Rebuilding the LC4 Mechanical Water Pump - a Guide

[Geekventure]

I sure hope it's not coming from that hole! Thanks for the info...I will try to look a little harder after I clean in next time.

So let's say it actually is the thermostat above...what needs to be done to fix it? (o-ring?)

• new gasket?

Originally Posted by gunnerbuck

Is it actually coming from that hole or the thermostat fitting above?

That hole is a drain for the spark plug well and shouldn't have coolant leaking out of it unless you have a cracked head in the plug area.... The purpose of the hole is to allow fluid to drain out after deep water crossing so it doesn't foul the electronics...

[gunnerbuck]

I believe it's just a regular o-ring.. 21mm x 2mm...

[Geekventure]

So there are 3 O-Rings for the thermostat...



P#31: 0770 320020 O-RING 32.00X2.00
P#33: 0770 021020 O-RING 21.00X2.00 NBR70

If my coolant is coming out of that little hole on the top right side of the head block...



Originally Posted by 666



Which O-Rings do I need to replace...#31(x2) or #33?

[slackmeyer]

You would replace all of them, they're just o-rings. But that hole goes directly to the spark plug. . . . are you sure it's coolant coming out of it?
You should take off the gas tank, take off the spark plug wire, and look down at the spark plug with a flashlight. Is there water or coolant down there?

[Geekventure]

99% sure it's coolant because it's orange...just like my coolant.

OK...so whatever it is that is coming out of that hole is originally going in up top where the spark plug wire goes into the cylinder head and wraps around the plug itself?

Or...is it coming from and internal area and seeping out that hole?

[warewolf]

I suspect that if o-ring #33 leaks, the coolant will flow down the head past that hole. Some of that leaked coolant could get blown back up the hole, making it look like the coolant is coming from the hole rather than above and outside it.

[makazica]

Replace #33, 5 min job. Dry the sparkplug hole, dry the drain hole with a q-tip, clean the engine and look if the leak repeats.....

[Geekventure]

I will do so and report back!

I have another issue...it' posted here if your feeling like some electrical engineering crap!

Thanks for all your time!

[vulture]

This a great guide, thanks LC4 Pilot. I rebuilt the water pump on my '99 640 Adv and it went smoothly.

Two questions:

1) After installing the new bearings/shaft/seal into the housing, how hard should it be to turn the shaft? I can turn it by hand but it's pretty stiff. Maybe it's just because the new seal is tight?

2) See the pin near the outer edge of the housing in LC4 Pilot's picture below? I don't have that pin, just a nicely machined little hole in the edge of my housing. The pin was never there or it fell out. I assume the pin fits in the engine housing groove and keeps the pump from moving outward away from the engine? I figure I can make one from a small bolt and press it & loctite it in there. Better ideas?

[Sean70]

Originally Posted by vulture

This a great guide, thanks LC4 Pilot. I rebuilt the water pump on my '99 640 Adv and it went smoothly.

Two questions:

1) After installing the new bearings/shaft/seal into the housing, how hard should it be to turn the shaft? I can turn it by hand but it's pretty stiff. Maybe it's just because the new seal is tight?

2) See the pin near the outer edge of the housing in LC4 Pilot's picture below? I don't have that pin, just a nicely machined little hole in the edge of my housing. The pin was never there or it fell out. I assume the pin fits in the engine housing groove and keeps the pump from moving outward away from the engine? I figure I can make one from a small bolt and press it & loctite it in there. Better ideas?

I'll just jump in; Quick answer to your questions:

1. Yes it'll be pretty stiff to turn with the new seal.
2. The pin will stop it from rotating, and make's sure it has the proper orientation, I think, as the groves will hold the pump in. Just make sure there's a matching hole in the engine for the pin, the pins not stuck in there is it?

[vulture]

Originally Posted by Sean70

I'll just jump in; Quick answer to your questions:

1. Yes it'll be pretty stiff to turn with the new seal.
2. The pin will stop it from rotating, and make's sure it has the proper orientation, I think, as the groves will hold the pump in. Just make sure there's a matching hole in the engine for the pin, the pins not stuck in there is it?

1. Cool, thanks.

2. After looking at this more closely, I think the pin is supposed to be missing. The way the pump fits into the engine, the pin would not work there. I know the design on the older pumps is different (1 o-ring vs 2), maybe this is another design difference.

[Sean70]

If there is no corresponding hole for the pin in the rocker cover where the pump slots in then it might not be meant to be there.

Mines a 2006 and it has the pin.

[wrk2surf]

my 03 has a pin

[makazica]

Vulture, my '01 has the pin and two O-rings, the pin goes in a hole on the rocker cover and defines the correct position of the pump in relation to the head and the rocker cover. Search the pump seat on the rocker cover side for the little hole.....

See the arrow on the pic? That "tooth" on the pump body has to be parallel to the head/rocker cover seat when mounting it.....the little pin fits inside the hole and keeps the pump from potential rotating in the seat....

I would for sure make some kind of pin and epoxy it in.

[vulture]

Originally Posted by makazica

Vulture, my '01 has the pin and two O-rings, the pin goes in a hole on the rocker cover and defines the correct position of the pump in relation to the head and the rocker cover. Search the pump seat on the rocker cover side for the little hole.....

See the arrow on the pic? That "tooth" on the pump body has to be parallel to the head/rocker cover seat when mounting it.....the little pin fits inside the hole and keeps the pump from potential rotating in the seat....

I would for sure make some kind of pin and epoxy it in.

No hole on the rocker cover side or the cylinder head side. There is nowhere for a pin to fit - the groove on the water pump side where the pin could go matches to a smooth ridge on the rocker cover/cylinder head side. Also, my water pump has no "tooth" like you pointed out. I don't see anything that would keep the water pump from rotating (other than it being a pretty tight fit). Maybe that's why they changed the design in later years??