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.
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This pic shows the score marks.
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This pic shows the "tipped hat".
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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
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
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
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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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.... :o
Oh and then there is the matter of OTR heat...
I'll think of a few more...
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
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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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 :)
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
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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They either use covers or shutters with fan clutches to disengage the fan
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
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
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.
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This the cavity in which the radiator lives--no rust or corrosion, I'm lucky.
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The engine less thermostats.
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Rubber mounted cam damper must be over 450 hp I would lose the R&M air scoops they do more harm than good
My bus came with rad air scoops from the PO. I removed them (don't like the "tired old church bus" look of them), and saw no difference. I think the factory lip at the leading edge of the radiator grill makes the air tumble into it and toward the rad. More effective than those afterthought scoops.
JC
Luvrbus, at the risk of repeating myself, you know more from looking at one picture of my bus than I do from hours of pullin' wrenches! Tell me more about the dampener and HP. Thanks Jack
Hello All. I got the cooling system back together again with new 180 degree t-stats and seals. The antifreeze tested fine at pH 7 and 50% coolant so I re used it.
I took the bus for a drive and the temp stayed at 175 degrees. As long as I gained speed at an easy pace, the temp didn't budge. When I did a standing start to 55 mph with my foot on the floor (this is a DDEE and the highway was flat) by the time I hit 55 mph, the temp had climbed to 200 degrees and stayed there for several minutes and then suddenly dropped back to 175 degrees. When I measured the water temp at the top of the radiator inlet it measured 175 degrees while the water leaving the radiator measured 140 degrees. Unfortunately I was not able to take heat gun readings when the temp was up to 200 degrees. Also, I did not have any shut down problems when the temp was at 200 degrees like I did when I was bringing the bus home after I bought it.
I was thinking about how the water manages to get to the top of the radiator considering the volume of water being lifted. I can't imagine that small water pump managing to do that via pressure so it must be that the pump creates a low pressure condition at it's inlet and the water passing through the radiator actually circulates as a siphon with some assist due to temp differences at the top and bottom of the radiator.
Is this temp thing something I still need to worry about or is what I have described more or less normal?
To end on a cool note, the OTR air conditioning is working fine. When I bought the bus I thought the A/C didn't work. I guess I just hadn't let it operate long enough to get things cooled down.
I will appreciate any insights you might provide. Thanks, Jack
You have 1 gauge or 2 ? the water pump moves a lot of water 80 to 90 gpm check the temp at oil cooler the water flows there 1st from the pump.
It should not heat in I would say the 30 to 40 seconds it took you to reach 55 mph
Luvrbus, yes there are two gauges. One in the engine bay and one on the dash. The one in the bay is slow to register and reads lower than the one on the dash. I'm not seeing any hot spots on the engine or radiator with my infrared temp gun but then I'll need to jump out and take a few measurements when I see 200 degrees on the dash. I'll do that.
Jack
Jack,2 dash gauges are almost a must on a 8v92 1 for each head it makes life a lot easier finding a problem, it has a heating problem or they would have not had the scoops mounted that is a tough engine to cool in a MCI with a factory setup>1st thing I would do is check the HP 400 was the MCI setting and people bump it up to 450 to 475 hp and they don't cool ? what does DDEE stand for
Typo.
You didn't mean DDEC did you looking at the photos yours is not a DDEC
Nope, not a DDEC. This morning I took the bus out for a test run and while it drives fine I was still able to get the motor to heat up to 205 degrees (by dash temp meter) if I built speed too quickly. At one point when the gauge reached 200 degrees I stopped the bus and ran back and took several temp readings around the thermostat housings and cyl head. None of the readings were over 175 degrees and fell off quickly as the bus idled. However, once the temp display was at 205, the engine shut off. By the time I was able to turn the key off and back on to start, the engine lit right off with the dash gauge back down to 180 degrees or so.
I spent the afternoon figuring out what most of the air lines do and how the actuators they feed control the engine. One of the pneumatic devices still has me guessing. It actuates only as the engine starts but has a pair of wires coming to it that must cause some change which unclear to me. It relates to the box above the crossover pipe that accepts the throttle linkage. I'd sure like to know what it does and what makes it work. Thanks, Jack
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Jack, that is a buffer switch for the Jake Brake,nice looking switch no one has removed the diode from it ;D FWIW that is a combo fast idle and buffer switch you have a photo of the box you are talking about ?
Thanks Lvrbus. I'll step back a few feet with my $3.00 camera and get a group shot. Jack
Luvrbus, here is a pic of the "box" I am talking about. The switch/actuator mounts on it. I'd appreciate your explaining how the combo works. Thanks, Jack
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That is not a box that is the micro switch you loosen the 2 screws on the side don't remove them lift the switch out you will see the lever and roller that works the button on the switch when in no fuel to active the Jakes.
The air line make the cylinder work to engage the fast idle there should be a tee and air line tying the holding cylinder on top of the governor housing to the fast idle cylinder they work in sync with each other when the fast idle is flipped on, it's a standard combo switch it has a cover to keep out the dirt than you can remove also
Damn I was I could post photos here I have one apart now cleaning it and replacing the rubber cover for the button on the micro switch that is your fast idle and buffer switch