Need some advice. Overheating on I 75 in north florida.

[Scott & Heather]

Driving 45 mph. It's cool and cloudy. Temp climbs to 200 degrees then for no reason drops to 165. Then it switches back and forth. When I stop I run to the engine bay and that gauge reads 175. Should I disconnect alarm stats and assume I'm not really over heating? Trying to get to MI and could really use some help! Thanks


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[thomasinnv]

if you can't get anything figured out, get you a mechanical temp gauge and pop it up into the rear of the cabin and have the wife go back and watch it to see if it agrees with the dash gauge when it starts bouncing up and down. a bad wiring connection or loose ground can cause the dash gauge to do all kinds of funky things.

[Seangie]

Scott,

Pick up a thermal IR gun and check the block temps that way.  Kinda hard while driving down the road but if you check the temps regularly with the IR gun you might be able to check against the dash gauge and see the difference when the gauge is reading incorrectly.
(Got that tip from Odyssey Sean in Acadia)
Also - Do you have a temp gauge in the back of the bus?  If not it might be worth tracking down the sending wires for the temp gauge and put one in the back.  The PO of my bus did that with a toggle switch to choose which gauge to send th signal to.

Nothing original here....just passing it on.



-Sean

[Busted Knuckle]

Many "old school" operators (or maybe their mechanics) used to install a temp gauge on both heads. (one on each side of the engine compartment)
That way when there was a problem with one running warm, they could instantly tell which head it was if a head was a problem!

And as said many times a dash gauge will read OFF way off sometimes! older MCI's are notorious for bad dash grounds!

My uncle had a "9" once that if you turned on the A/C the temp gauge would go up 20* and if you turned on the headlights too it'd go up another 20* so it's be rolling down the rd @ 185-190* and I'd get calls from drivers telling me "Hey this bus is running hot!"
I'd always ask got the A/C on? They'd say yup! I'd tell them to turn it off a second and see what happened. They'd call back and say it's running 20* cooler, but still warmer than it's supposed to. I'd tell them to turn the headlights off and check it and they'd say "what am I supposed to drive around in the dark?"

One driver one night was being a real pain in the you know what so I told him "George get out and go to the back and see what the rear gauges show!"
He did and  he happily reported to me "that it was running 175* now, but I know when I get back out on the road it's gonna shoot back up there!"
I told him "George if it's night time and the A/c is on it's gonna show hotter that it is.
Also I know for a fact the shut down stats are working so if it really gets hot it will shut down on you!"
He replied "So what am I supposed to do hire me some little man to ride back here an tell me when it's running hot?!?!"
I just hung up on him!
  BK 

[Dave5Cs]

Before worrying about the gauges and alarm stats, did you look at the antifreeze site glass to see if the water was down or leaking out a hose, oil temp and pressure. check the dip stick and see if you are way low. Is the tranny low on fluid.
Check each head with the heat gun and see if one side is hotter than the other. Is  your water pump moving water? Just some thoughts.

Dave5Cs

[eagle19952]

Put a wrench on something and see if the belts are slipping if you have a belt driven fan,Sounds like they are slipping....are the belts glazed ?
DO NOT disconnect your alarmstats or shut downs !!!!

[robertglines1]

Just checked he hasn't been back on since  his post so he is either runnin or dead in the water.  If running should be in northern Ga. By now.

[Scott & Heather]

Hi gents. Just outside of Atlanta. Temps seems fine but gauge was wacky all over the place. Had this problem last year too. Alarm stats. Tranny fluid and coolant are fine. Coolant isnt boiling and engine bay temp gauge is reading normal. Wires to the alarm stats are messed up. I now have another problem. Tons
Of black smoke And no power. Ugh. Probably my motor oil diesel mix. Not good


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[Seayfam]

Scott,
How much motor oil mix are you talking? I think the first thing I would check is the air filter and make sure there are no restrictions.

Good luck, I hope all goes well!

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[gus]

I'm having the same problem on my 4107, the gage is all over the place but a check with a  thermal IR gun shows all is well.

One time it will be below the green, the next time it will be mid-green, the next time it will be high green.  All this on the same day!!

Since these things work by electrical resistance my best guess is all this is caused by the very long and old wiring which causes high resistance and to the poor grounds mentioned in other posts.

I'm going to try loosening and re-tightening the senders, I've tried everything else!

My AT temp gage is doing he same thing except it is consistently high.

[belfert]

I'm going to try loosening and re-tightening the senders, I've tried everything else!

It could be the sender is bad, but the wiring on an old bus is likely too.  I replaced most of my gauges (same brand) and the oil pressure gauge was reading crazy after it was replaced.  Rear oil pressure gauge read fine and so did DDEC through Silverleaf.  I replaced the sender and all is well again.  It was coincidence the sender had failed at same time gauge was replaced. 

[luvrbus]

Scott,check the air filter, the turbo and all the connections if all is good it is injector time your mixture is hell on injectors   
The gauges on old buses are usually off because at onetime somebody has pulled the resistance loops out in the systems electric dash gauges can be made to be accurate just takes time and patience

good luck

[Lin]

The first motorhome I had had a gauge problem.  We were riding along and the temp began to rise with out me noticing it.  I looked down at the gauge and it read about 250*.  I panicked and pulled over.  The engine was still running smooth and there was not sign or noise that I would associate with a hot engine.  It was a Dodge 440 in a dog house by the driver.  I than saw that as soon as we pulled over, the temp went down and read about 180*.  We did not have and IR gun (this was the mid 80's.  I doubt they were common back then).  We did however have a roast thermometer which I would use for measuring water temp by dipping it in the radiator.  Anyway, we duct taped that to the out going radiator hose and started down the road.  When the dash gauge climbed to 250 again, I slid back the dog house and saw that the roast thermometer was at 180*, so all was okay.  I think I had to change the sensor.

It could be lots of things but, especially since the dash gauge is erratic, it would seem to be a gauge problem.  The IR gun is good standard equipment anyway to check the mechanical gauge and be sure that it is right. 

[Busted Knuckle]

Scott do yourself a favor and go by and visit Mr. Bowen & Joel @ the Choo-Choo Express Garage @ exit 1 in TN ! It' will be worth your time #1 to have Joel check and verify that the ALARMSTATS work properly! # 2 to help you diagnose your smoke problem!
Here is the info!                                                                                            Choo-Choo Express Garage
147 Prater Road
Rossville GA 30741 United States
Phone: 706-891-1242
Phone 2: 423-645-7456
Contact: Don Bowen
   
We are a diesel bus garage specializing in the 2-stroke engines and related drive train components that many bus nuts have. In business for over 30 years, we know our way around these old buses. At $55/hour, we also have the most affordable shop rates around. Less than two miles from the junction of I-75 and I-24 on the southern edge of Chattanooga, TN, we are conveniently located.

They will treat ya right an they are just off I-75 on your route!
  BK 

[Scott & Heather]

Thanks guys. Air filter is brand new. Going to Chang out fuel
Filters. No leaks anywhere around turbo. Exhaust is dry and just sooty. Power comes and goes as well as smoke but pretty consistently bad at the moment. Dropped to 35 mph on a gentle grade. Will keep updated. Bk I just might have to stop at choo
Choo


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