Engine/Transmission (1994 - 1998) '96 slowly loosing power

[catskinr]

My '96 3500DRW(which only gets driven 8-10k/yr. )is slowly losing power. A hill i pulled at 65-70mph a couple years ago with my camper I could only get 55-60MPH with my little 6'x12' trailer with two fourwheelers. The truck has 89k on the odometer. The engine sounds great it just won't pull. was wondering if anyone else has had similar problems. It gets a little worse every year.

I've blown the transmission lines off twice. Could it be a trans problem. Trans oil still smells fine but it does have a hesitation on acceleration after decelerating. Also, after sitting for a while it will take a little while for it to move after putting it in gear. I don't know what happens when a torque converter goes bad.



any suggestions would be appreciated.

 

[kenny61]

wastegate diaghphram on mine went. It happened very slowly and took me a few years to realize what happened. to test you can plug it where it tees off by the fuel plate thingie

 

[Missouri Mule]

You have been changing your fuel filter?

Are you blowing any smoke going up the hills? I would check for boost leaks from turbo to intake horn. Maybe loose intake manifold bolts?



Do a fuel pressure test to make sure your lift pump isn't going.

 

[hdm48]

Have you done anything for maintenance? Air filter, fuel filter, valve adjustments?

Do you have a boost guage? what kind of boost are you getting?

Won't move after sitting a while? When was the last time the trans was serviced.

sorry for all the questions,but info like this would help.

 

[Missouri Mule]

When you let it sit for a while the fluid in the torque convertor drains out of it. Shift it in neutral and let the torque convertor fill up again.

 

[K5IP]

This is too little too late, but here is why gauges are nice. If you happen to have them, has your boost decreased? If so (and higher EGT's are noticed),look for air leaks/waste gate problems. Lower boost (and lower EGT's) indicate reduced fuel input.

 

[surfbeetle]

This is too little too late, but here is why gauges are nice. If you happen to have them, has your boost decreased? If so (and higher EGT's are noticed),look for air leaks/waste gate problems. Lower boost (and lower EGT's) indicate reduced fuel input.

This is so true, mine started to have less boost as noticed on my guage. I inspected all of the boots on the intercooler and associated piping after tightening everything up, my power was back up. With a stock truck, you should have about 20 psi max boost, with a tst 5, you will get about 30.



If you don't have a guage, check the issue of the TDR before the current one for a parts list to make a tool that you can pressurize the intake and look for leaks.

 

[catskinr]

Change the fuel and air filters once a year(6-10k mi. ). No boost gauge. No valve adjustments.

Trans was serviced the last time i blew the trans lines off. about 30k ago. It only does that after setting for more than a couple of days.

The only time it smokes is when i'm in the mountains. It seems to load up on fuel freewheeling down the big hills and blows white smoke when reaccelerating.

 

[catskinr]

Kenny61, how many miles were on your truck when the waste gate went?

 

[dan.poitras]

Check the basics. Throttle lever going to full fuel. Fuel solenoid pulling all the way up. Can you hear the overflow valve "buzz" when pump the fuel primer.

Are you maintaining at least 5 psi of fuel transfer pump pressure under load?

 

[Joe G.]

It's a 12 valve. 5 PSI won't happen if it will start. 18 PSI at idle and 25 PSI at 2K RPM are the specs. Most 12 valves will be more than that. Mine never gets below 30 PSI no matter what.



The power lost symptom may be an AFC problem.

 

[catskinr]

I'm starting to think gauges would be a good investment.

The truck seems to run perfectly on the flat. But loses to much speed to quickly on the hills even with very small loads.

With your suggestions I have an idea of things to check. Hopefully it will be something fairly simple aka cheap to fix.

 

[Skydiver]

Are your tires up to proper pressure?

Has the fuel milage dropped?

 

[kenny61]

Kenny61, how many miles were on your truck when the waste gate went?

Its a 96 happened about 3-4 years ago fixed it 2 years ago. (only noticed when i test drove my buddies truck and felt the difference) probably had about 150K. what happens is the wastegate slowly leaks and eventually get bad enough that the boost doesn't make it to the AFC control and then you don't get any fuel. 10 minute test disconnect the rubber line going to the diaphragm at the afc and plug it make sure you dont disconnect or plug the line going to the AFC. if its the wastegate diaphragm plugging it off will will result in instant smiles on your face. Chrysler and Cuminns do not sell the diaphragm separately I had to get mine from Piers

 

[dan.poitras]

It's a 12 valve. 5 PSI won't happen if it will start. 18 PSI at idle and 25 PSI at 2K RPM are the specs. Most 12 valves will be more than that. Mine never gets below 30 PSI no matter what.



The power lost symptom may be an AFC problem.

I repeat, a minimum of 5 psi "under load" .

We work on lot's of older fire trucks with the same setup.

Although what Joe indicates is correct.

 

[catskinr]

skydiver,

The tires are to pressure. Mileage has dropped also. With the switch to low sulfur diesel is the mileage drop normal?

 

[Joe G.]

If you have a leak somewhere so boost isn't getting to the AFC properly you will get your symptoms. Especially if the leak is gradually getting worse.



The switch to low sulpher fuel dropped my mileage a couple of MPG, but the later switch to ultra low sulpher fuel had no additional affect.

 

[BSMcCauley]

Its a 96 happened about 3-4 years ago fixed it 2 years ago. (only noticed when i test drove my buddies truck and felt the difference) probably had about 150K. what happens is the wastegate slowly leaks and eventually get bad enough that the boost doesn't make it to the AFC control and then you don't get any fuel. 10 minute test disconnect the rubber line going to the diaphragm at the afc and plug it make sure you dont disconnect or plug the line going to the AFC. if its the wastegate diaphragm plugging it off will will result in instant smiles on your face. Chrysler and Cuminns do not sell the diaphragm separately I had to get mine from Piers

My '96 factory setup has a short rubber hose connecting the wastegate actuator to the outlet nozzle on the compressor side of the turbocharger. Then there is a separate short plastic line connecting the AFC actuator to the intake manifold. The only way boost gets to my AFC is through the intake manifold. Doesn't the wastegate open on rising pressure against the actuator? If the wastegate actuator had a hole in it, this would result in higher boost on my AFC, not less.

 

[Joe G.]

It's a feed back deal. Fuel makes boost. The AFC restricts fuel. The idea is to limit fuel until boost increases. The stock setup is tuned to allow enough boost to cause the AFC foot to move some. When this happens there is more fuel which produces more boost etc etc etc... until there is enough boost to move the AFC foot out of the way so the plate takes over limiting fuel. If the AFC does not get enough boost in the first place because of boost leaks or there is a problem in the AFC the feed back system stalls with the fuel limited by the AFC foot stopped in place.

 

[kenny61]

The boost comes out of the intake manifold and tee's into the afc and wast gate if the waste gate line leaks the boost will not go to the afc. the line is not big enough to flow boost to the afc if there is a leak in the line