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-   -   Overheating After reaching 160 (http://www.wakeworld.com/forum/showthread.php?t=798831)

wakerider69 06-27-2013 8:55 PM

Overheating After reaching 160
 
Hello Wakeworld...looking for some advice on where to go next with my overheating prob. I have an 01 Malibu VLX. It overheated on me a few weeks ago while go pretty fast at the River. It got all the way up to around 220. So I powered down, floated down the river to the sand bar and kicked it there all day. The next morning, I checked the impeller, it was fine but I changed it anyways. I also checked the line running from the raw water pump to the trans cooler...nothing. Took it back out and it still overheated just from idling.

So brought it home and put it on the fake a lake and same prob with no water being sucked up and obviously no water coming out of the exhaust. Checked all the lines from thru-hull to tranny to water pump to trans cooler. Found a little lakeweed but not much.

Changed the thermostat cuz the old one looked pretty bad. Tested the new one first in a pot with water brought up to 160 and it opened fine. Still overheating!

Pulled the thermostat out, engine sucked water for a little while but the engine would not get up to 160. Turned off the motor and re-started...this time no water being sucked up....crap!

Put the t-stat back in and this time took the hose off of the tranny (that connects to the intake side of the raw water pump) and put it in a bucket of water. Turned the engine on and it sucked water no problem and plenty of water coming out the exhaust. Put a garden hose in the bucket so the water would be replenished. Let it run to get it up to 160...everything was fine until it hit 160. As soon as it hit that mark the engine stopped sucking water and it started to overheat. WTF?

So that's where I'm at...any suggestions? Thanks!!!!!

boardman74 06-28-2013 8:07 AM

Do you run the boat in salt water? Is the trans cooler plugged or can you easily blow thru it? Weird that when it hits temp the water stops. How did the housing look?

razzman 06-28-2013 8:12 AM

Check all your hoses, are they the originals? Once the thermostat opens up it will re-route the water flow, you could have an obstruction in a hose. I've also have seen old hoses collapse once the hot water starts passing through them which restricts the flow.

wakerider69 06-28-2013 8:52 AM

RB - the boat never goes in salt water and the trans cooler is totally clear. From what I could see the housing seemed ok...couldn't get the 2 top hoses off of the housing so it was difficult to get a good look at it though. But even if there was a problem with the t-stat or the housing wouldn't water still be sucked up and then just re-routed out the exhaust. Yes the engine would overheat but water would still be flowing from the intake out the back...at least that's what I think...

Razzman - I pulled all the hoses from the pickup to the trans cooler and made sure they were clear and in good condition. They are the original hoses but they seemed ok. I will check the hoses going into and out of the t-stat housing tonight. Last night I was just wanting to verify that my water pump and impeller were working and they seemed to be fine. What's confusing to me is that at 160 it just stops sucking water...I thought that the impeller was pretty much always spinning which would cause it to ALWAYS suck water. If there was too much pressure in the system from a blockage or a collapsed hose, would that cuz the raw water pump to stop sucking water? Maybe cuz the system was already at full capacity and there was nowhere else for the water to go? I put my hand over the hose that I had in the bucket and there was no suction at all. Thanks!

wakedaveup 06-28-2013 8:57 AM

You seem technical enough to have looked for it but I will say it anyway. Have you checked the valve on the raw water pick up? There should be a valve on the raw water pick up and if that's closed it will not draw water (could of accidentally been hit while working around down there). Also check to see if you have weeds or anything stuck in the pick up. Just some recommendations but prob not the problem.

wakerider69 06-28-2013 10:43 AM

Thanks Dave...I do not have a valve on the raw water pickup and no weeds or anything. And when I was working on it last night I was using a bucket full of water being constantly fed by a garden hose to replenish the water in the bucket. I disconnected the line from the inlet side of the raw water pump at the connection on the vdrive. I put this line in the bucket and it sucked water no problem until it reached 160....then it just stopped sucking water.

zimme 06-28-2013 10:50 AM

Does it stop sucking water gradually, or all at once? When your thermostat opens, it does so slowly and should be fully open at 160* (if thats what t-stat you have in there). Have you verified that all hose clamps and connections are tight? No leaky hoses or water intrusion in the boat, correct? If there's no blockage, you have a fresh impeller, all connections are tight, and all hoses are good, the only thing left really is your raw water pump.

wakerider69 06-28-2013 11:24 AM

Not sure if it stops gradually or all at once. I will hook it up tonight and try to determine that. Last night what I observed was that the water level in the bucket was holding fairly steady - maybe slowly going down since the raw water pump in the boat was prob sucking water just a little bit faster than the garden hose was able to replenish it. I didn't notice the bucket getting fuller as the temp got closer to 160. But as soon as the temp hit 160, the bucket started overflowing and water stopped coming out of the exhaust. I shut it off and let the engine cool down a little. Started it back up with the same procedure and did the exact same thing. All clamps and connections are tight and no water intrusion in the boat.

I have a question about the water pumps in the boat....from what I understand, there are 2 pumps right? The raw water pump which uses the impeller to suck water into the boat and then there is the recirculation pump...what exactly does it do? trying to wrap my head around this whole system to better troubleshoot what the problem is. Thanks!!!

wakerider69 06-28-2013 1:28 PM

never mind about the pump question...just googled it and now I'm good...should have done that first I guess...hahahaha!


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