2011 SUPRA 22V Indmar 6.0L Engine Overheating at Low Idle Speed

I am having problems with my 2011 SUPRA 22V Indmar 6.0L Engine "overheating" at idle speed. This seems to occur more after initial startup, and not after it has been running for a while. If I allow the engine to idle for any length of time while the boat is still at its mooring, the VISION dash shows the engine is overheating. If I lift the engine rpm slowly the temperature normalises. The local dealer has replaced what they thought may be a faulty temperature sensor, but still no better. The water pump impeller has also been replaced. I have had this issue from day one basically. Noticed at 10hrs. I know have 81 hours and still have the same problem. ANY IDEAS?

I got this off the Malibu Forum . They use Idmar engines in their boats also . The service kit part number is 89-99003 I hope it helps.



The LSA and LS3 engines are the same, (6.2 L) aside from the supercharger. Although, it was explained to me by Indmar, it has something to do with the way water is pumped thru the engine...which is backwards from most. And the overheating problem is worse if you have a heater. Which I have. You may want to call and talk to JT at Inmdar.

Our LS3 had (may still have) the same problem. So I understand your concerns. Malibu installed a booster pump last fall. Not sure if it is the part number Peter was kind enough to provide, but probably is what Malibu installed on our boat. This will be the first weekend to run it, so I will let you know how it works. SInce there was no paperwork supplied by Malibu when we picked the boat up, I can't verify what part number/12V booster pump was actually installed. I can send a pic if you'd like.

Our boat never made it past 200-205 F, by then the alarms were going off and I would rev it up to 2000 rpm a couple of times and the engine temp would drop right back to the correct operating temp.

I plan on installing valves to shut off the flow to the heater, so during the summer months, it is one less thing to worry about.

The problem is exacerbated if there is some idle time/5 mph no wake zone and when first being run that day. I don't recall it ever happening after the engine had reached operating temp.

Initially I was told by Indmar to rev it up a couple of times, and that would take care of the problem. It did for me, but was not exactly the "fix" I was looking for. Specially after spending that kinda money!! ha ha

Hi there Michael

Thanks for your feedback - much appreciated. I will pass this onto my local dealer handling this issue. Sounds exactly the problem I am having. Only seems to "overheat" if allowed to idle for a while after initial startup from cold. I have not had it happen once the engine has been running at normal operating temp. I like your idea of installing shut-off valves to the heater system. I very seldom have the need for the hearter hear in South Africa.

Let me know how you do after the installation of the booster pump. The pic of the pump would be appreciated!

I understand your frustration/concerns completely. As you say, after spending that kind of money, you certainly dont need these hassles. Lets hope things get sorted out!

Keep in touch

Cheers

Keith

I don't have the problem so I wont be giving any feedback on the repair . As I understand the problem its a pump priming issue. Idmar runs the water pick up backwards from other brands . This problem occurs when you don't have the engine running fast enough to start the water flowing through the pump. It was recommended to rev the engine a few times after you launch to prime the system. Good Luck .
Make sure you post the fix you find on this problem to help others in the future.

Thanks. Only once I had read your post for the second time did I realise that it was not a problem you had yourself, but a post you had found on the Malibu forum. Thanks again. My dealer is picking my boat up tomorrow to run some tests again. I will post the findings and possible solution if found.

Still no solution to my overheating issue! Service from Indmar shocking!!!!

Sorry to hear that. It sure sounds like a priming issue. If you rev the motor to 1500 or so right after start does it prevent the overheat?

Quote:

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Originally Posted by CJD

Sorry to hear that. It sure sounds like a priming issue. If you rev the motor to 1500 or so right after start does it prevent the overheat?

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Hi there. It does help to rev the motor. Temp drops back to normal. Definitely a flow problem somewhere. Once the temp drops I have no probl until the boat sits overnight and cools down completely. Then the cycle starts over again!!

All good machines have a few little quirks. At least this one can be dealt with easily.

If it really bothers you, there are a few areas you could look at. I am assuming for all of these that it is just a matter of the raw water pump not getting a good suction when there is air in the hoses.

1) check for any hose leaks between the water pickup and the raw pump. Air sucks faster than water, so even a small leak can prevent the water from rising to the pump.

2) Check the tranny and raw filter for small leaks. These can be hard to find, since a lot of the hose and parts are above the water line while resting, and have a suction while running. A small leak may never leak water, just enough air to prevent the water from reaching the pump.

3) Check the pump for any issues. These would include a bad gasket, burrs inside the pump, and finally the way the impeller fits. Any mis-fit, especially undersize, can prevent decent suction.

Again, any leaks on the suction side of the plumbing may not leak any water...so it will be difficult to pinpoint an actual leak. After that, I would learn to goose it right after a cold start to get the cooling system going...

Thanks very much. Will pass your suggestions on to my local dealer.


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