Impeller waterpump quetion

[cbear34]

Question is about a 1989 maxum 2000sr, merc 305/230hp, alpha one drive.
Last time out last season my boat overheated on high rpms. Figured it was a bad impeller as it has not been replaced in a long time. I finally got around to removing my lower unit. The impeller looks fine but I found a completely melted piece in the lower unit. I think it is the water tube. It looks like it might be made of hard plastic and has a tube like look at one side. The other end is completely melted. Also the rubber centrifugal slinger is cracking like it was overheated, probably. Could this cause an overheating problem at high speeds?
Also the waterpump gaskets are hard and came off in split pieces. I checked the lower unit for corrosion at the pump and gaskets and that looks fine.
Thanks for all the help!

 

[achris]

Re: Impeller waterpump quetion

You have definitely had an overheat... Now the bad news...

An overheat that serious has compromised the 'water pocket cover', located in the bottom on the upper box. If you only took the lower box off and the upper is still on the boat, look up into the bottom and you'll see a copper tube. That goes into the water pocket cover, which is plastic.... the overheat has softened the plastic and it's now warped (just like me ) and needs to be replaced.

As your engine speed increases the volume of exhaust gas also increases and the pressure in that area is enough to force exhaust gas into the cooling system... ergo - the overheating..... Pull the water hose off the engine and you'll find it has a lot of engine soot in it.... The other test is to put a section of clear hose in and run the boat (on flushers it doesn't show, not enough pressure in the exhaust chamber) and you'll see bubbles in the water... those bubbles are exhaust gas, hot, exhaust gas.... Not suppose to be there....

The really bad news --- They was extremely difficult to replace. Unless you have the right drills and are very, very good at removing broken bolts and re-coiling a hole.... take the box to a shop....

Chris..............

 

[cbear34]

Re: Impeller waterpump quetion

Thanks for the info Chris.
I did look up in the upper box and do see the tube going in to a plastic box. So if I understand you this plastic part needs to be replaced. It looks like it is bolted to the upper part by 4 bolts. What is inside of the plastic piece? Is it a valve or some type of pump?

 

[ziggy]

Re: Impeller waterpump quetion

there's nothing in that waterpocket cover. it's just the connection for movein the water from the lower to, and thru the upper....

better be sure ya have to remove that water pocket cover with the test that achris is talkin about. i found on my last boat, after overheat, while flushing backwards from the t-stat to the water pocket cover. lower removed. i could see water flowin out from unerneath the waterpocet cover seal.... i removed them 4 bolts. 3 broke off.... 20 hours to drill them three out and helicoil em.... a horrible pain in the you know what.... let alone my sholder that hurt all summer after leaning on a drill for hours.... i did get good at sharpein a drill bit though. the ss will take the edge right off yer drill bit....

be real carefull the them 4 bolts. don't even look bad at them.. they'll break off. their stainless steel bolts too... mounted in cast aluminium. a real mother to drill them ss bolts out..... hope i'm gettin across how fragile them bolts are.... ya break one. it could be the end of yer upper........BE CAREFULL......

 

[cbear34]

Re: Impeller waterpump quetion

Thanks Ziggy for your input.
I will check it out very carefully before attempting to remove those bolts. I work on equipment with the same combination of bolts and aluminum and it is a huge pain to take ss bolts out of aluminum. I always have to drill it out and tap new threads.

 

[starsnstripers]

Re: Impeller waterpump quetion

I think i'll keep my pump serviced. Is there any way to safely apply some heat to that area to possibly remove the bolts in one piece?

 

[ziggy]

Re: Impeller waterpump quetion

Is there any way to safely apply some heat to that area to possibly remove the bolts in one piece?

the way it went for me was, i got one out. i broke two off. i busted off the waterpocket. i don't have heat... but took it to a feller that did..... unfortunetly, the feller heated it and just tried to unscrew it... snap... i think he was startin to have success, maybe if he'd done the bolt like a tap... i don't know.. was it safe. i dunno, seems like there's seals right around in that area maybe. when ya got them bolts broke off though, yer really up against it.... if ya can't have yer waterpocket cover mounted. end of upper....


on a good note. the last fella i read about removin his waterpocket cover here on the forum was successfull. he said his bolts removed w/o incedent. as noted though, that wasn't my experience.....

ditto on keepin the water pump impeller serviced....

 

[achris]

Re: Impeller waterpump quetion

The way I did it in the shop, because we did quite a few, was we made a jig. I would was the oxy and melt the plastic away. That gave us better access to get some heat into the bolts. All we needed was one to come out. Once the others were either broken off or out, we could mount the jig (a thick steel plate drilled to the right pattern) and use our extended drills to start drilling the broken studs. Once drilled we could remove the jig and re-coil the holes. Easy not!!! The only job I hated more was removing the thermostats from a Johnrude V4!!!

Chris..............

 

[Don S]

Re: Impeller waterpump quetion

The only job I hated more was removing the thermostats from a Johnrude V4!!!

Yea, tell me about it. I have one of those to do this week to. The good news is that it's a salt water motor used on a skiff for a dredge, and got little if any maintenance.

 

[ziggy]

Re: Impeller waterpump quetion

All we needed was one to come out. Once the others were either broken off or out, we could mount the jig (a thick steel plate drilled to the right pattern) and use our extended drills to start drilling the broken studs.

yep, ya put me onto yer idea when i was battlein mine.... it works..... thanks again.......

 

[achris]

Re: Impeller waterpump quetion

Yea, tell me about it. I have one of those to do this week to. The good news is that it's a salt water motor used on a skiff for a dredge, and got little if any maintenance.

How come you have all the fun??

 

[1970 Chieftain V]

Re: Impeller waterpump quetion

on a good note. the last fella i read about removin his waterpocket cover here on the forum was successfull. he said his bolts removed w/o incedent. as noted though, that wasn't my experience.....

I just did mine last week and had no issues. The bolts just came right out.

Jason

 

[cbear34]

Re: Impeller waterpump quetion

Sounds like this water pocket cover thing is a known issue with the alpha one drive overheat problems. I'll just check mine and hope it is o.k. and go from there. Thanks for all the info everyone!

 

[cbear34]

Re: Impeller waterpump question

Re: Impeller waterpump question

I want to again thank everyone on this board who helped me out on this problem!! I did check the water cover and the gasket is leaking. So fearing the worst I decided to bite the bullet and see what happens.
A little about my background. I am a mechanic for a company which makes industrial sweeper and scrubbers. I originally worked as an auto mechanic. Working on scrubbers we make aluminum scrub decks assembled with stainless bolts. So I figured to try what I have been doing at work. I don't know if I just got lucky or my technic worked.
What I did to remove my water cover successfully is before I started I did doublecheck by running water in to it and sure enough it was leaking. Using a long brass punch, I tapped the bolt heads a couple of times to "rattle'em up". Then using a 3/8 drive short ratchet with an extension and socket slowly worked the bolts like a tap. After about getting 1/4 turn I tightened them up again and hit them one more time. I then switched to a 1/4 drive short ratchet with an extension and socket and worked all four bolts loose. I took a lot of time working them on and off. But I did get them off successfully. If someone has to do this you can try what I did and hopefully it will help you.
Now another question about this cover. Do you think I can just replace the gasket or is it common for the cover to warp? The cover actually looks fine. I was going to put a straight edge on it to see if I can detect any warpage. The gasket for this looks pretty thin. Should I try to get a thicker gasket like a cork one?

 

[starsnstripers]

Re: Impeller waterpump quetion

Good for you Bear The ole shock treatment thats like the impact screw driver it comes in handy on marine stuff. I'll try this on mine if need be.

 

[ziggy]

Re: Impeller waterpump quetion

good job man..... i'd R&R the cover and all.... yer there and the price of the cover (or should i say upper houseing) aint worth ever attempting that again.......

 

[Don S]

Re: Impeller waterpump quetion

Have tried the shock treatment, doesn't always work. Usually melting and breaking plastic away so you can get a BIG torch in the area to heat the housing sometimes works. Even at that, many times they break. (Should have said usually) but it also depends on how long, and how much salt and how little flushing the area gets.
Gotta say, you were lucky.

 

[ziggy]

Re: Impeller waterpump quetion

Have tried the shock treatment, doesn't always work. Usually melting and breaking plastic away so you can get a BIG torch in the area to heat the housing sometimes works. Even at that, many times they break.

that was where i was at........ was hopeless.......

 

[cbear34]

Re: Impeller waterpump quetion

Thanks again to everyone!
I figured I am just going to change the cover and gasket and coat the new bolts. Might also have worked since this has only been a fresh water boat.

 

[Don S]

Re: Impeller waterpump quetion

Might also have worked since this has only been a fresh water boat.

That alone will do it. Personally, before a few months ago I never seen a freshwater boat. They are like working on brand new boats things don't corrode at all.