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Intense

Motor overheating with surf load only

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Intense

Hey guys,

I've got a puzzler.

My motor overheats when I load it up for surfing, but it's fine when we're wakeboarding or just cruising around. It's done this twice now. The first time, we idled back to the dock, I pulled my tools out and checked the impeller. It looked ok, from what I could see. I also pulled both hoses running into the raw water pump. Neither seemed to have any blockage...although, I didn't check the other end of the hose running into the the water distrib pump.

Also, I've built my own surfgates, so my boat isn't weighed down so that it's leaning. Yesterday, we had 850 in the middle on the seat, 500 on my swim platform (my Wedge broke off earlier in the season), and 900 in the rear lockers. The middle and front tanks were empty. Bilge was mostly dry.

Why would the motor overheat for surfing, but not wakeboarding? The loads are similar (minus the 850 on the rear seat) between the two.

Thanks all!

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Levi900RR

Did you check your trans cooler screen?

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malibu2004

Did you check the housing that houses the impeller. I've heard of that also going out where people needed to replace them. The spline that comes out starts to get rounded off.

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Intense

Did you check your trans cooler screen?

Where is that?...on a V-drive

Did you check the housing that houses the impeller. I've heard of that also going out where people needed to replace them. The spline that comes out starts to get rounded off.

The raw water pump was replaced last year. So, that should be ok.... which means the impeller was replaced last year, as well

I will say that we've put close to 250 hours on the boat this season. While I normally stick to the every other year impeller replacement policy, I might just need to change the impeller...

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Levi900RR

Follow the path of the water as it enters your boat. You'll run into a beer can shaped device with some hydraulic looking lines coming off it. Thats your trans cooler. pop the inlet side hose off it and look for debris.

I'd bet your impeller is starting to implode...

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tccombs

Here are a few thoughts of things to check... since you say it is while surfing only... then it is happening is at a extreme angle. and under a big load because it has to plow so much water out of the way.

Follow the cooling water path and folow the flow.

start by checking the water intake under the boat to make sure it is clear of debris. (it is doubtful but, could it possibley be sucking in air when the boat is at such an angle?)

if you have a strainer check to see if it is clogged.

Change your impellar even if it doesn't look bad... because you need to do it regularly anyway and it is the most likely is the culprit. (I change mine evey year which is probably more often than necessary)

check the transmissiion cooler strainer

Last check your oil level. if the oil gets too low to properly reach the oil pump, when at that severe angle it might cause a problem.

Look for low oil pressure when you surf next time to see if it is being starved for oil.

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Ndawg12

Did you check your trans cooler screen?

:plus1: starboard side near the transom.

untitled.jpg

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shawndoggy

Had a similar issue a couple of seasons ago. Had a loose raw water strainer bowl that was allowing just a bit of air into the system. I know malibu doesn't use strainers, but it's a good reason to check all of your hose clamps and raw water pump gasket to make sure they are tight. My boat was fine idling and wakeboarding but when going slow enough to surf it would get hot after about 10 minutes. Boat was fine wakeboarding cruising etc. probably the added speed was helping force water into the intake?

Edited by shawndoggy

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Baddog

:plus1: starboard side near the transom.

untitled.jpg

Nate, Is the inlet pipe to teh trans cooler supposed to be "D" shaped like that shown in the third Picture?

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Ndawg12

Nate, Is the inlet pipe to teh trans cooler supposed to be "D" shaped like that shown in the third Picture?

I don't think so, looks like someone got crazy torqueing down the hose clamp. FWIW, I cut and pasted these pics a long time ago from the Winterization.PDF that used to float around here.

photo_zps3779e013.jpg

Edited by Ndawg12

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REW

Change the impeller. They will sometimes start to spin on the brass insert that goes on the splined shaft. This will cause reduced water flow and overheating. During wakeboarding the speed of the boat will allow the water pick up to force feed the motor past the poorly operating impeller.

250 hours is a lot for an impeller to endure.

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Falko

Has it always done this? Or has it just started? I've seen car/boat engines overheat while at heavy loads and low(er) rpms. The engines get hot, start to detonate, and makes matters worse. Just throwing it out there in the event the impeller change doesn't help. But would agree that 250hrs is a bit on an impeller. (and good on you for getting out there that much!)

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