Have driven coach from Arcadia to Virginia so far. It has run perfectly. 21 psi of boost, 70 psi oil pressure, pulls hard and strong like a 500hp fresh rebuild should. I'm still breaking it in. Will be doing my first oil change on the new engine in Pennsylvania swapping out the 30 weight break in oil for the 40w delvac per Leid Diesel instructions. I have only one issue and Leid told me not to worry about it but I still do:
The coach is running really cool. As in, when we left Florida yesterday it was in the mid 80°'s and the highest temp she could muster was 175° running around 70mph. Today we're further north and high temps are in the 70°s and it only mustered the high 160°'s unless I pushed it 70mph or more. I tried to stick to around 65 mph with one short stint to 83 mph while passing. I did remove the transmission fluid heat exchanger and install a Hayden trans cooler with twin cooling fans on it. So that took a heat load off the engine coolant for sure, but I'm really concerned if I'm driving the coach in any weather in the 50's or below that I'll need to block off a radiator. I have brand new twin 180° tstats installed and Leid Diesel confirmed this when I called and asked them about it. But it just isn't building heat. How concerned should I be?
My bus ran at 175, never bothered me....if it started running hotter then i kept a close eye on it. Heat will kill it just about faster than anything......except running out of oil. :)
Scott,
Sorry I don't remember the details of your setup, what is the source for the temp readout? Is the signal coming from the engine computer DDEC? Or from an added sensor to the engine? The point being to check the coolant temperature independently to verify the reading at the cockpit is accurate.
170 degrees is minimum for a 92,you may need to switch to full closing thermostats,what is the temp on the Allison they don't like cold temps either
Different vehicle same issue for me. My '04 GRAND MARQUIS has a bad thermostat that where the temp. is almost always near the cold section according to the gauge. Better to be too cold than hot all things being equal. However, it may effect you MPG, since at least a FORD transmission, it doesn't go into lockup unless the engine is above a certain temp. A bit louder too since it runs a bit faster. I think the ALLSON behaves that way too.
You wont be sorry when the ambient temps are 90 and climbing a long grade..>>>Dan
Classic symptom that thermostats are not working properly. I'm no expert but assume a bus without circulating water will register over 180. Otherwise, radiator shutters are supposed to take care of very cool ambient temps, right?
Quote from: windtrader on May 14, 2020, 03:35:39 PM
Classic symptom that thermostats are not working properly. I'm no expert but assume a bus without circulating water will register over 180. Otherwise, radiator shutters are supposed to take care of very cool ambient temps, right?
Not the case the 92 series and 71 use a "Weir" type thermostat his cooling system is in great shape and the rebuilder has the engine well tuned or he would generate more heat.I always carried a full blocking thermostat for my 8v92 in extreme cold weather I would install it on 1 head to get the temperature up he doesn't have a problem ,let him cherish the moment it will change in July,fan clutches replaced shutters years ago
Isn't the part of the reason many buses were equipped with Webasto heaters? So the coolant would be hot enough to produce heat inside the bus?
The webastos weren't used to heat the coolant of a running coach. Rather to heat the coolant on a cold day so the bus would start, or to provide quicker heat for the interior. I will ask Leid about the full closing tstats cliff. To answer the earlier question, I'm getting my readings from the DDEC II computer and they are exactly matching the readings from both the mechanical engine bay coolant temp gauge and the dash gauge. Running too cool.
Scott diesel fired boilers like Webasto were used to warm the temps up on a running bus too ,the DL with the series 60 really needed the help in cold temperatures
Even when the t-stats are closed the bypass is still circulating coolant, sounds like your got a solid rebuild, be happy
Well Scott I would let you have a little heat coming Off my turned up 8V92TA if I could. It has me watching that gauge here in Texas when temp is running over a hundred pulling my tow car. Hope you get it figured out. Know you will. 8)
Cliff, 4 strokes, yes they need help sometimes to build heat but I've never ever heard of someone using a webasto on a warm two stroke to keep the coolant warm other than for starting purposes. I have no idea how this will play out this winter. But we will see. I may have to reinstall shutters.
I didn't know you have shutters for it. Just reinstall.
Scot sounds like you have a good cooling system and a good running engine.
On Huggy i have to take it easy in the summer and in the winter carry my cardboard for the radiator.
Uncle ned
I had the same problem when Leids rebuilt mine and the shutters were used a lot in the cold weather and for a short time I used 190 deg thermos but found after the engine finally got hot the 190's were to hot so went back to 180 's . if you can fix the shutters
dave
You know how many guys here wish they had your problem?
Just use a full blocking set of thermostats, how cold is the transmission running believe it or not Detroit engineers knew what they were doing with the double oil cooler, are the 2 blower doors above the engine open or closed ?, 168 I wouldn't worry to much about it
Good real life benefit of installing the separate trans cooler.
Good real life benefit of installing the separate trans cooler.
Quote from: chessie4905 on May 17, 2020, 05:24:51 AM
Good real life benefit of installing the separate trans cooler.
Not really Allison wants those transmissions running between 180F and 220F for long life,you check the fluid level at 180F
could you put a switch up at the dash to turn on and off the fan for the trans cooler ?
I installed a switch for the cat rad fan on the dash with a light , as when I got the coach the rad fan was on hi all the time and it took forever to heat up and if it was cold out it never did . now 95 % of the time I run the fan on low and only turn it on hi if I am pulling a large grade and the temp goes down fast as soon as I turn it on .
on a plus side my mileage went up from the 6.7 all time on the cat computer to 8.1 now and that is in a short 3 year time frame . but now I control the fan setting so I need to watch the temp gauge now and then . but do that anyway
dave
Part of the installation would be temp control sensor for fan/s. Also most of the heat issue conversions are non electronic Allisons that aren't so fussy about temps.
I'm not disagreeing with cliff, cause I respect his years of knowledge but it's important to note that I have had extensive conversations with an Allison trans specialist in Maryland who is one of the last guys still supporting the 700 series trans. He's very very familiar with the the 740/748 which are nearly identical transmissions one just has electronics, and he said running a cool 700 series will absolutely not hurt the trans. He said the trans will heat up its own fluid to a good running temp and be fine. If it's super duper cold weather, he recommended not turning the trans cooler twin fans on, but he said he's seen large trans coolers on the 700 series is with no coolant exchange system in the mix running cool temps their entire lives without causing any damage to the trans. I really pushed him on this subject because I was worried about this and he assured me very confidently that heat was the greater of the two enemies much more than cold would ever be unless I was running in northern Canada. I'm absolutely glad I removed the coolant heat exchanger because I'm running amazing temps for a 500hp two stroke. Very very happy. I run the trans cooler fans all the time right now and will only turn them off once I'm seeing cold winter weather.
Excessive heat build up over 220F is the enemy not normal operating tempature,Allions will only heat in the torque converter mode or wrong fluid levels not in lock up that is why a fire trucks have a lock up when pumping is to prevent excessive heat.Watch the heat when you use the retarder those will heat in a hurry so will the World Allison with the retarder
I am definitely curious how hot it gets when I activate the retarder. I love the retarder as I don't hardly have to use the brakes now for a normal slowdown to stop. I am running a fresh filter and fresh transynd fluid in the trans so that helps.
I have the retarder too so your experience with that will be helpful to me.
Jim
All the retarding/braking energy that used to become heat at the brake drums, goes into the transmission.
Physics, the energy has to go someplace.
It is incumbant on the driver to still throw the gearbox and engine into the mix to help slow/control speed.
Scott has an isolated cooler, with its own fans, Jim, you need the high revs of a downshifted engine to circulate coolant hard, and for the cooling fans to spin hard, to dump the heat overboard.
What killed the B500R in the DL was drivers going down mountains, in top gear, retarder on full, engine idling, huge heat into the transmission cooler, and no where for it to go. Burned Transynd was one symptom.
As the problem emerged back then, Allison demanded frequent fluid changes or would not honour the warrenty.
So, no free lunch, driver still needs to be smart, and do the right things, to share the load, and maximize cooling.
Happy coaching!
Buswarrior
Quote from: Scott & Heather on May 25, 2020, 05:42:16 AM
I am definitely curious how hot it gets when I activate the retarder. I love the retarder as I don't hardly have to use the brakes now for a normal slowdown to stop. I am running a fresh filter and fresh transynd fluid in the trans so that helps.
With a retarder you need a gauge on the torque converter they can get over 350F in a hurry and 330F intermitted use is all Allison says is ok,? is your joy stick control or pre set with just the switch
If not mistaken, a retarder on newer engines performs what Jakes do on earlier 2 strokes? If so, then are there guidelines and considerations for possible overheating of the older trans?
Quote from: windtrader on May 25, 2020, 10:38:48 AM
If not mistaken, a retarder on newer engines performs what Jakes do on earlier 2 strokes? If so, then are there guidelines and considerations for possible overheating of the older trans?
Retarders where mostly on buses for quietness for the passengers for a long time, the newer engines in the buses and trucks have the Jakes integrated into the engines,my ISX Cummins even the turbo is part of the engine braking now days and does it ever have a good engine brake I have never found a place to use 3rd stage yet
Quote from: windtrader on May 25, 2020, 10:38:48 AM
If not mistaken, a retarder on newer engines performs what Jakes do on earlier 2 strokes? If so, then are there guidelines and considerations for possible overheating of the older trans?
Retarder is a device associated with the transmission, and its purpose is the same as a jake/engine brake, to extend the life of the brake linings by taking on some of the slowing of the vehicle.
In particular, they have allowed for higher downhill speeds in the mountains, from days gone by, as they take on the heat that would have fried the brakes and caused a run-away.
The engine brake spews that heat out with every gulp of air, and some to the radiator.
The transmission retarder puts all that heat into the transmission fluid, and then must be dealt with by the cooling system.
As luvrbus said, retarders are silent, and do not disturb the passengers or the neighbours, especially in transit bus operations. But the heat has to be managed...
Nobody explained this to the bus fleet owners or the drivers as plainly at the time, "buy this, your brake life problems will go away..." was a lot of the sales talk.
Not a lot of materials with detailed operation instructions beyond basic function.
Keep the revs high coming down the mountain, that's about all you can do, except go down the mountain more slowly, putting less energy into the fluid.
Just like managing your brakes without these aids.
Happy coaching!
Buswarrior
I find retarders are usually quite abrupt engaging and disengaging. And they do put a lot of heat in the transmission. I prefer Jakes.
JC
Quote from: lostagain on May 25, 2020, 04:38:07 PM
I find retarders are usually quite abrupt engaging and disengaging. And they do put a lot of heat in the transmission. I prefer Jakes.
JC
Idiot engineers and fleet managers crank them up in the settings and then leave the driver looking like the one who is tossing the passengers around with "rough braking"
Automatic application with a brake pedal touch are horrible...
All the behind the scenes people care about is brake life, not passenger comfort.
The multi-stage, driver controlled retarder joystick on a B500 and siblings, is a lovely way to give a smooth ride, and save the brakes.
Happy coaching!
Buswarrior
The Joystick puts the driver in control only way to go IMO, on the Allison when you flip the switch you get the % the transmission is pre set for like 33,66,or 90%
Since Jakes do engine decompression, thereby creating less heat to be manage, then it seems the best approach to dissipate heat generated by the engine, transmission, and brakes, correct?
Sometimes Jakes alone are insufficient to manage lower downhill speeds and downshifting transmission help keep speed down, is the transmission working overtime when working as a brake and generating much heat? Is the transmission cooling system in the MC8 designed robustly enough to carry this heat away?
Some buses used the Telma electromagnetic retarder on the drive shaft they had their advantage and dis advantages