My wife and I purchased a used 2001 Allegro Bus with the 330 Cat engine. We took it out on a shakendown run today. It was about 95 degrees out and we had the dash air going full blast. We were travelling about 65 to 70 mph when I noticed the engine was getting very hot. Turned the dash air off and slowed down to about 50 and it cooled off very fast. Is this normal for this to happen? Does the dash air cause this to happen? Do we just need to run the roof air and forget about the dash air? Have read here about turning dash air off on long inclines but we were on a very flat road.
Newbie question on engine
- Thread starter Xsailor
- Start date
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Gary RV_Wizard
Site Team
The dash air adds to the engine cooling load because the a/c heat exchanger is in series with the engine radiator. However, it should not cause overheating in the circumstances you describe so it is not "normal". Unfortunately, it is also a fairly common complaint in a rear radiator design like yours. I would guess you have a dirty radiator and need to squirt it well with a degreaser and hose it down. Cooling air blows over your engine, which heats it up and picks up oily residue from the crankcase "slobber tube" and then blows into the radiator, where it then collects road dirt until the air flow through the radiator decreases.
If that doesn't fix it, look for a clogged coolant filter or weak water pump or maybe even an internally clogged radiator (unlikely).
If that doesn't fix it, look for a clogged coolant filter or weak water pump or maybe even an internally clogged radiator (unlikely).
wagon217
Active member
RV Roamer said:
Good bit of information...Cat engines and their slobber tube is famous for affecting cooling problems in rear mounted radiators. Once you get it cleaned up what many cat owners have done is extend the slobber tube so that any oil is NOT picked up by the fan.
Good Luck
