Replacing circulating pump on 8.1 w/v-drives

The plot thickens.

So the Sierra pump’s center hose fitting is larger than the Mercruiser.
It’s not much but enough to not allow the crossover tube to sit over it without some modification (open the hole by about 0.040”). The hole is shown with the picture that had the broken bolts.
Basically the crossover tube holds a flange type seal and the water pump slides inside of it. You can see the two pumps side by side and the Sierra won’t enter as the hole is about 0.040 too small.

I was at the boat so I hand sanded the hole to allow the port motor to go together. Now the stbd is apart and of course the flange bolts are stuck as is one of the thermostat bolts in the crossover tube. So back to the shop we go to get the bolts out of the stbd side.

I guess I should have bought the merc pumps, but this mod isn’t too bad.

If you have trouble getting the the pump and crossover tube together, hopefully this post will help.

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I ended up drilling the second crossover tube open to 1.125 dia.
For what’s it’s worth I’ll show some tips on doing this job.
The pictures are after it’s all apart.

Removal is started by draining raw water pump blue fittings, to empty the hoses connected to heat exchanger, or skip this and just remove raw water hoses connected to heat exchanger. Pull the belt off. Remove the bracket holding the pulleys and tensioner. (The tensioner may have to be removed first)

Using a catch pan, remove lower water pump hose and catch this antifreeze as this must be disposed of at an auto parts center. There is a lot of antifreeze so you will need a large container to dump your catch basin into a few times.

If you are just going to try to remove the water pump only, there is a small clamp to loosen between the crossover pipe and water pump which may need a hose pick after loosening, then just remove the 4 water pump bolts. You will have to pull it away and down to get it out of the connecting seal. More antifreeze will leak out so keep the catch bin there.

If you’re pulling the crossover tube, disconnect the two sensor wires. Remove the two bolts on the reservoir outside and the singe bolt inside. That bolts only needs to be loosened.
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Loosen hose clamps and gently pry up the heat exchanger. More antifreeze will come out of the flanges so again, catch the antifreeze. Remove upper two bolts on the tube and only loosen the lower bolts as the tube is slotted on the bottom. If the water pump is out just pull away and up. Muscle the short hose off.
I replaced thermostat, seal and the short hose to reservoir.
Reassembly is where I photoed.
With the water pump back on, lube up the seal to make it easier to slide over the water pump.
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I loosened the motor lift bracket to swing it out of the way to make it easier to reinstall the crossover tube. Don’t forget to tighten the clamp between the two.
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I lubed the rubber heat exchanger rubber seals with antifreeze to reinstall it and clamped it back together. The manual states to leave the thermostat bolts loose until the heat exchanger is on, then tighten which is what I did. Put on all hoses and belt.
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I hope this can help someone doing this project as it worked for me. While I had the heat exchangers off I made a leak test unit and changed the end gaskets so I could inspect for barnacles.
 

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