hose above waterpump

[lb7lbz]

i have a 01 duramax with close to 200000 miles i am experiencing a coolant loss. i believe it is coming from the short piece of hose just above the waterpump. i replaced the pump at 105000 miles and by the way the antifreeze is showing up it looks like the hose. i just wanted to ask you guys if this is a common problem and if there is an easy way to replace it, dosnt look easy to get at.

[chipper]

Mine broke at about 69K. Don't cut the new hose too long & use plenty of grease. Its a PITA & yes, plenty are breaking. The heat from the block cooks them. It helps if you lay the AC to one side.

[BradL07]

I had that hose replaced on my '01 LB7 when the water pump was replaced under warranty.

What purpose does that hose serve?

[chipper]

I believe it is the coolant thermostat by-pass to allow hot water to flow to the heater before the thermostat opens.

[DmaxMaverick]

The hose is for the turbo coolant return. Failure isn't common, but I think it is more common than it appears. A slow leak won't show because the coolant gets vapored off before it hits the ground. My 01 leaked for a long time before I noticed it, evident by the coolant stain trail. Finally got bad enough to drip. Coolant loss was low enough to discount it. If it weren't for the slime buildup around the hose, I'd have never found the leak. Originally, I thought it was corrosion of the pipe, but the pipe was fine once I cleaned it up.

Anyway, it can be replaced easily without removing much. I did mine twice (hose/clamp replacement, then clamp replacement), once at an RV park. You can get to it by removing the belt, idler pulley and oil filler pipe. It's tricky, but can be done if you have decent dexterity. It would be much easier to access if the fan pulley was removed, but I couldn't make sense of the time needed. The hose needs to be long enough to accept the clamps on the tubing inside the nipple swells. I cut the hose longer, suspecting I'd have to double-clamp it later (I did...hence the RV park repair). The small clamps just don't grab tight enough, and 2 (on each nipple) were necessary. There's not enough room under the fan pulley for large constant tension clamps. The OEM spring clamps don't fit the aftermarket hose I got (thicker), so that wasn't an option. I suggest using the OEM clamps if possible. They will not clamp as tight initially as the screw types, but won't loosen later. The hose can be had at the dealer, but the cost was the same as 20' of 3/8" coolant hose, and it had to be special ordered. I wasn't too impressed with the OEM hose, and replacing it with the same thing will yield the same result. The hose developed pin holes around the circumference at the nipple swell. 8 holes, equally spaced around the hose (???). The hose I replaced it with is high temp coolant hose, and should do as well or better. As long as I can keep it clamped down.

[jbplock]

The hose is for the turbo coolant return ... 3/8" coolant hose... The hose I replaced it with is high temp coolant hose, and should do as well or better ...

Dm,

Thanks .. good info ... I have some Gates 3/8" coolant hose left over from the coolant filter install ... I'll put a piece in the tool box - just in case ;)

Seems like this might also be worth the extra cost for a piece of Silicone coolant hose ...

:)

[DmaxMaverick]

Dm,

Thanks .. good info ... I have some Gates 3/8" coolant hose left over from the coolant filter install ... I'll put a piece in the tool box - just in case ;)

Seems like this might also be worth the extra cost for a piece of Silicone coolant hose ...

:)

I thought about the silicone, but couldn't get any in time (not locally available). It would be ideal, considering the location. Don't forget some clamps! The OEM's won't fit the 3/8" hose.

Cost isn't the problem. I'd have paid for the OEM, but didn't feel too confident, seeing the previous result. Silicone would be fine at twice the price, but it has to work. Silicone isn't that expensive, and were only talking about 3". It would have to be reinforced and fairly rigid (for sili). There's no room for it to baloon under heat/pressure. Only about 1/4" between the hose and pulley edge. Know a good supplier of sili hose??? Could be worth picking up a roll to share among the members.

The tubing is metric, thus is the hose. 5/16" is a little small. 3/8" is a little large, but the larger hose makes it possible to get it on w/o removing everything. Problem is, if replacing the hose w/o removing the pulley and return pipe, a "just right" hose would be nearly impossible to install. Silicone hose would be much more flexible, so it could be do-able. I'll try it when I can keep the truck down long enough. The function is simple.....all it has to do is not leak. I have the old hose, so I'll do some measuring and see what's out there. I couldn't get my calipers onto the pipe (no room), so I didn't measure it. Had a brain fart at the time, and didn't think to use an end wrench (duh).

[lb7lbz]

replaced the hose last thurs. removed belt,oil fill pipe,tensioner,a/c pump,2 idler pulleys,and the whole bracket that holds the alt. on (4 bolts, 2 clamp bolts) this allowed easy access. also removed bolt so i could move the metal line around a little longer to take apart but no frustration. all is well no leaks 197500 miles