I have an 87 4X4 with 163k on it. I bought it 3 years ago, and replaced the radiator. I have recently flushed the cooling system, replaced the t stat, and coolant. In the last few days I noticed the heater not working as well as before. The PO had alot of stop leak in the system due to the bad radiator I replaced when I bought the truck.

I'm wondering if the stop leak was stopping a head gasket leak as well? I'm losing about a pint of coolant a day give or take how much I drive. The truck doesn't run hot, and the gauge never gets half way between c and h. IS the head gasket going or is the heater core clogged or leaking? I looked under the pass floor mat and it's wet, but I don't think it's coolant.

Any ideas on this would be greatly appreciated..

GO HAWKS!!!!!

 

sounds like you have a leak or clog in the heater lines somewhere, its also possible your water pump is leaking after you flushed the stop leak out,

 

How do i Check the water pump?

 

Not sure about the location on your truck but its likely under the timing cover. Check for any weeping.

 

should have asked earlier but is there any coolant on the ground from around the engine?

 

That's a big negative, no coolant on the ground ever. I'm suspecting the head gasket is starting to go. I'll check the heater lines tomorrow, but I never smell coolant in the cab. The WP is behind the radiator on my rig I'll look for any leaks as well. It's just weird though the truck doesn't get hot,,,, Yet

 

Also the radiator is full I just drove it, and the heat is hot at first then fades to luke warm??

 

The low heat could be a clog in the heater core (gets hot but then flow is restricted, cooling it down) or your t-stat might be rated for too high of temperature. Did you use a 180 or 195 degree t-stat?

Also, you won't notice coolant on the ground unless you water pump has already failed (which it hasn't). Mine is going currently, you'll just notice coolant residue seeping out from the bottom of the timing cover on the front of the engine block. Look from below and you'll notice it if it is leaking.

 

Have you checked the oil to make sure there is no coolant in there? Also any steam from the exhaust?

 

disconnect the hoses to the core and just try to flush it out with a hose. see if it helps. back and forth. do it until the water is clean both ways.