Weird overheat.....help!

[dcauthen]

Two weeks ago.....my water pump locked up and broke the serpentine belt. Luckily I was near the dock and temps onlt got up to 220-230 or so. Replaced everything with a Sierra kit, new belt, changed oil, and hit the lake Sat. and Sunday......ran great both days.

Yesterday......I left the dock and the exhaust sounded really loud for some reason.....a few seconds later I got an overheat alarm....imediately turned and went back...maybe 75 yards. The engine almost stalled a couple times, and would not crank until it cooled down. After I checked everything and it cooled off......it started fine, but temps came right back up. What are the possible solutions here? Belt is fine and water pump pulley is spinning.

2001 21V.

DC

[R&T Babich]

Sounds like your raw water pump is not pumping. Without the raw water pump the "wet" exhaust would be dry and maybe sound "louder".

[dogbert]

Did you change your impeller? It sounds like the vanes may have flipped in the opposite direction. Now it sounds like they actually broke off.

[dcauthen]

Yeah...changed everything. I've heard of the impellers flipping......but still puzzled by the exhaust tone......VERY loud.

I'm going to crack the pump open this afternoon. Also....my old impeller had some splits but no real missing chunks. Where should I look for any obstructions?

[chpthril]

Sounds like a stuck thermostat. 220F is awfully warm for an open/unpressurized cooling system, water tends to boil Put it on a fake-a-lake and see if you get some water out of both exhaust ports. shouldn't take but about 5-10 seconds after start up to see some water.

[dogbert]

If your exhaust is loud, then there's no water circulating. I've had my impeller fail on me once and that's what happened.

[dcauthen]

Pulled the pump apart....impeller was shreded....kinda surprised me. Just changed all that and I've never destroyed one that bad. Flushed out the hoses and found most of the big pieces....got it all back together, hoping for the best Friday afternoon. Guess I sucked up some crap around the ramp...Wateree is low like all the others on the Catawba chain. Had to go to 6 different shops to find one.....seems everyone is killing them right now.

The good news is....I can now change them with my eyes closed!!!!

Having a hard time finding tune up parts around here....someone mentioned a website or two that stocks Mercruiser parts and is really great to do business with......anyone know those sites?

Thanks again for your input. This site is the reason I will ALWAYS own a Tige.

[spharis]

partman.com
skidim.com

and you can always order through one of the members here
lee @ skidock in TN
and dom @ fortes inboard connection in FL

[R&T Babich]

You might consider installing a raw water strainer. This one looks interesting: http://www.foreandaftmarine.com/108-906066.htm I have a different one that's all SS, but I can't find a source for it. I've picked up all kinds of twigs, paper, cardboard, leaves & string from the very "clean" looking lakes we use.

Most of the parts I use are Sierra aftermarket parts available from many suppliers.
I've had good service from Go2Marine.

[TeamAllen]

http://www.boatfix.com/
http://www.marinepowerservice.com/frm_mercruiser.cfm
http://marineengineparts.com/
http://www.stemtostern.com/

[TeamAllen]

Here was one I forgot.

http://www.perfprotech.com/store/