Coolant Consumption From Were?

[TBK]

Here is a brain twister. I am seeing coolant consumption from my 03 4.0L 4x4 T4R.There are no visible leaks from the main culprits Upper and lower radiator hoses are both in good working order and all hoses that are coming out of the radiator including heater core hoses are also in good working order. So I know that points to a head gasket issue but I am not seeing any white vapor out of the tail pipe. I have replaced the radiator cap and still a slight consumption around 8 to 10oz a week. The water pump also seems dry. And the last thing I have no visible coolant coming from the heat core it's self. Wow that is mouth full, any help will be great not sure were to turn.

Thanks,

 

[chitown40]

Any recent service to the cooling system? It could be possible that you are still burping out air bubbles if you had some recent service done or changed the coolant recently.

 

[TBK]

No I have not had any service done, but when I replaced the radiator cap the reservoir was below the low hash mark but still visible in the reservoir. The day I notice that it was low I filled the reservoir(Toyota long life coolant Toyota radiator cap) and replaced the radiator cap. But your question make me wonder if the system got low and was trying to draw from an empty reservoir maybe some air got in the system. Just a side note I have had no overheating issues.

 

[chitown40]

Fill it up and park the truck nose high and run it without the cap on and the heater valve open. You may want to even jack up the front of the car to get the nose extra high. Watch the see if you get any air bubbles out. when you're done make sure the overflow reservoir was filled to the appropriate level and then keep an eye on it and see what you get.

 

[TBK]

I will try that when get home. I will respond to this thread when I get the results.

Thanks for your help.

 

[Bob J]

You might want to pull your #6 plug and check it for coolant residue.... If you have a head gasket leak that is where most failures are with that engine....

 

[TBK]

I will check that cylinder also.

 

[TBK]

Quick update:

First thing I removed all the spark plugs (It was time to change them any way) And after a carful inspection of all cylinders and old plugs there was no visible leakage. So it looks like the head gasket is still in good shape(feeww) big relief. After that I "burped" the system (elevated the front of the vehicle about 12 to 16 inches and let it run for about 25 minutes with defrost on highest setting) Although I did not see any bubbles escaping this seemed to fix the problem. I drove about 150 miles since the maintenance and have not experienced any coolant loss. Thanks for the help.