Testing the thermost(s) on my MCI9 8v92

oltrunt · July 27, 2015, 03:00:17 PM

Hello All. I discovered that I had little or no cooling going on in the driver's side radiator while having obvious cooling taking place on the right side. I removed the thermostat (180 degree F) from the driver's side and tested it's opening closing point and measured initial opening at 164 degrees F with complete opening at 180 degrees F respectively. Closing temps were the reverse. I saw some scoring on the moving part of the thermostat where it slides up and down in a stainless steel sleeve between the inlet and outlet ports. The scoring is heavier on one side. Also, when the thermostat is in the open position it looks like the opening motion is not parallel with the sides of the housing leaving a "tipped hat" appearance to the open thermostat. Despite the fact that the thermostat responds as it should to heat, I wonder if the off center opening is causing the thermostat body to hang up and not open? Any ideas? Thanks, Jack

The antifreeze I removed from the bus looks very clean. I'll try to find some test strips to check it before I pour it back in the bus.

This pic shows the score marks.

This pic shows the "tipped hat".

luvrbus · July 27, 2015, 03:48:43 PM

Those are a partial blocking T stats not a full blocking T stat most all of those tip a little.The seal in the housing will cause air bubbles when bad and cause poor circulation did you check the seals,the T stats and seals are cheap enough change both sides and be done with it

oltrunt · July 27, 2015, 05:29:32 PM

Thanks luvrbus. The seal between the thermostat and the housing was fine until I gouged it out to free the t-stat. I can see how a bit of coolant could get by the ring (where the scratches are) and through the small hole you can see in the third pic. Is that what you mean by partial blocking or does the water bypass somewhere else? If so, I may still have a blocked radiator. Thanks, Jack

luvrbus · July 28, 2015, 09:06:20 AM

Jack, as you probably know they work a little different than most T stats the bottom slides to close and open the seal in the housing will get old and brittle and it won't slide but I can see the marks on the housing where yours did slide at one time

Change the bottom seals and I think you will be fine as far as the T stats go, fwiw people waste a lot of money changing those when a 4 dollar was the problem to begin with

Scott & Heather · July 28, 2015, 12:37:18 PM

Why don't we run straight without Tstats? Thinking out of the box here, I have brand new radiator shutter Pistons so my shutters on my 102C3 are in perfect operable condition...couldn't I use them at "Tstats" on a cold day?

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eagle19952 · July 28, 2015, 01:15:13 PM

Quote from: Scott Bennett on July 28, 2015, 12:37:18 PM
Why don't we run straight without Tstats? Thinking out of the box here, I have brand new radiator shutter Pistons so my shutters on my 102C3 are in perfect operable condition...couldn't I use them at "Tstats" on a cold day?

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Too cool can be as bad as too hot...
The motor and it's metallurgy are all dependent on a set of calculations and coefficients (of expansion) engineered over many years of science and trial and error....

Oh and then there is the matter of OTR heat...

I'll think of a few more...

luvrbus · July 28, 2015, 01:16:58 PM

T stats serve a dual purpose Scott control they the engine temperature and restrict the water flow from passing through the radiator to fast so the radiator and fan can do it's job.

Look at the way the T stats are made 4 bars on top and 3 on the bottom on a DD T stat water never stops flowing and when they open it just lets more water flow around the housing.

The top never moves only the bottom cylinder opens and closes a simple design but it works.The last time I checked there were 12 different T stats for a DD not temperature ranges but models the partial open is the most common for a bus

Keep your shutters you may need those even with T stats where you live fwiw without T stats the tempature will creep up and run hot most of the time

Scott & Heather · July 28, 2015, 07:25:26 PM

Interesting. Ok didn't know how much science there was behind them. I had a friend ask me about this the other day. He said down in Texas they used to run their cummins cement trucks without Tstats back in the day. Crazy. Ok, good to know. See what thinning out of the box gets me?

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eagle19952 · July 28, 2015, 08:03:20 PM

Quote from: Scott Bennett on July 28, 2015, 07:25:26 PM
Interesting. Ok didn't know how much science there was behind them. I had a friend ask me about this the other day. He said down in Texas they used to run their cummins cement trucks without Tstats back in the day. Crazy. Ok, good to know. See what thinning out of the box gets me?

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Normally/usually cement trucks are short haul.. and in TX, flat haul

luvrbus · July 29, 2015, 07:20:10 AM

They did do that on the older engines in industrial Scott use but Cummins,Cat and DD sold a screen to drop in where you removed the T stat.

These electronic engines are real touchy about engine temperature I just found that out on a 6.5 Chevy I could get no turbo boost when the engine was running cool.

I changed the T Stat per a guy I thought was a little off but what the hell it was worth the try as I had been fighting it for months gone from 4# back up to 12 # now I am a happy camper

Scott & Heather · July 29, 2015, 09:39:02 AM

Interesting. So, on cold days (they do happen in Texas) how do they get them up to temp? Is that what the vinyl radiator snap covers are for I see on heavy trucks?

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luvrbus · July 29, 2015, 10:27:29 AM

They either use covers or shutters with fan clutches to disengage the fan

sledhead · July 29, 2015, 02:34:00 PM

I adjusted my shutters with a dash switch to turn on the shutters when needed and use then most of the time ( even in the summer to get the temp. up to 180 f )
before I reinvented the wheel ( with my shutters ) in the winter I had times when I could not get the temp. up to 180 f even after 2 hours of drive time .

dave

IMABUSBOY · July 29, 2015, 03:48:53 PM

My mc9 6v92ta's running/ operating temp seems to be 190%. According to my manual, the T stat opens at 170%, the shutters open at 180% and normal operating temp is 190%. 190 appears to be about center of the dash gauge. Does this sound correct or maybe I misunderstood?
Thanks Danny

oltrunt · July 31, 2015, 07:48:17 PM

Hello All. I took the plunge and removed the driver's side radiator on my MCI9. It took me 4 hours to get the thing out as I've never done one before. Much to my delight, every fastener came out without any trouble. Even the shutters were cooperative. Once out I looked through the fill port and the drain port I saw no sign whatsoever of blocked tubes. I filled the radiator with water and then releases the bottom port. The water flowed out as if I had dumped a bucket.

While the dry weather where the bus was used can be credited with the ease of disassembly of the radiator, it can also be blamed for the fine grit that had all but blocked the radiator fins. They were so clogged that I couldn't see light through the core. Fortunately, a good rinsing with a hose was all that was needed to clean the core and now light flows through.

The County had installed fiberglass air scoops at the rear of the radiator. I suspect these scoops did more towards stopping up the core than they did to increase air flow as the plugging was the worst behind the scoop. I guess I'll put the thing back together without the scoops but with new thermostats and seals after I use test strips on the antifreeze. I'll report on the results. Jack

PS I weighed the radiator empty---130 pounds. Glad I asked for help lifting it out!

This is a pic of the shroud.

This the cavity in which the radiator lives--no rust or corrosion, I'm lucky.

The engine less thermostats.