Very little heat from dash heat registers while underway

[Buly]

Looks like the heat made by the engine can not overcome the cooling from the cold air blast and cooling from the oil and antifreeze circulation? Some diesel trucks have radiator grill covers for the winter. Many decades ago, we had a Russian car that had luvers for winter use Activated by the driver from the cabin.
Diesels running on 6th gear at 65-70 mph are very efficient = less fuel burnt = less heat generated. Me thinks?
My DS temp gauge stays in 1/3 of scale on the hottest days in the summer.

 

[Rustymayes]

Looks like the heat made by the engine can not overcome the cooling from the cold air blast and cooling from the oil and antifreeze circulation? Some diesel trucks have radiator grill covers for the winter. Many decades ago, we had a Russian car that had luvers for winter use Activated by the driver from the cabin.
Diesels running on 6th gear at 65-70 mph are very efficient = less fuel burnt = less heat generated. Me thinks?
My DS temp gauge stays in 1/3 of scale on the hottest days in the summer.

On a hunch, I turned off the heater loop valves to make sure the heater core was not contributing to the cooling issue. I let the coach run for 45 minutes in the barn. The temps came up to 174 on the digital display but on the temp gauge with the needle scale it only showed 1/4 scale. At the same time my TPM is wacky and my digital RPM reading wildly fluctuates. I understand the electronic engine monitoring on these coaches can be wonky intermittently. I am going to call the Freight Liner Service center in Sacramento in the morning and see what they say.
Rusty

 

[Rich W.]

I’ve had good results with them.

 

[Rustymayes]

I’ve had good results with them.

Good to hear Rich, I have the next five weeks off so hopefully they can get me in for diagnosis soon.
Cheers

 

[Rich W.]

I’ll be headed there sometime after the end of January. Guess I need to call - they are usually 6 - 8 weeks out.

 

[Rustymayes]

I’ll be headed there sometime after the end of January. Guess I need to call - they are usually 6 - 8 weeks out.

6 to 8 weeks? wow! I just don't understand these outfits that have that kind of lead time for service. For specialized work maybe, but one would think they would grow to fill the demand. I'll let you know what they tell me.

 

[Rich W.]

6 to 8 weeks? wow! I just don't understand these outfits that have that kind of lead time for service. For specialized work maybe, but one would think they would grow to fill the demand. I'll let you know what they tell me.

They did - they now have a separate RV facility on the south east corner. You enter off Harris St. But they are the only FL shop between Reno and the East Bay or Stockton.

 

[Dan_Frisbie]

Looks like the heat made by the engine can not overcome the cooling from the cold air blast and cooling from the oil and antifreeze circulation? Some diesel trucks have radiator grill covers for the winter. Many decades ago, we had a Russian car that had luvers for winter use Activated by the driver from the cabin.
Diesels running on 6th gear at 65-70 mph are very efficient = less fuel burnt = less heat generated. Me thinks?
My DS temp gauge stays in 1/3 of scale on the hottest days in the summer.

That reminds me of a pickup that I had in the 90s. In extreme cold weather, I had to block off part of the radiator to get cabin heat, even with a good 180 degree thermostat.

 

[widdershins]

6 to 8 weeks? wow! I just don't understand these outfits that have that kind of lead time for service. For specialized work maybe, but one would think they would grow to fill the demand. I'll let you know what they tell me.

Huge problem finding qualified mechanics, those that come out of the tech schools have been fed a line about how much money they can expect at entry level with no tools and little hands on experience. 6-8 weeks does seem a bit long, but not suprising.

 

[Rustymayes]

I decided to a little more investigating on my own after I gave up holding for service for twenty minutes this morning. I first spoke with the Freightliner customer service rep at headquarters which was a waste of time other that verifying that my warranty is active with them. I asked if he could tell me if there was a problem with operating the engine below normal operating temps. He asked me to hold so he could find out then came back and said no issues. I don't believe that running the engine at almost 1/2 of the design temp would ultimately cause issues down the road. At least there is a note in my warranty file that I recognized an issue and inquired about it. The customer service tech did tell me to check the fan clutch fuse but that can't be the issue as the thermostat needs to be closed to raise the temp to 185 before the radiator should cool the water. I am sure that somehow the water is circulating in bypass somehow around the Thermostat. I even took the drive belt off the fan drive and ran the engine with the heater loop closed and it took well over 25 minutes to get to as high as 175 degrees. I opened the heater loop and the temp dropped to 155 almost immediately. This is very strange. I am going to call the guys at Demartini and see if they have seen this issue and referred it on to either Cummins or FL.
I'll post results as i go thru this issue incase anyone ends up with a similar issue.
Cheers

 

[Rustymayes]

Apparently installing the new thermostat actually did fix the low temp issue. Since I had not seen normal temp indications after I replaced the thermostat, I decided to see if the Freightliner service center could figure it out. I called them this morning and as luck would have it, they had a couple of cancellations due to the holidays. I set off up the road towards Sacramento and low and behold, I saw 185F on my temp gauge. I ran the dash heat with fresh air and with recirculating cabin air and the temp gauge remained in the normal range. It would climb to 185 then cycle down to 177 and after a while hit 185 again indicating that the fan clutch is working as advertised. I still do not know why my first test drive after the replacement of the thermostat did not produce normal temps.
I cancelled my appointment with Freightliner Service for now. I will see how it performs on our next trip.

 

[Webz]

My temp gage stays at 1/4 pretty much all the time unless going up steep hills.
But it does take 10 to 15 minutes to get there.