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2000 K3500 Gone Mechanical Build

So far so good with the stock lift pump. I haven't hooked up the fuel pressure gauge to see what it is running but I had to advance the time some. Had a hard time running at idle and had a constant smoke and miss at idle and slight smoke and occasional miss off idle. I thought it was from air in the system originally, but it never cleared up. Advanced the timing and all is well. Hauled a few thousand pounds with it up to around 60 and pulled it with no issues. Boost, egts and everything seems the same as before. Hauled around 10000 lbs worth of grain but at only a top speed of around 25 mph, but still pulled it well.

Getting my nerve up to do some wot runs. I need the truck and with 243xxx miles on the engine and my other engine not together yet, I'm a little nervous about holding it to the floor and having something go boom... I need to test the limits of the turbo though to see if it will even be able to get all the fuel burnt at wot. That should help with the turbo decision. So it will have to be done one of these days I guess... Engine seems to be in perfect health, so it should be fine. But those sound like famous last words.

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Took the truck on a longer drive with a gooseneck and total trailer weight of around 6500lbs this past Monday. Was warm (low 80s) and muggy and the truck absolutely hated it. Definitely need an intercooler or wmi, or both. Was about a 45 min drive with a lot of long fairly steep hills. Most of the drive I was running 1000-1230 degrees. The longer into the trip, the higher the egts stayed and easier they would climb. Coolant temps were between 200-230 degrees depending on what grade I was on. Even pushing 12 psi and clearing up all the smoke running about 55 mph, egts would still climb rapidly and would not come down until I eased off. Most of the drive was at 55mph and boost between 3-7 psi in overdrive and the converter locked up, running between 1800-2000 rpm. Other than the temp issues though, it pulled it with ease. Could tell intake temps were getting pretty hot by the end of the drive as it did seem to lose some power, but I think with some type of air charge cooling, it would do far better with temps all around.
 
Probably the intercooler. I already have it, but I still need to get the piping and then figure out how I am going to mount it. I plan on putting it in the grille instead of under the truck like they normally are, so I'll have to figure out how I can get it to fit in there.

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Well, the cac will help as will the mist, but I don't think ((( and this is just my thinking ))) , you aren't in the better RPM range for towing even a little heavy... correct me if I miss read here, but you said you are at 55mph +/_ , and 1800-2000rpm's.. you would help the motor shed heat & let it breath more with -- say 2300rpm's or so...

I am only making this statement based on my own 20,000gvw rig going down the hwy, no I don't have the same setup as you do, but it doesn't even climb to 200* in 90*+ temps.. Mine will heat up IF I stay in 5th and try and stay around 55mph, with my 3:73 gear it is just NOT where the motor LIKES to be happy rpm wise anyway....

I have both cac & mist, I rarely even need to turn the mist system on.. but the cac is always working.
 
Stock, peak torque is right in that rpm range so it is an ideal rpm to be in. With my set up, I have no idea where peak torque is. From what I have seen and heard though, is that the att does bring peak numbers to a much higher rpm. With that said though, when I would give enough throttle to unlock the converter and cruise at around 12 psi of boost, egts would still climb and then settle in right at 1230 degrees according to my gauge. Those time would also be when engine coolant temps would get the hottest as well. And the engine would be running in the 2300+/- rpm range. Running that high of rpms with my truck would mean I would have to run with the converter unlocked, which is a whole other heat issue in itself. Tranny temps were already well above what I like reaching right at 200 degrees.

There was about a 7 mile stretch where I was on the highway and could run 65 mph. This would put me over 2000 rpm, in the 2100-2200 range, where the turbo usually really seems to open up and start moving some air. But in this case, it didn't help. Actually made it worse. That is actually when egts and coolant temps first climbed so high and stayed high. I ended up backing back down to 55 bc egts would not drop below 1200 at 65. I think I have just met the limits of the turbo with this set up and anything more than a few thousand pounds behind it. I think an intercooler AMD diverter valve would help, but I'm wondering if running the diverter valve would get the boost I need, but counteract any of the cooling the intercooler would do. I will be using the truck to haul over 10000 lbs with eventually, so I am seriously questioning whether or not the turbo will be able to handle the job, with or without other help.

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The torque convertor will lock in 3rd gear and give you the extra rpms without the heat of an unlocked convertor.

Sent from my Studio 5.0s using Tapatalk
 
I don't think mine will unless I put a switch on it to manually lock the converter.

Sent from my ST26a using Tapatalk
 
Well even if you did need a switch, I don't know the auto tranny, it would change the gear ratio and let it not work as hard but still do the same job??? just thinking here is all, I would think with 4:10's you would have a easier time than you are with so little weight ??

The only thing i can think of is to turn the fuel down a little and see, I know that when Unique built my pump it was toooo hot until I got the rest done, cac, etc... now I never need all I have and never heat up.... And I don't know the turbo you have either so I'm just guessing here really...
 
Yeah, for sure with 4.10s 6500lbs shouldn't be an issue. And it did pull it easy, just having the heat issue. My only guesses are not enough air or too hot of air. It definitely doesn't move enough air at lower rpms which contributes to the high egts no doubt, but I've pulled this trailer several times, twice with about 1000 more lbs, and once up to speed, egts would settle down in the 800-900 degree range. But that was on flat ground and 15 min trips. Which is why I think the intake temps is the biggest issue. I have my intake temp sensor in already, just need to hook up the gauge. Then I'll know for sure if that's the culprit or not.

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Gauge is hooked up. Hauling a few thousand pounds tomorrow, we'll see how it does.

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You have a setup that runs from 2000 RPM to redline and pulls like a freight train with improved MPG.

I assume you have removed the oil coolers and cleaned behind them? Radiator in good shape? Cooling fan clutch less than 5 years old?

Are you sucking hot underhood air or do you have a cover on the K-47 air cleaner - from the pics it looks like a underhood hot air intake. Hot underhood air makes an extreme difference in IAT and air density.

So you are watching ECT and other factors from your truck telling you you are in the wrong gear. You don't have enough fan RPM, You don't have enough water pump RPM, oil pump RPM (yeah oil cools too and this includes the 4L80E oil pump / cooler flow) and you don't have enough RPM for the ATT to work with all the fuel you are trying to throw at it.

After dealing with the factory turbo that rolls over and dies at 2200 RPM it is hard to understand you need to rev the engine up with your current setup. We are not dealing with a toy gas engine here that you need to fear revving up. The 6.5 is a high speed diesel with a redline of 3600 RPM. With any heavy power requests the automatic in stock form shifts the 6.5 into high RPM where the factory turbo chokes. Changing the turbo the factory program tries to wind out the little turbo you don't have anymore before shifting at heavier throttle. First thing I did with the DS4 1995 I had was have it shift earlier. This resulted in a lot less smoke on 10% grades unloaded at 45 MPH.

The concern that the 4L80E will heat up with the converter unlocked is valid. The converter should be locking in 3rd. Factory will lock after 30-60 seconds in my 1993 while in 3rd foot to the floor. Same for manual select of direct (1:1 direct is 3rd gear). I am not sure what stand alone controller you are using for your conversion, but, it needs the be able to run 3rd with the TCC locked. The entire point of a transmission is to run the engine in the power band. The highest gear is not always the best choice for conditions.

BTW 4L80E's run hot. 210-220 is perfectly normal for them towing even with a aftermarket big cooler in place.

Understanding your setup and understanding what your truck setup is telling you is difficult sometimes.
 
Fan and cooling system are working properly. 4l80s run hot bc of a very crappy factory designed cooling system. They even run the same horrible design on the Duramax and then wonder why transmissions are burning up... Trans should not reach 200+. If you're hitting 220, you are severely decreasing your tranny life. With an aftermarket cooler and doing away with the internal radiator cooler on other 6.5s, I have never seen above 190 on the hottest days pulling a load. 200 is too hot for me. I prefer my tranny to run 150-180, 190 max. Anything 200 and above is too hot for comfort for me. I have yet to burn up a tranny on any truck I've owned and I intend to keep it thay way.

Running at higher rpms didn't seem to make a difference with this load. I couldn't run 65 on a flat highway running over 2000 rpms.

I have ran the intake both ways. Didn't notice a difference in performance or egts running either way when "testing" it, but did not have a intake temp gauge hooked up to see the actual differences. It was running with the top off on this haul, along with all my other hauling. Today will be my verified testing as I have my gauge hooked up now. I plan to run both ways and see how much of a difference it will make. Won't be pulling the weight I was, or pulling in anywhere near the same conditions (much cooler-low 70s today- and not humid and muggy and no long steep hills to climb) but should give a good idea of the temp differences it will run.

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"Hot air intake" results:

Conditions: 65 degrees, low humidity. 15 mile drive with approx 1500 lbs pulling. Ac off. Mostly flat with occasional small hills.

55 mph 0-2 psi of boost. Consistent 145-160 degrees. Lowest was 142 and highest was 167. Generally stayed within the 145-150 range at 0-1 boost on level ground and steady throttle.

7-8 psi test: held throttle to hold 7-8 psi of boost for approx 10 seconds. Temps leveled off at 180.

12 psi test. Held throttle to give consistent 12 psi for approx 10 sec. Climbed to 230 degrees and was still slowly climbing when I let off. Had nearly leveled off by 230, but was still climbing.

Will install factory box for drive back and see what the results are.

This is no mods to intake side of engine or intake of turbo except has k&n filter. Filter is hooked to factory intake tube and has the box completely removed for the test.

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Also did 3rd gear at 55 mph. Running 2500 rpm, had no lock up, and was running 1-2 psi boost. Temp stayed around 167. Climbed higher with slightly more throttle, around 170-175 with 3-4 psi.

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Results with factory intake box installed:

Outside temp: 71. Similar weather, low humidity and sunny. Same drive, just going the opposite direction. Ac off.

Cruising at 55: 0-2 psi of boost, stayed mostly in the 133-135 degree range with a low of 128 and high of 139.

7-8 psi: 173 degrees. Biggest noticeable difference was that it climbed less rapidly. Was still climbing when I let off, but very slowly. Temp also dropped back down to the 140 range much quicker once I let off.

12 psi: 195 degrees. Same thing, slower getting to that temp and was still climbing slowly when I let off. Again, temp dropped much quicker when I let off.

3rd gear at 55: 145 degrees and pretty much didn't budge from there.

Also noticed intake temps were cooler at idle sitting at stop signs. Would get to the low 120s depending how long I sat. Without intake on, was slower dropping and only got to the 130s.

So all in all, not a huge difference, but definitely enough to notice and affect other things. Wonder if the differences would be greater under more extreme conditions? And for the what the ambient temp was, those under boost temps still seem fairy high to me. 200 degrees seems to be getting a bit extreme at 12 psi of boost on a turbo that is supposed to breathe far better than the stock turbo. Or maybe not? Never checked temps on a stock turbo.

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3500_6.5 said:
Fan and cooling system are working properly. 4l80s run hot bc of a very crappy factory designed cooling system. They even run the same horrible design on the Duramax and then wonder why transmissions are burning up... Trans should not reach 200+. If you're hitting 220, you are severely decreasing your tranny life. With an aftermarket cooler and doing away with the internal radiator cooler on other 6.5s, I have never seen above 190 on the hottest days pulling a load. 200 is too hot for me. I prefer my tranny to run 150-180, 190 max. Anything 200 and above is too hot for comfort for me. I have yet to burn up a tranny on any truck I've owned and I intend to keep it thay way.

Running at higher rpms didn't seem to make a difference with this load. I couldn't run 65 on a flat highway running over 2000 rpms.

I have ran the intake both ways. Didn't notice a difference in performance or egts running either way when "testing" it, but did not have a intake temp gauge hooked up to see the actual differences. It was running with the top off on this haul, along with all my other hauling. Today will be my verified testing as I have my gauge hooked up now. I plan to run both ways and see how much of a difference it will make. Won't be pulling the weight I was, or pulling in anywhere near the same conditions (much cooler-low 70s today- and not humid and muggy and no long steep hills to climb) but should give a good idea of the temp differences it will run.

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Click to expand...

"Running at higher rpms didn't seem to make a difference with this load. I couldn't run 65 on a flat highway running over 2000 rpms."
What was limiting you? Power, smoke, temperatures, unlocked converter?

If I recall correctly my IAT's were close to 300 degrees on a hot 110+ outside temp day. The IAT numbers posted are very helpful to illustrate hot/cold intake air. I am sure lots of folks will enjoy that.

I hold the same observation about GM cooling systems and I am more extreme with 121 degree days. The body style we have has a airflow issue over the stack. This is why they improved the fan in 1998. You already have the improvements. I'll take it that the cooling system is ok, again, the mat of junk that builds up behind the oil coolers on the AC condenser is a common problem and not well known on our trucks. Just one of those OMG moments when I found that to be an issue on a 1/2 ton Yukon long ago.

You may benefit from modding your fan clutch or a low temp Kennedy Diesel fan clutch to keep temps down. I have run them with awesome results. (Staying at or under 210 ECT no matter what I did to it.)

It's hot enough here that I am looking at moving the aftermarket trans oil cooler behind the AC condenser because it is warming up the condenser. (Cooler runs at 180 and condenser runs at 160 with hot spots behind both, engine/trans, oil coolers.) Yes, getting that coolant in trans oil radiator mess out of the trans oil system is a good idea! My 1993 runs even hotter with just the in tank radiator cooler as it factory did not have a second air to trans oil cooler. I have tested without the aftermarket cooler and it's scary hot, +20 degrees. No argument about short 50K life on hot transmissions towing out here. IMO the TCC clutch is weak and I was manually locking it at WOT towing causing an early death. I have a triple disk Yank converter on the floor going in one of these days on the 1993.

I would like to know what size trans oil cooler you are running w/o the radiator cooler in place? Compare notes... :cheers2:

I find that the TCC manually locking up is worth 1-2 MPH in OD with the factory turbo at 62 MPH.
At 55 MPH with the ATT I am usually on a 7% grade and in 3rd. Depending on trailer size and weight I don't need more power to keep 55 MPH.
The boost was 10 # higher with an HX40II at 24 PSI peak, but, the power on the rollers was the same. Boost isn't a total end all measurement.

With DOT service hours on my back I have had to extract all the truck has to avoid violations for time. This means most temperatures except ECT have proven to be "interesting". EGT is intresting to watch, but, I sustained 1550 EGT on a grade didn't hurt anything on my 1995. (Scorched the turbo blanket some.) Yes, we cooled the tune down some after seeing that. 1400 EGT is the peak I run.

With a smaller 6.2 pump I have now on the 1993 I don't go over 1100 EGT, 12PSI boost, and have a lack of power to go with it. I need a bigger pump one of these days.
 
300 degrees! Holy crap that seems really high.

" "Running at higher rpms didn't seem to make a difference with this load. I couldn't run 65 on a flat highway running over 2000 rpms."
What was limiting you? Power, smoke, temperatures, unlocked converter?"

Egts were too high. I was climbing above 1250 and they would not come down. Engine temps then started to climb to the 230 degree mark and then trans temps. Plenty of power, just not enough cool air to keep temps down.


I should clarify what a hot day is here, as I realize "hot" when referring to ambient temp is relative. A very hot day here is in the mid 90s. A "its too damn hot to do anything" day is low 100s and isn't very common. We have high humidity here though. I remember being in Vegas once and they were going on how high humidity was going to be there that day... I think it was somewhere around 30%. Here, in the heat of summer, a day with 50% humidity is a rare and welcoming day. Today would be an incredibly nice late spring day. Temp is currently 77 degrees and humidity is 32%.

The trans cooler I put on my Suburban is 12"x10". The ones I usually run on my trucks are a little bigger. Maybe 14"x12".

Another benefit of having an aftermarket cooler, you can hook it directly to the condenser so you don't have the dead space between them. I usually bypass the radiator cooler and replace the factory one out front with the aftermarket one. The best one we did was actually on a 92 gasser with a 383. He hauled 15,000lbs + on a regular basis. We put a huge cooler in place of the skid plate, where intercoolers are usually mounted, and put an electric fan on it. Hauled 18,000lbs 2 hrs north and said temps never climbed above 160.

I believe the culprit with my high ect lies in the egts/intake temps bc I have hauled double the weight with this truck with less fuel output and never had overheating issues. Could haul all day long and never see over 210 degrees. With the added fuel, egts stay consistently higher, causing everything to heat up. I think with more air flow and cooler air, I should have no more overheating issues. Kill all running hot issues with more cooler air. At least that is what I am leaning towards. I wouldn't be surprised if I was running up close to 300 degree intake temps like you experienced while I was hauling the 6500lbs.
 
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