Community Forums

Jimp2061 · 05-18-2025, 04:00 PM

Ok. I have a 2005 Newmar Kountry Star with the Cat c7 engine. Gauge on dash shows that the engine is overheating when I drive it. Temp stays down in the normal range when idling. No noticeable difference in engine performance but I don’t have any heat on the dash board which I thought was pretty odd. I’m waiting for a tow truck right now as I’m don’t want to take a chance with the engine. The info centre is also telling me to check engine and telling me it’s overheating. The coolant overflow is staying at the normal spot. I’m thinking thermostat. Any ideas.

Mr. T · 05-18-2025, 04:45 PM

All belts look good in the engine?

Jimp2061 · 05-18-2025, 05:50 PM

Best I can see. Everything is hard to see back then here. I’m also wondering if I lost the coolant pump belt.

SafariBen · 05-18-2025, 06:09 PM

The water pump belt is a small V belt to only the water pump, it's not the MULTI V, serpentine belt that drives the alternator, A/C compressor, etc.

If your "coolant overflow" reservoir is above the engine and has the radiator cap on the reservoir instead of the actual radiator, can you remove the cap and squeeze a big hose to see if the coolant level bounces, that will confirm the system is full. Then I wouldn't hesitate to drive until the temp rises near red, stop, wait for it to drop, continue. Obviously not safe in some places.

Skip426 · 05-18-2025, 06:19 PM

Your engine uses two engine temperature regulators ( Cat speak for thermostats ) if one sticks closed then the engine will stay cool at idle and slightly above ; but overheat under load ; because one t'stat won't allow enough coolant to get to the radiator fast enough to keep the engine cool , under load.

No heat to the dash , maybe an indication of another problem .

Jimp2061 · 05-18-2025, 09:44 PM

Thanks for the replies everyone. The tow truck has dropped the NM off at the dealer in Milton Ontario. I guess I'll have to wait until Tuesday (Monday is a holiday here) to find out more. Yes, when I started it and let it idle, it would stay cool, as soon as I drive it, the temp quickly rises. I post the response from the dealer, for anyone's future reference.

Ajhyman · 05-19-2025, 09:36 AM

Yup could be the thermostats Also if you can Power wash the Radiator fins out . This will clean out the dirt from the fins and help keep it cooler

wolfe10 · 05-19-2025, 09:51 AM

The water pump belt can be most easily seen from underneath. Left rear just in front of the rear cap. As said, it is a regular "V" belt, not the much larger serpentine belt.

Even if the thermostats/regulators are OK, if original and 20 years old, REPLACE THEM.

Also, when was the last time the front of the CAC was cleaned. If air flow through the CAC and radiator is restricted, it could have enough cooling capacity at idle, but not under higher engine loads. Easy to check with a strong flashlight from bedroom/closet access.

Skip426 · 05-19-2025, 11:51 AM

I have to ask ; did this situation come up on your first trip out of storage this year ?

SafariBen · 05-19-2025, 12:34 PM

Yes, I'm interested in the history of the problem also. I'm doubtful one bad thermostat out of two, or a plugged radiator would cause a sudden and severe overheating problem. The SECOND thermostat going bad, or a water pump belt breaking would.

Jimp2061 · 05-19-2025, 02:07 PM

I took it out of storage for an oil change and there were no problems. I then took it out of storage again to bring it home to get it ready for the season with no problem that I noticed. When I went to take it back to the storage facility that is when the problem came up. No indications before that point. When it happened the engine temp gauge shot up quite fast when driving.

wolfe10 · 05-19-2025, 02:29 PM

Please let us know what they find.

Thanks.

Jimp2061 · 05-23-2025, 08:38 AM

Well, it looks like it’s the water pump. When I spoke to the tech last night it was looking like it was the water pump belt but they called this morning and said it was the pump leaking, I’m assuming that might have been what caused the belt to stretch. Not a cheap fix as it’s hard to get to but the Freightliner dealer told me they would try to trim the price down as much as they can.