When I bought my bus it had a 4" straight pipe (really restrictive for 475 8v92 right or wrong? ) she would get warm pulling the mountain passes but managable with a radiator mister so I thought I would put a 5" exhaust system on it took 3 elbows for room to get it down and out the back with a short straight throw muffler I also wrapped the pipes to keep the heat down in the engine compartment hoping to solve the problem all together to my total surprise it wouldn't even pull the hills of north dakota on a hot day without having to pullover and let it cool down so thinking stuck thermostats I put new ones in no difference pulled the muffler off seemed to help I can get through the dakota's now but I'm not sure I can pull a pass on a hot day kind of scared to try. What the hell did I do wrong? Clifford any thoughts.
Have you used an infra red gun on the rad? Might be plugged.
What bus?
Some of them are really not capable of cooling 475 hp without religious attention to the cooling system, and still have to be driven like carrying a live grenade.
Might be nothing "wrong" with the existing bits, just overwhelmed?
Happy coaching!
Buswarrior
Bill it's got a new oversized radiator bigger then the screen door not sure how they got it in there and 5 core thick no I haven't used a ir gun on it because it new. Thing is I drove it home from Nevada after I bought it in the heat over passes with the 4" exhaust pulling a toad with no big issues all I did was increased the size of the exhaust to 5" I don't get it should have helped not gone backwards. I have heard the water pump impeller can spin on the shaft if the nut comes loose could be coindinence I guess haven't checked that yet. buswarrior I realize what your saying It was managable when it had the 4" pipe but not the 5" pipe.
Quote from: tr206 on August 22, 2022, 07:00:35 PM
Bill it's got a new oversized radiator bigger then the screen door not sure how they got it in there and 5 core thick no I haven't used a ir gun on it because it new. Thing is I drove it home from Nevada after I bought it in the heat over passes with the 4" exhaust pulling a toad with no big issues all I did was increased the size of the exhaust to 5" I don't get it should have helped not gone backwards. I have heard the water pump impeller can spin on the shaft if the nut comes loose could be coindinence I guess haven't checked that yet. buswarrior I realize what your saying It was managable when it had the 4" pipe but not the 5" pipe.
A 475 hp 8V92 the min is 5 inches with no bends, the air cleaner should be at least 1500 CFM on the 92 @ 475 hp
Clifford I here you, I can run the exhaust straight out the side of the bus it would be about 2 1/2' long straight pipe but I worry about the noise but it's the only way for no bends. Air intake is acceptable I think 7" tubing with a 2000 cfm filter again can't go with bigger tubing no room. With that said it still ran cooler with the 4" straight pipe with two bends any explanation for that would be appreciated?
outside air temps the same both trips?
Quote from: tr206 on August 23, 2022, 04:09:31 AM
You have something else going on the 5 in exhaust is not the problem, time to chase it down with a IR gun ,the water path in case you don't know it goes from the water pump through the oil cooler first,could be if a auto transmission it is causing the heating by not locking up or wrong fluid levels .The 8v92 has to reject a lot of btu's to cool and everything needs to be just right, those water pumps are 65 to 95 GPM , ? what model of bus is it.
After working on Van's 8v92 in his H-40 lol I look for shop towels left in the cooling system that rears its ugly head after a period of time
To finally get our 8V92 to cool after doing everything else, I installed a very large cab over diesel radiator with 6 electric fans with the radiator grill on the back can't tell where I'm coming or coming or going. I still have to be careful but it worked for me. Bus is a MCI 7 and they came with smaller radiators.
Quote from: edvanland on August 23, 2022, 09:39:04 AM
To finally get our 8V92 to cool after doing everything else, I installed a very large cab over diesel radiator with 6 electric fans with the radiator grill on the back can't tell where I'm coming or coming or going.
What direction is the airflow through it?
John
ok. Outside air temp's probably close to the same and I wasn't pulling a car when I had the heating issue either. Radiator like I said is big and new fan belts are tight. Clifford the tranny was rebuilt at Global idustial automatics in Tucson AZ your neck of the woods 7/24/2017 trans oil bulk at ever that means but 99% sure it's plain atf smells like it and it's red. How do you tell if it's locking up or not shifts the same as when I bought it? Model bus is Eagle 05 Lewis use to own it. I will post pictures of the old and new exhaust lot of bends I know but it was the only way I have seen more curve on trucks but they didn't have detroit's in them. Also what are the chances of the water pump impeller slipping on the shaft? Icenti John air flow the fan sucks outside air in. Air intake has been replaced to 7" tubes and disposable 2000 cfm air cleaner after the fact that's not in the pictures I guess I'm as sure that will help as I was about the larger exhaust.
If it ain't broke,, don't fix it..>>>Dan
I here yeah. Vee band on the exhaust side of the turbo was broke so glad found that anyway. If it ain't one thing it's six.
Years ago I redid the exhaust system. I used the muffler that was specified for the 8V71 only to overheat in 50 miles. Turned out the muffler was chocking the exhaust causing the overheating issue. I now run a 5" in and out resonater style muffler with no issues.
tap a pressure gauge after the turbo and see what it is at full throttle in 3rd. May need to run tube and gauge to rear side side window and duct tape fast and have someone watch and report.
Quote from: chessie4905 on August 24, 2022, 06:13:09 PM
tap a pressure gauge after the turbo and see what it is at full throttle in 3rd. May need to run tube and gauge to rear side side window and duct tape fast and have someone watch and report.
Agreed. Only way to take the guess work out of it.
Take a IR gun read the temp at all 8 ports on the manifolds they should all be close on both sides, then read the tip of the 5 inch pipe,the 5 inch pipe is not your problem though ? how hot is getting and how long does it take to overheat, back pressure will make the 8v92 smoke terrible, another? does the engine have a bypass blower, with the IR compare the reading on dash gauge if you haven't yet by the size of the radiator you mention sounds like it is the right size for a Eagle with the 8v92,the exhaust pipe should go out the rear on a Eagle not the radiator side
8V-92TA is THEE hardest engine to cool (except of course if you have a 12V-71TTA). Many have put a second radiator-like Ed Van. Mainly because most of the buses came from the factory rated at 400hp. Then pump them up to 475 or 500hp and the over heating starts. Many times a 2 tow aluminum radiator will cool better than a 5 or 6 row copper/brass. Good Luck, TomC
Eagle and Prevost usually don't have a cooling problem with a 475 hp 8v92.MCI never rated a 8v92TA over 360 hp till the C with the rear mounted radiators those would run cool at 450 hp
Clifford I will have to get a ir temp reader. It would get to 200 degrees 2/3's way up a mild hill in the dakota's it was about 90 plus degrees OAT (radiator mister seemed to have no cooling effects) I wouldn't let it go higher so I would pull over it took a good 5 minutes to cool to 180 I finely thought about taking the straight through muffler off that night the next day was cooler and it ran cooler 185/190 in the hills still cancel our trip and went home. Don't know what a bypass blower is? I've got a 1/8" npt weld in bung coming to plumb in a back pressure gauge it's cheap then I will know for sure or not. Like I said earlier I brought it home changed to a 5" exhaust and the oil and headed west a month later then the heating issues started. I will let everyone know what the readings are in two or three week. Thanks to all for know.
Quote from: tr206 on August 25, 2022, 06:05:25 PM
Clifford I will have to get a ir temp reader. It would get to 200 degrees 2/3's way up a mild hill in the dakota's it was about 90 plus degrees OAT (radiator mister seemed to have no cooling effects) I wouldn't let it go higher so I would pull over it took a good 5 minutes to cool to 180 I finely thought about taking the straight through muffler off that night the next day was cooler and it ran cooler 185/190 in the hills still cancel our trip and went home. Don't know what a bypass blower is? I've got a 1/8" npt weld in bung coming to plumb in a back pressure gauge it's cheap then I will know for sure or not. Like I said earlier I brought it home changed to a 5" exhaust and the oil and headed west a month later then the heating issues started. I will let everyone know what the readings are in two or three week. Thanks to all for know.
Back pressure on the 8v92 is 3.0 in mercury that is about 1.5 psi could be tough to read with a cheap gauge,those engines need to be around or above 1700 rpm when under a load to keep cool
Quote from: tr206 on August 25, 2022, 06:05:25 PM
I brought it home, changed to a 5" exhaust and the oil and headed west a month later then the heating issues started.
tr206If I'm looking at your photos correctly, it appears that you have at least five, if not six, 90º elbows, plus two 45º elbows in your exhaust plumbing. Going to my charts from my days in the pool industry, you've basically got the equivalent of just under
70 FEET of straight pipe restriction in your system! I think this is a lot of your overheating issue.
If this were my Eagle, I would come straight off the turbo into a 90º "sweep ell," then down to another "sweep ell" pointed towards the rear of the coach and finally into/out of a 5" resonator with a short, straight tailpipe. Or leave the resonator out, as the turbo muffles a lot of the exhaust noise anyway. All of this should be on the curbside of the engine.
FWIW & HTH. . . ;)
RJ
Clifford thanks for the spec's. my theory is I will try 0 to 8 psi gauge if it's restricking it should show. and RJ you may be right we will see.
When you need it you never can find it,I am looking for my Detroit engineering bulletin 134 that tells you the size of pipe and the restrictions for 2- 90 bends in a exhaust system on a 8v92
your transmission isn't running hot=extra heat? Downshifting on grade? my trans (8v92 with allison) in last coach ran 20 deg higher than engine until I got correct fluid in it. FWIW
My favorite, is that dash gauge correct?
All you have to do is breathe on the old wiring in the engine room and you can screw with the resistance...
You were in there swinging pipes around...
The wildly inaccurate behaviour of old dash gauges and their never replaced wiring have made more work for more busnuts...
Happy coaching!
Buswarrior
What is the "correct" tranny fluid I am assuming whatever type of atf they put in at the rebuilder is correct not sure? As far as temp gauges there are two separate temp gauges both are close to the same readings one on the motor and one indash. I will see what the backpressure is if it to high I might just get some of that insulated stainless chimmey run it up the corner of the bedroom and run the exhaust up through it and out the top of the roof that way there is only one 90 degree rest straight and would blow the noise up too. What do you think?
The gauge on the motor can be read during your indicated hot conditions?
Everyone agrees sitting parked, but...
Nothing linear about the irregularities of a dash gauge. Real temp went up 3 degrees, dash gauge goes 15...
I had an assistant, with an IR gun, shoot the big pipe coming off the top of the engine, down through the floor access, heater needs to be calling for heat to ensure some flow, and the assistant can call out the readings and driver can compare the dash gauge "in the moment"
With some big money and big headaches on the line, you gotta be sure you really have a temp climb...
Happy coaching!
Buswarrior
You are correct buswarrior. I have to get a good ir gun. I have compared the gauges on the way down as fast as I can walk back and forth while it's cooling down for what that's worth. Still gonna start with backpressure check I got to know.
The interesting part of this saga is your statement that you did not have a problem ,,,until you "fixed" the problem.. You have been on a goose chase since..>>>Dan
Quote from: robertglines1 on August 26, 2022, 08:54:04 AM
your transmission isn't running hot=extra heat? Downshifting on grade? my trans (8v92 with allison) in last coach ran 20 deg higher than engine until I got correct fluid in it. FWIW
What fluid was previously in it, and with what did you replace it?
John
It was rebuilt shortly before I bought it repair bill just said bulk oil I haven't changed it I have replaced the filter like I said earlier smells like atf and it's red. very low miles on the oil due to age I should change it soon though.
Well I said screw checking the back pressure removed and installed new exhaust new is 3 1/2' long straight pipe total length including 1 90 degree elbow that's it seems to run much different, first time I have heard the turbo whistle ever. Hope that was the overheat cure we'll find out in the future.