Tech Q&A Part #2

Bad Vibes

I have a 2007 Dodge dually with about 120k miles on the odometer. The truck has developed a vibration that can be felt in the steering wheel and with your feet through the floor. In a process of elimination to help identify the source of the vibration, I installed new tires, new U-joints, balanced both the front and rear driveshaft, and had the transfer case and transmission opened and inspected. I also installed a new aftermarket torque converter and checked the flexplate and harmonic damper. It’s a huge disappointment after the lengths I’ve gone to solve this problem, but the vibration remains.

During all this, I test drove the truck without the front shaft installed, and the vibration was diminished. But, even with a brand new front shaft a little vibration can still be felt through the floor. Not giving up, I’m thinking the problem may be with the rear drive shaft. Have any other Dodge owners reported a similar problem?

Thanks,

Steven Killmer
Millington, TN

Hi Steven,

Tracking down an odd vibration can sometimes be both frustrating and (as you discovered) costly. Owners of all three brands of trucks have reported odd vibrations at times, but there’s usually a cause and a solution.

My experience has been that a somewhat worn driveshaft slip-joint spline or U-joint will centralize itself above 50-60 mph, and not produce much if any vibration. Removing first the front then the rear driveshaft between test drives will usually highlight any problem with driveshaft balance – before buying a replacement driveshaft or rebuilding the original.

Owning a Dodge, you may have heard about “Death Wobble”. This wobble is an oscillation of the front steering components and tires/wheels that come and go depending on road speed. In the early stages, the wobble is felt as simply an odd vibration at certain speeds. As time and the miles pass, the wobble becomes worse and more alarming. These wobbles are usually due to worn suspension components that can be aggravated by out of balance tires or wheels with the incorrect offset. Big tires can makes these sorts of problems worse because big tires rarely balance as well as stock size rubber, and they wear in ways that can cause their balance to worsen as the miles accumulate.

Once the front and rear drivelines have been eliminated as the cause, check the condition of the front track bar bushings, tie rod ends, ball joints, control arm bushings, steering box, and have a total front-end alignment (including caster) performed. Worn suspension and steering-related components are the usual cause for a death wobble.

To help cure the wobble, BD Diesel Performance produces both a “Steering Box Stabilizer” and an “Adjustable Track Bar Kit” for this problem.

BD’s Steering Box Stabilizer works to eliminate steering wander and wobble caused by excessive shaft play in the steering box experienced by some model year Dodge trucks. The Adjustable Track Bar is said to improve steering stability, and would complement the Steering Box Stabilizer.

Years ago, I spent far too much time troubleshooting a vibration problem that was finally – and with great relief – identified as a bent wheel. This tire/wheel combo would balance perfectly on a computer balance machine, but the dynamic balance while on the highway was off just enough to produce a very annoying vibration in a specific speed range. In addition, a bad wheel bearing can create both noise and a harmonic vibration that can be very difficult to pinpoint due to acoustics inside the cab. I experienced this problem a month or so after fording a stream with my diesel pickup. A leaking front wheel bearing seal resulted in a badly pitted wheel bearing. Keep at it. Somewhere here is the answer to your problem. Good luck.

Sluggish TDI

I have a 1999 VW Jetta TDI with a manual transmission. When accelerating the first time after you start it, it acts sluggish, like it’s operating at half power. Full power returns once reaching approximately 2200 rpm. This first acceleration problem after a start happens with either a hot or cold engine. Dealer techs are at a loss. Any help?

Ben Martin
Visalia, CA

Thanks for the note, Ben.

The first step in resolving any sort of diesel engine starting or running problem is to first change the fuel filter, whether it’s a TDI, Ford Powerstroke, Dodge Cummins, or any other consumer diesel. Aside from eliminating a plugged fuel filter as the cause, a fuel filter replacement will also provide an opportunity to verify fuel quality. Does the fuel look and smell right?

The 1999 TDI turbocharger uses what’s called an N75 actuator valve to control boost pressure. With time and miles carbon can build to a point of affecting its operation. The experts we talked to mentioned the N75 valve as the most likely component that would produce the symptoms you’re reporting.

Swapping a 12V Cummins into a 1997 F350?

I have a 1997 F350 Crew cab 4×4 with the 7.3L PSD. I’ve added a number of performance upgrades, but I would really like to install a 1997/98 12V Cummins. I have some questions:

1. The PSD is a computer controlled engine and has the OBD-II port in the cab. I know that many states have started OBD-II testing for emissions. I realize that under Federal Law that OBD-II compliance only affects 1997 + model years with a GVWR of 8500 pounds or less so 3/4 and 1 ton diesels should be fine. I also know that the Powerstroke is not fully OBD-II compliant (hence why we have to use AutoE or other application specific code readers). Plus, the valve cover even states OBD-II EXEMPT. If I swap in a non-computer controlled 12V from the same year, would this still be a “legal” swap. I am worried that even though we are “exempt” that one day they will try to test us through the OBD diagnostic port.
2. Even though the 12V is a mechanical engine, was there any sort of OBD (on board diagnostics) for these engines? I read that all 94+ diesels were required to have some sort of OBD, just not OBD-II.

I want to do this swap, but I don’t want to end up with a truck that can’t be registered because of emissions certification. Thanks for your advice.

Marc Schwartz
Via E-mail

Hello Marc,

Sounds like an interesting project! 1997 was the last full model year for the 12-valve Dodge Cummins equipped with the Bosch P7100 mechanical fuel injection pump. Beginning sometime early in the 1998 model year, the Cummins was upgraded to a 24-valve cylinder head and the Bosch VP-44 rotary electronic fuel injection pump, which helped it comply with the more restrictive emissions regulations. Lots of 24-valve engines have been modified to run the earlier P-pump, but this doesn’t produce an EPA emissions-certified package.

OBD-II first arrived in the 1996 model year, but wasn’t fully implemented by the industry till the 1997 model year. Your Ford was built during the OBD transition period. The OBD-II was an evolution in the OBD systems, which expanded its capability in monitoring and testing the newest emissions control systems. OBD eventually grew to include all of the vehicle systems, but in the beginning it was just there to monitor and test the emissions control systems.

First generation OBD diagnostics on a mechanically injected diesel primarily looked at Exhaust Gas Recirculation (EGR) operation and the various engine sensors which provide input for the emissions control system. With regard to the engine, the vehicle computer could control the EGR, but that’s about it.

In general, you’ll have fewer emissions certification problems when installing a same model-year or newer diesel engine, but transplant owners can run into emissions certification problems when installing an engine that is older than the vehicle. While what follows couldn’t be classified as legal advice, if the 1997/98 Dodge Cummins you wind up using is running all of the emissions control devices and systems that were present in a 1997/98 model year Dodge pickup truck, it’ll likely be OK in your 1997 F350. The EPA has permitted these types of swaps in the past.

I spent some time online looking for a comprehensive state-by-state list of diesel conversion regulations, and have listed the governmental web site URLs for those I’ve found below that may help. Many people all across the U.S. have performed conversions similar to what you’re proposing, and didn’t have a problem with either vehicle registration or emissions certification. In fact, I haven’t heard of a single reported emissions certification problem, though this may be because most states don’t test diesels. You didn’t mention where you live, but I would check your state’s DMV web site for more info in addition to the links shown here. I suspect you’ll not have a problem registering your truck, but it won’t hurt to ask or search through these links first.

If you like the Q&A series, here’s the previous post in the series: Tech Q&A Part #1