Indmar LT1 350ci Circulating Water Pump Replacement

[jsturvey]

This is basically going to be repair thread since I'm pretty clear on what I am doing. I have noticed that there are not many posts regarding Indmar motor repair and maintenance, so I am posting this in hopes that it will help someone else down the line.

I was replacing my impeller and while test running the motor on the water hose, I noticed a constant water drip from the circulating water pump area. It was a pain to localize since the motor is in the boat backwards, and there is a water distribution manifold mounted in front of the water pump itself. So now it's time to replace it.

The challenge; Sourcing a replacement...an affordable replacement. I could not find a replacement water pump for any cheaper than $505! That's insane!!! There is just no way that I am going to spend that much cash on a water pump. Soooo, I am going to commit a cardinal sin in the boating world and install an automotive water pump on the engine. The boat has never been, or never will be in salt water, so it should be just fine.

Items Purchased...
1. Water Pump - (using one spec'd for a 1995 Corvette 350ci LT1) $140.00
2. A package of bypass plugs (need two 3/4" plugs) $5.50
3. 1" Hose Clamps (2 @ .99ea) $1.98
4. Engine enamel spray paint (I'm using Fire Red metalic) $9.00
Total spent - under $170

I'll post pictures later as I go through installation.

 

[500dollar744ti]

Re: Indmar LT1 350ci Circulating Water Pump Replacement

Good deal, you would have to corrode through 3 water pumps before you break even with the expensive one.

Being an LT1, you've got the opti-spark, distributor under the water pump?

 

[jsturvey]

Re: Indmar LT1 350ci Circulating Water Pump Replacement

Good deal, you would have to corrode through 3 water pumps before you break even with the expensive one.

Being an LT1, you've got the opti-spark, distributor under the water pump?

I am still learning about this engine since this is only the 3rd season I've had this boat, so I'm not exactly sure what timing system I have. Maybe you can tell me. The spark plugs get their charge from a group of coil packs mounted on the port side of the water pump. You can see it on the left edge of this picture.

I noticed a sensor mounted just to the upper right of the harmonic balancer that I can only assume had something to do with ignition timing. Pic below...

Is this that you are referring to?

 

[jsturvey]

Re: Indmar LT1 350ci Circulating Water Pump Replacement

Got the old water pump out, and the bearings on it were toast. The only real difference between the two is the absence of the heater core hose connector on the original.

Note the pipe connection on the lower left. Needs to be plugged on the new one. Also removed and repainted the thermostat housing, and move the temp sensor from the old pump to the new pump.

New pump after paint, plugs, and sensor installed. Also be sure to remove the impeller coupler from the back side of the old water pump and install into the new one. (I almost reinstalled the pump onto the motor without the coupler which is why I stress "be sure".)

 

[500dollar744ti]

Re: Indmar LT1 350ci Circulating Water Pump Replacement

Is this that you are referring to?

No, it looks like Indmar had enough sense to get rid of the stupid opti-spark which is literally a distributor mounted behind the water pump. It looks like yours has a block-off plate and coil packs, that's a very good thing. On a corvette the distributor is behind the water pump and it fails often, it also means you have to remove the water pump to replace the cap and rotor.

 

[jsturvey]

Re: Indmar LT1 350ci Circulating Water Pump Replacement

No, it looks like Indmar had enough sense to get rid of the stupid opti-spark which is literally a distributor mounted behind the water pump. It looks like yours has a block-off plate and coil packs, that's a very good thing. On a corvette the distributor is behind the water pump and it fails often, it also means you have to remove the water pump to replace the cap and rotor.

Yikes! Well I'm glad I don't have that system. Thanks for the info. The more I can learn about these engines, the better.

 

[jsturvey]

Re: Indmar LT1 350ci Circulating Water Pump Replacement

Here is a pic of the new water pump installed on the block before re-installing the water manifold with all the piping.

I didn't feel the need to take a finished pic, plus I ran out of daylight. Everything has been re-installed and will be splashing the boat again this weekend to really test this one out. It ran fine on the water hose.

 

[Fliz]

Did it work fine for you after this install? Thanks.

 

[southkogs]

Welcome aboard Fliz. Please read the forum rules about posting in old topics. This one is way too dusty to bring off the shelf

Closed.