GT-40 running hot

[pgmoore]

Specs: 1997 MB Sports Boss 190, GT-40

 

Problem: We pulled quite a few great sets this morning. Then, out of nowhere, the water temperature started creeping up on my engine. The temperature alarm eventually came on as we were limping back to shore.

 

I can see water pumping through the clear plastic filter in the engine box. Checked for leaks, blown hoses or belts, etc. No issues noted.

 

I'm a great driver, but a less good mechanic. What should we check to try and salvage the day?

 

For information, this is a relatively cold Alberta lake. Some normal algae but no thick gooopy blooms.

 

This is the first issue I've ever had with the boat! Bad luck!

[Andre]

First thing first:impeller?

[Wish]

Intake cleared. Tranny cooler cleared. If it came on fast like that could be a clog in the system or as @Andre‌ says, impeller. One blade of the impeller comes off and it can take the rest with it. The plastic filter is a very poor gage for appropriate amount of water flow. Best of luck.

[BraceMaker]

You can get a good idea if the amount of water getting to the engine is low by resting a hand on the metal cover of the raw water pump - keep the fingers out of the belt, but if it is not cool when running it isn't getting enough water.

 

Very commonly if you are idling with an old impeller (RPM's low) the temp will climb indicating low water flow, in these cases if you pop out the knob and rev it neutral the temps will drop quickly - showing that with added RPM you get the flow you need to cool the engine sufficiently.

 

 

 

 

[BrennanKMN]

Impeller.

 

Does it cool off at speed? If it runs cooler at speed you have a failing impeller. If it runs hot all the time you have a failed impeller or a cooling system clog.

 

Here is a really good guide to follow.

http://www.aquaskier.com/articles/impeller_replacement.htm

 

I did this just a few days ago. All it requires is 2 sockets and 2 spanners of the same size. 1/2 and 7/16 if I remember correctly.

[yardsale]

impeller. change it. takes 20-30 minutes tops. $20 at napa and a guy should have 2-3 spares in his tool box. an impeller can go every year depending on usage. is amazing such a simple cheap little part can be a show stopper.

[pgmoore]

Turns out the impeller was gone and the water pump was going. Replaced both and we appear to be back in business. Haven't ran the boat in the lake yet, hope to do that tomorrow.