View Full Version : LQ9 in X45 overheating help!!!

04-21-2008, 08:09 AM
I just picked up this 2005 X45 with a LQ9 and I am having problems with overheating. I replaced the raw water impeller, i have checked the coolant levels, I have verified that the raw water is circulating. I am wondering if the coolant pump has gone out or if the system could possibly have a vapor lock. I pulled the return coolant hose off the housing where you add coolant and with engine running, it didn't appear to be pumping coolant. Has anyone had this problem and any help you can offer would be much appreciated. This boat is my dream boat and I want to get on the water ASAP. Thanks

I have also heard that you have to purge the coolant system to get a vapor lock out??

04-21-2008, 08:33 AM
Just a thought, but did you check the thermostat?

04-21-2008, 09:07 AM
Thanks for the reply. Yes. I also took to the stove and heated it up to and over 160 degrees and it opened fully.
So that appears to be fine.

04-21-2008, 09:40 AM
Check engine Timing

04-21-2008, 11:01 AM
It is complete controlled by the computer...I don't see how that could help??

04-21-2008, 11:05 AM
Have you checked your transmission cooler for weeds etc? You might be limiting your water flow before it hits the heat exchanger.

04-21-2008, 11:24 AM
Some cars have a bleeder screw near the t-stat, maybe your engine has one too? If air is trapped in the cooling system that could be your problem.

Like someone said, make sure you have a good flow of water to your heat exchanger. Check for weeds, etc. that could be clogging it.

04-21-2008, 11:26 AM
Do you use Ethanol gasoline?

04-21-2008, 12:33 PM
I will check the heat exchanger for weeds.

Don't use Ethanol.

The problem that I see is that I am not getting any coolant coming out of the return of the water circulating pump(water Pump) Not raw water pump. That is good. I have replaced that impeller.
So to it appear that he circulating pump is not pumping at all. Could a vapor lock cause this?? I think it is the pump but not sure.
Thanks for the replys.

04-21-2008, 01:57 PM
Usually any weeds would get caught at the transmission cooler before the water gets to the heat exchanger. Follow the hose running from your raw water pump and you will see it goes into a cylinder that looks like a mini version of your heat exchanger. Remove the intake side hose(closest to the front of the boat) and stick your finger in to check for blockage.
As far as the vapour lock your guess is as good as mine.
I am changing the coolant on my LQ9 this week and have put in a call to a dealer to see about bleeding the system. I will keep you posted.

04-21-2008, 02:32 PM
Good to hear, I will check that...


04-21-2008, 11:14 PM
I have now checked the heat exchanger and its clean. I also pulled the belt off the pull and the water pump spin freely. I can hear coolant splash around in the pump. So I now thing the pump is good???
At this point I am out of ideas. I will run it again on Wed to see if anything has changed in the system with have just about every coolant house off checking for blockage.
If you have any other ideas brings. I could use the help.

04-22-2008, 09:11 AM
How was the belt tension on the water pump?

04-22-2008, 09:46 AM
Belt tension was good.

04-22-2008, 06:44 PM
Thanks for the reply. Yes. I also took to the stove and heated it up to and over 160 degrees and it opened fully.
So that appears to be fine.

For what it costs, you should just replace the t-stat with a new one and go from there. (I don't always recommend parts-replacement guesswork, but this is a cheap part)