Overheating mystery
Posted: Sun Aug 13, 2006 6:41 am
Hey everyone, I need help with an overheating in my '88 Milano 3.0. Here are the symptoms: I drive it for 15 minutes and the temp gauge progresses up towards 250 deg. F and doesn't stop. Although it's summer here, I have the problem regardless of temperature outside (it was 70 deg F this AM).
Here's what I've done so far: remove the Tom Zat thermostat, run the richest mixture I can (I have Megasquirt), bled the system of air (nose up in the air, opened bleed screw). I even shielded the heater hose by the passenger side header.
Diagnosis-wise, I've done a compression test (185+/-5 all around). I looked at the temperature (infrared temp gun) of the thermostat and it was 235 deg F. The upper rad hose was 205. The "lower" rad hose was 215. The driver side upper part of the radiator was 200-ish. The passenger side was 215-ish. There are no signs of coolant dripping cold or hot. There are no signs of coolant in the oil or oil in the coolant. The spark plugs are slightly carboned over - but I've been running a rich mixture.
The water pump is an IAP unit - 1 year old - no sign of leaking at the bearing. The radiator is a 3.0 radiator, 2 years old. The thermostat was a lower temp Zat unit, but I've pulled it out since having the problem.
The only thing I can think of that I haven't checked is the flow of the waterpump. Any idea how to do that? I'd also like to pressurize the coolant system, but haven't been able to successfully rig up a coolant bottle cap that I can pressurize.
Any suggestions would be most welcomed. The fall track season is just around the corner!
Thanks,
Bill in Maryland, USA
Here's what I've done so far: remove the Tom Zat thermostat, run the richest mixture I can (I have Megasquirt), bled the system of air (nose up in the air, opened bleed screw). I even shielded the heater hose by the passenger side header.
Diagnosis-wise, I've done a compression test (185+/-5 all around). I looked at the temperature (infrared temp gun) of the thermostat and it was 235 deg F. The upper rad hose was 205. The "lower" rad hose was 215. The driver side upper part of the radiator was 200-ish. The passenger side was 215-ish. There are no signs of coolant dripping cold or hot. There are no signs of coolant in the oil or oil in the coolant. The spark plugs are slightly carboned over - but I've been running a rich mixture.
The water pump is an IAP unit - 1 year old - no sign of leaking at the bearing. The radiator is a 3.0 radiator, 2 years old. The thermostat was a lower temp Zat unit, but I've pulled it out since having the problem.
The only thing I can think of that I haven't checked is the flow of the waterpump. Any idea how to do that? I'd also like to pressurize the coolant system, but haven't been able to successfully rig up a coolant bottle cap that I can pressurize.
Any suggestions would be most welcomed. The fall track season is just around the corner!
Thanks,
Bill in Maryland, USA