Testing the thermost(s) on my MCI9 8v92

[luvrbus]

Rubber mounted cam damper must be over 450 hp I would lose the R&M air scoops they do more harm than good

[lostagain]

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

[oltrunt]

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

[oltrunt]

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

[luvrbus]

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

[oltrunt]

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

[luvrbus]

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 

[oltrunt]

Typo.

[luvrbus]

You didn't mean DDEC did you looking at the photos yours is not a DDEC

[oltrunt]

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

[luvrbus]

Jack, that is a buffer switch for the Jake Brake,nice looking switch no one has removed the diode from it   FWIW that is a combo fast idle and buffer switch you have a photo of the box you are talking about ?

[oltrunt]

Thanks Lvrbus.  I'll step back a few feet with my $3.00 camera and get a group shot.  Jack

[oltrunt]

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

[luvrbus]

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