I've got a 99 durango with a 5.2L. The temp had been going up pretty high and then dropping back down to normal. Went to flush the cooling system and ended up breaking off a t-stat bolt. Long story short, I left water in the engine and it froze, blew out a freeze plug, and now all put back together the engine overheats pretty easily under driving conditions. With the radiator cap off, coolant slowly pushes out of the radiator, when I raise the RPM and the stat opens it seems to randomly shoot air out in spurts. Sound like cracked/warped head or cracked block? Or is there something simple I could be missing? Looking for some steps to take from here. Thanks.

First, it could be a airlock in the system.

Second, I would doubt a bad head gasket. If a head gasket anti-freeze would be in the oil or exhaust.

Third, T-stat could be bad.

Forth, water pump could be going out.

Lets try the cost efficient way first.

I don't think it's air, ran it for quite awhile with the cap off....any other way to cure an airlock situation? I put in a new stat. When I run it and let it get to temp, and pull of the radiator cap, there is an awful lot of pressure while it's running. What is the quickest way to check the water pump?

I am not sure on how to check a pump. The pump runs through the block so I cant seethe pressure test.

Did you check the T-stat before installation?

Did the T-stat have a bleeder on the side?

Turn on the heater to Hi to get any air lock out of the core.

Other than this I would go to the pump.

Does the t stat housing have a bleed hole?

Mr. I went through it recently. My crack in my head gasket was very small and it took a while for the oil and water to mix. Do whatever hydra suggest, but do not rule out that gasket. It cost me $1,304.83 in parts b/c I tried everything before I did the tear down to replace the gasket.

Ang :)

MDL:

First off, the earlier 5.2/5.9 motors were known for head gasket/cracking issues. That being said, when you had that freeze plug pop, not telling what other damage maye have occurred before it popped.

BTW, when you top off a cooling system after maintenance, there will be air in the system and some systems take more time than others to purge the air.

The coolant spurting or gushing out during that process is not uncommon. You will also want to run the rpms up to 1.5-2k several times during this process as it helps get the air out and get the engine up to temp.

Does the engine run rough or miss at all?? Usually when a head gasket is blown, that is a common sign. If the coolant is leaking into a cylinder in a significant amount, you will see lots of "smoke" from the tail pipe which is really water vapor. In this case, the engine will certainly run rough.

Cross your fingers and check things as thoroughly as you can.

Don

Don, I had the smoke with mine and an over powering coolant smell, but she ran like she always has, a dream.

Ang :)

Ang:

Sometimes the leak is very minor, and the vehicle will still run pretty good. Obviously the engine was not made to combust water, so this is not a good thing long term.

They can run a test that looks for combustion gases in the coolant, orpressurize the cooling system and see if it holds. They can also run a compression test if they do not think the leak involves the cooling system.

Don

Don, we did both of those and in both cases the test came back and said their was no problem. Combustion test ran fine and showed no carbon in my system. Pressure held fine with the pressure test even after an hour and a half. It took my engine quite a while before the water began to show in the oil and that's when we knew the extent of the problem. We finally tore it down and sure enough, there was a hair line crack in one of the head gaskets. Apparently the problem was coming in when the engine would get hot and we all know heat makes things expand, thus when the gasket and heads expanded under the heat of the engine the crack would open up and let the water in. I spent a boat load of money on my D, but she's in good shape now, just a little exhaust leak that developed last week and we'll get that fixed soon.

Ang :)

ORIGINAL: ghoghunter

Does the t stat housing have a bleed hole?

If you look at the picture on the upper side of the T-stat seal plate on the right upper side. It is hidden but you can se a piece of medal sticking up. That is a piece of medal is sticking througha hole that seals the hole when pressure is applied (water pump pressurizes). But when there is no pressure the small medal plug falls down and allows any air that might be trapped between the manifold and the T-stat neck to be released.

Some people drill a small hole in the seal plate to allow air out. I don't recommend this. You can just buy it with the bleeder.

As for the head issue; Yes there is a problem with the 52L/5.9L heads cracking. This is due to the old castings that Dodge continued to use on these motors. Problem is these head casts were made way back when and they used 180 degree T-stats. Well the same molds were in use for todays. Problem is they run 195 degree T-stats for emissions. They just don't hold up running that kind of temps that they were not meant for. Thiswas oneof the reasons for the Hemi.

Anyway test a T-stat before installation. Use a pot of water and a thermometer and make sure it opens when they are supposed too. Do not over heat them because the spring can relax causing issues.


local://upfiles/17201/20365F84644048B987AC47EDEFC74D2A.jpg

ORIGINAL: hydrashocker


If you look at the picture on the upper side of the T-stat seal plate on the right upper side. It is hidden but you can se a piece of medal sticking up. That is a piece of medal is sticking througha hole that seals the hole when pressure is applied (water pump pressurizes). But when there is no pressure the small medal plug falls down and allows any air that might be trapped between the manifold and the T-stat neck to be released.

local://upfiles/17201/20365F84644048B987AC47EDEFC74D2A.jpg


Hydra, I'm going to add a little to this if you don't mind. If you replace that thermostat, do not buy one from autozone. We did and the medal piece hydra is referring to is not on their stats. However, they do have the correct stats for a couple of bucks more at O'reilly's.

Ang :)

Ya, you need to look at em.

I really prefer these over the others. The 5.2L/5.9L do not have a bleeder on the side of the housing so it helps out great bleeding the system.