Caterpillar Raw Water Pump Repair - 3196, C12

[Storm]

I should have known better than to start this project on the 13th. At least it wasn't a Friday. A simple impeller replacement turned into a fiasco when I broke the cam liners while removing the impeller. The cam liner pin added insult to injury when it dropped into the pump inlet, requiring the inlet hose to be removed. Arggh.

Not sure what real mechanics do, but next time I will try C-clamping the cam liners to the pump housing to prevent them from sliding out with the impeller. Any better suggestions?

It turns out each cam liner half cost $138.57 from Caterpillar, or a whopping total of $277.14 for the set. They can be purchased online from CLRMarine.com for $72.13 each, or a savings of $132.88. I purchased the Sherwood impeller from Caterpillar for a whopping $257.50, but the same impeller can be purchased online from Associated Diesel, Inc. for $194.39, or a savings of $63.11. By purchasing online instead of from Caterpillar, savings to complete the project would have been $195.99 for the two cam liner halves and the impeller. I had additional freight charge from Cat of $30.72 for the cam liner halves. Unfortunately for me, downtime was a factor in my decision to buy from the local Cat dealer.

I had written to Cat Marine Power Systems in the past about what I considered to be a defect in the wear plate retaining pin design. Previously, the pin was cast into the pump housing and because the wear plate hole was considerably larger than the retaining pin, continuous slippage of the wear plate would shear the pin requiring replacement of the pump housing - not a cheap repair. When I pulled my rebuilt pump apart, it was interesting to learn that the wear plate now has a rectangular hole and the retaining pin is stainess and removable. No more pin cast into the housing. Now if only Caterpillar could make necessary changes to their defunct aftercoolers to go along with the redesigned Sherwood cooling pumps. Too much to ask?

What annoyed me most during the pump repair was installation of the interior o-ring cam liner seal. I have yet to understand exactly what function the o-ring performs and wonder why a plastic lip can't be molded onto the plastic cam liners which might serve the same function - which I suspect is to reduce vibration and center the cam liners rather than to actually create a seal.

Storm

[algdog]

what are you talking about when you say cam liner
are you talking about the impeller itself or some other part of the water pump.
If you are having trouble installing the new impeller I take a very heavy wire tie and put it around the impeller and tighten it down
in the correct direction of rotation.
slide the impeller half way in with the wire tie on then snip the wire tie and finish installing the impeller with a slight turn
some soap helps. I have a 3176 and have never had a problem like you are saying with wear plates and pins and all

[Big Jay]

I don't know how that motor differs from the 3126's but i always pull the entire pump housing off to do the impellar. That way i put a new housing to drive gear seal on so it doesn't leak oil.

[Storm]

The impeller itself wasn't a big issue. Although, I like the idea of using a cable-tie to cinch the blades. The bigger issue was the plastic cam liner that surrounds the impeller.

I'm thinking that I might cut a hole in a used cover plate with a holesaw which will allow the impeller to slide out of the housing without disturbing the the cam liner, pin, and o-rings.

Basically, I'd just unbolt the good cover plate and replace it with the cover plate with the hole while I remove the impeller.

Storm

[Storm]

I don't know how that motor differs from the 3126's but i always pull the entire pump housing off to do the impellar. That way i put a new housing to drive gear seal on so it doesn't leak oil.

I've done the pump housing removal routine in the past. The Sherwood impellers have a threaded insert that makes removing the impellers much easier than other type impellers, Jabsco for example. You simply screw a jacking bolt into the threaded insert and the impeller slides off the shaft. Unfortunately, I wasn't prepared for the cam liner to slide out with the impeller.