Overheating

[DaveB 5]

Last season my boat started to heat up a bit at idle, so over the winter I replaced the impeller, although it looked pretty much perfect. Anyway now still have the same problem at idle it will go up to over 200 and once you rev it up a bit it cools right back down. Thought maybe it was the belt so I tightened it up but that didn't change anything. I guess the next thing might be the thermostat but not sure what else. Its a 2005 avalanche black scorpion

[h20king 794]

sounds like you are getting cavitation in the pump from a worn rear section of the pump housing. Mercruiser is aware of the problem and has come out with an update kit that replaces the back half of the pump so the impeller wears on a stainless backing plate instead of the bronze or plastic units.

[truekaotik 458]

Did you check the transcooler T after the pump when you replaced the impeller? There may be debrie in there slowing the circulation at idle...

[DaveB 5]

I'll take a look at that, I even removed the hose up at the water pump just to see how much water is being pumped and at idle there was next to nothing, once you rev it up a bit it seems to pump fine.

[duramat 462]

Did you check the transcooler T after the pump when you replaced the impeller? There may be debrie in there slowing the circulation at idle...

$5 on red......

 

Lets see if I gambled right.

[DaveB 5]

If that's it i'll gladly give you the 5 bucks but you'll have to take canadian monopoly money

[duramat 462]

Deal!

 

Check your filter on the tranny cooler. I'm 3/3 heating up over 175 only to check and find junk in that filter.

 

I'm feeling lucky....

 

[DaveB 5]

Hope your right thanks I'll check it out

[superdtf 68]

As much as I dislike encouraging Dura...

 

I think he's right.

[superdtf 68]

As much as I dislike encouraging Dura...

 

I think he's right.

Actually True had this one... I don't mind encouraging him.

 

Right on True! KORITFW!

[duramat 462]

LMFAOROTF!

 

Edited May 22, 2013 by duramat

[DaveB 5]

Hate to say it but not the problem only a tiny little piece of crap in there. I would have gladly given Duramat the 5 bucks.

[PayCheck 20]

Did you not try the update kit like H recommended? If mercruiser has an update kit and is aware of the problem, it would make sense there be a problem there.

[DaveB 5]

Im going to talk to the merc guy tomorrow and try and get that upgrade. Does anyone know if there is any type of filter in the v-drive because I tried taking the outlet hose off the v drive (pump side ) and stuffed a garden hose down that and ran it and the temperature remained a constant 170 ish.

[superdtf 68]

Im going to talk to the merc guy tomorrow and try and get that upgrade. Does anyone know if there is any type of filter in the v-drive because I tried taking the outlet hose off the v drive (pump side ) and stuffed a garden hose down that and ran it and the temperature remained a constant 170 ish.

 

Im going to talk to the merc guy tomorrow and try and get that upgrade. Does anyone know if there is any type of filter in the v-drive because I tried taking the outlet hose off the v drive (pump side ) and stuffed a garden hose down that and ran it and the temperature remained a constant 170 ish.

 

Im going to talk to the merc guy tomorrow and try and get that upgrade. Does anyone know if there is any type of filter in the v-drive because I tried taking the outlet hose off the v drive (pump side ) and stuffed a garden hose down that and ran it and the temperature remained a constant 170 ish.

You could have sucked up some debris from the lake that is lodged in the v-drive. It has an internal heat exchanger with a course screen. This is super common if your lake has "spring runoff" with lots of floaty sticks and leaves and crap. You could put your hose in the pump side of the v-drive and see if you can flush it back out the intake grate on the bottom of the hull.

[DaveB 5]

If I pulled the top off the v drive is anything accessable from there

[superdtf 68]

Oh don't do that. Just flush it from the pump side to the thru-hull side. You could take the hose off on both sides. But cracking the lid on your v-drive seems like overkill.

[Pildo 6]

I am having the same problem. Mercruiser said I may have a impeller a little shorter than it should be. I'm going to take it back out and compare it to last years impeller. If this is the case they recommended an aftermarket impeller

[tuneman 6]

I have this issue too. Temp is just over 175 (~180) and stays there. 2005 350 Mag MPI. It's been that way since I bought the boat last year. It's got a new impeller, clean transcooler and a new thermostat. I haven't checked the V-drive plumbing, but the temperature holds constant. You'd think that if there were blockage, the temperature would fluctuate. Could the water circulation pump have anything to do with it?

[DaveB 5]

I compared my impeller with the one I took out cause my mercruiser dealer told me about the shorter impellers that mercruiser made, so I waited for him to get the longer ones in, the one I took out and the new one were identical. I am going to check on the upgraded pump plate today and then the only thing left is the circulation pump, but I have my doubts it is an issue cause it spinns fine no bad bearing and it doesn't leak or make any of those weird noises that a bad pump makes.