Hey guys. So, this is nothing new. Just kinda curious. I have a cclb 3500 lifted 6". 4.10 gears. I am running stock wheels & tires right now. This truck doesn't like to move. At all. Under 50, its ok. But still grumpy. I was going down the freeway (steep hill) today, & it was hard pressed to get it to go 60. Like I gave it gas, & it downshifted to where it was nearly redlined. I wasn't flooring it at all, I just gave it a little more & it downshifted to 2nd. The engine sounds healthy. Idle's great, responds well to throttle. Truck has nearly 210k. Maybe the 4l80e has just given up on life? If so, is there a way to diagnose that? It would be nice to have a decent truck again. I live near Tahoe & going up the pass sometimes is a stress filled rollercoaster. I refuse to make that drive during the day. Night time only when it's cool out. The trans doesn't get that hot. I have a deep pan on it as well as I put a bigger trans cooler on it. Maybe the torque converter is going? Idk. Maybe the engine just doesn't make the power I remember? Idk. Thoughts, ideas. Thanks!
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Engine or Trans Dying?
- Thread starter Scholioso
- Start date
ak diesel driver
6.5 driver
Is your rig all stock? Any codes?
Will L.
Well-Known Member
It would really help if you fill out the signature line with your truck and every modification made to it. All of ours is there for this reason.
On This issue- aren’t you having the issue right now of bad cps, or at least in question? Could be I am confusing you w/ someone else- I only get confused when I breathe so... yeah. Haha.
My rpm (gearing), power, way different from yours- but sounds like what I always went through before adding the turbo to mine. Main issue was lack of power to do the work.
Is this a new problem you did not have with the same teuck before? Or just what this truck has always done in the situation and other trucks don’t? It sounds to me like you are at a cruise rpm then when you need a tad more power she downshifts but is having the gm asthma attack...’
On This issue- aren’t you having the issue right now of bad cps, or at least in question? Could be I am confusing you w/ someone else- I only get confused when I breathe so... yeah. Haha.
My rpm (gearing), power, way different from yours- but sounds like what I always went through before adding the turbo to mine. Main issue was lack of power to do the work.
Is this a new problem you did not have with the same teuck before? Or just what this truck has always done in the situation and other trucks don’t? It sounds to me like you are at a cruise rpm then when you need a tad more power she downshifts but is having the gm asthma attack...’
MrMarty51
Well-Known Member
While the truck is pulling on the steep grade, is it blowing out a lot of black smoke ?
No black smoke. Turbo was rebuilt around 1k miles ago. So I got the truck stock. She was ok running. Then I lifted it big tires, etc. Worsened it but still ok. Then I hauled a cummins with it over a steep grade & ever since she hasnt been the same. Engine is still good & health but I feel like the trans is messed up. I was going up a hill today, & rpm was at 2100. When I dropped it to 3rd gear (4l80e) it jumped to 2250 rpm. Not a huge increase. Did ok, but still. Is my lockup just not working well? I think the trans torque converter is shot or the trans is slipping. But I don't know how to tell without pulling it. Are there tests you can do to test these?
I will update my sig block.
Yes, the engine has a bad cps. Due to this, I disconnected the crossover coolant sensor & the truck runs fine. This power issue has been around for a while.
I will update my sig block.
Yes, the engine has a bad cps. Due to this, I disconnected the crossover coolant sensor & the truck runs fine. This power issue has been around for a while.
ak diesel driver
6.5 driver
Check for codes
Will L.
Well-Known Member
Get that cps issue corrected first. Use an AC Delco the extra $3 is worth it. Once that is feeding the info the komputer needs, then see what she does.
If you can do a video of it after that and post on YouTube with a link to here, that could help.
A scanner or some software in a laptop could record everything to see what’s happening. A pressure gauge to
The 4l80e could say what’s happening there.
Without seeing it or having any technical info, can’t really say anything horrible is going on.
The stock engine and turbo peaks torque at 2200 rpm. Not knowing all the modifications or engine condition- no telling.
Keep the temp down under 210. 205 is ok but dont hit 220 till you want an excuse for a new engine.
I remember you put some big heavy tires on and are under geared for them, that steals a lot of power. When I put skinny short pickup tires in place of my 37s- it is a noticeable difference.
If you can do a video of it after that and post on YouTube with a link to here, that could help.
A scanner or some software in a laptop could record everything to see what’s happening. A pressure gauge to
The 4l80e could say what’s happening there.
Without seeing it or having any technical info, can’t really say anything horrible is going on.
The stock engine and turbo peaks torque at 2200 rpm. Not knowing all the modifications or engine condition- no telling.
Keep the temp down under 210. 205 is ok but dont hit 220 till you want an excuse for a new engine.
I remember you put some big heavy tires on and are under geared for them, that steals a lot of power. When I put skinny short pickup tires in place of my 37s- it is a noticeable difference.
Ok. So I have two trans temp sensors. One is in the pan, & the other is in line with one of the trans cooler lines. The one in the pan gets up to around 170 hottest. The other one gets up to around 200 to 210. Can I put a pressure gauge in place of the temp sensor that's in line of the trans cooler lines & see if it has enough pressure? What would that tell me?
The truck no longer has 37s. It has stock wheels & tires on it. Still has the 6" lift tho.
I don't really want to replace the cps since I am going to be a traitor & swap a 12v into it. I know, I know. Save your breath, I'm stubborn & invested in the truck & the cummins already. Just trying to figure out if my trans is the reason for lack of power or if it's the 6.5
The truck no longer has 37s. It has stock wheels & tires on it. Still has the 6" lift tho.
I don't really want to replace the cps since I am going to be a traitor & swap a 12v into it. I know, I know. Save your breath, I'm stubborn & invested in the truck & the cummins already. Just trying to figure out if my trans is the reason for lack of power or if it's the 6.5
Will L.
Well-Known Member
Umm, wow- Left turn on thw freeway! Haha.
Being respectful here- don’t take as attitude.
I can respect a cummins swap, they are good engines.
Figure the 6.5 IF (big if) stock and good condition is 190-210 hp and 420-440 torque. The cummins IF (again big if) is stock is well, the same or less. Look at the chart below.
So will the cummins give better power?
Swapping an engine instead of a $40-50 part is alot.
The cummins CAN be built to make a lot more power. I love the cummins 6bt. But if you think your going to drop a cummins into a rig that was SO NEGLECTED that a person wouldn’t swap a $40 part to get the engine to run right will have a transmission in great condition- your dreamin. The cummins puts it torque out much lower. It is a lower rpm engine and the 4l80e is loved by so many because it is a high rpm loving trans. That was the primary reason jaguar and rolls royce chose them- that and they are amazing strong and long life.
But it has to be set up for it’s use. Absolutely you would be happy with it behind the cummins AFTER you have it built.
My point is- your question is moot. Pretend the Cps is your issue right now- so what if your going to yank it for the cummins- just do it and use the sell of the crappy running 6.5 for $250. Or fix the 6.5 and try to sell it for more when people can test srive the engine and see it running good and test for things like no blow by. Then you could maybe sell it for more and offset the $40-50. Just my 2c.
If you are set on the cummins- I get it. If not- you can hop up the 6.5. 4” exhaust- you will want for either engine. Fire a big turbo on there that is a good choice for either engine hopped up- hx40wii maybe?
The injection pump on the 6.5 you have is SO controlled by the cps that adding red dye fuel to it right now would possibly not allow the engine to run! If it isn’t worth $100 in parts for more power right now- just go a little slower until swap day.
There is 1 pickup and 1 Hummer right now on this forum doing cummins swaps that I can think of off hand. Have you been watching them?
Being respectful here- don’t take as attitude.
I can respect a cummins swap, they are good engines.
Figure the 6.5 IF (big if) stock and good condition is 190-210 hp and 420-440 torque. The cummins IF (again big if) is stock is well, the same or less. Look at the chart below.
So will the cummins give better power?
Swapping an engine instead of a $40-50 part is alot.
The cummins CAN be built to make a lot more power. I love the cummins 6bt. But if you think your going to drop a cummins into a rig that was SO NEGLECTED that a person wouldn’t swap a $40 part to get the engine to run right will have a transmission in great condition- your dreamin. The cummins puts it torque out much lower. It is a lower rpm engine and the 4l80e is loved by so many because it is a high rpm loving trans. That was the primary reason jaguar and rolls royce chose them- that and they are amazing strong and long life.
But it has to be set up for it’s use. Absolutely you would be happy with it behind the cummins AFTER you have it built.
My point is- your question is moot. Pretend the Cps is your issue right now- so what if your going to yank it for the cummins- just do it and use the sell of the crappy running 6.5 for $250. Or fix the 6.5 and try to sell it for more when people can test srive the engine and see it running good and test for things like no blow by. Then you could maybe sell it for more and offset the $40-50. Just my 2c.
If you are set on the cummins- I get it. If not- you can hop up the 6.5. 4” exhaust- you will want for either engine. Fire a big turbo on there that is a good choice for either engine hopped up- hx40wii maybe?
The injection pump on the 6.5 you have is SO controlled by the cps that adding red dye fuel to it right now would possibly not allow the engine to run! If it isn’t worth $100 in parts for more power right now- just go a little slower until swap day.
There is 1 pickup and 1 Hummer right now on this forum doing cummins swaps that I can think of off hand. Have you been watching them?
I completely get it. I hope no one took my comment earlier as attitude. I have nothing against a 6.5, I have owned 2 of them. I think they are neat engines. The short story of why I'm doing a cummins swap is it's been in the works a long time. When I got my first truck at age 16 (6 years ago), I saw a cummins on the side of the road for sale. I had no idea what they were. (I was also just getting into mechanics). But it looked cool, & I knew they had power. So I vowed to put a 12v in a GMT400. At the time, I had a k1500 Z71 ecsb. I did a lot of research, went thru a lot more cars/trucks, but yeah. That's what started it all. I've had my cclb 6.5 for 3 years now which is the longest I've owned any vehicle. Theres just a lot of history there.
I looked into rebuilding vs swapping. Swap will cost more, no doubt. But like I said, I've wanted to do this for a long time now. I get it, the sensor is $50. Just replace it. But my viewpoint is everything on this engine has fought me. Oil filter? Got stuck, came off in pieces. Starter? Missing bracket (replaced), sheared flex plate. Flex plate? Shimmed like no ones business (I didn't reshim it, just bolted it back up). Crossover tube? Broke 5 out of 6 bolts. It's all the little stuff from prior owners that neglected it that are now eating me & it's just eating at me since all the money I just spent getting it running again, could have gone into the cummins.
I think I'm going to just limp it around for now. I don't expect to have a good trans behind that cummins. Actually, I'm pretty sure OD is bad. I was driving today & it was screaming in 4th on flat ground going 55. Finally, a few minutes later it shifted into OD. Even then, it would only sometimes fully shift, sometimes it would just kinda slip into it. So that's not good.
Back to the cummins, I'm still deciding on whether or not to keep the 4l80e or upgrade to an allison. Either way, I have to modify driveshafts & crossmembers, cooler lines, etc. Plus I will have to get a standalone for either trans as well. So still trying to decide on that. I will look for those other cummins swaps, follow along to their builds for ideas.
I looked into rebuilding vs swapping. Swap will cost more, no doubt. But like I said, I've wanted to do this for a long time now. I get it, the sensor is $50. Just replace it. But my viewpoint is everything on this engine has fought me. Oil filter? Got stuck, came off in pieces. Starter? Missing bracket (replaced), sheared flex plate. Flex plate? Shimmed like no ones business (I didn't reshim it, just bolted it back up). Crossover tube? Broke 5 out of 6 bolts. It's all the little stuff from prior owners that neglected it that are now eating me & it's just eating at me since all the money I just spent getting it running again, could have gone into the cummins.
I think I'm going to just limp it around for now. I don't expect to have a good trans behind that cummins. Actually, I'm pretty sure OD is bad. I was driving today & it was screaming in 4th on flat ground going 55. Finally, a few minutes later it shifted into OD. Even then, it would only sometimes fully shift, sometimes it would just kinda slip into it. So that's not good.
Back to the cummins, I'm still deciding on whether or not to keep the 4l80e or upgrade to an allison. Either way, I have to modify driveshafts & crossmembers, cooler lines, etc. Plus I will have to get a standalone for either trans as well. So still trying to decide on that. I will look for those other cummins swaps, follow along to their builds for ideas.
ak diesel driver
6.5 driver
Not to be rude but did you actually hook up a scanner and check for codes or just no light on? Tranny codes do not always trip the light
New symptom. When the truck is cold, it seems to work fine. When it gets warm is when it starts losing power. OD worked fine when I first started an hour trip. On the way back, OD no longer really wanted to function. Took a while for it to finally kick in. Going up a steep hill unloaded CCLB, downshifted to 3rd, 10psi boost, accelerator not all the way pinned, just to where it reached 10psi, truck was losing speed (going 70, it fell down to 45 at the top of the hill). The egt gauge maybe got to 500, definitely hovered around 400. Boost pretty steady at 10, rpm around 3k, just going nowhere fast. Transmission to cooler line got to 200, fluid in pan was around 170. Talking around, it seems like my trans is pretty much done. A tranny specialist said it sounded like the torque converter is cracked & letting fluid get onto the clutch which slips the clutch & it won't lockup. So yay! More fun!
1999gmc
Active Member
Could be what caused the flexplate problem
That problem was caused by a few things. The flex plate had a shim spacing it away from the crankshaft, & the starter had a couple shims spacing it away from the block. On top of that, the starter was also missing the forward bracket which keeps the starter from rotating/twisting. These things combined = rounded teeth. Truck starts waaaay quieter & smoother now.
ak diesel driver
6.5 driver
unless it's a typo those EGTs are way low
Lol unless the gauge is wrong, that's the egt reading. Its plumbed into the turbo downpipe. Not exactly the spot I would have chose but oh well.
ak diesel driver
6.5 driver
that's only good for about 1-200 degrees pulling a hill like that you should easily see 8-900. Me thinks your tranny is fine and your not getting overdrive/lockup because the PCM thinks you've floored it