View Full Version : Overheating engine

06-23-2008, 03:21 PM
I have a 91 Maristar 210 with 454. I have been the owner coming up on 2 years (about 35 hours of use). The last ride of last year and this last trip a few days ago it has given me the overheating siren.

When I am driving it holds between 145 and 160 degrees. The skier or boarder is done and I turn off the engine and someone else gets ready. So that takes about 5 minutes. I then start the engine again and the temp goes to 210 or so and the siren beeps until I put it in gear and the rpms go up, then it goes right back to that 150 range.

It has only done that 6-10 times. I have checked all the areas where debris could be and they are clean, and I changed the water pump impeller last fall after the first time it did it.

Anything to worry about?

Could it be a faulty temp gauge?

Any help would be great.

Prostar Rich
06-23-2008, 03:27 PM
How old is the t-stat?

Prostar Rich

06-23-2008, 03:43 PM
I would assume original, I have not replaced it.

T Scott
06-23-2008, 04:02 PM
That certainly sounds like a faulty impellar to me. I know youmentioned you changed it last season, but I would pull it and check it if I were you.

06-23-2008, 04:08 PM
it sounds to me like some kind of blockage in your cooling system, a common place for this to happen would be between the exhaust manifold and risers ,after years of use these narrow passages can get clogged with sediment . at higher revs this wont be a problem but will cause issiues at low revs after a good run , just an idea , best of luck with it .

Prostar Rich
06-23-2008, 04:10 PM
Diagnosing an overheating issue is a process of elimination. I would certainly replace the t-stat if it's original. As mentioned check your impeller even though it was replaced. Did you put some lube on the impeller when you fired the boat up from storage? If not running the impeller dry can cause damage to the impeller.

Prostar Rich

06-23-2008, 04:34 PM
[QUOTE=Prostar Rich;508607] Did you put some lube on the impeller when you fired the boat up from storage? If not running the impeller dry can cause damage to the impeller.

I keep an extra impeller, the tools to install it and a small can of "plumbers heat proof grease" in the boat. I apply a thin coat of grease to the inside of the impeller housing and to the leading edges of the new impeller. Due to the fact that the grease can withstand some heat, it seems to work pretty well. The first impeller that I pulled out of my 454 was in multiple pieces.

06-23-2008, 04:49 PM
I did not grease the impeller, but I did have the hose hooked right up to the pump when I started it, so I can't imagine it had more that a few rotations without lube.

06-26-2008, 10:49 AM
I would start from the water intake and inspect the intake, the line between the intake and the strainer (if you have one - if not the line to the transmission cooler). Then the line from the cooler to the raw water pump. Definately inspect the impeller. Inspect the line leaving the raw water pump. Drain the manifolds and observe for large debris or heavy amounts of rust draining out. Inspect the thermostat housing. You can test it by heating water in a pan (controlled with a thermometer) and it should pop at the right temp (then go back after it cools).