Can't get it to pump water, 35hp

[Capt dave 258]

Picked up a 1988, Mercury, 35hp. Thought I'd change the impeller, as I have no history on the motor. Changed it out and cannot get it to pump water out of the tell tale. I took the hose off at the cowling and can blow air thru it, so it doesn't seem to be blocked. I believe the pickup tube is not in the proper location at the powerhead. What exactly is it supposed to push into. I've had this thing apart a few times and looked up inside with a flashlight and cannot determine what the pickup tube should be going into, and yes, the key is in place inside the impeller. I've tried looking at diagrams but haven't been able to find one that would help. I appreciate any help. Thanks

 

[DeepCMark58A]

Is there a rubber Gromit on the top of the pick up tube? Or is the existing one damaged and stuck in where the tube goes?

 

[Capt dave 258]

There is not a rubber grommet on the end of the tube. It must be stuck up in there. I can see where the pickup tube goes into the powerhead. My flashlight just died and I'm waiting for it to charge

 

[jimmbo]

Perhaps the Water Tube didn't go into the Water Pump, when the Unit was installed.
How long did you run the Motor? If the Water was getting to the Block, there would be some being discharged through the Idle Reliefs and the Water Drains just above the Anti-Ventilation Plate, as well as the Prop when the Engine is running.
Are you running it on Muffs, or in a Tub? If in a Tub, the Water Level has to be be above the Pump, in order to Prime the Pump.

 

[Bobbywolf]

The tube is friction fit into a rubber grommet under the power head, and another one at the water pump. I've had trouble before guiding the lower one on before. A little grease helps. No grease on the top one, you don't want that one to move.

One thing you can do to prove to yourself that everything else is working, is to hook a rubber hose to the water tube, with the lower unit removed. Turn on the tap, and you should have water coming out the exhaust housing and the telltale.

 

[Capt dave 258]

Perhaps the Water Tube didn't go into the Water Pump, when the Unit was installed.
How long did you run the Motor? If the Water was getting to the Block, there would be some being discharged through the Idle Reliefs and the Water Drains just above the Anti-Ventilation Plate, as well as the Prop when the Engine is running.
Are you running it on Muffs, or in a Tub? If in a Tub, the Water Level has to be be above the Pump, in order to Prime the Pump.

I'm running on muffs. The pickup tube is in the impeller housing with the grommet around it at that end. I believe I'm not getting the upper end of the tube to seat in the power head. I took the pickup tube out of the impeller housing and tried to get it in the power head but it won't stay.

 

[Capt dave 258]

The tube is friction fit into a rubber grommet under the power head, and another one at the water pump. I've had trouble before guiding the lower one on before. A little grease helps. No grease on the top one, you don't want that one to move.

One thing you can do to prove to yourself that everything else is working, is to hook a rubber hose to the water tube, with the lower unit removed. Turn on the tap, and you should have water coming out the exhaust housing and the telltale.

That's a good idea and I will hook a hose to the end of the tube if I can get it to stay seated up at the power head.

 

[Bobbywolf]

It is possible the upper grommet is damaged. It is replaceable, but not easily. With the tube out, you need to get a good look at it. Judging by the diagrams of your outboard, they are the same part top and bottom, but the top one has a retainer to hold it there.

 

[airshot]

Muffs should not be used to test a water pump. The pressure from the hose could create a false impression that the impeller was pumping when it is not. To test a water pump, a tank or back into the lake is necessary.

 

[Capt dave 258]

It is possible the upper grommet is damaged. It is replaceable, but not easily. With the tube out, you need to get a good look at it. Judging by the diagrams of your outboard, they are the same part top and bottom, but the top one has a retainer to hold it there.

I found a YouTube video of two guys changing the impeller, along with the plastic part, rubber seal and retainer that hold the top of the pickup tube in place. Yes, it does look difficult, and they used long socket extensions to reach up in there to remove it. I will be attempting that later today.

 

[Capt dave 258]

Muffs should not be used to test a water pump. The pressure from the hose could create a false impression that the impeller was pumping when it is not. To test a water pump, a tank or back into the lake is necessary.

Thanks for the info.

 

[Capt dave 258]

I got the two screws out that hold the upper water tube retainer in. You have to pull the exhaust tube down in order to get an 8mm socket on them. A long extension and good flashlight was needed. Obviously the retainer is melted, judging by the plastic on the screws. I'm still trying to get the retainer to drop out. Must be melted in place. It's going to be difficult to get a new retainer back on. Oh well, back to trying to get the old one out.

 

[mike_i]

I agree 100%.
Do you know if the motor pumped water before you took it apart?

Muffs should not be used to test a water pump. The pressure from the hose could create a false impression that the impeller was pumping when it is not. To test a water pump, a tank or back into the lake is necessary.

 

[Capt dave 258]

It did not pump water and I'm left wondering if there's more damage as a result of the overheating. I tried to get the retainer to drop without luck. I busted the two screw lobes off, but the remainder is still melted in place. I've tried various methods but it won't budge. Unless someone has an idea as to how to remove what's left of the retainer, I think I'm going to abandon this motor. I have another running motor to replace it. I have to prioritize my time. The boating season goes by quick in Wisconsin. Thanks to all for your help.

 

[Chris1956]

I do not have any experience on your motor. However I have had IL6 motors from the same era, which have mostly the same design. If the copper water tube pulls out of the seal in the exhaust extension (under the powerhead), it is real hard to get it back in properly, without pulling the powerhead. I would recommend that before tossing the motor, Pull the powerhead, pull the exhaust extension and see what is up with the seal. Make sure the seal (same one) in the waterpump outlet is good.

 

[jimmbo]

The Powerhead is going to have to be pulled to do the repair correctly

 

[Capt dave 258]

The seal in the water pump outlet is new

I do not have any experience on your motor. However I have had IL6 motors from the same era, which have mostly the same design. If the copper water tube pulls out of the seal in the exhaust extension (under the powerhead), it is real hard to get it back in properly, without pulling the powerhead. I would recommend that before tossing the motor, Pull the powerhead, pull the exhaust extension and see what is up with the seal. Make sure the seal (same one) in the waterpump outlet is good.

The seal and the housing for it is melted. It is correct to say the powerhead would have to be removed to do the job correctly. If I could get the melted housing off, I could not properly clean the surface.

 

[Chris1956]

Gee, I am not sure I understand your post. The housing is NLA, but the internet may have a used one somewhere. You may even find a used exhaust extension. i.e. I found a swivel pin for my '93 Merc V6 in Green Bay, after the original rusted away in the salt water here in NJ, so you never know what is out there.

It seems like you are determined to throw the motor in the trash.

 

[Capt dave 258]

Gee, I am not sure I understand your post. The housing is NLA, but the internet may have a used one somewhere. You may even find a used exhaust extension. i.e. I found a swivel pin for my '93 Merc V6 in Green Bay, after the original rusted away in the salt water here in NJ, so you never know what is out there.

It seems like you are determined to throw the motor in the trash.

Greetings Chris. This 35hp Mercury needs the fitting and seals that the top of the water pickup tube goes into. The current plastic fitting is melted. I cannot get it off and clean the surface properly without removing the powerhead. A quick check of supply houses on the internet shows that piece is unavailable. If the previous owner ran that motor to the point that it got so hot as to melt that piece, what other damage may there be? I did start the motor for a few seconds, and it does run but is leaking gas from the carb. I have a spare, running, 50hp, Evinrude with power tilt/trim to put on that boat. I would rather do that and get on the water, than to spend more time and money on a gamble. I will sell the Mercury to someone that may want to repair it or use it for parts. My thanks to all for your input.

 

[Chris1956]

Sorry, I had thought you wanted to fix it.