Pulling a heavier toad thru Wyoming I'm seeing some unusually high temps on analog gauge and could use some advice.
Should there be any correlation between trans temp gauge and eng temp gauge? Trans gauge reads much lower than eng., aren't they both sensing the same coolant?
Is there any way to get an accurate coolant temp, possibly with an IR gun? Where and how?
Are sender's generic with standard resistances or is Cummins spec reqd for replacement?
Tapping gauge per standard procedure as first line of troubleshooting made the engine cool off by ten degrees so maybe looking at gauge replacement also.
Appreciate the help.
I have tried using the ir gun to get reading and I can never get close to what the gauge is saying.
On a side note one day I had 3 different IR guns in my office. They all gave me different reading aimed at the same thing. I do not remember what the differences were but I think they were pretty big or I would have though nothing about it.
My trans temp is almost aways way lower then engine temp. I believe the trans temp is checking the temp of the trans fluid where the engine is the coolant.
I guess I missed the lesson on tapping the gauge if you do not like what it is showing.
I know mine and others show a warmer temp when the headlights are on vs being off.
When I went on a trip a few weeks ago I was also running hotter then what I remember (190-195).
The trans temp gauge is measuring the trans oil temperature in the sump. Using an IR gun sounds like a good idea, but I am not sure where the best place to correspond to the gauge reading would be. I would think shooting the radiator tank would give an indication, but it would be good to get baseline temps from different places when operating temperatures are in the normal range to get the lay of the land... I don't know about the sending units, but I am also interested to find out.
Don
Thanks guys. I'm going to be in Missoula for an extended stay, reckon I'll deal with it there. Would like to come up with a wireless reporting system for engine systems, this may be what gets it done. In the meantime will monitor temps, hope there really is a high temp alarm and unhitch toad if necessary. Anyone know if there is a high temp alarm independent of gauge and how it reports?
Segal's law is an adage that states:
"A man with a watch knows what time it is. A man with two watches is never sure."
Same principle with IR guns...
Like Don says:
Use
one good quality IR gun.
Aim at the
same spot on engine/cooling system every time.
Accumulate a
baseline data set of temperature readings during "normal" operation.
Any
unexplained deviation from baseline temps requires investigation into cause.
Information from instrumentation is also just data. It's up to you to interpret it correctly.
I do not know if there is a high temp alarm in our old coaches. I will not rely on their being one even if their is one. It may be a costly mistake.
When I was running higher then normal temps a few weeks ago I noticed shortly after I pulled up to a stop light the temp would go back to the 180 mark.
Our coach has VDO dash gauges and senders match gauge specs. Our gauges and senders are spec'd by Foretravel not Cummins. I don't assume there is a 'standard' sender resistance in the gauge industry. When we added a sender to the generator that could be switched to be read out at the original dash coolant temp gauge, we got the same sender model that is plumbed to our engine, from Foretravel, and it works just fine.
Our transmission temp sender is Foretravel installed and was screwed (1/8" NPT) into the large after-cooler coolant elbow on the lower forward end of the tranny. We later plugged the after-cooler elbow and mounted the same sender in the before-cooler elbow so tranny dash gauge would read retard temps before tranny-cooler reduced them.
We used to occasionally see above 200 coolant temps on hot climbs. We did several things to help reduce temps, but the only thing that consistently worked for us was to keep exhaust temps below 900, tachometer closer to 1600 RPM, always manually downshift and drive up hills (mountains) at a much lower speed. Throttle feels to be at about half position, never seem to press pedal all the way and coolant temps stay below 190 degrees. Towing a 5,400 Jeep may dictate the need for slower climbing.
Engine and transmission gauges are not reading the same things. Our engines do have a high temp ringer that goes off when the temps hit 205 or 210 and I've had it happen a few times. This was lessened when I changed the coolant out and I suspect I still had the original coolant in the engine when it was changed
Have you pulled through the mountains before (and therefore know what you are used to seeing) and what is the ambient temperature? I've ended up with high engine temps when pulling in the mountains of Colorado (8000'+) with a fairly heavy toad and 100F ambient temperatures, even when not going over a pass.
What coolant is in your engine and how recently was it changed?
I'd be checking to make sure your hydraulic fan system is working along with making sure your radiator is clean also.
Basically, I'd be thinking that the gauges are accurate and you might be having another problem though you don't state just how high of a reading you are getting.
OK. This is kind of a strange resolution. I realized last night that the motoraid water heat wasn't working then remembered it was valved off in preference of dash heat. I had switched it last winter and forgotten about it. Reset the valve to its normal position. Then drove the coach to operating temp, picked up an IR temp gun, 180 on dash corresponded with readings of 172-186 on various parts of engine, metal coolant tubes etc with highest readings beind the coolant filter and cast elbow next to it. Good enough. Baseline of sorts.
Then put coach and toad into a good pull headed out of Casper and the gauge behaved as it normally has in the past, 185 degrees. Stopped at crest and shot engine, a few degrees higher. Highest reading for the day was 190. I had seen temps in the 220 range yesterday.
The only other thing I had done other than reset valve was to reseat connections on back of gauge. I'd rather be lucky than good I guess, but stuff like this drives me up the wall. Will get to the bottom of it in Missoula.
Chuck, could it be your thermostat sticking a bit?
When I flushed out my coolant a couple of years ago since I had no idea how long the coolant had been in there (and suspected that it was original), all kinds of sediment/granule type stuff came out. Ended up flushing the system about 10 times before I was getting water coming out with no stuff in it. The sediment that was coming out seems like it could easily obstruct the thermostat.
Kind of acts like it but coolant is clean and well in spec. It is time to install a new blank coolant filter so will cut the old one open.
Tstat was replaced 4 years ago along with flush and fill.