Water Pump & Impeller Replacement Question

[rtflew]

After reading my maintenance manual and here in iboats about replacing my impeller & water pump, I decided to take my first trip into the lower-unit of a boat. I got through the replacement last night but came away with several questions.

Boat: 1990 Bayliner Capri (2050 I think?), 4.3L Merc, AlphaOne. Recent oil & filter change, new plugs, new fuel filter. To the best of my knowledge it has only been run in fresh water, no salt.

First, the issue: Impeller on the boat was very old, maybe 8 years (won't make that mistake again), and it is clear after removing it that likely the 15 year old $5 muffs I was using to de-winterize the boat weren't likely up to the task - the impeller was clearly melted. Found this out on the lake of course. Temps got hot, but hopefully not too hot. (I don't remember exactly, but do think it was approx 200) The plastic "guide tube" was also very melted, I found once things were apart. The driveshaft o-ring was also torn to pieces. The driveshaft housing in the upper part of the lower unit looked good, it did not look melted that I could tell.

Picked up the water pump, the base, impeller & all the gaskets at a local shop - very impressed that their prices were the same as I saw for the parts on-line, btw. Also picked up some new muffs while there.

So here are my questions:

The Quad Seal? Is that just the orange colored rubber seal that goes in the oil passage? If so, I'm good there.

On top of the water pump housing there is supposed to be a seal on the drive shaft - it was mentioned in the book or online that the seal should be square. There was no square seal in my kit, but there was a round one that fit like a glove. Safe to assume I'm okay there?

Gasket Sealer: I sealed the bottom gasket (connecting the base to the lower unit), but that is the only I saw mentioned to use gasket sealer on. did I need sealer on the gaskets between the base & housing (with metal plate in between)? (I did use gasket sealer on the o-ring on the base, too)

Leftover Gaskets & O-Rings: are these kits somewhat generic? I had quite a few gaskets & various sized o-rings left over. I think some of the gaskets at least were duplicates from the base kit & housing kits. But also had some extra rubber and fiber round washers that I never saw mention of in the replacement steps.

Any advice on if that all sounds okay would be grealty appreciated. First time working on a drive unit of a boat, so no idea what looks spot-on, and what doesn't.

If I don't need to re-do the water pump I'm hoping to finish cleaning the thermostat housing up a bit - lots and lots of rust - and install the new thermostat tonight, put the prop back on and test everything on the muffs.

Thanks in advance!

RT

 

[zbnutcase]

Re: Water Pump & Impeller Replacement Question

Sounds like you covered all the bases just fine. The driveshaft seal on top isn't a seal in the normal sense and if the one you installed is black and square(referring to cross section, not shape) your good. Quad ring is for oil passage, and yes the kits are made to service several different models, there are always leftovers to discard.

 

[rtflew]

Re: Water Pump & Impeller Replacement Question

Thanks for the response!

The o-ring seal that I put on the driveshaft was not square, it looked like a regular round o-ring. It came in the package w/ the water pump. It did fit like a glove, so I assumed it went there?

That did remind me of one other question I had, too: I did not see any seal or o-ring to put under the plastic guide tube that goes into the pump. I didn't see one on my old one, didn't see anything that would fit in the kit. But the instructions I saw mentioned making sure it was there?

Thanks!

RT

 

[mdlee]

Re: Water Pump & Impeller Replacement Question

Just a word of caution. I just, 3 months ago, installed a water pump in my alpha 1. every thing fit fine, except the water pump impeller. It seemed the outside diameter of the impeller was to big. It pumped fine for about 3months, then the impeller went out. Turns out the impeller was the wrong size. Went to NAPPA and got the right impeller. The kit I used originally came from an offline company.

 

[John_S]

Re: Water Pump & Impeller Replacement Question

You didn't mention what kit you used, be it Merc or aftermarket. On a recent pump replacement for alpha 1 gen II, there were no extra parts, using a merc kit. You may have a gen 1, too. Maybe the the following will help:

- Bearing carrier seal is below the pump. Merc has a full replacement, but an aftermarket might only supply o-rings.

- O-rings for inside of water tube. 2 on the gen II.

- Seals for oil drain and fill indicators on drive.

- On gen II the seal just above water pump on drive shaft is not a standard oring. It is squarish with a flare on bottom. It is installed with a special tool (hard plastic) such that it is not compressed.

 

[rtflew]

Re: Water Pump & Impeller Replacement Question

You didn't mention what kit you used, be it Merc or aftermarket. On a recent pump replacement for alpha 1 gen II, there were no extra parts, using a merc kit. You may have a gen 1, too. Maybe the the following will help:
I used a Merc kit from a BayLiner dealer for both top & bottom of the pump
- Bearing carrier seal is below the pump. Merc has a full replacement, but an aftermarket might only supply o-rings.
I did not open this up at all, left the driveshaft (?) alone and installed the base & impeller & pump over top of it.
- O-rings for inside of water tube. 2 on the gen II.
I have a 1st-gen Aplha - do they have any at all?
- Seals for oil drain and fill indicators on drive.
Haven't refilled with lube yet, waiting to confirm I did it right! I think I remember which 2 those would be though...
- On gen II the seal just above water pump on drive shaft is not a standard oring. It is squarish with a flare on bottom. It is installed with a special tool (hard plastic) such that it is not compressed.
since I have a Gen1, hopefully the round o-ring was okay. The bits I dug out of the old one looked like they were from a round one, too - maybe previous service got it wrong too?

Thanks for the info!

RT

 

[rtflew]

Re: Water Pump & Impeller Replacement Question

Just a word of caution. I just, 3 months ago, installed a water pump in my alpha 1. every thing fit fine, except the water pump impeller. It seemed the outside diameter of the impeller was to big. It pumped fine for about 3months, then the impeller went out. Turns out the impeller was the wrong size. Went to NAPPA and got the right impeller. The kit I used originally came from an offline company.

Thanks for the warning - the impeller does appear too big, but is same as the old one that was there (just not melted & shredded ) From what I saw / heard, that should be okay, just use some soap (I used car wash soap as it was near the boat) and turn driveshaft clockwise while pushing the pump top over it (with impeller already on shaft & installed over the "key"). As long as the arms are pointed the right direction, it should be a very tight fit, by the accounts I've seen.

From what I understood, if the driveshaft isn't turned that right way to get the impeller fins in the right alignment, the impeller is in for a short service life. I'm sure others can confirm.

So was the NAPA impeller you got fitted to be only as big as the housing, with no squishing & twisting required?

Thanks!

RT

 

[mdlee]

Re: Water Pump & Impeller Replacement Question

Yes the new impeller from NAPPA is the right one. It still is a tight fir, but that is normal. The other impeller was so tight I considered not using it... in retrospect I shouldn't have used it. The warn impeller even after being removed , still had a bigger outside diameter than the new one. Fortunately the impeller housing was not harmed.

Good luck buddy

 

[Rocky_Road]

Re: Water Pump & Impeller Replacement Question

The round fiber washers (blue?) should be for the fill and vent plugs. It is customary to replace them whenever you remove these plugs...although I have reused them without any problems.

Just make sure that the original washers didn't remain in the drive....

Happy boating!

 

[rtflew]

Re: Water Pump & Impeller Replacement Question

Bad news...

Impeller may be pumping plenty of water, but it is spraying out of what look like cracks in the exhaust manifolds and back behind the engine, downstream in the exhaust path. I guess it is time to read up on exhaust repair. Grr...