the temps are from the ignition coils -- then compare.