1973 Mercury 850--Low water flow through "tattle tale"

[egclassic]

Motor runs great, had it out several times and no signs of over heating. Flow does pick up at higher RPMs but still seems weak, at an idle, it barely trickles out. I have even taken an air hose and blew through the hole to make sure there was no obstructions. I have replaced the water pump impeller and related parts. Any ideas what else to check? or, is this normal? My 88' 35hp mercury "blows" the water out.

 

[douglas1978]

Re: 1973 Mercury 850--Low water flow through "tattle tale"

i remove the tattle tale and clean with some wire but i run mostly rivers gets alot of mud and clay up there. when you change your impellar was there any blades missing or broke off, if there was could be cloging the pickup tube or your block

 

[egclassic]

Re: 1973 Mercury 850--Low water flow through "tattle tale"

i remove the tattle tale and clean with some wire but i run mostly rivers gets alot of mud and clay up there. when you change your impellar was there any blades missing or broke off, if there was could be cloging the pickup tube or your block

No, the impeller was in good shape. Of course, I don't know the history of this motor so anything is possible. It "seems" to be clear since I can blow air through it with no resistance.

 

[Moody Blue]

Re: 1973 Mercury 850--Low water flow through "tattle tale"

No, the impeller was in good shape. Of course, I don't know the history of this motor so anything is possible.

You can't really "tell" the condition of the impeller by just looking at it. The vanes may be hard and set, or the wear plate and /or cup insert may be grooved. If there is any question as to the performance of the waterpump, change it out, or at least replace the impeller.

 

[douglas1978]

Re: 1973 Mercury 850--Low water flow through "tattle tale"

Don't get me wrong air is a good way to tell if its plug or not but if it is hard as cement and caught in the 45 degree of the elbow of tattle tale it could be restricting the water flow take less the 2 minutes to pull it out(1 screw) run wire down both sides. another thing you can try is pull lower unit and jerry rig a garden hose to the pick up tube turn on the water and see if the tattle tale streams better or not

 

[egclassic]

Re: 1973 Mercury 850--Low water flow through "tattle tale"

Don't get me wrong air is a good way to tell if its plug or not but if it is hard as cement and caught in the 45 degree of the elbow of tattle tale it could be restricting the water flow take less the 2 minutes to pull it out(1 screw) run wire down both sides. another thing you can try is pull lower unit and jerry rig a garden hose to the pick up tube turn on the water and see if the tattle tale streams better or not

Good Idea! may try this on Saturday.

 

[stubbstheman88]

Re: 1973 Mercury 850--Low water flow through "tattle tale"

what may help is to look on top of the powerhead there may be (there is on my motor) a small screw that dosent seem to go anywhere but into the block. I took a powerwasher to that hole and a bunch of junk came out the pee hole. its a small water jacket flushhole above the cylinders behind the flywheel