1996 Plymouth Voyager

[lordmorg]

Hey guys, I don't know if this is there right thread but here my problem.

My dad has a 1996 Plymouth voyager and has 180,000 Km. The trouble is that whenever the car comes to a complete stop at signal and stop sign, it sort of jerks for some reason, you have feel it jerk the whole jerk. We found out that its coming from the under carriage. It also occurs when he starts the van and wait for it to warm up.

I was thimk that it could be the Catalytic converter, but I'm not sure.

If you can tell what the problem is and the seriousness it would be appreciated.

[KManiac]

First of all, let me reassure you that whatever is causing the "jerk", it has nothing to do with the catalytic converter. Your catalytic converter (cat for short) is just a passive part of your exhaust system that has exhaust gases passing through it. It can fail either by clogging up or it will just stop burning off unburn gases. Should it clog, the performance will decrease and the van will feel sluggish from the increase back presssure in the exhaust system. If it fails to work without limiting the passage of exhaust gases, you won't know it until if fails a smog test for excess hydrocarbon (HC) emisions.

Now I realize that what you are experiencing is some type of "jerk". Unfortunately, that description is a little vague. It would help to have a more detailed description of this experience, including anything that occurs leading up to the "jerk". For example, my wife periodically complains of a "clunk" in the front end of our Town & Country. This clunk occurs infrequently when she is backing up. She will put the van in reverse, apply throttle and then hear a clunk from the front end and a feeling like she just ran over something.

What we need to have you do is experiment with your van a little bit. Do whatever it takes to make the "jerk" occur and see if you can get it to "jerk" on command. Then tell us what you did to make it jerk on command and a detailed description of what the jerk feels and sounds like. Then we will have better idea of where to direct you to look.

Please give this some thought and let us know what you come up with.

[lordmorg]

I did some test over the weekend and found out that the jerking motion only occurs when the heater is on. There isn't any noise coming from the engine. The jerking is up-down movement rather than right-left. Its felt throughout the whole van.

[vipergg]

The next question does it happen when the defrost is on ? The defrost runs the air conditioning compressor . The defrost is on when the knob is all the way to the right. If so then its possible that the compressor is on the verge of seizing and is putting a big load on the drive belts and that is what you are feeling . Try it when you set it to just blow out the front panel instead of the defrost and see if it still happens , that is the only thing that could cause something like what you are describing when the heat is on . The compressor does not run when it is just blowing out the front panels .