Diesel Motor question, 500hp Cummns

[Darby1]

We just took delivery of a new fire engine :cheer: but it came with some bugs. It has the Cummins 500hp diesel and before we could put it in service it kept giving us check engine alarms. They found out the problem was some type of computer interface problem and Cummins isn't able to remedy the problem anytime in the near future, I don't really understand, it's just some type of computer glitch i guess. My question is in regards to the "fix" that they choose. In order to prevent the check engine light and alarm from sounding constantly they bypassed our clutch fan and hot wired the belt driven engine fan so it runs all the time, full time, fan always going. Is it a bad idea to have that fan running the whole time, even before the engine is warmed up, or should this be fine? I know the increased noise in the cab sucks but what about loss of power or lack of normal operating temp? I don't know crap about big motors, educate me please.

 

[boardbysled]

... and a (very small overall) parasitic drag on the motor...

Its actually quite a large drag, big truck motors use very, very large fans, and you notice the loss in power when they kick on IMO.

 

[Darby1]

Its actually quite a large drag, big truck motors use very, very large fans, and you notice the loss in power when they kick on IMO.

Yeah, you really do notice the loss of power when our Detroit fan kicks on, and they are huge fans. I've never driven this one without the fan running so I can't compare the power loss.

 

[WHITE TRASH1]

Generic figure is you lose about 50hp when the fan kicks on and it revs a little slower due to the drag.

 

[Darby1]

But if it's hot-wired, you'll never notice it kick on


Good point though. Wouldn't the fan already be engaged most of the time you're really working the motor enough to notice the difference? I don't drive big rigs, so this is all my imagination...


Edit:


Nevermind.

The fan normaly only kicks on after you've been driving it hard for more than maybe, 10 minutes. And then you notice the rpms do climb slower. It's normaly only a 10 minute response time to most emergency's anyhow.

64FJ40, your best guess is nice but absolutely no help here.

 

[TreeClimber]

On smaller gas engines, when the clutched-fan-assembly fails, we regularly wire the fan into the ON position. It then turns full RPM with the engine and pulls significant amounts of air thru the radiator. Other than the noise and slight loss of horsepower, there is no significant problems.

I see no differences between the larger diesel application.

I wouldn't worry about it.

 

[ain'tstuckjustresting]

Most class 8 trucks have such a large cooling system that in our climate the fan only kicks in under heavy load like pulling a long hill.
I can't believe Cummins would fix it that way. That's busch league. Your power and fuel mileage will suffer greatly and you're right about the warm up time.

It won't hurt anything but still only a temp jimmy rig fix.

 

[Darby1]

Most class 8 trucks have such a large cooling system that in our climate the fan only kicks in under heavy load like pulling a long hill.
I can't believe Cummins would fix it that way. That's busch league. Your power and fuel mileage will suffer greatly and you're right about the warm up time.

It won't hurt anything but still only a temp jimmy rig fix.

Good points! That pretty much summed up my thoughts.

 

[Bunk1]

Maybee you could so some searching to figure out the codes/how to pull them and what they indicate? Does it come up to temp with the fan on all the time?

 

[Lucky Jeff]

You'd be amazed how often that happens nowadays... Usually only large fleets have to deal with such issues though. I'm surprised it trickled down to a fire truck...

 

[ain'tstuckjustresting]

Most smaller fire depts. end up buying a used freight truck and having it turned into a tender or tanker. Or the company they buy it from has done that.

Bunk,
Unfortunatly ISX and QSB engines are pretty much impossible to do anything with w/o Cummins software. You can read codes w/ a class 8 Genesys but you can't change anything.

Sounds like a program glitch or a cornfused tech trying to baffle w/ bullshit.
Either way it should be fixed asap. Cummins corp has great tech support and training, but the locals can easily drop the ball.........................

 

[Darby1]

Most smaller fire depts. end up buying a used freight truck and having it turned into a tender or tanker. Or the company they buy it from has done that.

Bunk,
Unfortunatly ISX and QSB engines are pretty much impossible to do anything with w/o Cummins software. You can read codes w/ a class 8 Genesys but you can't change anything.

Sounds like a program glitch or a cornfused tech trying to baffle w/ bullshit.
Either way it should be fixed asap. Cummins corp has great tech support and training, but the locals can easily drop the ball.........................

We don't buy used, I think used fire trucks only get shipped to Mexico, serious. And they havent converted tankers into tenders for years due to the highest death rate of any fire apparatus on the road, the live load of water tanker is a dangerous thing. When you buy a truck you spec out every little detail before they start building it for you and then you visit the factory several times while it's being built so you can monitor the process and make changes. Sorta like having a fab shop build you a one off buggy. We just put it in service 2 weeks ago and we started the process more than a year and a half ago.

Yes, it's a software issue on Cummins end, fault codes said it was a problem that didn't really exsist. The truck was built by Crimson with a Spartan Chasis and a Cummins motor. Since Cummins has no fix for the problem the Crimson fire truck company implimented the fix. Cummins is aware of the problem but doesn't have the software written to correct it, or atleast thats my loose understanding. Obviously you wouldn't buy a new car with a hot wired fan but after waiting a year and a half for a new fire truck, apparently we will. It's weird and I wouldnt have signed off on it but I'm not the Chief. The question is now, how long will we have a hot wired fan on a brand new $500, 000 truck? Their guess was 3 months, knowing how the fire service works, I'm guessing more than a year.

How big of an impact would this have on our fuel economy? This new rig has been sucking the gas quick, we've been blaming it on a smaller gas tank but now I'm not sure. We have to keep our tanks full so we've been fueling up a lot more than we'd like to. Which of coarse takes away from our time flirting with girls and sitting in recliners

 

[ain'tstuckjustresting]

Most of the Fire Depts. I've dealt w/ were small rural county fire dists. Most of which could only dream of a $500k truck. I know they don't convert tenders to tankers but there are many companies that turn 500,000mi freight trucks into tankers for rural areas.

I couldn't speak to a close number on economy as it depends on useage. Town driving and idle time not being too bad but lots of hiway would be a real difference.

What engine are you used to? A Signature 500 is gonna suck some serious fuel no matter what.

 

[Lucky Jeff]

It's definitely not some idiot tech who doesn't know what he's doing. It happens quite a bit now with all of the crap they have piled onto these trucks. There is a laundry list of issues they have to work through, and I'm not surprised that it will take them a while to figure out a fix for it.. It sucks, but everyone is having issues in the heavy duty segment nowadays..

 

[ain'tstuckjustresting]

That's why Cat bailed on the truck engines and JD never got involved.
The Series-60 was a joint venture of JD and Detroit but deere only wanted the 10.5 & 12.5 engines.

They spend so much time and money on the emissions **** they can't get the rest to work right.

I do have a tough time believing that it would take 3mos to fix it. Is Cummins going to tell GTI, Swift, Hunt, Interstate that even though they are losing 10% fuel econ they will need to wait 3mos for a fix on all their new trucks?

 

[Glenn]

Try posting over in The Diesel Stop in the medium duty forum. There is a guy over there who is a long-time fire department mechanic/truck driver named Birken Vogt.

 

[GRW]

I would contact Cummins and request a proper fix.
As far as soft wear issues, they have and will continue to be an issue.
From aerospace to automotive to you cell phone.
Most of the automotive issues in the news the last year are all soft wear.
If the customer does not demand and good working product it will not get addressed.

JMHO

 

[Lucky Jeff]

The trucking world doesn't work quite like the car world....... You can demand all you want, but the resources just aren't there. And they are worried more about fixing issues that the LARGE fleets have first.