Tech Q&A

The editors of Mopar Magazine answers reader's technical and general service questions.

We own a 1998 Dodge Intrepid with close to 100,000 miles on it. I drive the car every day and I’ve noticed over the course of the last year or so that the car is beginning to wander quite bit. The steering seems to have become very vague and imprecise. It’s actually hard to keep the car on-center. Any ideas about what could be causing this?

MM: With the information you’ve provided it’s difficult to diagnose an exact cause. Any number of items can cause vague steering. Having said that, you might want to have the inner tie rod bushings and rack and pinion bushings checked. Worn bushings can definitely cause steering wander. Also the steering rack itself could be worn. Many other steering and suspension components—as well as tires—can cause steering wander. What ever the cause, it’s a big safety issue, so you need to have a qualified technician check it out right away.

I have a 1980 Dodge Class C motor home. It’s in very good condition and it generally runs great. My problem is this: I changed from a ThermoQuad carb to an Edelbrock 795 cfm model 350-1905 carb. The ThermoQuad had been rebuilt twice and the shop could not stop it from leaking gas into the intake manifold, so I replaced it with the Edelbrock. I now have a hesitation problem once the engine is warmed up. At highway speeds, it’s great, but when I stop or slow down it bucks, then catches and runs fine. I’ve been told the carb is getting too hot and the gas is boiling in the float bowls. I never had this problem with the ThermoQuad. I have a flex fan installed and the radiator is fine. Do you recommend a different carb, a bigger radiator, an electric radiator fan, or what? I can’t seem to get an answer and I really want this problem to go away.

MM: If the gas is boiling, you more than likely have a vapor lock. A vapor lock happens when liquid gasoline turns into a vapor due to high heat. The vapor essentially blocks the liquid gasoline from flowing and that’s what could be causing the hesitation—especially at low speeds. At higher speeds (like on the highway) there is more air flowing to cool the engine, and the higher rate of fuel flow associated with faster driving could overcome any potential blockage by fuel vapor. Before you replace the carb or get a bigger radiator or install an electric fan, you might contact Edelbrock for some carb tuning tips. Visit www.edelbrock.com, click on Edelbrock Automotive and follow the Carbs and Accessories link for tips and to find a dealer near you who could offer some assistance.

I currently own a 1997 Jeep® Grand Cherokee with a V8 engine in it. It has 60,000 miles on it, and I keep it well maintained using mid-grade gas on most fill-ups (call me crazy with gas prices being what they are). My problem is that the engine pings or rattles on acceleration. Does this engine have a knock sensor? Any ideas as to what could be causing this?

MM: Our information shows that your 1997 Grand Cherokee is not equipped with a detonation or knock sensor. The condition you describe could be the result of a variety of problems, mostly regarding engine management (fuel and spark curves), which can be caused by nearly any of the vehicle sensors. We’re aware of three Technical Service Bulletins (TSB) that refer to spark knock in your Grand Cherokee. They are: Spark Knock due to Manifold Gasket Oil Leak (09-05-00), Ignition System Cross Fire (18-48-98), and Light Spark Knock Timing Retard Feature (18-24-98). Your local Jeep dealer can get you copies of these TSBs. Good luck.

Will a 440 engine bolt into a 1970 Plymouth Fury w/383 engine? Will all the accessories bolt up to the 440?

MM: As a general rule, the engine mounts front accessories and bellhousing patterns are the same between the “B” (361-383-400) engines and the “RB” (413-426W-440) engines, although minor differences can be found from year to year. For technical assistance and advice, see the Engine Swap chapter in Mopar’s Chassis Manual (P5007160).

I own a 1984 Dodge Ramcharger that occasionally has no spark at all. I’ve replaced everything electronic related, and yet sometimes it has a spark and sometimes it doesn’t. It has power to the coil all the time. What gives?

MM: Any electrical/no-start problems are very difficult to diagnose in this manner. There are simply too many questions we’d have to ask to begin a proper and thorough diagnosis. If by chance you have a Mopar Performance ignition kit installed, consult the troubleshooting section in the directions, or the Ignition chapter in any of Mopar’s racing engine manuals. If you’re dealing with a factory ignition, get yourself a copy of the appropriate service manual, which can be ordered online at www.techauthority.com.

I own a 1985 Ramcharger 4x4 with a 5.9L and automatic. The engine is tired, so I purchased a low-mileage engine to replace it. The engine is a 5.9L out of a 2000 Durango 4x4. The engine came complete with starter, power steering pump, alternator, A/C compressor, flexplate, exhaust manifolds, computer and wiring harness. I have a few questions about swapping the engine. According to the Chrysler service manual, since it’s a 5.9L, the trans is a 727. Will the Magnum 5.9L bolt up to my original trans? The Magnum engine has an rpm sensor located at the rear of the engine. The bellhousing on the Ramcharger is not made for this sensor. Can the senor by relocated? Will the original engine mounts work. What problems with the electrical system do you foresee? Do I need all the sensors for the Magnum or can some or all of them be bypassed?

MM: Yes, your transmission will bolt up to the Magnum engine. As for the rpm sensor, your best bet is to modify the bellhousing to accept the sensor. If you get the sensor out of synch the engine may not run, or it may run very poorly. Your original motor mounts will bolt up to the Magnum, but remember they are more than 20 years old; you should replace them while everything is apart. As for any electrical problems, if you take your time with the service manuals, you should be OK. For the engine to operate properly, you should use all the sensors.