1968 Penn Yan Mercruiser 160 impeller time.

[AKPilotnboatman]

Hey again,

I was so close to making a test run of the restore project, but i started overheating in the driveway. I had it running the other night at idle for about ten plus mins. Everything was working. I traced the problem I had today back to the water pickup impeller/pump in the drive unit. Being that I have never taken one of these apart before, I was wondering if anyone had some tips and pointers. I would rather not have to do this more than once this summer.

Thanks

 

[Bt Doctur]

locate a manual and start reading. its a fairly simple job as long as everything just comes apart to service it. Any service history?
On a scale of 1-10 ,what is your mechanical ability?

 

[Sangster21]

I would have a look at this video by achris from i boats.
https://www.youtube.com/watch?v=ev4NVyyyIkU
I just did mine the other day...... I started the engine on the muffs and didn't turn on the tap. I bet I am not the only person who has pulled off that gem of a move! Pretty straightforward procedure. I am not one of the experts here, but you may want to get a water pump kit that includes the pump base and everything. There is seal in the bottom that can let water into your gear oil, may as well change it out and you will know it's done! Good luck with it.
Alan

 

[AKPilotnboatman]

Mechanical ability is quite stable i would say, but only so good when nothing to reference and having never seen anything before. i am having trouble separation the lower and upper unit.

 

[Bt Doctur]

you remove the 5 nuts, the bolt holding the trim tab, and then the bolt UNDER the trim tab http://www.boatfix.com/merc/Servmanl/6/6covr3.pdf

 

[Eric 3.7LX Alpha 1]

See if this will help: These were what I watched when I first did mine:

Here is another for the impeller job:

 

[Eric 3.7LX Alpha 1]

If you have to pry them apart at all, there is one area you want to stay clear of when prying.... The seal between the halves called the quad ring gasket. is shown in the pic below. That is how oil runs from the lower up to the upper half and out the vent hole.

After you have them apart. There is a hollow void around the shift shaft at the front end of the lower. It runs down to a small drain hole also noted in the picture. You want to clean out that void of all the gunk that will be in there so water can drain out that hole.

Your impeller kit will probably have extra gaskets in it, just go slow and stack the correct gaskets in the proper orientation on the side as you take it apart so you won't 2nd guess yourself when you install the new.

A little trick I do, is to slowly turn the prop while in gear which turns the vertical shaft. ( will turn the same way in forward or reverse) while pushing the new impeller in place. It will move the impeller veins in the correct position to fit back in the cover.

When you reinstall the halves make sure they are both in forward when mating. With your hands, rotate the shift shaft on the lower half clockwise and turn the prop CCW until it locks. It must be held there in forward the whole time. Some will use a bungee cord. The shift shaft in the upper is in forward when pointing straight ahead .

 

[AKPilotnboatman]

If you have to pry them apart at all, there is one area you want to stay clear of when prying.... The seal between the halves called the quad ring gasket. is shown in the pic below. That is how oil runs from the lower up to the upper half and out the vent hole.

After you have them apart. There is a hollow void around the shift shaft at the front end of the lower. It runs down to a small drain hole also noted in the picture. You want to clean out that void of all the gunk that will be in there so water can drain out that hole.

Your impeller kit will probably have extra gaskets in it, just go slow and stack the correct gaskets in the proper orientation on the side as you take it apart so you won't 2nd guess yourself when you install the new.

A little trick I do, is to slowly turn the prop while in gear which turns the vertical shaft. ( will turn the same way in forward or reverse) while pushing the new impeller in place. It will move the impeller veins in the correct position to fit back in the cover.

When you reinstall the halves make sure they are both in forward when mating. With your hands, rotate the shift shaft on the lower half clockwise and turn the prop CCW until it locks. It must be held there in forward the whole time. Some will use a bungee cord. The shift shaft in the upper is in forward when pointing straight ahead .

You mention the shift shaft and the drain hole. Currently there is a bunch of grease and junk around the shift shaft. Is this area supposed to be greased up, or squeaky clean? And what do you mean by "make sure they are both in forward when mating?" They being what?

Does the impeller turn when the engine is not in gear? And being that I forgot to have water running, is there another pump (circulating) that could have been messed up too? I noticed this from the engine overheating while running it in my driveway (water on) before my last test run, which obviously has been postponed.

ALSO... THANK YOU ALL for the help. I find forums to be complete life savers. Especially with my truck. Ha!

 

[Eric 3.7LX Alpha 1]

The cavity is suppose to be Clean!! Nothing in there. A skinny wire thru the hole and shop vac from the top keep working it.... water and degreaser, and the shop vac again.... so that water poured in the top drains out that hole.

When you re attach the halves of the drive the lower half has to be in forward gear the whole time they are being assembled. The shift shaft in the upper half should be pointing straight ahead for forward.

 

[AKPilotnboatman]

Does the impeller turn when the engine is not in gear? And being that I forgot to have water running, is there another pump (circulating) that could have been messed up too? I noticed this from the engine overheating while running it in my driveway (water on) before my last test run, which obviously has been postponed.

 

[Bondo]

Does the impeller turn when the engine is not in gear? And being that I forgot to have water running, is there another pump (circulating) that could have been messed up too? I noticed this from the engine overheating while running it in my driveway (water on) before my last test run, which obviously has been postponed.

Ayuh,..... EVERYTHING, but the propeller shaft turns with the motor, in neutral,.....