'72 20HP Chrysler 202HD Water Pump Service (pics)

[i386]

Skip past the first paragraph if you don't want the gory details.

The last time I had the boat on the lake my little Chrysler ran hot. I waited until it cooled off to check it out. It hadn't siezed up which was good. It started right up. While idling there was enough water circulating to keep the engine cool. If I ran it fast enough to plane the boat out, no water came out of the telltale and I could feel the head heating up. Backing it down to idle it would cool right off enough that I could hold my hand on the head so we idled back to the ramp.


I dropped the lower unit today to see if I could locate the problem. The first thing I noticed was the drive shaft was blackend with grease/oil. The second thing I noticed what I think was lower unit lube on top of my pump housing.

There's always been a little water in the lube when I change it and I knew sooner or later I'd need to repair it properly.

Next I removed the 4 screws securing the pump housing. I expected to see a mangled impeller. This was not the case. Sure there were a few cracks so it needs replacing but nothing that would make me think it would just totally fail.

The water tube "grommet" looks like it's got some heat damage. I don't know what one of these is supposed to look like in a Chrysler but it looks nothing like the one in my 'rude. It's hard and does not want to come out.

I think I should replace the seals in the pump housing and the one under the pump housing. My manual says to use a special tool. Is this tool really required? If so where to get one?

There was some grease on the splines on the top of my driveshaft (good), but no o-ring or seal. Shining my light up into the leg I don't see one either.


Just whatever information you can throw at me would be appreciated.

 

[eurolarva]

Re: '72 20HP Chrysler 202HD Water Pump Service

Re: '72 20HP Chrysler 202HD Water Pump Service

Most of the chryslers do not have a well for greese on the top of the driveshaft. the manual mentions using anti sieze compound on the threads. The leak in the lower unit may not be repairable. A motor that old developes wear spots where the seal and the shaft come together. Maybe go to high performance merc lower unit oil. It helped me on mine. I still get a bit of oil leak but not as much. The oil you mentioned on top of the water pump is probably unburned oil gas mix and the left over is the oil. Take a whiff of it. Nothing smells nasty like lower unit oil. If it smells like gas it is probably unburned fuel mix. The grommet is usually located in the kingpin up by the power head and will probably require the powerhead to be removed and the upper and lower king pin gaskets to be replaced in order to replace the water tube gasket. Even new they are hardened rubber. For your over heating I would examine the water pump closely. Make sure it is not pitted or worn. Replace with a new impeller and when installing it apply firm downward pressure to the water pump while slowly turning the drive shaft clockwise till the water pump is seated. Make sure the impeller key is installed.

 

[i386]

Re: '72 20HP Chrysler 202HD Water Pump Service

Re: '72 20HP Chrysler 202HD Water Pump Service

Thanks Eurolarva, I'd like to clarify things a bit. The "grommet" I was referring to is the piece the water tube mates with as it's inserted into the pump housing. The chrysler parts manual calls it a "seal, water line lower". In the parts drawing the seal at the top of the driveshaft is part number 24342. I'm not sure where the kingpin is as I don't see that on the drawing.

If I understand correctly, the other 2 seals I was referring to (p/n 901307-2) may not help if replaced. Looks to me the only way a new seal wouldn't help is if a groove was worn around the driveshaft where the seal makes contact. I don't know if that is the case as I have not removed the seals. But my service manual shows these being insalled with a special tool.


Upon further examination, I don't think it was L/U oil on top of the pump housing. It smells like gas. Good call.

Here's some pics. I hope this makes things clearer...

^^^ Waterpump hosing. The "grommet" I was referring to is sticking up just to the right of the hole when the driveshaft comes up through. It looks burned which may explain why it's hard.

^^^ A better view of where it looks burned/melted

^^^ Top view of the rubber seal. There's an identical seal (same p/n) under the plate. The manual says this removed with a screwdriver, but installed with a special tool.

^^^ Another angle of that seal.

 

[i386]

Re: '72 20HP Chrysler 202HD Water Pump Service (pics)

More info...

I'm just trying to get my ducks in a row before I order parts. My parts manual is showing a seal at the top of the driveshaft. My parts dealer is telling me there's a groove around the driveshaft and the seal is just an o-ring. My Evinrude is exactly like that. But this old Chrysler has no groove and no seal of any type came down with the L/U and driveshaft.

The other thing I have noticed that's different than my 'rude is the water tube. On my 'rude the tube is pretty stiff. On the Chrysler it will wiggle a maybe 1/4" - 3/8". I would like to know if this is normal.

 

[eurolarva]

Re: '72 20HP Chrysler 202HD Water Pump Service (pics)

Are you confusing the drive shaft with the water tube? The water tube will show a seal at the top however it is not there. It is located on the kingpin. The kingpin is the plate that the powerhead sits on. There is an upper gasket that touches the powerhead and a lower gasket that touches the kingpin and the motor leg. The seal for the water tube is mounted between the kingpin and the lower exhaust gasket and is usually only accessable by removing the powerhead. It might be possible to get there with removing the lower unit and the motor leg. There should be no seal on the upper drive shaft.

 

[i386]

Re: '72 20HP Chrysler 202HD Water Pump Service (pics)

Maybe it's a misprint. I'm not confusing the two. I'm talking about part number 24342 "Seal, driveshaft".

My parts vendor is now telling me not to worry about the seal since I run in fresh water. He also says the wiggle in the water tube is normal.

I'd just like to figure out why it failed. There was another forum member that posted the same problem but he never posted the solution.

Circulates water at idle speed. Does not circulate at running speed.

 

[i386]

Re: '72 20HP Chrysler 202HD Water Pump Service (pics)

I finally had an opportunity to take the boat out after putting in a new water pump kit over a month ago.

The engine did not overheat. I have fogged it and put it in the basement for storage until spring.

I am still curious about something though. At idle there's a good sputtering of water from the tell tale. At planing speed there's still not much more than a sputtering of water when I expected to have a steady stream. Is this normal?

 

[eurolarva]

Re: '72 20HP Chrysler 202HD Water Pump Service (pics)

Yes this is common. When at higher speeds the water is going out the exhaust down the motor leg and out the lower unit. At idle and slower speeds the water will come out the telltale.

By the way. That grommet you mentioned on the water pump. It is suppose to be hard. Even new it will be hard. The one I thought you were refering to is the one up by the power head where the top end of the water tube connects. The king pin or spacer plate is where that grommet is and is not a fun one to replace. I was just confused by your description. The drive shaft seal special tool is mainly a 3/4 inch deep socket with a mallet.

 

[i386]

Re: '72 20HP Chrysler 202HD Water Pump Service (pics)

That's good to know. I was concerned about it.

Yes, I think we're on the same page with the grommet now. The new one was also hard like you said. The seal tapped in just fine. It shifted fine too so I feel good about it.

Thanks!