mercruiser 165 water pump questions

[michael s.]

i recently removed the lower unit to check pump impeller. needless to say it was trashed. my question is where can i locate a new one reasonably priced and is there anything special i need to know during reinstallation? i believe i need to replace the housing also due to signs of wear (grooves in face)can i replace just the cover or do i need to purchase the entire unit? i was also wondering if it is ok to use a silicone sealant or is it necessary? any help would be appreciated by the waythe motor is a mercruiser 165and the serial on the stern drive is 4906281 if that helps

 

[ziggy]

Re: mercruiser 165 water pump questions

my question is where can i locate a new one reasonably priced

personally, i've not found anything in particular that is reasonably priced for boats. i also prefer mercrusier parts. they're the ones who designed the parts. aftermarket parts are cheaper for sure. but they can also be substandard in quality and fit. i'm sure many folks get by with aftermarket parts. myself, i just prefer that the parts are right the first time. parts that don't fit can sure be a drag time wise to make the fit.

and is there anything special i need to know during reinstallation?

yes. do you have the service manual? all the special instructions are in it. along with specifications that may be relevant.

i was also wondering if it is ok to use a silicone sealant or is it necessary?

i wouldn't. no where in the service manual does it call for silicone sealant when servicing the water pump.
for sure replace the housing too. good insurance that the job will be done proper. also, if the impeller lost it's blades. ya need to go find as many of the pieces as you can. they can be trapped at the tstat. there can be pieces anywhere in the water circuit leading up to the tstat. i flushed back and forth from the tstat back to the waterpocket cover into a bucket and have found many fragments that way. what ya don't want is for the pieces to get into the block and block water passages inside where you can't get at them. also look for melted parts. water pocket cover (DON'T TOUCH THESE BOLTS unless you have too, they BREAK OFF) a over heat usually melts the flappers off that are located in the exhaust pipe at the top. the bellows from the riser to the exhaust pipe can also be degraded by an overheat.
on the lower drive shaft. look for seal wear right below the splines. also look for wear at the seal under the water pump. in the water pump base.
i think there's more. just can't think of them...

if ya don't have a service manual. you really need to get one to service the drive...

 

[michael s.]

Re: mercruiser 165 water pump questions

thanks zig i do have manual i downloaded from sticky at top of page just checking to make sure there wasn't something covered in manual.i did find several pieces of the impeller down in the intake ports on foot and looked up ih discharge tube going into upper housing ,but i will take your advice and backflush system as much as possible to remove remainderof debris,iknow these question may seem elementaryto some of you but i just wanna do it right the first time and i ain't to proud to ask for help thanks again i'll probably have a few more questions for ya i aday or two lol

 

[bryen813]

Re: mercruiser 165 water pump questions

I have a mercruiser 180 that i'm just now getting back up and running hopefully(fuel pump arrives tomorrow). Well I was told from searay tech that I need to check my waterpump because manual fuel pump connected to it or something that he didn't elaborate on so I have no idea how to go about checking water pump functioning?!?! Any help guys?!

 

[cr2k]

Re: mercruiser 165 water pump questions

no sealer is necessary on the pump housing top to bottom.
Check for any signs of melted housing top and bottom.
An impeller KIT will come with gaskets. If you need a housing you can get top and or bottom as needed. Check with your NAPA store if you get a decent discount there. If you have a plastic flush screw on the side of the drive
PNs are 18-3321 complete kit, 18-3116 upper housing, 18-3517 upper pump kit (housing, impeller gaskets etc), 18-3421 base, 18-3217 impeller kit.

NO flush screw 18-3317 complete kit, base 18-3417, all other parts the same as above.

If your vertical drive shaft has NO spring loaded little plunger on the top it has retro fitted with an Alpha lower...
Complete kit 18-3320, base 18-3420 all others the same.

If you have to replace the base use some NON hardening permatex on the o-ring that goes in to the drive on the bottom of the base. other than that no sealers are needed. Use some silicone spray on the impeller and rotate the shaft clockwise from the top while pressing down on the housing over the impeller.

If the plastic tube that goes on the water pump housing, the water tube used to help align the pick up tube in the drive is melted you will most likely need top and bottom housing.

Also don't go looking for MOST of the old impeller pieces, find the ALL or you may have problems. If you have power steering they are most likely in the heat exchanger found either across the back of the engine or down the port side.

It's a simple deal, but there are things you need to know to do it right.

Most kits come with a quad ring (small o-ring but square) that goes between the drives to seal the oil passage, replace it when ever possible to ensure good seal. I use a dab of Gask-a-cinch to glue it in place. The big square ring that goes on top of the water pump is there to prevent water from shooting up the shaft and washing out the spline grease from the top of the shaft as well as the o-ring on the top. Check for the o-ring if it does not come out with the drive or you will never get it back on.

If you do this on the boat with the drive raised (easiest) put the drive in forward gear as this is where the shift dogs will end up at this angle.
Then for spline alignment just turn the prop backwards a little as needed.

 

[spoolin01]

Re: mercruiser 165 water pump questions

Check for the o-ring if it does not come out with the drive or you will never get it back on.

Oh...how...I...wish...I'd...read...this...little...gem...earlier. Two hours of sweating and swearing, trying to see what could possible be keeping the lower unit from seating that last 3/4 inch, imagining issues in the upper end that would require major disassembly. Then I noticed the o-ring missing from the shaft, and went looking. It wasn't easy to see, but it was there, hiding behind the seal lip, perfectly hidden.

Great summary of water pump parts and practices, thank you for this.