Can you rebuild water pumps???

[wilkboater]

I'm trying to chase down an overheat problem on an 88 Bayliner (5.0 GM engine). I've pulled the circulating pump, housing looks good, impeller looks good. Can you buy bearings and the seal for a marine application? It doesn't leak, but the bearings feel a little rough, though it could be my imagination. I'm not sure it warrants a $100 water pump, but with bearings and a seal, it would be pretty much like new.

 

[bruceb58]

Highly unlikely your circulating water pump has anything to do with an overheat unless the impeller fell off. They are not rebuildable.

 

[jerryjerry05]

An 88 v-8 overheating.
Most times the culprit is the riser's clogged.
Possibly the impeller fell apart and the vanes are in the passages.

 

[HT32BSX115]

I'm trying to chase down an overheat problem on an 88 Bayliner (5.0 GM engine). I've pulled the circulating pump,

Howdy,


You're looking in the wrong place. Circulating pumps are almost never a cause of an overheat in a marine v-8.

You should be looking at the raw water circuit from the pump to the engine, manifolds and risers.


Cheers,

Rick

 

[Lou C]

I agree my OE circ pump lasted 22 years and half of that at least was in salt water, they rarely cause overheating. Overheating is most often due to:
Low raw water flow (impeller, clogged water intakes, clogged PS cooler, corroded and clogged thermo housing or manifold/risers)
Leaky head gasket that allows exhaust gas into the cooling water
Air leaks into raw water hose that aerates water flow
Sticky thermostat but they usually stick open, never had one stick closed.

salt water or fresh?

 

[Lou C]

No Title

heres the pic...see the water exiting....

 

[Lou C]

No Title

new software still sucks.

 

[wilkboater]

Thanks for the responses. It's a freshwater boat, always has been(wife's dad bought it new). Only has 127 hours on it. I really didn't think the circ pump would be an issue, but for the price of gaskets it was nice to actually look at the impeller. To answer some of the questions, it has never had a raw water impeller melt, the one it now is from last year, but still looks new. I have put muffs on it with the impeller housing open, and water comes out. I have taken the incoming hose off of the tstat housing and ran water backwards-good flow out the impeller housing. I've had the risers off recently(flapper replacement), and they weren't stopped up. One thing that I haven't done yet is to pull the incoming water hose with the boat in the water to see the output of the raw water portion of it. I'm going to change the tstat while it's apart(it is original) and then do the raw water test.At this point, I'm thinking it may be sucking air in the lower unit(it hasn't overheated when on the muffs and has good flow, just like the picture above). Thanks again for the guidance.

 

[wilkboater]

Update. With the muff hooked up, and the inlet hose unhooked from the thermostat housing, I had water flowing out of the hose before the engine started(while the engine was cranking over, but not before)-it was almost instant. Took it to the lake again, at around 2500 rpm it shows a constant 175 on the gauge. If I idle around it climbs (fairly quickly) to up above 200 and was still climbing. If I go back up to 2500 rpm it steadily cools back down to 175. Did the raw water test with it in the lake, I got water from the inlet hose, but it took several seconds, and it wasn't nearly as much as when the muffs are hooked up(not surprising since it's not under pressure). It's hard to look at the flow of water and know if it's enough. I'm still leaning towards water pipe seals in the outdrive(that's about the only thing that I haven't looked at). Am I on the right track? Thanks in advance.

 

[jerryjerry05]

If the hose was on the drive and you had water coming from the hose on the thermo housing then the water pump isn't sealing right.
You shouldn't get water past the pump until the pump starts to turn.
If the motors heating up the faster you go then that directs me to the risers maybe manifolds.
127hrs isn't much but setting for 26 years the inside of the risers and manifolds continues to rust and corrode.
Might be time for a change.

To test the water tube and seals try unhooking the hose at the housing and back flush through the drive.