'71 Merc 800 water pump 3 bolts or four?

[Huron Angler]

I'm in the process of reassembling my lower unit and had a quick question.

3 or 4 bolts? There are three that face upwards and a spot for one more bolt to be inserted. Of course I should know the answer since I took it apart but that's not the case.:facepalm:

My concern is that I lost the 4th bolt, but it may not exist. My manual says that some have three and some have 4.

I'm waiting on getting grease and a new impellar with gaskets so I figured I'd try to figure this out in the meantime. Thanks

 

[Laddies]

Re: '71 Merc 800 water pump 3 bolts or four?

3 studs - 1 bolt

 

[Huron Angler]

Re: '71 Merc 800 water pump 3 bolts or four?

Thanks for the quick reply Laddies, now to see if I can find the missing bolt.

Normally I put parts in ziploc bags and label them, I must have been slacking that day.:facepalm:

 

[douglas1978]

Re: '71 Merc 800 water pump 3 bolts or four?

hey huron remebered you posted awhile back did you decarb the motor did your compression come back up?

 

[Huron Angler]

Re: '71 Merc 800 water pump 3 bolts or four?

hey huron remebered you posted awhile back did you decarb the motor did your compression come back up?

Once I get the lower unit bolted back on I'll run it on the muffs and make sure the water pump is working. I won't be able to water test it until I finish rebuilding the transom on my Starcraft.

I'm still not 100% sure that the compression on the bottom cylinder is bad. The last test I did with some oil squirted in was a tight band, and I see other folks do the same.

It might be a few weeks before I get a chance to run it on the lake and hook up the tach.

 

[douglas1978]

Re: '71 Merc 800 water pump 3 bolts or four?

after you decarb it i've read a couple guys running amsoil snythetic on here with good results have not tried it myself though no need to i have 145 psi on each cyl. on a 1974

 

[Huron Angler]

Re: '71 Merc 800 water pump 3 bolts or four?

Good news! After speaking with my buddy who let me store the boat for the winter...it seems that we have a baby food jar with the "missing" parts

The bolt mentioned by Laddies is in there along with the O ring and a key.

Hoping to get her bolted up after work tonight. If I can get my transom finished this weekend I might be able to get her on the water and rigged with a tach in a week or two.

If the compression is still low on the bottom cylinder I'm gonna sell probably.

I am hoping that the fishing line that I removed when I took the prop off was causing the low WOT rpms but that's pretty optimistic. We'll see

 

[Chris1956]

Re: '71 Merc 800 water pump 3 bolts or four?

usually the bolt comes with the WP repair kit. It is a self-tapping bolt that screws into the WP base, right?

 

[douglas1978]

Re: '71 Merc 800 water pump 3 bolts or four?

hey mike have you tried the decarb yet, i hate for you to go to the rudes or johnny's, but i know from the resto thread the transom has been your pain in the @$^ hope you get in the water this weekend. Have tried adjusting the screws on the carbs ?