Temp Gauge - Question

bcaddel · October 04, 2009, 04:06:10 PM

Can someone tell me what the mark after 180 supposed to represent (200 I hope)? On a hot day my needle is usually half way between the 180 and this next mark which I am thinking puts the engine around 190 or 195 depending on what this second mark represents (either 200 or 210).

hargreaves · October 04, 2009, 07:29:03 PM

We had these guages on our older transit buses, the alarmastat ( hot engine light ) would come on just above this mark and it was set for 210 degrees.

bcaddel · October 04, 2009, 07:35:17 PM

Would you guess the mark is 210 or since the alarmstat came on at 210 would that lead one to think maybe the mark is 200?

hargreaves · October 04, 2009, 07:51:25 PM

I would guess it is 200 degrees.

Chuck Newman · October 04, 2009, 08:39:37 PM

Bob,

If it were my gauge, I would laser temp the sender while someone watched the gauge and make many comparisons up to 180, or as high as it would go at idle. Simply because I have seen so many gauges of this type 10 to 30 degrees in error.

A good accurate, high resolution 270 degree face electric gauge and sender will run about $100.00. To me, in comparison to the worth of the engine, that's cheap insurance. FWIW

Chuck

JimW7 · October 05, 2009, 05:16:03 AM

I have the same gauge on my 7 On a hot day it would read just over 180.Not knowing the age of the thermostats, I had them changed to 180's. When I drove it, the gauge showed right at the line you pointed out. That made me nervous. When I stopped to check the mechanical gauge in the engine compartment, it was right on 180. When I talked to bus mechanics, they seem to agree most of there buses are like that. It is misleading, but stays 20-30 degrees off. Jim.

Len Silva · October 05, 2009, 05:35:32 AM

By their very nature electrical temperature gauges will tend to read high if there is any electrical problem, low voltage or high resistance. Electrical pressure gauges will tend to read lower in the same circumstances.

Busted Knuckle · October 06, 2009, 08:58:26 AM

FWIW My past experiences with older MCI's is that the dash assemblies tend to develope ground issues over time. (not sure if it "just happens" or if it is due to lazy mechanics!)
But it usually effects the temp gauges as described the most.
I have seen them jump 20-30*hehe headlights or A/C was used.
I now this does not answer the question asked but provides a insight to the gauge inaccuracies.

BK

buswarrior · October 06, 2009, 08:07:33 PM

On an MCI, your assistant can use an IR gun down through the floor access while you are driving, in the hill climbing moment, to get the real deal. Shoot the big coolant pipe heading for the front, be sure it is set up to allow water flow...

The diagnostic trouble is, by the time you pull over, and get to the back, the temps have changed....

Daughter #2 reports that the wind is strong and it is quite noisy. Glasses and ear protection might be a good idea.

A wrist strap on the IR gun might be a good thing for future relations too.

happy coaching!
buswarrior

bcaddel · October 08, 2009, 06:10:47 AM

Buswarrior
I can get to my access door and I think that is probably the only real answer. I plan to have the wife drive and I will check the temps. We are driving over Donner Summit on I-80 in two weeks for a little jaunt to Sacramento CA. in two weeks so we should be able to get her warmed up pretty good, but hopefully not to my hi temp mark since the outside temps will most likely be in the low 70's or mid 60's.

Thanks for all the good suggestions everyone.