Originally Posted by Phair
We are traveling with an old Chevy 454, on a 28' motorhome from 1991. Since Texas with more than 90° a lot of wind and some steep climb (NM, Colorado, Utah) the engine is overheating ... We removed the AC (which was not working) and added two fans (with a switch), and even like that it's still overheating.
So our 2nd guess was the fan clutch which was changed last year (around 6,000 miles ago), and even when the engine is hot, it seems to run freely ...
My questions are :
* Is it possible that the fan clutch broke that fast ?
* What is a correct speed/RPM when climbing ?
1. When climbing grade did you hear the 'loud roar' from the clutch fan being engaged?
2. Do you have the (OEM) fan shroud in place?
3. When is the last time you cleaned out the exterior radiator?
4. Radiator fins in decent order (not overly tweaked or bent out of shape)?
5. When did you last service the radiator?
6. The trans cooler can be flushed without unbolting it. It will generally be mounted in front of the AC condenser off to one side (small radiator looking).
7. The clutch fan is engaged bi a small copper bi metallic coil on the front side of the clutch fan (dead center). It begins to engage
when the 'radiator discharge air' temp
reaches roughly 150-190F. Radiator discharge air temp is the temperature of the air that has flowed thru the radiator.
8. To make veering behind the AC condenser a lot easier get one of these...
9. When the engine is stone cold can you freewheel spin the clutch fan? If so, how many turns does it spin? If it freewheels easily and spins many times it is shot. Only use a GM one.
10. Check and make sure the AC condenser fan is working correctly. Wire it straight to battery. It should spin. Also check to make sure the sensor (single wire) for it is plugged in. It is mounted into the passenger side cylinder head. That fan serves more than just the AC condenser cooling. The large condenser is a 2 piece unit (AC cond./Oil cooler). The condenser fan will kick on when wired when the coolant temps reaches approx. 221F and/or when the AC press. reaches a given point.
11. As for the dash gauge. They are not very accurate for those year coaches and are often as much as 20-40 degrees inaccurate. Use either a phone ALDL app that pulls the temp reading from the ECM or a IR temp gun aimed at the upper radiator hose as close to the T stat housing as possible.