Some of you may remember the 99 Avenger my Grandmother gave me with a blown headgasket. 2 months and a few hundred dollars later,... the car will drive fine and usually stay around normal temp. If you get on it at all or drive for an extended period of time the temp will go up and the heater will stop blowing out hot air.

List of parts replaced:
Headgasket
Timing belt plus bearings
Water pump
Thermostat and of course coolant.

The car has plenty of power, so I dont think its the headgasket again. I noticed it was building up excess pressure in the cooling system though. After a while of driving and being shut off the overflow tank was pushing out air. It wasnt pushing coolant out, it was just bubbling for probably 10 mins after being shut off.

The only thing I have left to check is the radiator. Some jackass that owned the car before tried to fix a blown headgasket and coolant leak with that stop leak bullshit from autozone. The inside of the blocks coolant passageways and the thermostat were caked with a white powdery substance and Im wondering if that shit clogged up the radiator and is making it hard to cool.

At this point, is there any way to check and see if its something small or if its catastrophic? Im not pulling the head again, if it comes to that Ill either just sell the car for a few hundred or scrap it. Any help/advice is greatly appreciated.

Wish I knew what to tell you. I'm hunting the same problem with Malachi, but his heater works the entire time (which is what I've been using to keep him from overheating)

Here's my little check list;

Leak in the cooling system;
Look for the easy obvious; signs of leakeage. Puddles on the ground. Lots of coolant on the tranny/backside of engine (pesky heater hoses)

Cooling fans;
Sit at idle to see if the fan comes on (duh). If they don't, you may have to rev it up a couple o' few of times to get heat going. Of course, watch the gauge as you do it.

Thermostat;
Pull thermostat and check it by boiling it in water and seeing if it opens fully (though most just replace it. Cheap and easy flip flop).

Radiator cap;
Have the radiator cap pressure tested (though, like the thermostat, most just replace it),

Radiator;
Look for obvious signs of rust and green/white flake build up on the exterior (usually located on the lower half). See if fins are just flaking off. Look for "wet spots". Pull radiator and have it pressure tested.

Blockage in the cooling system;
Flush the cooling system seperately (radiator then engine side) to check for blockage.

Water pump;
Check for signs of "weepage" under the water pump. Listen for grinding or squeaking (usually a chirping sound) coming from water pump. Look in the radiator cap opening and see if the coolant is actually moving (obviously, do this when engine is cold).

Headgasket;
Comp check and leak down. Look for oil contanimation or oil levels filling themselves up, lol. Look for air bubbles in the coolant as well as hardening of the coolant lines(pressurizing from the headgasket allowing combustion chamber pressure in the cooling system). Look for white smoke out of the exhaust after warm up. Check for hydrocarbons in the coolant (though this all could be good, but you could still have a bad headgasket. That's the tricky part).

.....and the etc. is for whatever I forgot/missed

If the coolant is bubbling in the overflow you have overheated the car regardless of what the gauge says. Do all the checks Mark Gave you and get a new set of temp sending units in it.

My advice after you do what Mark said is to pull the water pipe off the block and see if the water pump impeller is still there or attached to the water pump shaft.

The heater stops blowing hot air becuase you are getting air in the system. Chances are your looking at a warped head or cracked head.

Originally posted by Star Turbo Talon
Chances are your looking at a warped head or cracked head.

I didn't want to burst his bubble right off the bat, but this is a strong suspicion to me. In his list of items, he did not list "decked head". That's something I always do with an overheat.

A current example would be the 98 GS I just picked up. Bad headgasket and the owner said they, "pulled over just as soon as they noticed the temp going up" ("and it never went ALL the way up. Only 3/4").

Yeah right. We shaved .013 off it to make it flat! I also ended up throwing out all the componentry in the head (cams, lifters, rockers etc.).

Keep in mind that many don't notice the car is overheating until the engine actually let's them know. By then it has been doing it for a while. On any overheat, I have the head flattened.

But be sure you check out the other stuff first. Bottom line is that you are losing coolant. The question is where?

Originally posted by bullettdsm

Originally posted by Star Turbo Talon Chances are your looking at a warped head or cracked head.

I didn't want to burst his bubble right off the bat, but this is a strong suspicion to me. In his list of items, he did not list "decked head". That's something I always do with an overheat. A current example would be the 98 GS I just picked up. Bad headgasket and the owner said they, "pulled over just as soon as they noticed the temp going up" ("and it never went ALL the way up. Only 3/4"). Yeah right. We shaved .013 off it to make it flat! I also ended up throwing out all the componentry in the head (cams, lifters, rockers etc.). Keep in mind that many don't notice the car is overheating until the engine actually let's them know. By then it has been doing it for a while. On any overheat, I have the head flattened. But be sure you check out the other stuff first. Bottom line is that you are losing coolant. The question is where?

Damn, bullet you got another 2g, all you need is a 1995 make a complete set.

Good thread and tips.

Originally posted by dalesmitsu
Damn, bullet you got another 2g, all you need is a 1995 make a complete set.

Lol, I just realized, you're right. The 98 fills my inside straight :P

I can't imagine getting a 95 at any point, though. Just don't want to ever deal with the "questionable" ECU situation.

But the 98 is going to my kid's fiance/girlfriend. Pretty clean full stocker. She cleaned up really nice. Engine bay close to original looking.

Of course, the fiance/girlfriend lives here with my kid, and he's the one that own the 99 OZ. So we'll still have a little 420a family in the driveway; 97, 98, 99 (plus the GSX) :thumbsup

ill third the head warpage.

mine was never overheated to my knowledge but i had to shave .009 when the head was done to get it in true.. removing the head bolts too hastily can cause a warped aluminum head also.

comp/leak down test will tell you right away.

good luck

I`m going to be a little more optomistic. I had the same problem a year ago and the problem was two-fold. First, my radiator was half clogged. A mechanic checked it with a gun. The second problem was the fan. The fan did spin, but a half the speed it should have, so it was fine idling and during short trips, but it wasn`t enough for long trips. But definately look for leaks. Sometimes you need to really get in there and look.

Finally got it fixed, stop-leak-ridden radiator was the problem. Noticed a drastic improvement in flow even in filling it up. Hasnt overheated or built up cooling system pressure since the install.