[Vwdiesel] Quantum questions?

[Val Christian]

With the car at temp, pulled over and running, with the fan on (use AC
to force that), check the radiator inlet and outlet temps with a passive
IR radiometer ("laser thermometer").  If the outlet of the radiator is 
above 150 to 160, you probably have a restricted cooling radiator.

You might try looking into the radiator ("Seasnake by Rigid") and seeing 
how much corosion there is there.  

A radiator flush _might_ help.

If the cooling water is restricted through the radiator, then the pump 
will be unable to move sufficient quantities of water, and it will 
excessively heat in the engine, and "bump", where it boils.  My guess
is that this might be happening.    What's the history?

Obviously, if this occurs severely and often, you are at some risk for
having the cyl head gasket fail.



> 
> My Quantum TD is still loosing water & then overheating. Stop leak hasn't helped. The water loss seems to come from the coolant expansion tank which is now cracked. Suspecting a leaky head gasket, I bought a testing device at our local Napa Auto parts store. It works by pulling any exhaust gas that may have entered the cooling system into a device you put on the hole where the "radiator cap" screws onto the expansion tank. If any exhaust gas is present it is supposed to change the blue color of the test liquid you poor into the cap you place on top of the cap hole from a bright blue to yellow green for diesels & yellow for gas engines. Mine stayed a bright blue suggesting the problem is something else The prior owner said he took it to a local garage & were unable to diagnose the problem, which he said happens on mountain grades & hot weather. Temperature this afternoon was about 90 F. I think this is why he gave up on the Quantum. I wonder if a sticky thermostat or partia!
 lly
>   plugged radiator could be the cause? Something else?  When pressure builds up in the cooling system, shouldn't the expansion tank coolant cap release the pressure? I just put on a new one. 
> I also say what looked like a leak from the rear of the injection pump with the engine warm & ideling. Will check to see if everything is tight . Anything I should check for?
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