Originally Posted by NegroTundra

First time its allowed me to start my own thread!

History: Picked up a 99' Limited, 3.4L Auto, 4x4 w/elocker with 195k miles. Seller wouldnt admit it, but I'm sure he flipped it based on the extensive amount of recent work on it and the title. Anywho, I drove it for about 2k miles without issue, very happy.

Then got the bug: replaced radiator, and a whole list of suspension and steering components, along with MAF, O2 sensors (CA truck), and other things. I'm really only interested in signaling to you that I replaced the radiator, as after that, I could not get my heater very hot. Didnt mind it much as it was summer so thought to myself, deal with it later.

About a month after radiator install (oh, forgot to say - also did upper and lower rad hoses and thermostat at same time), I notice coolant loss. Then, I get stuttering upon a cold start up. Stutters for 5-10 seconds before smoothing out. If I run into the liqour store and come back, starts up smooth. I hit the forums and immediately get the AIDS scare. Is my head gasket going? Do I have a cracked head? Been a few sleepless nights with these burning questions on my mind. No smoke at start up, but a noticeable ~1 inch of coolant loss in reservoir tank every ~2k miles. And what is with the heater still not getting HOT? It's warm, but not like it was prior to rad change.

So, next step is compression test. I'm hoping for the best, really like this rig. Much better than the other two vehicles in our family fleet!

Heres hoping!

Originally Posted by Elan750

When you changed the radiator..
- did you "burp" the lines well?
-Did as much new fluid go in as it went out?
-no thermostat replacement, right?

- Did you disconnect the coolant temperature sensor and forget to connect it back? or damage it? this could tell the thermostat to stay open causing no heat.

A number of above senarios could cause an overheat until the system ends up burping itself, which could cause the coolant leak. But you sound like a person that would notice the temp needle rise....

Originally Posted by TheDurk

Huh? No, it can't. The ECT sensor has NOTHING to do with the opening and closing of the thermostat. That is done by a bi-metal spring built in to the thermostat. Further, even if it did affect it, it would cause no heat if the thermostat stayed CLOSED, not if it stayed open.

Originally Posted by Frdmskr

Jiggle valve in right orientation? Rad cap good?


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Originally Posted by 3rdgensr5

Im currently dealing with this, after hours of diagnosis i have come to the conclusion that i have a cracked head which is fairly common according to the head rebuilder. started with coolant loss, and steam from the exhaust. 280k on the clock, i have a donor motor ready to go and the truck is still driveable. Just need the time to Complete it.

Originally Posted by NegroTundra

12 0 clock, and yes, radiator cap was replaced.

Originally Posted by mtbtim

BTW, jiggle valve should be at the 6 o'clock position pointing down towards the ground. Many members on this forum have reported 10-15 degrees higher coolant temps due to the jiggle valve being in the wrong position. Not that this helps you with your coolant loss issue but it will help you run cooler when you get everything sorted out.

For your coolant system pressure testing, members have reported the below kit is really good.
https://www.amazon.com/gp/product/B0...=ATVPDKIKX0DER

Originally Posted by thegipper

Have you checked your oil to see if it has coolant in it?

Is there any sign that it is just leaking on the ground or burning off on the engine block?

When was the timing belt/water pump replaced last? It could be weeping out of the water pump and burning off on the engine or just leaking down.

It could very well be a head gasket or cracked head but it could also be other things. Definitely do the leak down test.

Keep us posted.