I have my reservoir fulling up with exhaust from something, I changed my water pump and timing chain cover. Could the timing chain cover be letting in exhaust into the system? What esle besides the head gasket?
2001 3.0
Thanks Steven

 

Welcome to the forum

With engine cold remove radiator cap
See if there is coolant/water inside
If not top it up with water
Start engine
If coolant/water starts to over flow and then you see bubbles, then you have a blown head gasket or cracked head

You can also do Glove Test, search for it here

A cooling system has no internal pressure when cold, the pressure comes from the coolant heating up and expanding, which takes 5 minutes or so

But each cylinder in an engine has 150psi when cranking and 1,100psi pressure when it fires
If there is a leak from a cylinder into the cooling system then you get INSTANT pressure in the cooling system when engine cranks or starts
This can only come from blown head gasket or cracked head

Metal expands when its heated up, the head gasket allows the head metal and block metal to expand as engine warms up and then contract as engine cools down, quite amazing they last so long in this daily use, lol
But...............if an engine is OVER-heated the head metal expands TOO much, and this will CRUSH a head gasket, so it leaks cylinder pressure into the cooling system
If Head metal expands too much it can also CRACK, and same result, cylinder pressure can get into the cooling system

 

Thanks for the info,
I did top off the radiator, and start it up and ran it for 3 min. before one bubble and it started to over flow.

How This happens after it warms up the coolant ends up pushing into the resevoir, with exhaust pressor and the heat in the truck stops. The heater core runs out of coolant. Then it sort of comes back into heater core and all is fine. The system is low 1/2 gallon. The resevoir stays full.
I turkey base the coolant back into radiator. I changed the cap, the old cap had grease and durt in it. The coolant looks dirty like exhust has run thru it.The oil looks fine, as with the trany oil. I think maybe the head is warped, and the heat. I have had this for 3 years and 70,000 miles with no over heats. 130,000 on it now.

Thanks Steven

 

Cold enginme

Remove either heater hose from the firewall
Refill system until water is coming out hose and core
This flushes air out of the heads
Then see if problem reoccurs

Try by passing the heater core and its valve, bad valve or clogged core can cause overheating
get a coupler and a couple of clamps or just loop the longer hose to the other hoses port

Exhaust can only get into coolant via a cylinder leak, so blown head gasket or cracked head, warped head is a blown head gasket, so that most likely what you have

There is a chemical test for exhaust in coolant, google: Block test

 

I did a new heater core 1 year ago. My old h.c. before it leaked wasn't letting coolant thru it, until after realy heating up. The new heater core did the same thing. No heat until at least 25 min.
I change the two line and that fixed the heater core, I guess the lines to it are directional.I awithc the direction of the two lines. I had a problem burping the air out of the system, so

way to burp heatercore
I removed the thottlebody cooling lines and also the vacuum line valve on the heater core line. (picture supplied)

I have refilled the system with no air in it. It worked for a day, came home and no fill up at all to the reservoir after turning off. Then later same day as I was driving and it over filled the reservoir and no coolant to the heatercore. It ran out of coolant to the heatercore. I pulled over, went under hood opened that valve in picture and it blow out high pressor air.
I have to do a cylinder test I guess.

 

Yes, you have a blown head gasket or cracked head

 

I took out the thermost, and unhooked the heatercore. How safe is this to operate if the head may leak a little? I havnt used yet. I did start it up to get the coolant full, and ran it enough to get top hose to the radiator firm. I guess I will drive and see if it pushes coolant over to the reservoir. The oil looks ok.
Thanks,
steven

 

A working thermostat actually helps cooling, it slows flow thru rad so it can cool off better before it returns

But yes its fine to run that way
If a cylinder is pumping air into the cooling system, the heater bypass and no thermostat may help in getting that air to the top of radiator and then pushed out to overflow tank as bubbles, vs coolant/water being pushed out

New head gasket material usually prevents coolant getting into the oil, but depends on where the gasket fails, there are only a few oil passages between block and head
Cracked head can't let coolant into the oil, no connection

 

I think this is the radiator cap. The first thing I did last week was get a new cap. The very same kind I had. It was filling up the reservoir still. Now when it get very high pressor on the top hose. The cap will throw some over to the reservoir. (normal i think)I rented a block tester with blue fluid and it doesn't turn yellow over the reservoir when it does this.
I need to put the thermostat and heatercore back on.

Why does my heat gauge in dash not work at all unless the heatercore has coolant?
Before with the heatercore hooked up, and this just started doing this. The heat was blowing hot, then it would blow cold. (The coolant level was to low to run thru heatercore) and the gauge in dash would dive to no temp. Now with no heatercore hooked up and no thermostat, it never moves at alllllllll in dash. There is some heat after 2 hours of driving, and good hard pressor on top hose.

 

I bought another cap, and this cap work allot better. (I bought 2 caps.) The first did the same, and the second a diffrent kind seems to work.