M1008 loss of power at high end

[Husker67]

I have a loss of power when my 6.2 M1008 reaches operating temperatures. I don't lose low end performance. I have driven it at speeds of 65-70 mph with plenty of pedal remaining but once it gets around 160 degrees I feel the truck get sluggish. If I stop and restart the truck it idles and operates fine even up to 45-50 mph but struggles to go above 55mph. I have read 8 posts in regard to my problem but none seem to match. The reman injector pump, mechanical fuel pump (from US Diesel Parts) and filter were all changed in May. The injectors were changed in Nov of last year. I haven't detected any leaks around the fuel sytem allowing air in, the fuel tank is after market with no sock to check and good flow to the fuel pump. Any suggestions?

 

[Iceman3005]

Transmission, check fluid, is low, smell burnt, dark or black in color?

Sent from my SM-G928P using Tapatalk

 

[Dock Rocker]

I didn’t think 70 was very attainable in a 1008? That’s a lot of RPM’s for that 6.2!

My guess is if you have done that often you will need another longblock. The one I had was not happy at 61 or above.


Sent from my iPhone using Tapatalk

 

[LT67]

I didn’t think 70 was very attainable in a 1008? That’s a lot of RPM’s for that 6.2!

My guess is if you have done that often you will need another longblock. The one I had was not happy at 61 or above.


Sent from my iPhone using Tapatalk

What Dock said..... lol, I have 35's on my m1008 and I keep it under 60mph.

 

[Iceman3005]

They do make a good point, the governor only protects the engine from over revving. But if your constantly running in the yellow arc of the rpm range it decreases the life of an engine very quickly. The yellow arc starts around 2800 rpm. With a turbo 400 and the engine at 2800 rpm, that puts the speed right around 55 mph. I only ran mine over 55 mph a few times in the last 10 years I have had it. Until I installed the overdrive trans. Do a compression check, that will give you an idea of the condition of the engine.

Sent from my SM-G928P using Tapatalk

 

[Iceman3005]

70 mph is at max governor of 3600 rpm. Which is red line. Engine failure is immanent at those rpms. The engine harmonics for the 6.2 are horrible. Operating at those rpms causes extreme harmonic differences inside the engine. Cranks break, rods snap, head gaskets blow, blocks crack, main caps shear off, heads crack.

Sent from my SM-G928P using Tapatalk

 

[sandcobra164]

Check valve on the injection pump hanging up momentarily. It's the black 6 sided fitting hooked to the return line. There is a glass ball inside that likes to stay clean. As for the 65 to 70 mph in a M1008, that's spinning the engine pretty fast. Soldiers have done it many times in order to hasten the convoy they were assigned to but they don't have to pay for the damage to the engine if they run it at such a high speed. My M1028 stays at a maximum speed of 55 and I doubt the engine likes spinning that fast for long periods.

 

[Lizard Dog]

I had what sounds like an identical issue and turned out to be a very slight air leak at the supply line at the tank. If I remember correctly, I just saw it was ever so slightly damp there. Changed that section of fuel line, and the problem was gone. Good luck!

 

[cucvmule]

Put on a section of clear fuel line at the return line off of the injector pump and check for air bubbles. Is there blue smoke out the exhaust? sandcobra164 has a good idea for sure, had it happen.

I would like to tach my 82 civi K30 just to see what rpm I am running with 6.2, 40 over, 3.73, Turbo 400, 205, 285 16 BF Goodrich, 160 thermostat, dual snorkel air cleaner to the radiator support hole, 80 mph for 70 miles plus and that old redblock just keeps going.

I am still waiting to melt it down. sorry not my thread.

 

[Husker67]

Transmission checked good! I have a buddy who owns a transmission shop and he looked at it today. No leaks, presure at the module, no overheating noticeable when touching the transmission cooler lines. Oil is pink/red with no burnt smell.

 

[Husker67]

I didn’t think 70 was very attainable in a 1008? That’s a lot of RPM’s for that 6.2!

My guess is if you have done that often you will need another longblock. The one I had was not happy at 61 or above.


Sent from my iPhone using Tapatalk

I don't run 70 often and when I do it's not for long stretches. My truck at 70 on 35 inch tires runs 2500-2600 rpm so I'm not pushing it to hard.

 

[Husker67]

70 mph is at max governor of 3600 rpm. Which is red line. Engine failure is immanent at those rpms. The engine harmonics for the 6.2 are horrible. Operating at those rpms causes extreme harmonic differences inside the engine. Cranks break, rods snap, head gaskets blow, blocks crack, main caps shear off, heads crack.

Sent from my SM-G928P using Tapatalk

Iceman, my truck doesn't go anywhere near that high of rpm except when revved in neutral 1800 rpm=45 mph, 2100 rpm=55mph, 2400 rpm=65 mph and 2500-2600 rpm=70mph normally with about an inch pedal left till floored.

 

[Husker67]

I had what sounds like an identical issue and turned out to be a very slight air leak at the supply line at the tank. If I remember correctly, I just saw it was ever so slightly damp there. Changed that section of fuel line, and the problem was gone. Good luck!

Thanks Lizard Dog, I just found a drop on the mechanical pump today. I'll check tightness tomorrow then chase the lines to look for other areas that might be wet.

 

[Husker67]

Put on a section of clear fuel line at the return line off of the injector pump and check for air bubbles. Is there blue smoke out the exhaust? sandcobra164 has a good idea for sure, had it happen.

I would like to tach my 82 civi K30 just to see what rpm I am running with 6.2, 40 over, 3.73, Turbo 400, 205, 285 16 BF Goodrich, 160 thermostat, dual snorkel air cleaner to the radiator support hole, 80 mph for 70 miles plus and that old redblock just keeps going.

I am still waiting to melt it down. sorry not my thread.

So one time, when I pushed on instead of pulling over, by the time I hit about 40 miles it was spitting out smoke but it was faint and white or blue/white. I didn't lose coolant and was just a bit low on the engine oil but never got that a second time.

 

[Husker67]

Hey all, i just noticed I didn't post the results of my troubleshooting. Turns out there was a plastic in line filter tucked under the cab. It was collapsed and restricting the fuel flow. When the heat from the engine exhaust and the pressure from the pump suction worked together I'm sure there was very little room for the fuel to move through.

 

[nyoffroad]

Hey all, i just noticed I didn't post the results of my troubleshooting. Turns out there was a plastic in line filter tucked under the cab. It was collapsed and restricting the fuel flow. When the heat from the engine exhaust and the pressure from the pump suction worked together I'm sure there was very little room for the fuel to move through.

I hope it didn't take till now to find that! It sucks when people ask and then never get back with the results. Thank you for coming back. I wonder who and why that filter was put there.

 

[Husker67]

No, I fixed it back in 2018 but forgot to let everyone know.