Int'l Straight Truck DT466 Coolant issue

mbalbritton

mbalbritton

#@$%!
Joined
Mar 22, 2005
Location
Lakeland, FL
Having a coolant pressure issue with our Box Truck. After just a 1 mile drive, coolant will be foaming our of the reservoir cap/radiator cap. Things I've found online so far:

Thermostat
Radiator Cap
EGR
Air Compressor pressurizing the system
Combustion gases getting into Cooling system

Anyone run into this before? This is the second time it's been in the shop. First time they replaced the Radiator Cap and put a high pressure oil pump in it.
 
Radiator cap is gonna be the cheapest and easiest fix, thermostats next. Is the coolant clean or is there trash in it? Is the exhaust smoke white while under throttle? You could have a bad radiator, back flow it to clean trash out of it. Is your fan kicking on when it starts to warm up? If you're in Trinity I can recommend you a couple mechanics to try if your guy can't figure it out.
 
Head gasket or cracked head could also be a possibility.
 
checking the oil and fill points for residue might help.....but a pressure check of the system would narrow it down rather well. Aeration is most likely going to be an outside pressure source like combustion chamber or egr cooling. I'd replace the cheap cap, then pressure test. A blocked t-stat should cause over heating before pressure relief.
 
Cap has been replaced
Coolant looks clean looking, bright green and clear.
No white smoke in exhaust.
Engine doesn’t even get up to temp before this starts happening. This makes me think that pressure is being pumped into the system from somewhere, or it’s not able to bleed off that pressure.
 
My bet is on the compressor pumping pressure into the cooling system.
 
Air compressor would be the first thing to check, next would be a head or injector cup problem.
 
jeepinmatt said:
Head gasket or cracked head could also be a possibility.
Click to expand...
My First guess, too. Head gasket. Diesel truck I was driving, kept pumping out water. Shop put a pump up gauge on the radiator, with no pressure. Cranked it up, & watched the gauge slowly build. Shut it down at 20psi. Was head gasket. And we've had 2 other trucks do the same over a 3 year period. Somewhat common.
 
That is how we would check for a bad compressor, first we would see how fast it built pressure with the compressor hooked up then disable the compressor and test again to see if it slowed down. If it didn’t it was time to go deeper.
 
My personal favorite method for checking for a head gasket leaking between combustion chamber & coolant passages on a gas motor is a leak down test with compressed air while the motor is still hot (and cold). Not sure how one would rig that up in a diesel, but given that the pressure is higher if you have eliminated the alternate sources and still build pressure with a coolant system pressure tester, It's pretty much got to be the head/gasket.
 
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