engine heating problems

mlafarge · 10-08-2010, 08:46 PM

I just purchase a 1999 Holiday Rambler with a 5.9 Cummings in it, my question is,
it runs only about half way to the normal temp on the gauge, I have changed the thermostat and it still runs very cool, I have checked the temp with another gauge so I know it is correct.
Also the heater doesn't put out much in the way of warm air, we plan on using the coach in the winter time and we would have to use the furnace to keep from freezing...
I have had ideas of partly blocking the radiator as trucks do but thought I would check to see what others have done.
Has anyone solved this problem?? Thanks Mike

Robi.1014 · 10-09-2010, 09:37 AM

My thought is to continue discovery as to why your meters read as they do, etc. For starters, with a properly operating thermostat, the block's coolant temperature MUST BE that of the thermostat's setting. What did you install? 200-degree? That's what the installed sensor should be reporting to you. Where (in the coolant path) did you measure with your 2nd temp meter?

Given the age of your coach, it could be that the coolant flow-rate through your dash heater is reduced because of deposits (clogging). As you know, the coolant to/from the dash must traverse quite a distance. Suggest testing this path. Disconnect the dash-heater's feed & return -hoses AT THE ENGINE, and use a garden hose to force water through this path....to determine the flow rate. Reverse-flowing of this path might dislodge some debris. Keep in mind another thought: my Diplomat's dash air can't keep the back of the coach toasty-warm when driving in freezing climate. It's not designed to do that.

walt2137 · 10-09-2010, 07:10 PM

Mike not that it makes any difference but pretty sure your 99 is a Freight Liner chassis, I would suspect the heater valve on the fire wall not opening all the way, the gauges are notoriously inaccurate on these coaches if you have a friend with a Silverleaf VMSpc you can hook it up to the computer and read the temp accurate on a laptop.

Caemlyn · 10-11-2010, 11:21 AM

I too have a 1999 HR on a Freightliner chassis. My gauges are wildly inaccurate. I have a VMSpc from Silverleaf and it shows 200 degrees yet the dash will show 1/4 up from cold. The dash and idiot light will also show I'm overheating when pulling a grade, VMSpc will show 208-213 degrees and that is well within range for this engine per Cummins.
On my rig there is a valve in-line on the hose leading to the heater core that can be closed in warm weather to improve the A/C performance at the dash, you may also find on on your Rig. Mine is located under the rig between the rear axle and engine. Not the most user friendly place to locate it.