Very high temperature in Engine compartmentment

[richardkillmon]

I think I need to do more for the high temperatures in the engine compartment.

!. When I go to check the transmission level I have to lay thick rugs down on the engine compartment floor and hold my breathe and rush in and grab dipstick and pull out and get out because of the heat.
Then I wipe down the stick and stick it in and get out.
Wait and minute take a breath and grab dipstick to check.
once checking put dipstick back in and guess how much oil the transmission needs.
The next time the engine is cool  (morning) or after sitting a while - add what you think you need.

2. Just replaced a second valve that the rubber and plastic was old and brittle in that compartment and I see more coming -- I know old bus.

3. The engine runs at steady 180 on a hot day - I have checked both gauges and the run the same. The model I have was only out for one year with V8 but it was put in the V6 frame. The V8 frame is 10 feet longer and has an extra axle and huge engine compartment. I don't have an oil temperature gauge and only radiator gauge and transmission temp gauge. What should the engine compartment  temperature be?

4. If we open more vents to make it cooler, can we make it too cold? Would that do more harm? This bus and owner do not travel in below 40 weather.

5. I have attached two photos - I have seen more and more buses, even Prevost's, that have added slots and vents in the rear doors. They all have said it lowered the temperatures in the compartment. Should I do that?

6. The other picture is the passenger rear side with the engine radiator with scoop and below that is the slotted, side engine service door. Should I add another scoop to this to force air to engine compartment like we did above?

7. On the inside of each door we put a picture so that we can slide in the flat piece of metal if caught in cold weather. Like the old days when truckers put card board in front to the radiator.

thanks

Rick

[RJ]

Rick -

Your post is a little confusing, but I'll try to answer your questions and offer some suggestions. Am I correct that you have a 1976 MCI MC-5B with an 8V71 and an MT-644 automatic transmission? And what do you consider "very high temperatures in the engine compartment?"

1. Accessing the automatic's dipstick is a pain (literally) on MCIs, simply because you have to crawl over the hot muffler underneath the driver's side compartment floor, adding to the heat load. If you'll notice, the curb side is much cooler, comparatively. Unless you've got a transmission oil leak, you shouldn't have to torture yourself very often.

2. What valve are you talking about?

3. Be thankful your engine runs at a steady 180º all the time - that' a good thing! MCIs of that vintage are notorious for overheating - but mostly the 40-foot models, the 35's are usually more stable, unless abused.

Of the 2100+ thirty-five foot MC-5s (266), MC-5As (1548) & MC-5Bs (350), all were built originally with the 8V71 coupled to a Spicer 8844 4-spd manual transmission. (5Bs were built from '71 - '77, btw) Due to increasing demand, MCI didn't officially offer an automatic transmission in the 5-series until the MC-5s came out in mid-'77, but then the MT-644 was only available with the 6V71 engine, due to reliability issues when coupled to the higher torque of the V8. In the last year of 5 production (1980), if you ordered an automatic, you got the HT-740 coupled to a non-turbo 6V92 - I know, I own one, albeit a parts bus. So if you own a '76 with an 8V71 with an automatic, chances are good that it's a retrofit by a previous owner, and not a factory install.

The 40-foot, three-axle MC-7s came out in 1968, and yes, their engine compartments are huge, comparatively, because they were designed originally to accommodate the 12V71 engine, altho none were ever sold that way. The standard powertrain was the 8V71 with the 4-spd Spicer manual gearbox. In late 1973 you could order an MC-7 with an automatic, in this case the venerable workhorse HT-740.

The engine compartment will always be hot, but not as hot as the coolant in the cooling system - which is what you really should be concerned with - but apparently isn't an issue with your coach. Just make sure that all of the cooling air for the radiators is actually going thru the rads and not around them, plus that the blower compartment door seal is in excellent condition as well. The jury's still out as to whether or not scoops mounted at the rear of the radiator intake screens actually work, are simply a band-aid, or just psychologically satisfying. Many busnuts think they're aesthetically ugly.

4. The engine's thermostats control the operating temperature, as well as the radiator shutters (if still equipped and operational.) So even in colder temperatures, the engine will still come up to 180º, it just might take a little longer. And even the engine compartment itself will come up to somewhat normal operating temperatures while running, but will obviously cool down faster with colder ambient air temps when parked.

5, 6, & 7. No photos in the post, so my comments are from memory (and Google Images!): The slotted engine service doors on both sides of the 5B provide sufficient air flow thru the engine compartment as is. No additional scoops are necessary. The exception would be if you were to add an external transmission oil cooler to the curbside access door, in which case you would also need to add an electric cooling fan(s) to overcome the engine compartment pressurization created by the main cooling blowers. MCI actually eliminated these slotted service doors on the MC-5Cs, as well as subsequent models.

Most of the older Prevosts with louvered engine compartment doors have the monster 500 hp 8V92Ts that are perfect examples of turning diesel fuel into heat and noise while attempting to push 45,000 lbs down the super slab at 70+ mph. Newer coaches (2010+) are adding the louvers because the EPA's smog requirements have heated up the whole back end of the bus. Overkill on your little 28K coach.

Now here's an idea you should consider that's a leaf out of GMC's engineering book for their coaches, starting with the 4104s in 1953, : A full-width mudflap directly behind the rear axle - which is basically a continuation of the mudflaps behind the duals. What's the purpose? GM discovered that this created a low-pressure area directly below the engine compartment, thus helping to naturally draw hot air out while rolling down the highway. Now, granted, the V-drive GM's have the engine compartment bulkhead right in that location, making it easy to install the full-width flap. It's a little trickier with the T-drive MCI, but it can be done, MacGyver-style, and with similar results.

Hanging a mudflap, or one of those brush-style flaps off the back bumper completely disrupts the natural hot air exhaust flow out of the compartment, potentially leading to overheating issues. If you have one, move it up behind the rear axle. "But it's there to keep the schmutz off the toad!" If that's the case, you need to fix the oil leaks and install a "catch can" for the airbox drains (slobber tubes) to control the schmutz.

Don't know if this answers your questions, but hope this helps.

[oltrunt]

Nice wright-up.  Jack

[richardkillmon]

Wow you are amazing. Who are you!! you are correct on almost everything.The stuff that is off is do to after market add ons.  thanks you for answering. I did a bad job in writing the post and you didn't know my history on the bus but you nailed most of it. I'm sorry and should have wrote all the past work. I do better and here we go:

My bus was featured in BCM Dec 2021 and the previous owner installed the Allison MT-644 trans in this bus. On the passenger side of the engine is a transmission oil cooler installed with engine coolant lines attached.

I did a lot of replacing of parts due to my dream of driving around the US touring sites. I can drive 12 hours without even thinking, I know I'm sick person but driving and looking is fun for me. So I'm a preventive overkill person and I want no break downs (right). I replaced so many things to prevent work on the rode. $$$.

Here is just a sample of this: When the bus was 95% done I took it on a 20 day test run -- from Ft. Lauderdale, Florida to Breakenridge, Colorado in August.
I climbed to 14,000 foot elevation, hills, and summer heat. and tow car. Couldn't abuse the bus any better.

Guess what? I over heated. It is funny now but not then. As I climbed a hill slow and reached the top as the engine temperature was reaching 200 degrees I would roll over the top and cruise to the next hill climb with engine cool and start the slow climb again. The temperature would rise and cool each hill. I prayed for the last hill each time. Oh Lord please be the last one. On one of this event as I started up the hill and the bus went into to turtle crawl mode and slowed down and engine being bogged down and then it happened -- it's not blogged down the engine stopped. Once I realized this I barley got to the shoulder. I was hanging one foot into the slow lane.
My temperature was 210 and basing on your IQ of buses you already know what happened. I learned later. I spent 30 minutes checking the engine for oil and coolant. I opened the fuel tank to see if maybe a fuel vapor lock up. I was trying everything. Then the engine fired up and I continued my drive up and down the mountains for another week and that never happened again. I was asking all my experts what may have caused the shut down. I got a few answers but none were the correct one. As I was returning to Florida and stopped in Texas for fuel; a gentlemen parked in front of my bus in his pick up and waited until I was done fueling and started talking about he had a bus and so on. I gave him a tour and he asked how was it running. I told him about he engine stop and you guessed it - he said the fuel pump shuts off at 210 degrees as a safety device so you don't ruin the engine and drive hot. When I was checking stuff at the time - the engine cooled and I could start it. I never got the engine that hot again during the trip.

When I arrived back to home port, my friend, who has never worked on buses but have a long history with dragsters came up with a plan. First thing was I removed the radiators and had them cleaned. They were not bad but they needed cleaning. When we put them back I replaced all the rubber around them to seal the air intake. I even sealed the underside with high tempempture silicone so the intake was at 100% no leaks. I was told the the squirrel fans were designed to work at 55 MPH. That was the national speed limit back then So when I went over 65 HPH the temperature rose due to the air passing by the radiators was so fast that the fans couldn't t pull in the air in. I cruise at 75 MPH. I put scoops on the radiators. I replaced the thermostats.
You mentioned the service door on the squirrel fans. You have hit the big one. My gasket was gone and the system is designed to be sealed so the fans can only pull air through the radiators and not through the door. I replaced the gasket and put caulk on every hole or around hose or wire etc. I wanted a 100% air tight compartment. I know over kill but it worked. Now at an idle I can trow a tissue up at the radiator and it sticks to the grill.
Next I sent the exhaust manifolds pipes and cross over pipe to a special metal treatment plant for heat coating. In addition, I had the cross over pipe wrapped in an exhaust insulation wrap they use for boat generators.
We discovered that my after market canister air filter was not connected to the air duct work in the side wall of the bus the leads up to the radiator intake. I originally had oil bath air filter system. My system was pulling air from the engine compartment. I would clog my filter in 3,000 miles. My friend who is a metal fabrication God built duct work that fixed that. I now have cool and clean air going to the air filter. The previous owner had a Peterbuilt truck filter installed. Very big filter and $$$. But clean air is good.
One of the devices I have changed was connected to the fuel filter. I don't know the correct name for it but I was told that it is a safety device the prevents the starter from being engaged if the engine is already running. One side of the devise is getting fuel pressure which touches an electric switch to stop the starter. The rubber gasket inside the device was old and hard, which caused a fuel leak. All the plastic, rubber, and wires were in bad shape. They were hard and brittle.
Another device in the compartment I changed was an air deverter valve for the brakes and air system. It fills the priority systems first and then the other systems as air system is building pressure. This had to be rebuilt and I found the same thing with the rubber "O" rings. Hard and brittle. This devise was only put on buses for one year and not ever again.
I know, old bus what did you expect. As you know there are many rubber, etc. items back there and they all are exposed to age and heat but I would like to reduce the heat. As I walk around the engine the heat that is coming out I feel is extreme. I have been around 18 Wheelers, boats, planes, and cars but never felt this much heat. I know I need to put a thermometer there. I just fells too hot. Like I said I drive 5 hours straight and only stop for fuel. I let the engine cool before turning off and check the fluid levels, fill up and go another 5 hours.
Again you were right on about the side doors. On my model the doors were solid but the previous owner did some modifications  to them and put in slots. I can only speculate he did this for cooling. I have had many people as they walk around the bus and come to the back end and stop -- they make a comment about - wow hot here.

I do have a slobber box and just fixed two oil leaks on the engine. I'm on my third month of a 9 month maiden voyage. I left Ft. Lauderdale enroute to Mt. Rushmore, Yellowstone, red woods etc. I have been during 5 or 7 days stops on this west coast tour. this is the first time that I'm sitting for a month. I have a tow car I use to sight see and here is so many thing to do here. Soon I will start the road again with 5 day hops until Dec. which I will be back in Florida.

I'm old/dumb and have issues with this site and putting pictures on. I hope I got it right this time.

I would like to talk to you on phone because my fingers ache noe LOL.
thanks for answering and you are good.
Please let me know if the pictures are there and if you have more input.

Thanks

Rick

[ts311@yahoo.com]

where can i find the scoops for the radiators.  looking to out them on mine to aide in cooling.  also will be venting the engine bay bottom 2 doors along with the top door.  also where did you find the insulation for the exhaust.  looking to do the same

[RJ]

where can i find the scoops for the radiators.

Name? -

Scoops were originally made by a company in OR that is no longer in business. Nowadays if you want a pair, you have to fabricate them yourself. They're also just a "band-aid" solution that really aren't that effective in conditions where the engine has a tendency to overheat. Far better to make sure the radiators are in excellent condition, that they're sealed properly so all the intake air goes thru them, not around them, that the squirrel-cage blower compartment door seals properly, and the air cylinder belt tensioner is working correctly. One other tip is to make sure that the exhaust side of the squirrel blowers is approximately 14" square blowing down over the engine. Some early production coaches only had a 7" x 14" opening.

. . . also will be venting the engine bay bottom 2 doors along with the top door.

Venting the rear engine compartment lower two doors is fine, International Bus Parts in Apopka, FL, may have them available, or can make them for you.

Venting the top engine bay door where the squirrel cage blowers reside will totally negate what you're trying to do. Think about why.

. . . also where did you find the insulation for the exhaust - looking to do the same.

Altho not exactly the same, there's an advertiser here on Bus Conversions Magazine that sells a similar product, "EHP" I think it's called. Poke around on the main BCM website and you should be able to find contact info. Be aware, however, that this has a tendency to shorten the lifespan of the wrapped exhaust components, some of which are becoming very difficult to replace. Also consider that Greyhound ran all over the country with the turbo engines and never wrapped the exhaust on any of their coaches. I have a 500hp 8V92T in the back of my coach, and it's exhaust isn't wrapped, either.

Finally, don't hang a mudflap or brush off the back bumper - that traps the hot air trying to escape from the engine compartment.

FWIW & HTH. . .

RJ

[luvrbus]

Wow does this come in the paperback edition or hardcover only,engine compartments get hot with the EGT above 500 degrees on the N/A 8v71.I am not a fan of the wraps on N/A engines, on turbo engines it helps ,turbo boost gets rid of some of the heat and wraps are proven for adding boost on the turbo engines,seldom do you find diesel engines in boats not wrapped for heat expelling even with the water-cooled manifolds.In short engine compartments are made for the heat and buses are the worst for heat build up ,2 stroke cooling is on the driver most of the time they have always been hard to cool because they never relax, one is always under constant firing.It takes a well-kept system too the system has to reject a lot of BTU produced by the 2 stroke engines     

[Van]

I tthink scoops won't help.

  "1994 mci conversion.  Shelled out.  Found rusted areas in walls.  Steel.  Does anyone know where i can find metal for it.  Is there any prefab metal or does it need to be made.  Looking to remove old air filter system, all the weight and replacing with CAI and does it need the other air intake rube other than the turbo.  [Removed squirrel cage fans in back and replaced with x6 3000cfm each for radiators.  Is that enough tp cool a 6v92].  I have more more questions but this is a starting point"

[RJ]

I think scoops won't help.

Van -

After following up on the post you quoted, and reading the related threads, sounds a bit like Two Dogs, if you remember him. . .

RJ

[luvrbus]

Van -

After following up on the post you quoted, and reading the related threads, sounds a bit like Two Dogs, if you remember him. . .

RJ

He is still around in the Rio Grande Valley but not as 2 dogs he is 3-perros now ( 3 -Dogs )I got a Email not long ago he was looking for an Eagle part

[Van]

Van -

After following up on the post you quoted, and reading the related threads, sounds a bit like Two Dogs, if you remember him. . .

RJ

Yep! But just removing the squirrel cage fans has me scratching my head.

[ol713]

where can i find the scoops for the radiators.  looking to out them on mine to aide in cooling.  also will be venting the engine bay bottom 2 doors along with the top door.  also where did you find the insulation for the exhaust.  looking to do the same

     EHP are the folks with the exhaust wrap.  @ (951) 302-2212.  tHEY ARE BCM  advertisers.
                                              good luck.