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MCI 102-C3 coach to RV - Engine Bay

JNHEscher

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This thread is the engine bay offshoot of the original thread that migrated from Pirate4x4. As the subtitle implies, all things related to the engine bay will be here. The mother thread, which begins as the bus purchase and teardown, lies here - https://irate4x4.com/tow-rigs-and-tr...eral-floorplan

The second post of this thread starts off where I was knee-deep in stripping the bus floor out and getting my hands extra dirty in the engine bay.
 
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JNHEscher

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Not much left to cut out. I'm recessing the rear step by about ten inches to extend the floor a little. Once I get a few more measurements tomorrow, I'll lay them up in SketchUp to figure out where and how I want to rebuild engine bay access from the interior. Pulling all of this apart brought us to realize that there's quite a bit more space to utilize.

I pulled the turbo inlet pipe out, along with the filter canister and some of the associated piping today. The turbo inlet is getting rerouted to either the right side or upward where the radiator fans and motor currently reside. Removing all that opened up a hell of a lot of room in the engine bay. I can comfortably sit on either side of the engine to work on it. Yanking the AC compressor tomorrow.

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Again, the rivets. When I pulled the air filter can out, this air box just fell off. None of the rivets left. None. Same with some of the AC air ducting. It was just sitting in place with nothing attaching it. Despite everyone's concern that I'm causing myself too much work by pulling all of this apart, I sure am glad that I have. The buses were built well, but, aluminum rivets in steel, man.

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More stuff happened. Radiator fan is out and staying out. Likely some Flex-A-Lites going in. To be determined. There's an amazing amount of crud built up on the fan mount. Years of oily goo slinging around and dust to make crud balls that the fan tossed up there, I guess.

OE coolant overflow tank won't be used. Instead, I'm thinking of a sight column that I can fill from the back without the need for a ladder. The space atop the read deck will be capped off and integrated as bedroom shelving or something of the like.

The top of the step is only 11" above the floor. I'll be rebuilding the step to be recessed towards the rear by a few inches and it will be part of what the bed sits on.

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JNHEscher

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The plan with fuel storage is to move it to the rear. Don't really need 142 gallons, but rather than make a tank to fit in the engine bay and cause safety and confinement issues back there, I believe I'll slide it into the rearmost storage bay. Potable and grey water tanks will be going in the front bay. Batteries will go in the engine bay. There's a rhyme and reason to all this. I'll let the pictures tell the tale as it happens.

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Oh, and get this - the 8V92TA is mechanical. After conversing with numerous people privy to MCI specs and decoding the VIN prior to retrieving the bus, we were all certain it was a DDEC engine. Throughout the weeks of tearing this bus down, I've been on the lookout for the ecm. Googled several times to get an idea of where the ecm should be after not finding one and still didn't see it.

This past week brought on some headaches due to tracking down air leaks and various other nickel and dime parts runs just to move the bus to a different part of the yard. I hadn't done a "walk-through" of the air system yet to familiarize myself with it and had to reach out to group member a few times in order to solve my problems.

Through tracking down air lines, I noticed that there were no wires leading into the top end of the engine. A DDEC engine should have injector wires. AND, not being able to build air pressure with the engine running required I put my hand over the turbo compressor inlet to shut it off. Lo and behold, I bounced this curiosity over to group members again to confirm my suspicions and our engine is in fact a mechanical Detroit. Happy days for me. I wanted mechanical in the first place.
 

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MarkObtinaro said,

Interesting about a mechanical -92 series. I thought all -92 series had at least a DDEC I system to operate it.

In regards to the cooling system, every MCI with the twin radiators overheated to a greater or lesser degree. Part of the problem is the system was never sized large enough particularly once the buses went to automatic transmissions. Another part of the problem is due in large part to the fact it is a rear engine bus. Getting enough air flow across the radiator cores was always just barely adequate. I don't know that you will be able to get enough air flow across the radiator cores with electric fans.

MCI had two different sized squirrel cages to move air through the radiators. Most buses that were purchased by someone who was anticipating using the buses in the west and SW would have spe'c'ed the larger capacity squirrel cages. Those buses that were going to see service in flyover country or the east coast generally had the normal spe'c squirrel cages.

I would determine how much air flow you can get with the electric fans. The high capacity squirrel cages were able to move a huge amount of air. It is going to require a LOT of air movement to keep from overheating.

With the advent of the D-model MCI went away from twin side mounted radiators to one large single radiator mounted above the engine at the back of the bus with a HUGE single fan to move air from side intakes to go across the radiator core. While it would require a lot of fab work it might be a better idea to swap in a D-series single radiator than trying to make electric fans do the work to move air.

In regards to the fuel tank, I am not sure exactly why you would want to swap it out for a smaller tank. One of the problems with the D-, E-, and J-model MCI's is MCI moved the fuel tank and A/C condenser from just behind the front axle to an area to the rear of the luggage compartments. That tended to make the front end a whole lot lighter. It helped with weight limits particularly on the 45' coaches. However the lighter loads on the front axle make the newer coaches a bit harder to control on slick road surfaces. Rear engine buses always tend to understeer on slick surfaces. Moving several hundred pounds towards the rear will make the understeer worse when things get slick.

Your efforts to strip everything out to get down to the bare bones in order to build things out properly is to be commended. Seeing all of the ugly under the surface sure points out the necessity of doing what you are doing.

Good luck and happy trails to you!
 

JNHEscher

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MarkObtinaro said:
Interesting about a mechanical -92 series. I thought all -92 series had at least a DDEC I system to operate it.

In regards to the cooling system, every MCI with the twin radiators overheated to a greater or lesser degree. Part of the problem is the system was never sized large enough particularly once the buses went to automatic transmissions. Another part of the problem is due in large part to the fact it is a rear engine bus. Getting enough air flow across the radiator cores was always just barely adequate. I don't know that you will be able to get enough air flow across the radiator cores with electric fans.

MCI had two different sized squirrel cages to move air through the radiators. Most buses that were purchased by someone who was anticipating using the buses in the west and SW would have spe'c'ed the larger capacity squirrel cages. Those buses that were going to see service in flyover country or the east coast generally had the normal spe'c squirrel cages.

I would determine how much air flow you can get with the electric fans. The high capacity squirrel cages were able to move a huge amount of air. It is going to require a LOT of air movement to keep from overheating.

With the advent of the D-model MCI went away from twin side mounted radiators to one large single radiator mounted above the engine at the back of the bus with a HUGE single fan to move air from side intakes to go across the radiator core. While it would require a lot of fab work it might be a better idea to swap in a D-series single radiator than trying to make electric fans do the work to move air.

In regards to the fuel tank, I am not sure exactly why you would want to swap it out for a smaller tank. One of the problems with the D-, E-, and J-model MCI's is MCI moved the fuel tank and A/C condenser from just behind the front axle to an area to the rear of the luggage compartments. That tended to make the front end a whole lot lighter. It helped with weight limits particularly on the 45' coaches. However the lighter loads on the front axle make the newer coaches a bit harder to control on slick road surfaces. Rear engine buses always tend to understeer on slick surfaces. Moving several hundred pounds towards the rear will make the understeer worse when things get slick.

Your efforts to strip everything out to get down to the bare bones in order to build things out properly is to be commended. Seeing all of the ugly under the surface sure points out the necessity of doing what you are doing.

Good luck and happy trails to you!
Click to expand...​
The single, rear-mounted D series radiator has been a consideration. The fab work required would be cool with me. No biggie. Finding one of these rads for a reasonable price without having to travel at least five hours away to get it is another story. I did find that the Flex-A-Lite 180 is pretty much an exact fit the each radiator and moves as much as 3,300cfm, according to their specs. Ideas are still up in the air. I may very well go with something entirely different.

I've been wanting to move all the major engine-related stuff to the rear to make room for everything else towards the front. All weight placement is being kept track of. 142 gallons of diesel comes to roughly 985 pounds. I'm building our rig with the intent to keep us going for a good two or three weeks of boondocking without water or power hookups, if not more. The water tank will go in place of the fuel tank and hold at least as much volume, which will weight more than diesel. Slowly working up all the calculations so weight distribution from front the rear and side to side keep the rubber planted. Our bus had a lot more fuel range than I anticipated, but we think we'll keep the OE tank and slip it into the rear bay for ease of reconstruction and to keep the range. I can see where keeping the tank up front when the bus is used for intercity travels and running without passengers to keep the load even.

All the pointers are still appreciated. It's a big build and I have to consider every scenario. A couple more days into tearing crusty stuff out and we should be preparing to build the new floor.
 

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I'll add a little more on the rad fan for good measure. Every time I've started our bus in our frigid temps, I cannot get the temp gauge to lift at all unless I run the engine hard, which I serious hate to do on a cold diesel. The squirrel cage constantly running pulls too much frosty air over the radiators for the coolant to heat up. The louvers don't work, so that adds to the problem. Albeit a decent fan setup, I still didn't want it and know that the side rad setup isn't quite adequate in hotter climates with steep grades.

Whatever I end up using, I'd like to fab up some ducts to force air across the heat exchange and use the vacuum off the back of the bus to help pull the flow out. I suspect there's something I can do to the engine bay to better the flow over the engine, as well.

For the time being, the engine has been running great without a fan. Thought I'd make note of that. Getting it started and idling smooth happens much quicker and I've been able to run it for at least 40 minutes straight, even with pretty high idle to run the air compressor faster, and it sits just under operating temp on the gauge. Not that I'll drive this without a fan, mind you lol.
 

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Today, I pulled out all of the pneumatic apparatus that controlled the belt tensioner air cylinder and the radiator louver air cylinders. If I keep the louvers, they'll be as reconnecting the feed line to an air source. The thermostatic valve may be faulty, being the reason the louvers weren't working before. I'll have to open it up give it a few pokes. I put a cap over the air feed that dispersed to everything I pulled out today so the rest to the system still functions.

The next task was pulling and labeling all of the wiring leading to the AC and headlight relay junction box that was in the first storage bay. Unused wiring and components will get ditched and what's left that will be needed will get run in conduit that is going to go in the center chase. All wiring, air lines, and plumbing will be installed through conduits in the chase to allow ease of installation, testing, removal, and future additions. The whole bus will be rewired, but I'm keeping necessary systems connected for the time being so that I may trace them all.

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bggrnchvy said,

I would really really rethink flexalite fans to try and cool the engine.

7k cfm isn't even in the right ballpark. I seem to recall reading an 8v92/6v92 cooling fans on buses pull near 40hp at full lock. That's like 32k cfm using a crude calc. Sure it only needs 5hp or less most of the time (less than 10k) and you will be at less than GVWR all the time, but you're still undersized there.
 

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nitecop said,
bggrnchvy said:
I would really really rethink flexalite fans to try and cool the engine.

7k cfm isn't even in the right ballpark. I seem to recall reading an 8v92/6v92 cooling fans on buses pull near 40hp at full lock. That's like 32k cfm using a crude calc. Sure it only needs 5hp or less most of the time (less than 10k) and you will be at less than GVWR all the time, but you're still undersized there.​
X2 I have to agree 100% I can't see a Electric fan(s) working at all in this situation.

And I'll add just as Na engines get less air at higher altitudes so do radiators. they need more airflow to work at the same efficiency.
 

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Sask466 said,

Here is a company that builds fans specially for on-highway applications. I am not fully sure why you would retrofit a newer truck with these, as they all seem to have air clutch fans now, so they are highly energy efficient anyway.

Running down the flat highway, the natural forced air flow through the rad meets most cooling demands. A highway tractor has a big advantage over a bus, as the rad is so much more open to airflow.

http://www.electricfanengineering.co...an-assemblies/


This company builds retrofit’s for specially for transit busses:

http://www.emp-corp.com/products/advanced/Mini-Hybrid/

They are brushless as use 500amp 24v alternators!!!! That’s over 10kw, so almost 15hp of electrical power.
 

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mjlogan88 said,

For reference, newer transit buses run electric fans. Lots of medium sized ones, not just a single big one. One big street side mounted radiator.

The ones I worked around are powered by a Cummins ISL 9.0L which probably doesn't put out the heat that a V8 detroit would.

Looks something like this

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Sask466 said,

I did some digging and their 11” fans are 20ish amps and their 15” is 40 or 50amps. There are 8 fans on that housing. So it would seem you need 200 amps when cooling demands are high.

And that’s on a transit bus, so an 8v92 on a hot dry day up a big steep hill is going to be higher.

Between all the AC and engine cooling requirements on these busses, you wonder when it would make more sense to run everything off of a diesel genset.
 

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The Flex-A-Lites are really just a starting point. Lots to dig into yet. Keep the ideas coming. I have some time to figure cooling out since the floor is a priority and I'm in the process of moving everything to where we want it before it gets trapped under the floor.
 

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Sask466 said,

I don’t mean to obsess over your engine fan choice! It’s that I am working on a project where I had to mount the radiator lower for hood clearance. I plan to use electric fans, but have been pining over how much fan to install. There are no formulas or rules of thumb that I can find to figure out required fan sizes.

It’s a slippery slope - more fans/larger fans means bigger alternator, etc.
 

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Sask466 said:
I don’t mean to obsess over your engine fan choice! It’s that I am working on a project where I had to mount the radiator lower for hood clearance. I plan to use electric fans, but have been pining over how much fan to install. There are no formulas or rules of thumb that I can find to figure out required fan sizes.

It’s a slippery slope - more fans/larger fans means bigger alternator, etc.​
Indeed. More variables than one cares to ponder. Once I get the opportunity to sit and stare at the engine bay for a while, I'll hopefully come up with some mods to increase the static airflow. Where there's a will, there's a way.

I think the stock alternator is only 270 amps. Makes me wonder how it ran the passenger heater core/evaporate blower motor, the condenser fan motor, the overhead blowers, the driver's blower and the 400ish light bulbs on these things. I'm sure relays were set to only allow so many motors to run at once, but damn. I've eliminated all but the driver's blower. Surely this can handle an electric radiator fan or two or four.
 

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Java said,

Most of the time this will be a highway cruiser wont it? How about a giant NACA duct or giant sized scoop ala aircooled VW?

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You would still need fans for traffic/stop and go, but I cant imagine 40+ MPH ram air would hurt, and could possibly cut down on fans needed at least at highway speeds.

Fell free to tell me to fuck off too, just thinking out loud.
 

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87manche said,
Sask466 said:
I did some digging and their 11” fans are 20ish amps and their 15” is 40 or 50amps. There are 8 fans on that housing. So it would seem you need 200 amps when cooling demands are high.

And that’s on a transit bus, so an 8v92 on a hot dry day up a big steep hill is going to be higher.

Between all the AC and engine cooling requirements on these busses, you wonder when it would make more sense to run everything off of a diesel genset.​
is that running amps or startup amps?

You can get away with less if you stage the startups, but then you need a rather complex fan controller.
Batteries can accommodate the huge startup load if they all kick on at once, but wiring is gonna be pretty fucking big.

Personally I'd just stay engine driven if at all possible. Mechanical fans just flat out work and can pull way more CFM than electrics. Especially when you're getting it in 2nd gear WOT going up a hill and the RPMs are up.
 

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SkZuk said,
JNHEscher said:
Ordered in a 4-1/2" diamond grinder wheel and a new trigger switch for my Rigid grinder. Hope that strips all the mill scale off in a decent amount of time.​
ALL the millscale?? You don't plan to mechanically remove millscale from all those sheets do you??? All of it?




PS I agree with the fans. Flexalite fans cant keep most v8 swapped hot rods cool. :flipoff2: You're in heavy duty territory with poor air flow. You'll have to aim misters at your rads and keep 50 gallon drums of alcohol on board for evaporative cooling if you don't run enough fan.
 

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parkers30 said,
bggrnchvy said:
I would really really rethink flexalite fans to try and cool the engine.

7k cfm isn't even in the right ballpark. I seem to recall reading an 8v92/6v92 cooling fans on buses pull near 40hp at full lock. That's like 32k cfm using a crude calc. Sure it only needs 5hp or less most of the time (less than 10k) and you will be at less than GVWR all the time, but you're still undersized there.​
I was working my way down to pass along the same thought.

No clue on this specific application, but we just did some work on an electromagnetic fan clutch for a similar application that is ~50hp for the fan. They were roasting the clutch due to overload in the bus applications. :smokin:
 

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Java said:
Most of the time this will be a highway cruiser wont it? How about a giant NACA duct or giant sized scoop ala aircooled VW?​


5de6af1bb8b220844238c62aee1d796b


You would still need fans for traffic/stop and go, but I cant imagine 40+ MPH ram air would hurt, and could possibly cut down on fans needed at least at highway speeds.

Fell free to tell me to fuck off too, just thinking out loud.
Click to expand...Air ducting is already on my mind. Something similar to the pic. There's ample room for ductwork to be added and room for big air channels throughout to make a hell of a wind tunnel. No need to fuck off lol. Something will come together with help from all the posts.
 

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SkZuk said:
ALL the millscale?? You don't plan to mechanically remove millscale from all those sheets do you??? All of it?




PS I agree with the fans. Flexalite fans cant keep most v8 swapped hot rods cool. :flipoff2: You're in heavy duty territory with poor air flow. You'll have to aim misters at your rads and keep 50 gallon drums of alcohol on board for evaporative cooling if you don't run enough fan.​
I was thinking a bank of CO2 fire extinguishers triggered to unload on the radiators at a certain temp.
 

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Satan's_Minion said,

The airflow required is not so much the issue, its the pressure that will be generated as you try to create that.

The electric cooling systems posted above are in about the 10-15k cfm range and can be from 200-300 amps total on a 24 volt system. Used for transit and some coaches 280-450HP engines.

The restriction of the radiators in those systems are designed to work with the fans at the heat rejection required. Your MCI coach using a centrifugal blow type air moving device means that it is likely working against a very high static restriction, probably at least 4" H20 range. That is where all the horsepower goes.

Power usage is directly couple to the airflow restriction 2" vs 4" = half the power assuming you had 2 different fans systems with the same efficiency at the respective operating points.

To correctly engineer your cooling system you need to know required heat rejection and flow rates and the detailed specifications of the heat exchanges and fan(s). Unfortunately most of that information is not available in the aftermarket world so the best you can do is educated guess.

My recommendation do not even bother with the Flexalite fans, those cfm numbers are not even all that real in the first place plus they are not designed to work against any amount of static pressure that you would find in a heavy duty rad. Delivered airflow will be VERY low.


bggrnchvy said:
I would really really rethink flexalite fans to try and cool the engine.

7k cfm isn't even in the right ballpark. I seem to recall reading an 8v92/6v92 cooling fans on buses pull near 40hp at full lock. That's like 32k cfm using a crude calc. Sure it only needs 5hp or less most of the time (less than 10k) and you will be at less than GVWR all the time, but you're still undersized there.​
 

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Valley Rock said:
Have you made a video of that Old Screamin Jimmy running ?

I am the only one who wants to hear that bastard run ??​
I actually haven't. Got a teaser pic, though. I'm in the middle of rerouting fuel lines, wiring, and the air and power steering lines. It'll be a few before I fire it up again.

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Snow day. Woke up to 3" of it. Had plans to do some bus parts shopping in Santa Fe and Albuquerque. The route we take through northern New Mexico can get heaps of snow, so we opted to push the trip to tomorrow. Not a bust of a day, though.

Stopped in to Car Quest with my power steering hose quote and had those made up. Dudes were super cool. I overheard a customer and employee talking about s-cams. Then I saw the customer unrolling some black line at the back of the store. I asked the guy that was making my lines if the guy in back was working on air brakes. He told me that he was and that they have all kinds of nylon line from 1/4" to 3/4". Told him we just ordered a case of DOT air line and needed fittings. Sure enough, they have every size we need.

The 100' of 3/4" DOT line came in, along with the two-gang weatherproof junction boxes that I'll be using for the 120 volt AC stuff. We're hoping to get all the conduit and fittings we need. Picking up an 80 cubic foot bottle of 75/25 at Matheson as well so that I can start playing with ESAB welder.

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