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Help with the tranny cooler and water intake


Vegas Wakesetter XTI

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Hi everyone. Just got a Malibu XTi direct drive and have a few questions that I hope someone can help me with. After idling out of the no wake area the engine temp hit almost 200 and then the boat bogs down until the engine temp comes back down to 160. This only happens once and then it is fine and idles without the temp going up again for the rest of the day. The impeller was just changed but not sure if the previous owner ever checked the cooler and or hoses for debris. If I could get some basic directions on how I can check all that and do the backflush to make sure I am getting proper water flow I would really appreciate it. Thanks everyone.

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Since it only happens once, is it possible that the thermostat is sticking? After it hits 200 or so there is enough pressure to "un-stick" it and it operates normally... at least until it gets cold and stuck again.

Just a thought...

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If it only happens once it sounds like you have an issue with your thermostat. Should be opening up sooner. If it's bad it won't open up at all until a higher temp and cause the overheating issue you are speaking of. Once it get's to 200 it finally opens and you are back to normal temp. I would start with a thermostat replacement.

If I were you I would also check out the screen just before the engine for any sort of debris. It's fairly easy to access. Follow the hose coming off the impeller housing towards the engine. There will be a cylinder looking casing that this hose hooks to. Loosen the hose clamps and you should find any debris in this hose or against the screen going into the cylinder. Stick your finger in there and it will feel like honeycomb. Pull out anything that shouldn't be there an put back together.

Edited by SMERRILL
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If it only happens once it sounds like you have an issue with your thermostat. Should be opening up sooner. If it's bad it won't open up at all until a higher temp and cause the overheating issue you are speaking of. Once it get's to 200 it finally opens and you are back to normal temp. I would start with a thermostat replacement.

If I were you I would also check out the screen just before the engine for any sort of debris. It's fairly easy to access. Follow the hose coming off the impeller housing towards the engine. There will be a cylinder looking casing that this hose hooks to. Loosen the hose clamps and you should find any debris in this hose or against the screen going into the cylinder. Stick your finger in there and it will feel like honeycomb. Pull out anything that shouldn't be there an put back together.

Thanks much.I will get a thermostat kit and hopefully that works.

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Yep, disconnect the hose coming from the raw water pump into the proximal end of the transmission cooler.

Get a flashlight and maybe a mirror (I have a v-drive, so the mirror is a must) and look up towards the

screen. You can also stick your finger up in there blindly and get an idea if there's anything there. If so,

try to remove it. You can then get a syringe or turkey baster and squirt water up towards the screen to

help rinse. You could also disconnect the hose from the distal end of the cooler and run water straight

down to flush it clean.

Just be careful when you hook it all back together. Tighten those c-clamps so they are snug, but don't

overdo it. You can, without too much effort, actually crush the cooler walls if you over-tighten. The

clamps only need to be tight enough that there is no leak while the engine is running.

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While waiting on your new t-stat, you could take the old one out and heat it up on a stove with a meat thermometer to see at what temp it opens up at. I would definately check your tranny cooler and hoses before ordering anything. You could have debris in there positioned in a way to block all or most of the water flow, then you idle down and the water pressure changes and some of that debris shifts around and now its clear enough to allow enough water to pass through.

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Always a good idea to fully unhook the hose going to the trans oil cooler & flush it while you're at it. This will make sure it doesn't have any debris hiding in it either.

You can have debris that gets pushed up against the trans cooler screen when running & then falls back down into the hose when stopped. I had a few pieces of debris come out of my hose when I rinsed it in the fall. How the debris made it past the impeller intact surprises me.

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While waiting on your new t-stat, you could take the old one out and heat it up on a stove with a meat thermometer to see at what temp it opens up at. I would definately check your tranny cooler and hoses before ordering anything. You could have debris in there positioned in a way to block all or most of the water flow, then you idle down and the water pressure changes and some of that debris shifts around and now its clear enough to allow enough water to pass through.

:plus1:

Had to do it.... :salute:

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Have the new thermostat and will do all these things with the tranny cooler this weekend and let you know how it goes. Thanks again everyone!

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  • 2 months later...

Ok. So still have the problem. Changed the thermostat, impeller, and tranny cooler screen is clean. Only happens at initial start up and idle out of no wake area. Temp goes up to 200 and then if I shut it down and wait a minute and then restart it and get moving the temp goes back to 160 immediately and stays there. I can let it idle after that through the same the no wake area back in to the dock and the temp doesn't rise at all. Even when I run it with the hose hooked up to it in the driveway the temp doesn't rise over 160. Any ideas would be great. Thanks everyone.

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Sounds like you may not be getting prime at first startup. Give the boat some throttle in neutral after start up to get the water flowing.

I like to physically test water pressure by squeezing the hose after the impeller if you are not confident in water flow.

-Chris

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Sounds almost like your impeller is not priming. Since you have a direct drive, put yor hand on the impeller housing to see if it is heating up, which it will be doing if it's not primed.

I would double check all hoses from the thru hull water pick up back to the impeller for debris or a loose connection. A loose connection could cause the impeller not to prime until you get out of the no wake/idle conditions and increase the engine speed.

Edit: sorry for the echo...my wife called me before I finished my thought and posted....silly girl...she'll hear about this tonight!

Edited by rts
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Sounds almost like your impeller is not priming. Since you have a direct drive, put yor hand on the impeller housing to see if it is heating up, which it will be doing if it's not primed.

I would double check all hoses from the thru hull water pick up back to the impeller for debris or a loose connection. A loose connection could cause the impeller not to prime until you get out of the no wake/idle conditions and increase the engine speed.

Edit: sorry for the echo...my wife called me before I finished my thought and posted....silly girl...she'll hear about this tonight!

CAREFULLY " put your hand on the impeller housing to see if it is heating up". maybe use the back of your hand. it can get HOT.

Edited by tvano
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It sounds like an air leak somewhere in the suction side of the impeller to the raw water intake or even a worn seal / gasket missing from the impeller housing. The impeller is a good pump as long as all the previous conditions are OK. It most likely runs hot initially due to the lack or ability to prime the system, then after you running for a while it's finally able to prime itself and remains primed throughout the day. Depending on the hours on your BU you may want to just buy a new complete impeller and housing. Also, check the raw water intake that it's wide open and the hoses going from the impeller for any kinks.

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  • 3 weeks later...

Changed the impeller and back flushed from the impeller back to the water hook up and tightened all the clamps and hoses between. Just took the boat out and temp never came over 160 all day. Thanks everyone for the input. Appreciate the help!

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