Leaking thermostat housing

[Larryjb]

It looks like the water pump and thermostat were replaced recently by the previous owner, and the thermostat housing is already leaking. I strongly suspect it was replaced with non-ACDelco parts. That is the case mostly, when parts are replaced at local garages in Canada. Usually the aftermarket parts up here are priced close to or above the price of ACDelco parts if I got them in the US. This thing can't have been in there for more than a couple of years, and now I've got to tear into it myself. I'll be putting in ACDelco parts. While it's open, I might as well change out the water pump, upper and lower rad hoses, heater hoses, and the one to the throttle body.

What a pain in the caboose.

I've had lots of bad luck with aftermarket parts. I'm posting this as a reminder to not go cheap on parts.

 

[Larryjb]

And just today the AC tensioner literally broke off.

 

[Larryjb]

FYI: The broken AC tensioner looks nothing like the ACDelco ones. This, too, was a replacement part. Visually it looks closest to a Dayco, except that where ACDelco has a series of 14 lines on the cast aluminum part holding the pulley itself, Dayco has what looks like a single arrow. This one has "2" stamped in that location. This could be a cheap copy of Dayco. There may be evidence of "compressor slugging" on the casting ( https://www.gates.com/~/media/files...h-tips-and-tsbs/38159_compressor-slugging.pdf )

I don't think this tensioner was as cheap as a Dorman, but not as much as the ACDelco original.

 

[Larryjb]

Thermostat was old style with the replaceable thermostat in the housing. The gasket was compressed and no longer sealing. I suspect the previous owner's mechanic just replaced the thermostat without replacing the gasket. Those gaskets have very little compressible material. Once it's squashed, it need replacing.

 

[Tonyrodz]

FYI: The broken AC tensioner looks nothing like the ACDelco ones. This, too, was a replacement part. Visually it looks closest to a Dayco, except that where ACDelco has a series of 14 lines on the cast aluminum part holding the pulley itself, Dayco has what looks like a single arrow. This one has "2" stamped in that location. This could be a cheap copy of Dayco. There may be evidence of "compressor slugging" on the casting ( https://www.gates.com/~/media/files...h-tips-and-tsbs/38159_compressor-slugging.pdf )

I don't think this tensioner was as cheap as a Dorman, but not as much as the ACDelco original.

There's no fix for the slugging? Just replacement I'm assuming? I've never heard of this before.

 

[Larryjb]

This was the first time I'd heard of slugging.

My AC compressor was making the same sounds today. The coolant leak was right above the tensioner and compressor. I'm wondering if coolant got into the compressor clutch plates and damaged the clutches? If so, the clutch plates may be slipping when accelerating, causing the tensioner to "bounce", which would be the evidence of slugging.

Anyone else have a coolant leak damage the AC clutch plates?

 

[Larryjb]

New thermostat housing is leaking too. I've read elsewhere that if sealant might be necessary for this. Frustrating

 

[Tonyrodz]

New thermostat housing is leaking too. I've read elsewhere that if sealant might be necessary for this. Frustrating

I hate doing jobs twice.

 

[ScottyBoy]

I suffered from the "slugging" issue on mine. I read all the service bulletins about it and my truck was pretty much doing those exact symptoms. At idle, my AC was working just fine and cooling my truck very well. But once the RPMs got above 2000-2500, the compressor started locking up really hard and yanking the belt off. I broke one belt tensioner so I replaced the tensioner and the belt. The cheap ass belt broke, so I put my old Goodyear Gatorback belt back on, and then the tensioner broke AGAIN. I ended up breaking 5 belt tensioners all together. The last one was a brand new AC Delco tensioner, and by that time I was pretty pissed and I finally accepted the fact that I did indeed need a new compressor if it was slugging that bad.
I just removed the AC belt until I could save up the money to get the compressor replaced. I replaced the compressor with a brand new AC Delco unit from Rockauto, along with a new Delco drier, orifice tube, and new belts and tensioners while I was at it.
And speaking of the water pump, I had to redo my water pump as well. I replaced it with an aftermarket pump a little over a year prior and it was already seeping coolant from the weep hole. But I was putting off replacing it because I knew I had to replace the compressor as well, so I planned on doing them both at the same time. And I will tell you this, the AC compressor is a HELL of a lot easier to get to with the water pump removed!! Every repair manual said to go it from the passenger side wheel well. But with the fan and water pump off, it was VERY easy to get to from the front and underneath. I didn't have to even remove the wheel and go from the side at all.

 

[Larryjb]

The slugging began at the same time my thermostat housing started leaking. I didn't know about it at the time as I could never see it leaking. It turns out it's been leaking right over the compressor clutch. I am suspecting that the slugging is a result of coolant causing the clutch plates to slip just enough to bounce the belt around and slug the tensioner. Or the coolant split on the pulley is causing the belt to slip, causing slugging. I could be wrong on this, and there may be no other choice but to replace the compressor.

As of now, the leak has been worse, and when I removed the thermostat housing to change it, a while pile of coolant spilled over the clutch. I should have tied a plastic bag over the compressor clutch area, but I didn't think that far ahead. Now that the leak is worse, the slugging is worse. Much worse.

Once I fix the coolant leak, I'll clean off the pulley as well as possible. I'm not sure what, if anything, I can do for the clutch. It may be that the internals of the compressor are toast too.