Mercruiser 470 Water Pump question

[tc123]

So Spring is almost here and soon I will be working on the infamous water pump seal issue on my 470 (slight coolant leak from weep hole). Has anyone tried or heard of using an external pump (electric or mechanical) to eliminate this issue altogether with any success? Bad design having coolant and oil systems separated by a seal on a rotating shaft IMO.

 

[stonyloam]

No. Actually it is two seals with a space and a weep hole between. If you keep the weep hole clear and install the seals correctly (both facing away from the block) it does a pretty good job of keeping the coolant where it belongs. The best bet is just replace them, use spedi sleeves if the cam is grooved.

 

[Scott Danforth]

the bad design is the non-hardened cam nose that wears and leads to a groove. hence the need for the speedy sleeve. the whole seal thing is what seals are intended to do.

 

[SDSeville]

Seems like the bad design is having a water pump that requires so much work to get to. I did the seals and speedy sleeve on my 470 and it took me about 6 hours, including gluing the new piece of gasket to the front of the pan (yes I am slow). I haven't done done it on my 7.4 yet, but it sure looks easier (I would guess 30 minutes or so). It looks like a car water pump bolted to the block and run by the belt.

 

[QBhoy]

Been a while since I messed with my friends failing 3.7’s....but often wondered if these would be better with a raw cooling conversion. As in, blank off the engine driven pump, remove exchanged etc and just let the drive driven pump flow through the engine.
Might solve one of the many silly faults these things have.

 

[thumpar]

Been a while since I messed with my friends failing 3.7’s....but often wondered if these would be better with a raw cooling conversion. As in, blank off the engine driven pump, remove exchanged etc and just let the drive driven pump flow through the engine.
Might solve one of the many silly faults these things have.

The dissimilar metals might be an issue and cause corrosion.

 

[QBhoy]

That’s always going to be an issue no matter what cooling I suppose, if you mean the head and block.

 

[ImperialV184]

I wish there was a alternate method. I had a machine shop sleeve my Cam shaft during rebuild. He was very carful to align the sleeves with the seals. After two years I noticed a small leak. I have rebuilt two of these motors and on both what a saw was a badly worn areas with the first seal and the second seal was fine. Almost like it leaked through the first seal and went out the weep hole saving the second seal. Which I guess is the intention. I plan to run mine this year and keep an eye on it but I may be having to take apart and re sleeve the shaft.............what a bummer.

 

[tc123]

Thanks for all the replies on this subject, I agree with SDSeville that a water pump (of which the seals are a wear item) should not have been driven by a major internal engine part, namely the camshaft. It turns what should be a simple repair into a major project with many pitfalls such as speedi sleeve installation problems, oil pan gasket damage,etc. Much simpler if it was a belt driven pump! But it is what it is and needs to be dealt with. It always makes me wonder "what were they thinking ?" when I encounter a design like this. Usually the answer is "cost savings" unfortunately.

 

[stonyloam]

Awful lot of complaining here. Yes the second seal and weep hole are designed that way to keep the coolant out of the crankcase. No you can not convert to raw water cooling, the cam would rust under the seals in about two days and tear them up. It is set up to use the exchanger and that is the way you must run it. Yeah about 6 hours to change the seals, but what about the 6 MINUTES it takes to winterize it (if you are slow). Yeah the 470 can be a pain sometimes but it is a pretty good light and powerful little engine if you treat her right. Yeah I’m kinda grumpy tonight

 

[Bondo]

Ayuh,..... If ya wanta keep that ole 470 Runnin',....

I suggest ya listen to Stonyloam,.....