a few '86 merc 3.0 impeller replacement questions

1/2 way through replacing the impeller on the boat I recently got. These are simple questions which I probably could have figured out myself if I finished the job today, but I had to stop to do something else, then I grabbed some dinner and it started raining AGAIN so I will finish tomorrow and it got me wondering about the water tube...

The guide tube in the impeller kit fits very loosely over the tube on the gearcase, it will just slide right down(there was no guide tube when I removed the case) and the upper has no tube, just a "collar" with a channel that the guide tube fits into but not tight enough it'll stay in. So if the guide does not stay in the top part and it slides right down the tube from the pump housing, how does that help guide it? I'm thinking a couple dabs of superglue to keep it in the channel in the upper casing, but I suspect that won't help. My '72 Evinrude OB on my other boat has a guide tube that fits more snugly on the water pump tube, plus another tube on the upper, which makes it easier to use as an actual guide.

When I ran the engine soon after I took possession of the boat, I ran it for around 15 minutes and the temp gauge never moved. So I'm thinking it's not working. How else would I check for proper water flow when I get the gearcase back on - Does the 140 I/O Merc with Alpha drive have a peehole? I didn't notice one when I ran the engine, but I'm not used to one, only owning a '72 Evinrude OB which also doesn't have one, so I didn't think to look.

Re: a few '86 merc 3.0 impeller replacement questions

Welcome to I/Os
No...no pee hole on outdrives. The water and exhaust exit through the prop.
I don't know about gluing the water guide, mine went up and in ok.
Are you doing this on the bench or on the boat?
With the motor running and properly cooling, you should be able to place your hand on the manifold with out burning..
Or get a thermal point n read temp gauge

Re: a few '86 merc 3.0 impeller replacement questions

the plastic water guide tube pushes into the top of the water pump cover. the copper tube gets its connection from the rubber grommet in the water pump top cover.

Re: a few '86 merc 3.0 impeller replacement questions

The plastic guide tube goes into the top of the pump hsg. That's all it is, a guide tube! The "copper tube" should STAY in the water pocket cover in the driveshaft hsg. If it came down with the gear hsg, you should replace that grommet that holds it inplace. If you choose not to, OK.
Put the "copper tube" back in & just push on it with a hammer HANDLE! With the guide tube in place, it just sits there during reassembly & guides the copper into place.Happens all the time.

Re: a few '86 merc 3.0 impeller replacement questions

Pete104 said:

The plastic guide tube goes into the top of the pump hsg. That's all it is, a guide tube! The "copper tube" should STAY in the water pocket cover in the driveshaft hsg. If it came down with the gear hsg, you should replace that grommet that holds it inplace. If you choose not to, OK.
Put the "copper tube" back in & just push on it with a hammer HANDLE! With the guide tube in place, it just sits there during reassembly & guides the copper into place.Happens all the time.

Click to expand...

Yeah, that's what it was- the copper tube came out with the pump housing. Still having problems getting the gearcase to go the last 1/2 inch, but the water tube is no longer a problem, thanks.

Re: a few '86 merc 3.0 impeller replacement questions

rotate prop 4 your last 1/2" as the shaft splines not quite inline.