mystery coolant leak identified (2 Viewers)

[sean2202]

I have been chasing this mysterious coolant loss for a few thousand miles now. I have been topping off coolant to the overflow tank about every 800 miles. It has'nt been too much but any coolant loss is a concern. I have changed coolant T 's and some hoses and inspected others for leaks. There was some dried coolant on the back of the engine which I thought was the loss of coolant from changing the T 's. Upon further inspection I found that a coolant pipe entering the engine on
drivers side had what looked like sealant
of some kind applied to it(pic 1). I have
read reports of failed castings in the water pump inlet pipe. Anybody hear of that here? Sorry for poor quality pics, hard to get a camera in there.

 

[slimbuddha]

Is this the driver side, rear part of the block? I had the same thing after apparently bumping it when putting the TB back in after replacing the starter. I'll try and find a pic/post.

 

[sean2202]

Is this the driver side, rear part of the block? I had the same thing after apparently bumping it when putting the TB back in after replacing the starter. I'll try and find a pic/post.

Yes drivers side rear.

 

[slimbuddha]

I don't think I ever made a post about it, and can't find the pic, but the part is called the Heater bypass.

I think it is this part #16 Part Number: 1635650120.

 

[2001LC]

Can't see clearly in your picture, what is pipe/tube with open end?

Nice job finding the leak. I've not heard of any known issues with the bypass. Coolant traveling down water pipe from heater hose T could do this, and would be easier fix then R&R the heater bypass.

 

[sean2202]

Thanks @slimbuddha Sounds like this could be a weak part if bumping it could break it. Looks like an all day project.
@2001LC pipe tube in pic 2 is a vent hose I disconected for the bad pic. I replaced these T's and hoses a while back and don't see any leaks there. Like U said that is what I originally thought it was. What concerns meis it looks like someone put a sealant on the hose for a quick fix to sell the truck. I don't see any sealant on the pipe in your picture.

 

[slimbuddha]

No, I don't think there are any sealants on those parts, but I recall the downpipe was the problem. For me, it was definitely this part, I could see the coolant leak specifically on leaking at the base of the downpipe.

 

[sean2202]

@slimbuddha I assume the intake manifold has to be removed for replacement.

 

[2001LC]

Does it look like pipe at point pressed into bypass housing, as slimbuddha's Or gasket between bypass an head?

If pipe this would be a warning to all who change t's or pull intake to use care.

 

[sean2202]

Does it look like pipe at point pressed into bypass housing, as slimbuddha's Or gasket between bypass an head?

If pipe this would be a warning to all who change t's or pull intake to use care.

I believe it is where the pipe is pressed into housing. That is where the sealant was applied. How many people use force in getting the hoses off to replace T 's? I agree with @2000 LC

 

[2001LC]

You may be able to remove "rear water bypass" with intake on, but would be easier with off. Try and get socket wrench on those four nuts first. You'll need to un-bolt & move the black plastic holding wires first.

 

[slimbuddha]

@slimbuddha I assume the intake manifold has to be removed for replacement.

Yes, unfortunately.

 

[sean2202]

Guess I'll do starter contacts when I'm in there as well. What does number 13 in your pic go to in front of engine? I can't see it is just out of 2001lc pic. Now I'm getting paranoid.

 

[slimbuddha]

I believe 13 is the one that goes down the middle of the bank, next to the starter.

 

[sean2202]

I believe 13 is the one that goes down the middle of the bank, next to the starter.

Yes. What does this go to on the front of the engine and is it easily replaceable? If it doesn't break the bank I'll replace it with age and salt exposure here in NE.

 

[slimbuddha]

I don't recall specifically, but based on the diagram, I think it is connected to part 19. If you are going to do all this, and you haven't done it in a while, just add in a full coolant flush as well.

 

[sean2202]

Well I finally got around to replacing this "heater bypass hose" and gaskets. The heater bypass can be removed without removing the intake but is a tough job. The wire harness has to be unbolted to get a little slack and I pryed it towards the back of the truck while removing the bypass. There is also a small vent line held on by three 10mm bolts that can be moved. The nuts on the bypass are 12mm which I used a magnetic socket with a 15 degree wobble on a 10" extension. I found that sealant was applied to the bypass and that the gasket was ripped. Cleaning the gasket surfaces on the block with 1000 wet sandpaper was one of the hardest parts

.

 

[2001LC]

Good job, in a tight hard to reach place.

I may have to do front bypass. By the looks of it I'll be pulling intake. But first Ill verify leak (washed today) then re-torque nuts. Who knows I may get lucky. If not I'll needless do yet one more starter just because I'm in there.

 

[sean2202]

Thanks. Personally I think on older higher mileage rigs that when the starter is repaired or replaced and the intake is off that the gaskets should be replaced on BOTH of these by pass hoses even if they are not leaking. When the intake is off it would be easy PM. As I have seen on other items that age takes its toll.

Also I can not stress enough when repairing those heater T 's to use a heat gun and not to pull on hoses. Someone yanked on this bypass hose at one time as you can see in the picture where it is slightly seperated. Then they tried covering it up with some caulk.

 

[PabloCruise]

Did this solve your coolant loss?

I am losing a small amount of coolant - I have not quantified the loss, but it is leaving the cooling system. No drips on the ground when parked. Exhaust does not smell like coolant. Oil does not have coolant in it.

If I am pulling intake, might as well deal with starter while in there - either contacts or replace...