searay sundander overheating

texjetmech04

New Member
Jun 1, 2009
9
I have a 1980 sundancer chev 350. It will slowly creap up the guage at cruise but only run on warm side not in the red. Then at faster speeds it will go into the red slowly. if i slow down it will cool down and just run on the warm side. I have a new thermostat. water flow appears to be good. Could it be timing? or sand in the block?
 
When is the last time the impeller (and wear plate) was changed?
 
i had disconnected a water line to check water flow. it appeared to have good flow. I also had a small leak at exhaust bellows gasket. so there isflow thru engine to exhaust.
 
Sand will typically collect at the two block drains - that's a good idea you ahead to check that. Just remove the drain petcocks and see what comes out. Expect some black scaling.
 
Sterndrive with the impeller in the drive? Hard to tell with you having provided so very little information. Those pumps are high pressure, low volume types. They might appear to be working OK, but often are marginal or inoperative. The sterndrive boat I formerly owned, and happily do not own any longer, required a new pump every year.
 
yes it is stern drive with impellar. I replaced the impellar late last year. is there a way to check the quality of water flow prior to replacing impellar again
 
Well, usually it's based on what your temperature is doing. Although it's typically best to replace before a problem arises - as part of normal, good PM.

Is there a GPM vs RPM scale? If there is one, I've never come across it, but that certainly doesn't mean it doesn't exist.
 
I am going to check the block drains for sand or blockage. It has been suggested to pop out the freeze plugs to look for sand. is this a good idea? is there a good way of evaluating water flow thru the system? The impellar was changed late last year and I remember that i had this poblem before and after changing the impellar
 
ok opened block drains just water came out. i pulled the water pump. It is corroded the impellar shows wear but its not disfunctional. I will replace it either way. does anyone have any other ideas
 
Could be the gauge or the sender is starting to go, but it does seem as though they're functioning. Can you verify temperatures with a thermometer? Do you have an infrared or a DVM with Temp Probe? Can you borrow one? What temp T-stat is in there?

Other than the heat, does the engine start and run well?
 
I am replacing the water pump for pm. I also have a temp sending unit i am putting in. It is a bit hard to start. and runs good. idle does fluctuate a little. ( a carb job is my next project after i figure out the temp problem) I have noticed a big difference in fuel consumption. This year it is seems to burn more fuel then last year.:huh:
 
Do you have quick-connects on you engine flushing system? Hopefully not, as a quick-connect will leak causing your cooling system to suck air and overheat with speed.
 

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