Overheat Issue

[LaMonte Monnell]

Well. Our 2001 Contessa has been in the CAT shop since the end of August!

Today the shop foreman called, we went to the shop. He said everything is finished, but he did a test drive and coach temp went to 225. That was on the scan gauge, dash gauge was higher yet.

We have never had a temp over 210 and that was in the mountains towing our auto in July! We wanted the coach back before now as we have a trip planned starting the 25th of November. Can't go with overheat issue.

He said they are going to flush radiator then check the thermostats out. What else could it be? Stuck thermostats nothing else has been done and it has never ever overheated on long trips or short ones.

here's what has been done:

1). serpentine belt replaced
2). water pump belt replaced
3). 2 thermostats replaced
4). rear wheel seals replaced both sides
5). a/c compressor replaced
6). ac condenser fan motor replaced
7). ac receiver/dryer replaced

[Steve Huber Co-Admin]

LaMonte,
Assuming you are in FL, it probably wasn't due to him lugging the engine up a hill. Based on what you had replaced, possible culprits would be wrong temp thermostats, wrong size or loose water pump  belt causing the water pump not to turn at proper RPM. Fan is direct drive so it is probably OK. One other thing to check is if they refilled the antifreeze after draining to replace the t'stats.
Steve

[David T. Richelderfer]

ELC in the engine?  TranSynd in the transmission?  All fluids full?  Check for a dragging brake?  Tires properly inflated?  Plugged radiator?  Collapsed coolant hose?  Anything else I could think of would be expensive!  And I don't want to mention any of those!

[LaMonte Monnell]

ELC in the engine?  TranSynd in the transmission?  All fluids full?  Check for a dragging brake?  Tires properly inflated?  Plugged radiator?  Collapsed coolant hose?  Anything else I could think of would be expensive!  And I don't want to mention any of those!

It was fine when I dropped it off there. transyd for three years, Elc for over three years, fluids full, radiator has been fine, no overheat for 4 years,

I'll have them check coolant hoses, he said they are going to flush radiator and pull the thermostats out and check them. They did replace the radiator fan with a new one but was exact one they removed because of a cracked blade!

[LaMonte Monnell]

LaMonte,
Assuming you are in FL, it probably wasn't due to him lugging the engine up a hill. Based on what you had replaced, possible culprits would be wrong temp thermostats, wrong size or loose water pump  belt causing the water pump not to turn at proper RPM. Fan is direct drive so it is probably OK. One other thing to check is if they refilled the antifreeze after draining to replace the t'stats.
Steve

No hills,  they are going to remove and check the thermostats they put in(correct ones?).

water pump belt was correct and adjusted correctly(they just checked it out).

elc topped off(they checked it).

they installed a new exact replacement fan as other had a cracked blade.....

[Steve Huber Co-Admin]

May sound like a dumb question but are they sure they installed the fan correctly so the blade pitch pushes rather than pulls air?
Steve

[LaMonte Monnell]

May sound like a dumb question but are they sure they installed the fan correctly so the blade pitch pushes rather than pulls air?
Steve

Funny you should ask that. That was my first question? Not to insult you but the fan is blowing air out the back, correct?
I have heard of sticking thermostats but ?

Always something extra to deal with, and the wife ready to leave next week for Thanksgiving.

[Dave Atherton]

Lamonte, looking what has been repaired on your engine and heating problem. One question
is there not any coolant loss because sounds like a fault heat temperature sender. I can pull your
engine up on Cat SIS and go deeper into the subject if you would like. Would need your engine
S/N number.  Dave Atherton Retired Cat Mechanic

[LaMonte Monnell]

Lamonte, looking what has been repaired on your engine and heating problem. One question
is there not any coolant loss because sounds like a fault heat temperature sender. I can pull your
engine up on Cat SIS and go deeper into the subject if you would like. Would need your engine
S/N number.  Dave Atherton Retired Cat Mechanic

Dave, I will get that for you tomorrow.....off the top of my head it is 8YL6299   CAT is going to check the new thermostats in the am...they said the dash gauge was over 225 and the scan temp was 225. He said he only drove it a short distance and the temp came up quickly.

Now that you mention it they did change a sender just above the starter because of an oil leak, could that be the sender you are talking about?

[Dave Atherton]

Lamonte, the temperature sensor should be located up around the temperature regulator housing.
Another thought I had happen with 3126 B, the pac-brake located on the exhaust side of engine,
sticking and not opening all the way and increasing exhaust back pressure on engine above 40psi,
and woud cause engine to heat. Found air cylinder was stuck and movement of gate valve about
5/8 open ( after tear down had to replace the air cyylinder.) If you have a hydraulic fan it is possible
hydraulic motor on fan is not producing enough rpm"s. and needs rebuild or replacement. One
thing in the thermostat replacement, the jiggle pin is not installed in correct location on the
smaller thermostat housing. Going back to the above temperature coolant sensor, you have a very
high temperature reading and light and buzzer going off. when this is happening there should
be fluid or steam coming out from the little hose just under raadiator cap. there should be coolant
loss in top tank. If there is no coolant loss will again point to temperature coolant sensor. One
more thing did mechanic bleed the aiir from engine head after thermostats were installed.
Dave Atherton Retired Cat Mechanic

[Steve Huber Co-Admin]

LaMonte,
If I remember correctly there are 2 separate temp sending units located on the top of the engine (front of engine / rear of coach). One feeds the dash gauge and I think the other feeds either the Sliverleaf or the gauge in the engine monitor bay. In any case, if you are getting over temp readings on multiple readout points (gauge and Silverleaf) would seem that a bad sending unit is not the problem unless 2 went bad at same time.
Steve

[Dave Atherton]

LaMonte, information pulled with your S/N, basic leads to install of new thermostats. The
question first did tech bleed air from head after install of coolant. Second install of the
smaller thermostat with ( Jiggle pin not installed in regulator housing in correct position ).
Third test drive and rise of coolant temperature in cab, again follow up upon return to shop
was any indication of water or steam exit from over fill hose on radiator. As Steve mention
temperature sensor fault with two sensors ( one sensor is low coolant and other sensor is
temperature sensor is for heat, Both sensors in this case should work together if overheat
is sensed. Many times with sensors fault, light than alarm but no coolant loss. Not knowing
if problem has been ongoing before present work. Being tech is going to retrace install of
thermostat sounds possible one thermostat is stuck part way open. Information if problem
is not in cooling system, than restriction in the exhaust as indicated last eve.
Dave Atherton Retired Cat Mechanic

[LaMonte Monnell]

LaMonte, information pulled with your S/N, basic leads to install of new thermostats. The
question first did tech bleed air from head after install of coolant. Second install of the
smaller thermostat with ( Jiggle pin not installed in regulator housing in correct position ).
Third test drive and rise of coolant temperature in cab, again follow up upon return to shop
was any indication of water or steam exit from over fill hose on radiator. As Steve mention
temperature sensor fault with two sensors ( one sensor is low coolant and other sensor is
temperature sensor is for heat, Both sensors in this case should work together if overheat
is sensed. Many times with sensors fault, light than alarm but no coolant loss. Not knowing
if problem has been ongoing before present work. Being tech is going to retrace install of
thermostat sounds possible one thermostat is stuck part way open. Information if problem
is not in cooling system, than restriction in the exhaust as indicated last eve.
Dave Atherton Retired Cat Mechanic

Just came from CAT...glad its around the corner a few miles away.

Pulled cover and checked the thermostats, everything good.

Going to flush the radiator and refill with ELC and bleed the system.

Test drive again and watch temps... hopefully that will be it.

No prior overheat in the 4 years of coach ownership so its something they didn't do or did wrong. 11000 miles in four years and never had one overheat condition prior to this work....

[Edward Buker]

Lamonte,

I wonder if the thermostat is defective, given that is one of the things that was changed. If you watch the temp climb when you start out from cold, does it rise to a higher temp and then remain there in a stable state? Is that repeatable? That would fit with a thermostat that is incorrect or out of calibration. If the overheating was not repeatable and more random then maybe system bleeding of trapped air, or perhaps a fan issue, or some plugging of the radiator. Hope you get an answer and fix soon...

Later Ed

[LaMonte Monnell]

Lamonte,

I wonder if the thermostat is defective, given that is one of the things that was changed. If you watch the temp climb when you start out from cold, does it rise to a higher temp and then remain there in a stable state? Is that repeatable? That would fit with a thermostat that is incorrect or out of calibration. If the overheating was not repeatable and more random then maybe system bleeding of trapped air, or perhaps a fan issue, or some plugging of the radiator. Hope you get an answer and fix soon...

Later Ed

They pulled the thermostats back out today and checked them, they are ok and reinstalled them. The temp rise was intermittent the two times they had it out on the road. They installed a brand new fan but its also correct.

They didn't bleed the air out as they started the rear wheel seals right after. so now they are flushing the radiator and refilling then bleeding all the air out. Hopefully more to come tomorrow. They did get the dash air working again so that's a plus.

Supposed to go away for Thanksgiving for 4 days but we will see about that......