water pump - clean mating surface and silicone?

**findalex** · 07-22-2019 05:47 PM

Hi,

I'm in the process of changing my water pump and I'd like your opinion on the following:

1) how best to clean the mating surface of the engine block

razer blade? scrub pad?

2) should I use some type of silicone sealant on the gasket?

Blauparts says no sealant if gasket is paper, but ours is a rubber one (https://www.fcpeuro.com/products/aud...ring-06j121119)

3) should I flush out all the coolant?

how do I get all the coolants out if there's only a drain plug on the bottom of the radiator? there must be some left in the engine/water pump/pipes/hoses

Thanks in advance.

Alex

**Smac770** · 07-22-2019 06:41 PM

The only thing the repair manual says is coat o-rings with coolant. I don't see any need for any kind of sealant in the procedure.
It also mentions to make sure both centering pins are installed in the block.
And on new pumps there's a cap on the cog wheel that the toothed belt goes on? That should be removed.

I think for cleaning the mating surface, I'd do it just like for the intake manifold.
Brake clean (non-chlorinated) applied with a towel, scrub pad like you showed, and plastic prys for the stubborn. Razor blade, maybe but be damn careful.

How to fill the system? There's a 6 page process in the repair manual, using tools no normal person is likely to have.
So I no guidance on the fill and burping process without said tools.
The manual does say "don't reuse dirty coolant", and "do not reuse coolant if the radiator, heat exchanger, cylinder head, head seal, or block were replaced". You're just replacing the pump. If the coolant looks fine, reuse it and don't worry about what's left in the system.

**Spawne32** · 07-22-2019 06:41 PM

scotch brite if necessary, razor blade should suffice, although there shouldnt be much at all of any gasket residue as its a viton gasket. No sealer required, and you can just drain through the bottom of the radiator where the plug is on the lower hose and refill as necessary, no need to flush as your draining most of the block anyway. Unless your coolant is rat ass nasty.

**Theiceman** · 07-23-2019 08:40 AM

there wont be residue of any kind as there is no gasket, just an oring , the only think to worry about will be if it leaked past the seal there might some corrosion of the block sealing surface. just use the scotch bright to clean it up and slap on the new one. edge motors uses a spray on sealant that wont hurt but i didn't bother and it has been fine.

**mtroxel** · 07-23-2019 12:04 PM

I didn't use any sealant. I used a razor blade to clean the surface. It left no scratches behind on a cast iron block. No leaks here.

**findalex** · 07-23-2019 12:58 PM

Thanks for all the replies. When I took the water pump off, the mating surface looked fairly clean. Very little residue from the o-ring or any dried up coolant.

I will proceed with some scotch pad scrubbing and then some brake cleaner to make sure surface is clean.

**Theiceman** · 07-23-2019 01:04 PM

Originally Posted by findalex

Thanks for all the replies. When I took the water pump off, the mating surface looked fairly clean. Very little residue from the o-ring or any dried up coolant.

I will proceed with some scotch pad scrubbing and then some brake cleaner to make sure surface is clean.

yeah you will be fine.. just dont over torque those bolts. i remember it being low as the part is plastic.