Cloud9...68

My car has been leaking coolant for some time, and I've traced it to the fat radiator hose that goes to the water pump (its other end goes to the bottom of the radiator - the hose's part number is 951 106 237 04). Looking from underneath, there's some crusty coolant residue around the lip of the water pump where the hose is connected to it, and you can see evidence of coolant dripping down the hose itself. I've replaced the hose, and this hasn't helped. One thing that strikes me is the fact that the section of the pump's flange where the hose goes over it is pretty wide - approximately 3/4", and the clamp is much narrower - not even half the width of the area that it's clamping on (I wish I could describe this better - I can take come pictures later, but I'm on my way to a wedding in a few minutes). It seems like the clamp needs to be much wider to effectively clamp the hose to the pump. Does anybody know (or could somebody check) if this clamp is supposed to be on the order of 1/2" to 3/4" wide? The clamp I have now looks more like a clamp for an intake boot. Thanks.

thomasmryan

The castings connections in my boat get really crusty so I have been using hylomar gasket dressing on the hose ends for a couple decades. It works on corroded pot metal and aluminum stuff very well.

My car is a 92 and the clamp is a heavy 7/16" at the pump and I would assume the same at the radiator.

Cloud9...68

Thanks - interesting that you should mention Hylomar - I showed a neighbor my leaky spot, and he recommended the same stuff. Would you recommend smearing a coat of Hylomar around the lip on the water pump that the hose slips over before pushing the hose on?

Here's a picture of what I'm talking about, for you visually-oriented folks out there:

Attachment 921323

Edit: Sorry the picture came out so big - you have to scroll down a little to get to the area I'm talking about.

You can see that the width of the indented area where the hose slips on is significantly greater than the width of the clamp, which I have laying against this part of the water pump for illustration purposes. This just doesn't look right - it looks like a significantly wider clamp would do a much better job of holding the hose against the pump. Not sure how easy it's going to be to find one, though. Maybe at Grainger.

Rob in Oz

Be aware that wider clamp = less pressure on the part being clamped, so to achieve the same pressure as before on the hose, you'd need to do the wider clamp up to a higher tension. In practice, better sealing is achieved with the narrowest band width compatible with ensuring minimal damage to the underlying hose material.

thomasmryan

Expansion and contraction comes into play also. Amazon has hylomar. Kinda like 574.

Works on paper gaskets also.

Cloud9...68

Hmmm... So what would be your guess as to why I'm getting coolant leaking at the point where this hose connects to the my water pump? And does anyone know the width of the OEM clamp that secures the hose at this point? It's very hard to see, with the belts and rollers in the way, but I don't see any traces of coolant leaking anywhere else from the pump.

Cloud9...68

Yes, i agree that expansion and contraction comes into play, but I'm not sure what to do with this fact. The next thing I'd like to do is put everything back together and fire up the engine and watch this spot to get a better idea as to the nature of the leak, but I'd like to get the right size clamp on there first, as I still think my skinny clamp on this wide area doesn't seem right.

thomasmryan

7/16"

kwikt

Did you try lightly sanding the ridge with emory cloth or a wire wheel dremel to remove the corrosion. Worked for me!

Jay Wellwood

Go to Lowe's or Home Depot - plumbing dept. and get a Stainless hose clamp to meet your needs for much less. Just make sure it is a worm drive hose clamp with a combination slot/bolt head to get good torque when you tighten the screw.

While wider may not provide the same clamping effect as a narrow clamp, this is based on the same torque applied at the screw connection. Typically a wider clamp has a larger head, which in theory would be proportional to the amount of torque that would be applied. YMMV

Cloud9...68

Well, it looks promising. I lightly sanded the surface of the pump where the hose slips on with some fine emory cloth, and placed a wider clamp (from Lowes, just under 1/2" wide), tightened it up, fired up the engine, and let it get fully warm. No trace of coolant leak or smell. I have the car up on jacks because I've got a few other things I need to do it, so I won't really know if the leak is fixed until I take it to the track, but I'm cautiously optimistic that the leak is fixed. Thanks for all the replies.