question for a 6.5td worker

[Clean your ducts in PA]

Just got a 1994 6.5td. The truck runs a PTO that turns a 41" fan, and quincey air compressor for duct cleaning. I run the truck at 2 different speeds for cleaning. Low is 15-1800rpm, high is 2200 (max). engine is totally stock at this time.

On a typical job the truck will run at these rpm's for 2-3 hours at a time. Should I bother with a new downpipe / exhaust, and intake? Intercoolers etc.??

I was keeping an eye on engine temperature and it seemed to peak @ 200-210. I would assume that the dual thermostat would be one of the first things I will want to do no mattter what. The turbo was dead (being replaced now) and was causing major power loss.


My truck: 1994 C3500 6.5td (stock) 5 speed manual /w PTO and throttle lock.

[DA BIG ONE]

A freeflow exhaust will be far better right away;
dual stat conversion should be priority;
charge cooler aka intercooler (air to air) would not be of any benefit standing still unless you wire some strong puller fans to it, however, standing still a water to air intercooler would work for you.

Good luck!

[Bnave95]

A Kenndy fan and clutch combo with the High flow cooling upgrades.
http://www.kennedydiesel.com/categoryresults3.cfm?Category=1&SubCategory=65&SubCategory2=10
http://www.kennedydiesel.com/categoryresults3.cfm?Category=1&SubCategory=65&SubCategory2=9
Open up the Ex. and intake.

[Hubert]

Exhaust would help engine be more effiecent. Clean radiator would help reduce temps. I don't think you are loaded enought to require an intercooler, ie not running elevated boost. Initial thought is running pto is a decent load compared to the air flow over the radiator.

I would get EGT gauge and would expect them to be OK but its good to keep an eye on it and better indication of load on motor.

I've asked this one time before but no real good ideas for you. I'd think some way of improving air out of engine compartment or increasing air flow over radiator would be your best improvement.

Do you pop the hood when extended PTO load to help allow heat to escape. You could also turn on heat to max and let windows open to incease cooling capacity.

[Mark Rinker]

All the advice given here is valid...since its 12 years old, you might need to replace the radiator. Definately install JK's fan clutch, make sure you have the HO flow water pump, and upgrade to dual thermostats if you can. Pretty expensive for a truck of this age...

But, if it were me, before you do any of these, remove the stock single thermostat and try running it without. You'll be amazed to see how much of a temp drop you'll get from simply removing the most restrictive part of the system, and your truck will still make good heat, if its like my stock '94 up here plowing snow in Minnesota.

If you chip it and/or tow heavy you'll need mods. I am betting all your application will need is a good clean radiator and a little help with flow. If its the stock '94 water pump (doubtful) you may want to get a HO model that are readily available.

[Clean your ducts in PA]

Thanks for all the advice!

Since we're heading into winter, I think i'll start with just a larger fan and go from there. I still have alot of body work and lettering to do, so I want to try and spred out modifications if I can.
In addition to the turbo, I also needed to replace the downpipe, oil cooler lines, oil cooler, tie rods and 2 fresh batteries.

Between what Ive read here, and what Ive talked about with the mechanic I plan on doing the following:

fan & clutch (asap)
duel stat / high flow pump (by next summer)
downpipe, and exhaust (no eta)
High flow intake of some type.. probably just a K&N filter replacement (soonish)

[Clean your ducts in PA]

ok, so i found out why this truck is so underpowered... The weight is just over 9,000lbs. With this new information, I'm guessing I should look at how some of the other folks here have set up for towing / hauling.

[rustyk]

I feel your pain (but you can't feel mine) - my soon-to-be-replaced (with an uprated version) 6.5L TD is in a 16,000# motorhome. With the fairly short rear end, it actually performs pretty well.

BTW, someone (and I'll post a link if I can recover it) makes a speedup device for using a PTO.

[Clean your ducts in PA]

BTW, someone (and I'll post a link if I can recover it) makes a speedup device for using a PTO.

speed up device? Do you mean some type of throttle control?

[DmaxMaverick]

If yours is EFI (electronic), the electronic speed control is the way to go. Not only is it push button, the speed is governed. That means minimal speed fluctuations with load/no load transitions. I don't know about the '94, but later models are controlled through the cruise control stalk. If you don't have cruise, you can add the stalk and adjust the programming (EPROM) to make it work. An added bonus to adding it, is cruise control. Kennedy or another TDP Advertiser (http://www.thedieselpage.com/vendors/main.htm) will be able to help with it.

[Clean your ducts in PA]

If yours is EFI (electronic), the electronic speed control is the way to go. Not only is it push button, the speed is governed. That means minimal speed fluctuations with load/no load transitions.

right now the truck (and ones like it http://wrpringle.com/newtrucks.ivnu ) have a cable throttle "lock". Mentioning load / unload conditions are something I was actually starting to wonder about. In addition to turing a 41" fan, the PTO also runs a big Quincey 325 Air compressor that feeds a 30 gallon tank @195 psi/25cfm. Once the compressor unloads I get a pretty good spike in RPM. Therefore I have to run at a lower overall rpm than I want. This results in lower fan speeds, or less vacuum (thats a bad thing).

I am also a one man operation, so the truck is out in the driveway or street, while I'm inside runing the air tools. The list of "what could happen" in my mind is pretty long:

I heard there was some type of engine shut-down system (can't remember name now, but I was told alot of big truck have this). It monitors 2-3 different peramiters that you can select and if any one fails the sytem shuts down the engine.

1. Is there a "safety" like this for a 6.5?

2. Is there something that would incorperate both of these functions into one unit (engine rpm, and safety shutdown)?

[DmaxMaverick]

Murphy switches. I know them well. They should be easy enough to set up. ECT and oil pressure should be all you need. You could do it yourself (shadetree) or shop around for someone to do it. All you need to do is interupt the fuel shutoff solenoid. I wouldn't mess with the ignition circuit. They have problems enough without help. An oil pressure switch (N/O), coolant temp switch (N/C), a relay, and an overide button should do it. Wire the two switches in series to the relay, along with a parallel to the overide, and install the relay on the FSS wire. Very similar to stationary power units. The overide is used to start the engine before the oil pressure comes up, and can be a toggle. Just don't forget to set it before you leave the truck. The parts would be cheap. It's the labor that would cost if you paid a shop to do it (probably 2 hrs). Napa will have all the parts.

Is your throttle lock linked to the pedal? I think it would have to be. There is no trottle linkage to hook into on an EFI, it's "drive by wire".

John Kennedy at www.kennedydiesel.com (http://www.kennedydiesel.com) is probably the one you need to speak to. Could be all you need is a C3500HD PCM or program to activate the PTO control.

[Clean your ducts in PA]

Is your throttle lock linked to the pedal? I think it would have to be. There is no trottle linkage to hook into on an EFI, it's "drive by wire".


Yes, it's mounted on the bottom edge of the dash, and a cable ties directly to the pedal. You pull the arm out and twist a "lock" button to hold throttle position.

Thanks for the info on the Murphy switch. That sounds like something i can wire up with no problem.

[Hubert]

I still pretty much believe its an air flow and radiator effeciency problem and ~205-210F is not in itself a problem for coolant temperature (more how it gets there and how much it swings). Heck its been working since 94 right??? (Which makes me wonder did it always do this)

IMHO ~200F-210F coolant temps is pretty dang hot for a parked vehicle for extended time. I imagine underhood temps are even more than that. The valley of the motor could be 220-230F or more and around and under turbo would be even hotter ???? Its a wonder starter life and other stuff hasn't been a problem.

Hmmm your throttle control description that might make it more interesting. How much throttle does it take when you set it? The stock programming does different things for different scenerios. One is light throttle no appreciable load (at somewhere around 1800-2000 rpm) it reduces wastegate solenoid duty cycle to minimize boost. Such that you might be getting some compounding of problems ie just running your pto for the duct fan - Boost might be low. When compressor cuts in it might load up a little and increase boost then when compressor cuts off it dumps boost. Plus the ECM might be searching and constantly adjusting to hold a set rpm with the set throttle position but w/ variable load.

I wonder if PTO throttle control is more similar to cruise control where it changes fuel for load and adjusts accordingly. Sounds fairly different than setting a set RPM via fuel rate (throttle position) and changing load on motor.

If I hold my foot in one place it does not act like cruise control when I hit a hill. Which is kind of what you are doing when your air compressor cuts in and out.

Kennedy would be a good person to ask about electronic PTO controls and just what the ECM is doing to control holding RPM's steady.

Keep us posted kind of a new twist I haven't read about.

(edited something I did not communicate well enough)

[JohnC]

I didn't notice if you posted the PTO speed or not, but there are some electronically controlled speeds available with the stock PCM. They're pretty low, though. (oops... I see you're running 1500-2200 - these speeds are too low. What is the preferred speed?)

Another option is to find an old style aftermarked cruise control setup and hook it to the pedal and put the speed sensor on the PTO drive shaft.

Or, get someone to burn you a PCM chip with the desired PTO speed in it...

[big61fourby]

With RJ's fast idle mod-if you ground BOTH of the pins listed, it jumps to 1500 rpm or so, right? I suppose that might still be too low at times, but it might be a start...

[Clean your ducts in PA]

Unfortunatly 1500 rpm is about the lowest rpm I can run and still maintian enough air pressure, and vacuum. If I have all 150' of vac hose streched out and wound around a few corners, I'll take it up to 2200 (max) but again the problem comes in when the compressor unloads. At that point I jump to 2400. Due to this I run at 18-1900 rpm.

I gave John Kennedy a call today and discussed allot of this with him. He also said that the "fast idle" controls are not going to give me the rpm I need. he mentioned some software, and it sounded like it would work, but I would need to carry a laptop to run it, and I really don't want more "stuff" in the cab.

I think I'm missing something though. If this was something that can be burned into the pcm, how would it be enabled? Remote mounted switch?? If that were the case, I would imagine a 2 pole relay could be wired to enable a Murphy switch set up at the same time

[DmaxMaverick]

If you can't get it managed electronically, what you have is fine. The way you made it sound at first, the engine would run away when it went to no load. 2400 RPM's is nothing to worry about. Stationary power units will cycle between 2600 and 3600 (governed speed) for thousands of hours. In your case, it may be better to let it wind up to shed some heat built up during a load session.

[tommac95]

'Newbie'
Clean the area between radiator and condensor of leaves , etc. Also clean the radiator and condensor cooling fins of varied debris. May drop temps a bit.