12 Valve Cummins Isues

xjmarc · Jun 13, 2015

I have a 97 2wd lwb ext. cab Cummins that has decided it doesn't like climbing hills towing. Without the trailer it pulls great, spins the tires etc but no rolling coal because it's basically stock. I've noticed it's been struggling a little lately but today I went to GMP which require crossing a couple of mountains and it wasn't happy. It's an auto so about all I can do is put it in drive instead of overdrive. At the bottom I'm pushing 70 and by the top I'm barely hitting 45mph with the pedal on the floor and temps got pretty hot too. Trans was around 200 and motor 220ish, hard to tell since it's the stock gauge and only has 3 number marks. It has 200k on it but that's barely broken in from all I read. Not sure if it's the tranny or motor but it just seems to fall flat when I hit a hill even small ones. Though about adding an electric pusher fan in front if I can find one thin enough but that only helps with the heat. I figure there are some diesel experts on here so lets here how I need a dirtymax or powerchoke cause Cummins suck and so on. Seriouslly I need so advice on what's killing my power.

halcat · Jun 14, 2015

Caigle mountain is a pretty good pull and 45 is not bad fr a low hp cummins like yours. There's not much that can happen. Fuel filter air filter. I have a 97 5.9 in a track hoe that probably has a million miles ( in hours) and that's the only thing that causes it to loose power. Check your turbo outlet tubes. There may have a leak that shows up at boost. If your motor is 220 and your trans is 200it's probably not your trans. have you had this truck for all of it's miles?

TheViking · Jun 14, 2015

Re:

I would say it's the transmission that's your culprit not the Cummins. That being said check what halcat mentioned it can't hurt. When was the last time your transmission was serviced? Also think about a shift kit and different converter those two items may help and a better than factory cooler. High temps can kill a automatic.

If that trans goes I recommend Jim at Lakesite Transmission, he has built a C6 for me in the past and I tortured that thing and nine years later it's still going and living a hard life.

111 has some pretty good pulls in and out of the Sequatchie Valley.

ranger11 · Jun 14, 2015

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Not sure what trans you have but on my 05 48re they recommend the bands be adjusted every 40k miles. Once I done it it was like a new truck. I wasn't having any problems I just decided to service it when I done the rear main. Its fairly easy and would be the first thing I would try along with a filter and new fluid.

5BrothersFabrication · Jun 14, 2015

A friend of mine who is the diesel guru at the Dahj dealer says-

"Who knows. Dropping 25 mph while towing a trailer up a long steep pass isn't unusual. If boost and fuel pressure are ok, then I would suspect auto trans issues. Check the basics like fuel and air filters, boost and fuel pressure, and trans fluid level."

Dunno if it helps, but there ya go. :dunno:

Craig_c · Jun 14, 2015

Need to make sure the boost reference line from the p-pump to the engine is good and not leaking. That line having a leak would keep it from adding fuel under load. Check turbo shaft play, and check the wastegate. Easiest thing would be to check boost under a load.

xjmarc · Jun 14, 2015

I have a boost gauge and it stayed right at 25psi the whole climb. I had to turn on the heat to keep it from over heating which sucks this time of year.
On another note I've wondered about the trans because when i first start it up cold it doesn't like to move. I usually put it in neutral and let it run a minute or two to let the fluid move a bit plus the truck is cold natured so that helps the motor too.
And I've had it around 50k miles or so and it's only used to tow.

ranger11 · Jun 14, 2015

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My trans done that for a while. If you cycle the trans to drive and reverse it will build pressure. There is a valve that's real easy to replace. I did the valve at the same time I did the band adjustment. Also fixed another problem with it not down shifting when coming to a complete stop. When I said earlier about not having problems when I adjusted bands I meant slipping problems. But I'd still adjust the bands when you replace the valve.

ranger11 · Jun 14, 2015

Re: Re: 12 Valve Cummins Isues

Here's everything I bought.

ranger11 · Jun 14, 2015

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Band adjustment
http://igotacummins.com/showthread.php/756-How-too-Adjust-the-Bands-47RE-48RE-518-727-Dodge-Transmission-with-a-Cummins

I have another link on the delay shifting on CPU. Will dig it up later.

TheViking · Jun 14, 2015

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Sounds like bottom line the Dodge automatic transmission is the culprit.

Buy a mega expensive and unwarranted competition transmission lol

xjmarc · Jun 14, 2015

Viking I'd be more than happy to let you buy me a new trans.
I thought it would be a motor thing since it seems to fall flat when it gets under a load, taking off seems fine though. Even considered a fuel plate since I bought one years ago but never put it in but I guess trans makes sense too. Guess I'll look into that before trying to add any power.

Craig_c · Jun 14, 2015

Id bet big money it's not the trans. If it's slipping it's slipping and the rpms are going up with no forward movement. You say no smoke, so my money is on a pump issue not adding fuel when it sees boost (load on engine).

Sawzall · Jun 14, 2015

What is your total weight with the trailer?

xjmarc · Jun 14, 2015

No slipping whatsoever just falls on it's face when I climb a hill much less a mountain.
No clue on trailer weight, XJ with 3/4 tons and 38s and the trailer is 16' with a wood deck.

mcrob0202 · Jun 14, 2015

have the same truck i got rid of the heat exchanger by the turbo made a big difference turned the pump wheel a little and put in a wire to control the converter lockup when i need it to made most of it go away and this was after the trans was redone all at 250000 mi

jayphizzle · Jun 15, 2015

I'd put my money on a fuel issue. Either a boost reference leak to the AFC or a fuel pressure issue. In stock form, those engines will smoke under a load regardless. The overheating issue is what concerns me, do a bit of research on this if you do not believe me. Dodge put radiators in those trucks based off of the engine GVWR, not the truck GVWR. Thus having a greatly oversized radiator. The temperature gauge will vary greatly when the thermostat opens. They remedied this problem in 98 with a slower reacting gauge assembly. All that being said, its hard to imagine your truck overheating with all that cooling capacity. Your problem may be related to the overheating. As long as you have 20 or so psi to your injector pump and you are building boost, you should have plenty of power at the flexplate. Although I build 30-35 psi of boost at full throttle loaded on mine, its got to be lack of fuel. Running an engine lean=overheating. Do you know what your EGT's are running?

BigJ20 · Jun 15, 2015

Check the spring and check ball on the return line. I have a 97 that was pushing fuel back to the tank. Removed the spring, stretched it out, and pushed the plate a little, pulls like a new truck.

muddinmetal · Jun 15, 2015

jayphizzle said:
I'd put my money on a fuel issue. Either a boost reference leak to the AFC or a fuel pressure issue. In stock form, those engines will smoke under a load regardless. The overheating issue is what concerns me, do a bit of research on this if you do not believe me. Dodge put radiators in those trucks based off of the engine GVWR, not the truck GVWR. Thus having a greatly oversized radiator. The temperature gauge will vary greatly when the thermostat opens. They remedied this problem in 98 with a slower reacting gauge assembly. All that being said, its hard to imagine your truck overheating with all that cooling capacity. Your problem may be related to the overheating. As long as you have 20 or so psi to your injector pump and you are building boost, you should have plenty of power at the flexplate. Although I build 30-35 psi of boost at full throttle loaded on mine, its got to be lack of fuel. Running an engine lean=overheating. Do you know what your EGT's are running?

x2

xjmarc · Jun 15, 2015

Where exactly is the boost reference tube? Google is helping any. And it doesn't smoke at all pulling. Had a buddy mention it to me that was behind me.