240 Car overheating, new water pump, radiator and thermostat

VolvoPunch said:

The car is a 91 Volvo 240 with a 91 940 Turbo B230FT block and head. It's using MegaSquirt 2 and I'm able to use both the dash gauge and the MS coolant gauge to judge the temps. Yes the car is over heating, I have tried three different thermostats two new, one used. I install them with the air bleeder valve facing up. You cannot install these thermostats backwards. I burped the system several times and I made sure the squeeze the top house many times before starting the engine. I'm going to try one more thermostat and see if I get any results.

Click to expand...

*if* all of the "tests" you've done are results as reported - you have to consider the
WATER PUMP... (and I say this w/trepidation for knowing there may be a gasket issue
in the head)....
if the following are TRUE (it is the next logical step):
heater core flows clean and clear volume output equals input
radiator flows clean and clear and volume output equals input
with system CLOSED *SANS* TStat temps "in and out of RADIATOR follow (or "track"
the engine temp) at least CONVECTION CURRENTS are working in the engine...this
scenario VERIFIED by "infrared / non-contact THERMOMETER" scanning the block, etc...
*then* to only remaining player is the PUMP ITSELF

Volvo pumps are NOT *positive displacement* pumps..they are "turbines" and CAN AND WILL
CAVITATE if given half a chance - I have had THREE waterpumps in my career do this...
two of them due to INCORRECT IMPELLER DIAMETER (thus allowing the coolant to "step
aside" at the vanes passing and essentially NOT MOVE)...the third was due to a corroded
BLOCK that just didn't have the "correct CLEARANCE" anymore...
what BRAND of water pump did you install??
what PRESSURE CAP do you have installed??
have you read any SYSTEM PRESSURE with the engine running *HOT*??

the above are all ASSUMPTIONS (and LAWD KNOWS I HATES ME SOME ASSUMPTIONS)
but from what you've reported and what I've gleaned from that reportage is the "direction
I would take my investigations"....

As a few others have mentioned 190 is not overheating. In fact, your thermostat is probably set to open at 192.

Overheating to coolant bubbling out would be in the 225-235 range, with no damage to anything, and once you get into the 40's and 50's expect some problems.

190 though, that's operating temp.

I know I'm bumping this old thread, but have you figured out what was the problem?
I have these exact symptoms, except i haven't changed anything in it since summer, when it was working well. I drained the weak mixture in fall, and now as snow season comes I wanted to get it up running... I'm thinking it is either a sludge somewhere or a failing pump, but im not sure.
I'll do a system reflush with clean water, and report back.

After trying and resolving all the above mentioned issues I took the radiator to an old time radiator shop. The bottom half of the radiator was not functional because the right tank was filled with junk to the point that only the top half functioned. The stuff was too big to pass through the cooling tubes and did not flush out with a hose out of the car.