First, I absolutely SCOURED the internet and read up on everything and anything I could regarding the symptoms my 1999 GTP has. I could not find anyone with the same combination of symptoms as my car. I have only had this car for a few weeks, and I immediately went through basic maintenance.
Me: I am reasonably mechanically inclined, but I am not a certified tech, so there are definitely holes in my knowledge and ability.
The Car: 1999 GTP with 188k miles, bone stock except a 180 T-stat I put in. I bought it 3 weeks ago, so history is a mystery. It has a upper-end ticking noise at startup that goes away within one minute. I’m thinking lifter/tappet oil drain on that.
Here is the spread of symptoms that are keeping me up at night (maybe related?):
Smell of hot coolant under hood when warmed up (no visible leaks or puddles)
Engine runs hotter than I think is normal, especially with a 180 T-stat. It usually stays steady at 2-3 marks below the 210 line on the dummy gauge, though it climbs above that if I drive up long hills in 90 degree+ weather. I had to turn around and head downhill the other day because the temp got too high for comfort (3 marks above the 210 mark on the dummy gauge, I stopped and turned the engine off and opened the hood to help it cool. When the engine was off I could hear boiling coolant in the overflow). That night I tested the cooling ability by running the engine at 3000 RPM in park for a few minutes. The fans come on at about the 210 mark, but if I keep the RPM at 3000, it seems like even the fans are insufficient to bring the temp back down while stationary or uphill at low speed. The temp kept climbing until I stopped my test when the gauge reached 2 marks above 210 and rising. So yesterday I flushed the whole cooling system (ran the car for about 30 minutes with the heater blasting, feeding water into the radiator and letting it drain out the plug at the bottom, occasionally revving it), I drained the water, and put in fresh coolant, a new 180 t-stat and radiator cap, took a 20 minute drive and bled the air out through the valve on the t-stat housing. I have re-bled it a few times with the engine hot, and there is NO AIR. Radiator level under the cap looks good. I tested the cooling ability again today, but got the same results. The engine can’t cool itself under load without significant airflow.
So my worries are the following:
Lower intake Manifold Gasket?
Head Gasket?
Water Pump?
Clogged CAT?
Here are some of the other tests I have done so far:
Oil level looks good, and is clear. No “milkshake” look from coolant in the oil
Exhaust is clear and smells normal. No noticeable coolant burn smell or white smoke
Took the radiator cap off and checked for bubble while running, there were none
Checked the cooling system for pressure first thing in the morning. There was no pressure
No hint of oil in the coolant that I can see
Heater in the car blows good and hot when the engine is warmed up
Other than the cooling issue and the mild startup tick, it starts up and runs smooth.
To help eliminate head gaskets as suspect, I am going to compression test tonight.
So what do you think? Am I expecting too much of this car wanting it to go up hills during the summer? What about the smell? Without the presence of coolant in the oil and exhaust, could the intake manifold or head gaskets still be suspect?
Also, what are some of the other symptoms of a clogged cat? If the water pump is quiet and not leaking, can I assume its ok?
