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Question about cooling
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thanks for the ideas! I think one fella misunderstood about the radiator. I replaced the radiator, NOT recored my old one! Also when I did that, I installed all new blue silicone hoses so I doubt the hoses are collapsing! I do know that my shutter system was not functioning at all due to major rust and when I replaced the radiator, I left the shutter assembly off! I will look in the morning to see if there is a gap of sorts that I need to close up. I’m thinking that the gap I’m looking for is at the top of the radiator or any surrounding area of the radiator?
I also am using a small silver leaf box that is plugged into the coaches wiring that reads directly off the ddec! The dash gauge reads close to 199 to 200 when the silver leaf reads 193ish.
The silver leaf reads around 196 while running 68-70 mph at around 1800-1900 rpm on flat interstate, no trailer or road, and ambient temps around mid to high 70’s. I think I have to get this figured out way before summer heat comes! Oh and to add, I used to have a myster installed that would drop the temps after being on for about 5 or so miles! I left it off after re-doing some bay plumbing but can easily put it back on!
Thanks
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Ace, from my memory banks I seem to recall that around the early 90’s on DDEC engines folks realized they could bump up the horsepower without any other changes other than some DDEC programing or a chip replacement.
The problem was as horsepower increases there has to be an equal or greater increase in the ability of the cooling system to reject heat. Since nobody did that because it involved larger radiators and additional cooling slots in the engine bay doors just when the driver could make use of the increased HP, DDEC was taking it away in response to temps beginning to push the upper limits of the coolant temp.
As a seated coach I would guess nobody messed with your HP, but if it is possible someone did such as an engine swap that might be part of the consideration.
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Hi Ace,
My H3 has a rubber seal on the radiator door that is supposed to seat againt the shutter assembly to force outside air in to the radiator. The seal is all the way around the perimeter of the door. If you still have the assembly I would replace it and if it does not work lock it open to at least control the flow of air.
I am still looking for one so that I will not have to fabricate it to go on mine but so far have not found one.
One other question. The H3s had 2 different radiators for our models with the 39 inch wide being the largest. I do not remember what the other size was but hopefully yours is the 39 inch wide radiator.
Are you going to be at Stone Mountain in May? We are planning on being there.
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The radiator perimeter should be sealed AND there should be a shroud around the fan.
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just went out and looked at my radiator. After replacing the radiator a year ago or so, the shutter assy was left off due to it being badly rusted and not functional. There is about a 3 inch gap between the outside of the radiator and the inside of the radiator grill or body work. Does this need to be filled in? If so, what is it I should use? Thinking last night about the rise in temps, it only happened since the radiator replacement and it boggled me as to why a new radiator would run hotter than the old dilapidated one that wasn’t leaking! It’s never run these temps in the prior 6-8 years of owning the bus but only after the radiator replacement.
It has a 7 blade plastic fan that is NOT on a clutch! It’s locked direct! The fan is in the shroud and the shroud is up right to the radiator. Also checked the hoses. All hoses are pretty short and all were replaced new with radiator. They are blue silicon.
Anxiously waiting to hear what suggestions are about sealing up the gap!
Also I mentioned the gap to above mentioned mechanic/shop owner over dinner last night and he says “hogwash”! He also said when then have MCI’s come in for related service, they even leave some sort of fan shroud off and never have anyone complain the temps are different! “??????”
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I do not believe that if it were not important, Prevost would not have gone to the expense of engineering to make it a sealed fit with rubber seals. Buses with side radiators have a cooling disadvantage from the start due to the negative air pressure along the side of the bus. A truck has the air forced through the radiator while driving while we have to do all we can to pull outside air in. I do not know what the air temp in the engine compartment is but with a 190 degree engine and 300 degree exhaust it has to be high. The fan is pulling through the radiator and the air current is going to come from the path of least resistance. Trying to cool a radiator with air that is probably hotter than the coolant in it is a loosing battle.
If I cannot find a used frame for the shutter I am going to manufacture one. You do not need the shutters, just the frame around the shutters. It does not have to be fancy just functional.
Ace, do you still have the old shutters? If so and the frame is not usable you can at least use them for a template to make a frame.
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I don’t have the shutters or the frame so I guess I’m going to have to improvise! I don’t remember removing any type rubber, just the meta frame around the shutters!
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The rubber seal on mine is mounted on the inside of the radiator door. I may try a temporary out of plywood just to see what it does.
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Ace,
We have a 500 hp 8V-92 DDEC II in our 1992 shell. We are utilizing Ray Davis’ glass dash app with IPad to supplement our analog gauges. It is informative to see the comparison between what the analogs read and what is coming from the coach diagnostic port. Coolant temps per glass dash app on flat at 65 mph outside temps in th 40-50 range coolant doesn’t go much above 183 degrees. Hill climbing it goes up to 187. Warmer weather hilly country with OTR on we climb to the 191-193 range. All along our pyros hit about 1100 with the cruise on. More using foot feed and backing off the throttle tot calm the pyros. Several instances we have had too pyros in that its almost impossible to keep under 1100 degrees while gearing down we have discovered our fuel filter is plugged. I know, I know folks say a diesel running leaner than it should doesn’t raise temps like a gas engine but….. Each time the temp creep happens I change filter and presto. Happy coolant registering the 180’s once again. The two times this has happened and most recently March 1st we fueled at the Barstow Ca Flying J using the RV car island. 2 years ago we used the RV island at Beaver Utah Flying J and later couldn’t keep pyros down coolant temps went up to 195 on the analog in first gear going over Vail Pass we barely made it. Once agiain chaned filters And Voila happy coolant. So when was the last time fuel filters were changed and maybe you got some questionable fuel. We have learned now twice never go to Flying J RV island for fuel. Two separate instances two years apart hmmm
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I would think that gap would have to be sealed for the cooling to do it’s job and get all the air goiing through the radiator fins.
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Hey Jim,
How do the Glass Dash and analog guages compare? -
Tom. We like the glass dash. Economically for us being able to use the iPad for other than coach stuff is great Comparing analog vs G-Dash gauges:
turbo boost right on the money
speedo analog 3 miles an hour faster
tach is 200 rpm faster than glass dash
oil pressure pretty much equal
Coolant temps eliminates guessing do to sparsely placed analog gauge numbers. Always wondered if coolant is SO important why the lack gauge numbers.
When we don’t have obstructed fuel filter we can pull 7 percent grade in 2nd gear doing 35-38, pyros at 1050-1100, and coolant goes to 187-189 maybe 193 if I don’t back off. We don’t have as much info from our diagnostic port like series 60’s like gear selection, but glad we did it
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Thanks Jim,
I am still trying to decide since I do not own an iPad yet. Probably will get it.
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okay after looking the situation over I think I have a solution to sealing the gap where the old shutters used to be. Seems like it might be pretty simple the way Im thinking of doing it! i just hope it works or at least keeps the temps closer to normal and I can prove my buddy wrong! Gonna work on it this weekend! Wish me luck!
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Ace,inside the t stat housing you have seals that go bad it maybe worth your time and 8 bucks to change those it does affect the cooling.
A 180 t stat does not open fully till around 190 degrees ,190 to 195 is the norm for a DDEC also the 9 or 11 blade will work better for you at 70 miles per hr I always run the 11 blade with no heating problems on a 8v92
I don’t like the price the last Horton 11 blade I bought was 600 bucks still cheaper than cracked head or leaking cylinder o-ring
Clifford
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