Alpha one gen one... new Water pump overheates

[joseph.signore]

Water pump help 1991 Regal:

I recently changed my water pump in my Alpha one /gen one outdrive that cools a mercruiser magnum 350 engine. I installed a new impeller, housing and gaskets. I put everything back together exactly as removed and carefully double checked before reassembling. When I connected the muffs to the outdrive and ran the motor It took about 45 seconds of running the engine at 1500rpms before water started coming out of the back of the outdrive spitting not flowing. After a few minutes of running I noticed the temperature gauge start to redline. I shut the boat off and changed the thermostat then reconnected the muffs and tried again and quickly overheated again.
What did I do wrong? Any help would be appreciated

 

[Don S]

Re: Alpha one gen one... new Water pump overheates

When I connected the muffs to the outdrive and ran the motor It took about 45 seconds of running the engine at 1500rpms before water started coming out of the back of the outdrive spitting not flowing.

Shouldn't take more than about 5 seconds at that rpm to get water out the back.

Did you replace the gaskets for the pump in the drive?
Was it cooling ok before you replaced the impeller?
Did you follow the OEM manual, or just replace the impeller by memory?

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

Thanks Don,

The motor did not overheat before replacing the pump. The old pump was in great condition.
I did replace all gaskets and new upper and lower housing.
I do not have a manual. I replaced using memory.

 

[paultjohnson]

Re: Alpha one gen one... new Water pump overheates

Don, is it possible to put the impeller in with the vanes curled the wrong way? Like he twisted the impeller in ccw when he should have gone cw ? Or is it the other way around--whichever And if he did, would they correct themselves ?

 

[dubs283]

Re: Alpha one gen one... new Water pump overheates

did you remember to install the key on the shaft to drive the impeller??

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

I did install the key, but i could of installed the impeller fins bent the wrong way ???

 

[Don S]

Re: Alpha one gen one... new Water pump overheates

It doesn't matter on the MC1 drives to the Alpha I drives. They will flip the short vanes over to the proper direction. The Gen II drives won't but they have much longer vanes.

Something is wrong in your pump.
Have a look at this thread. http://forums.iboats.com/showthread.php?t=387864

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

Thank you!!!

 

[cr2k]

Re: Alpha one gen one... new Water pump overheates

Was the old impeller complete or were there pieces missing? If pieces missing you will have nothing but problems until you find EVERY and I mean EVERY piece of the old one. Most of them get caught (and block flow) in the heat exchanger.

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

Thank you everybody for your advice...Using the manual that Don sent me, I pulled my outdrive apart again today, removed the pump, impeller and all gaskets. I followed the manual step by step and everything went back together beautifully. Hooked up the muffs, started the engine and once again it took about 40 seconds before water started barely spitting out of the exhaust ports and my temperature once again went up.

- There are no broken pieces of impeller - old impeller was intact and in good condition
- I replaced both upper and lower housing, impeller and all gaskets
- I made sure the copper tube and guide lined up perfectly when reinstalling drive
- took garden hose and ran water through both exhaust risers and water flowed perfectly out of both exhaust ports
- ran water through the hose that pumps water in from the outdrive, in reverse, and noticed that water going in reverse was slow going and backed up...(is this normal?)
- I'm now thinking something might be clogged between the water pump and the inlet hose
- I also briefly ran the motor with the inlet hose disconnected from the circulator pump and noted water is pumping in, but at very low volumes

Any ideas?

Thank you again in advance.

 

[Pete104]

Re: Alpha one gen one... new Water pump overheates

Take hose off at the transom inside. And follow flow from there. You may not be the first to change a pump on your boat!
#1 don't let water spray all over distributor.
#2 don't overtighten clamp when reinstalling incoming hose.

 

[Don S]

Re: Alpha one gen one... new Water pump overheates

What engine do you have?

 

[dingdongs]

Re: Alpha one gen one... new Water pump overheates

pull hose off from thermostat housing that comes from outdrive.briefly start engine on muffs.if no water is flowing out there is something wrong and you'll have to pull apart again.

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

1991 mercury magnum 350:

Alpha one gen one outdrive:

1. Today I filled a tub with water and tried running the boat with the outdrive submerged and still the same week flow.

2. I disconnected the lower half of the outdrive and everything looks in perfect order and mated properly mated. I spun the shaft looking to see if the impeller is spinning or slipping and that was fine.

3. With the lower half of the outdrive and the copper tube removed, I connected a garden hose to the inlet hose from inside the and the water ran thru fine.

I?m now convinced that the $34 water pump that I bought online is no good or the copper tube, plastic guide and or the rubber grommet is not mating correctly and leaking back from there (any tricks to mating this properly?) or the circulator pump on the engine is bad?

With the outdrive apart for the third time I?m going to spend the cash and buy a Merc OEM pump and try again.

Thank you all

 

[Bt Doctur]

Re: Alpha one gen one... new Water pump overheates

Why did you decide to change the pump?
How did you see thru the plastic housing?
do you have the manual?
Describe exactly how you installed the pump.

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

I decided to change the pump because it had three seasons of saltwater use.

I was able to see the impeller spinning in the housing by removing the four nuts and slighting lifting apart while turning the propeller. I could also feel and hear the impeller spinning inside the housing.

I did use a that manual Don S sent me the second time I removed the outdrive and pump.(i've done this three times).

1. Lowered the outdrive? the copper tube came with the lower half? it did not stay in the outdrive.
2. Split the pump and removed the impeller and key.
3. Removed two gaskets and one metal plate and laid them out in the order they were removed.
4. Popped out the lower housing and removed one gasket.
5. Installed one new gasket and the new lower housing. (it popped right in)
6. Install paper gasket the one metal plate followed by the last paper gasket.
7. Installed keyway and impeller.
8. Installed the upper housing using plenty of grease turning on the impeller
9. Installed one screw and three nuts being sure not to over tighten.
10. Slid down rubber seal/grommet down shaft till mated into pump upper housing
11. Installed plastic guide in upper pump housing and the copper tube into upper drive (I was unsure which way the rubber grommet with the nipple goes on?. Nipple up or down??? I could have put on backwards). I installed it on the tube with the nipple down because it fit better in the upper drive.
12. Replaced oil seal on drive unit and bolted the drive halves back together making sure the plastic and the copper tubes mated and at the same time lining up shifter spine and lever.

 

[Brentathon]

Re: Alpha one gen one... new Water pump overheates

After you did all the work to the drive impeller/pump, are you sure you still have weak flow coming from the drive? Did you pull the hose that goes to the Power Steering cooler and see the flow at that location?


p.s. Don't get discouraged; I once bought a Sierra pump kit, and somebody put a Mercury impeller in it that was defective (rubber was very hard), which made my over-temp problem very difficult to troubleshoot because I knew the impeller was new........at least, I thought it was new.

 

[Bt Doctur]

Re: Alpha one gen one... new Water pump overheates

the rubber grommet you refer to with the nipple. the nipple locates in a hole in the water pocket cover.
then the copper tube slides in the upper unit. there is no up or down, it must be in the locating hole.
#5 , gasket and "o" ring on the base

 

[joseph.signore]

Re: Alpha one gen one... new Water pump overheates

Thank you to all, especially to Don for sending me a manual.

I fixed the problem...

I removed the cheap impeller and housing that I got on line for $34 and replaced with the $70 Merc OEM impeller and housing also, using perfect seal on all gaskets. I suspect the lower housing was sucking air from the bottom.

Thanks again,
Joe