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snowboard9360
09-17-2013, 01:31 PM
hello, This is my first boat and I need some help. Its a 1996 Mastercraft 190 prostar with a 5.7 indmar not lt1.
Here the problem. The boat started overheating. I brought it home and the impeller was wasted. I flushed out the hoses and didnt find any parts of the impeller. I replaced the impeller and it ran fine for about an hour. Then I noticed it over heated but when I idled it cooled off again. It seems that when im at speed it gets hot and when it gets to idle it cools off again. i checked the trans cooler and appears clear. Any ideas?

mikeg205
09-17-2013, 02:24 PM
Pull the t-stat you may have pieces there - hopefully there are not stuck other places... hate reading about disintegrated impellers...

good luck

snowboard9360
09-17-2013, 02:38 PM
Thank you for the response. I checked the thermostate and found nothing. Should I unbolt the all the way at the manifold. Its not like a car 350 it looks like the thermostate is raised up a bit. And yes it was disentegrated and I found nothing in the hoses. Any help is appreciated.

mikeg205
09-17-2013, 03:39 PM
iirc the next step is to check if piece are in water jacket. pour water thru t-stat a couple gallons... then take out block train plugs... see if water flows out freely... if it does then you may want to open up the risers and see if the pieces are stuck in the slats.

hopefully JimN or others will have some insight as well.

thatsmrmastercraft
09-17-2013, 03:45 PM
When you change the impeller, did you remove the raw water pump? It won't pump water well if hooked up backwards.

ricford
09-17-2013, 07:56 PM
When you change the impeller, did you remove the raw water pump? It won't pump water well if hooked up backwards.

It's a prostar (direct drive) so I doubt if he took the pump off to change the impeller.
It won't hurt to change the thermostat. Also, is the impeller the right one? I'm only asking because I've read on here that there are 2 types. One is a little shorter than the other. If you have the short one, when you need the long one that would cause it. With the impeller all the way in, the cover should touch it. It should not be recessed in the housing at all.

thatsmrmastercraft
09-17-2013, 08:22 PM
It's a prostar (direct drive) so I doubt if he took the pump off to change the impeller.
It won't hurt to change the thermostat. Also, is the impeller the right one? I'm only asking because I've read on here that there are 2 types. One is a little shorter than the other. If you have the short one, when you need the long one that would cause it. With the impeller all the way in, the cover should touch it. It should not be recessed in the housing at all.

I am aware it's a Prostar and that it's a direct drive. When I offer assistance, I try not to assume anything, including their knowledge of their boat, or their skill level. People have been known to remove raw water pumps and reinstall them incorrectly.

Good point on verifying that the correct impeller is in place.

EricB
09-17-2013, 08:49 PM
Snowboard;
When you run the boat at the lake, is the RW pump cool to the touch or warm/hot? If it is warmer than the lake water, it's not working. It can draw air from the shaft seal vs. water