1974 Merc 1500 Telltale issue

[Matt129]

Hello everyone, I recently replaced the water pump in my Merc 1500 and I’m getting a strange issue. I know I installed the new one the same way the old one came out so I don’t think that’s that’s issue. I tried running it with a a motor muff and got no telltale or water coming from the exhaust. I tried running it in a bucket of water that *barely* covered the intake holes. Still no telltale but I was getting smoke and a few drips from the telltale. I tried running the water muff in the bucket under water and low and behold that worked for some reason? Good strong flow. But when I turned off the motor the telltale kept squiring for about 5 seconds??? I thought that maybe the water from the hose was the only thing that kept it spitting so I removed the muff and no telltale again. But here’s where it gets even weirder, I put the muff back on under water like I did before, and no telltale again! What gives lol?!?! Please help me I’m so confused, thanks

 

[racerone]

Water MUST be 8" above the pump when running in a test bucket.----So get a bigger bucket is take boat to the launch ramp to test.----Hard to assemble those pumps so they don't work.

 

[Matt129]

Water MUST be 8" above the pump when running in a test bucket.----So get a bigger bucket is take boat to the launch ramp to test.----Hard to assemble those pumps so they don't work.

Oh so 8” above that inlet? Geez lol. What’s the point of motor muffs . How on earth did it start pumping that one time lol. I hope I didn’t burn it up, I only ran it a minute or so when it wasn’t pumping and it’s brand new. Even then it was still spitting lol. Is it normal for smoke to come out of telltales?

 

[racerone]

Why argue.-----Test run at your local launch ramp.

 

[fatlenny]

Dont you love it when someone comes on with an honest question and gets an honest good answer but then gets berated for answering.

Many motors, not all, have issues running on muffs. I am new to boating and that is one of the first things I have learned. My muffs are now used to hold the hose in the 55 gallon drum that I use for running out of the water LOL. Keeps it away from the prop if I am testing gear changes.

 

[Matt129]

Dont you love it when someone comes on with an honest question and gets an honest good answer but then gets berated for answering.

Many motors, not all, have issues running on muffs. I am new to boating and that is one of the first things I have learned. My muffs are now used to hold the hose in the 55 gallon drum that I use for running out of the water LOL. Keeps it away from the prop if I am testing gear changes.

Why argue.-----Test run at your local launch ramp.

I wasn’t intending to argue? I was just confused lol about how inconsistent my motor was, I’m thankful for your answer. I’m sorry if offended.

 

[racerone]

There is a chance that the impeller ran dry.----A wise man would have a look at it again.------Remember there is nothing on that motor that shuts it down on overheat.----And I doubt it has a warning horn for overheat.

 

[Chris1956]

Your TOP will run fine on standard flusher devices. That is not the issue. The possible issues are that you forgot the drive key in the impeller, the water intakes are clogged with dirt/barnacles/insects, the water tube pulled out of the exhaust extension, or the water tube is damaged.

You did replace the impeller, SS wearplate and 2 gaskets, right? You didn't crack the cover, right? You used the plastic tube to make sure the watertube went into the pump, right?

The telltales do clog easy, but the grating above the antiventilation plate will always have water discharge when the motor is pumping water.

 

[Matt129]

Your TOP will run fine on standard flusher devices. That is not the issue. The possible issues are that you forgot the drive key in the impeller, the water intakes are clogged with dirt/barnacles/insects, the water tube pulled out of the exhaust extension, or the water tube is damaged.

You did replace the impeller, SS wearplate and 2 gaskets, right? You didn't crack the cover, right? You used the plastic tube to make sure the watertube went into the pump, right?

The telltales do clog easy, but the grating above the antiventilation plate will always have water discharge when the motor is pumping water.

I remembered the drive key, almost forgot it but I didn’t . The tube had pulled out of the exhaust system but I stuck it back in when I reassembled the lower unit and I did use the plastic tube. I redid the wear plate and gaskets and I don’t think it’s clogged because air is puffing from the hole and one time I did get water squirting. The one time it seemed to be working water was coming out of the exhaust and that grating. I’m just as a loss lol, where should I go from here? I really hope I just didn’t have it in deep enough water lol.

 

[racerone]

Fact ------When there is no water in the block , exhaust can come out the tell tale.----That is the way it is !

 

[Chris1956]

Those exhaust tubes are tricky to get them in correctly, as the seals can bend and clog the tubes. Drop the lower unit and put a garden hose on the water tube and turn on the water a very small amount. Now water should come out the prop, gratings above the A-V plate and telltale. If not, the water tube is not working correctly.

The water tube seal is a rubber grommet, with one large end. Say you cut a empty thread spool in half. The water tube can fold the bottom of the grommet and get clogged. Unfortunately, unless you can work the water tube into the grommet (grease and twisting motion can help), you probably need to pull the powerhead to replace the grommet, and install the water tube. I also had a water tube get crushed by salt buildup. It was restricted at the top end.