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Discussion Starter #1
1997 Dodge Grand Caravan ES
3.8 L
181,000 miles

The van leaked approximately 2 gallons of coolant, resulting in overheating after short initial warmups. I replaced the thermostat and the worn upper radiator hose. I then filled the radiator and bled the system, which ended the overheating. However, I spotted a leak--a significant one and probably the principal source of the coolant loss in the first place--coming from the smaller hose just under the thermostat (see picture). It appears to be leaking at the upper end. Its upper connection is obvious, but I don't know what the hose is called, how long it is, and how or where it is connected below.
Any info or tips would be most appreciated.
Thanks.
 

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Just looking at it, I noticed you are using the wrong clamp.

Using a worm type clamp on a big hose is not that bad, but using a worm type clamp on a small diameter hose can prove catastrophic.

See, remove the clamp, tighten it to about the size it would be when installed and tightened, then look at it and let me know if it looks round, it would not. The part where the "worm" is would look flat. In order to avoid leaks, you'll need to over-tight this clamp, eventually destroying the hose.

Use a spring type clamp or at least a fuel line or power steering type clamp, like this one:


57757


Those clamps are especially made for small diameter hoses.
 

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Discussion Starter #3
Just looking at it, I noticed you are using the wrong clamp.

Using a worm type clamp on a big hose is not that bad, but using a worm type clamp on a small diameter hose can prove catastrophic.

See, remove the clamp, tighten it to about the size it would be when installed and tightened, then look at it and let me know if it looks round, it would not. The part where the "worm" is would look flat. In order to avoid leaks, you'll need to over-tight this clamp, eventually destroying the hose.

Use a spring type clamp or at least a fuel line or power steering type clamp, like this one:


View attachment 57757

Those clamps are especially made for small diameter hoses.
Levy, thanks for the tip on the clamps. I'll get some. Do you know anything about the smaller-diameter hose in the picture? It's a heater hose of some kind.
Again, thanks for the tip on the clamps.
 

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I don't know if fuel line clamps are available in a large enough diameter to use on a heater hose? I'd think it would be too small. I've used the worm-style clamps on that hose and not had a leak. The steel fitting the hose connects to can rust, pit and leak.

I think it is the coolant bypass hose. There is a steel pipe under the front exhaust manifold that it connects to on regular system. In the heavy duty system (towing package) there is a water-to-oil cooler plate/adapter between the block and oil filter.
 

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I don't know if fuel line clamps are available in a large enough diameter to use on a heater hose? I'd think it would be too small...
I never say use a fuel line clamp, what I said was use a fuel line or power steering "type clamp":


Use a spring type clamp or at least a fuel line or power steering type clamp, like this one:
But yes, you can fine almost any size you need, including stainless steel:

57764
 

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Discussion Starter #6
I don't know if fuel line clamps are available in a large enough diameter to use on a heater hose? I'd think it would be too small. I've used the worm-style clamps on that hose and not had a leak. The steel fitting the hose connects to can rust, pit and leak.

I think it is the coolant bypass hose. There is a steel pipe under the front exhaust manifold that it connects to on regular system. In the heavy duty system (towing package) there is a water-to-oil cooler plate/adapter between the block and oil filter.
Thanks for the reply. Is there possibly another name besides "cooler bypass hose" for this part? The online parts websites aren't giving me any hits under that label. Is this generic heater hose you buy by the foot and then clamp at both ends?
So far I haven't been able to "see" the front connection--no way of telling what clamp was used at the front end. When I replaced the upper radiator hose, I had to remove the front brace and disconnect the coolant reservoir to access the front clamp. Any ideas how difficult access will be to the front connection of the coolant bypass hose?
 

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I looked at my 3rd gen yesterday, and saw the hose goes from the lower intake manifold to the top of the water pump/timing cover. It's just a short length of 5/8" heater hose, so easy to get (but hard to replace since the A/C compressor is right in front of it).

That larger clamp pictured is a T-bolt clamp. I've seen those used on turbocharged pressurized intake hoses. Never thought they would be available in a heater hose size, so cool to know.
 
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