2002 Dodge Caravan Ticking noise.

Hey, thanks for the reply. I spent more time under the hood poking around with the stethescope, and I think I've located it in the a/c compressor. When I place the tube over the engine case or valve covers the sound is very faint. However, when I move the tube over the compressor, the sound intensifies. It has a rhythm like helicopter blades chopping the air (very fast) but the tone sounds most like the knock caused by low octane gas (only it doesn't have to be under load to hear it). The sound intensity varies depending on where on the compressor case I place the tube.

I assume there is no way to service the compressor, but does anyone know of a way to isolate it to confirm if it is indeed the problem? Can I run the engine for a short time with the belt off or not? It doesn't make a difference whether the a/c is on or off. I guess there are probably bearings that could be going bad?

I'm sure that wouldn't affect the cat converter or cause the P0240 code. So, I may have an entirely different problem where that's concerned. I replaced both O2 sensors last year.

Well. I have been driving my Caravan continuously since first noticing the ticking sound. I just made sure to keep a close eye on fluid levels. About two week ago, the ticking stopped completely, and that made me think it must have been a lifter. I must have been wrong about the A/C.

Last week, I made a long, cross-country trip to the Smokie Mountains. We drove about 500 miles or so to get there and the engine still sounded fine when we arrived. We drove all throgh the mountain region for about 4 days with no ticking at all.

Then about half way home, I noticed the tick starting again when I pulled in for gas. It was not loud enough to hear while on the interstate though. I know the engine was under more stress than usual. I ran an average speed of about 75mph most of the way. When I finally pulled into my driveway, the ticking noise was loud and clear again.

Probably a lifter, huh? Is there any way to manually pump them up or check them without any major disassembly?

Hey guys,

Thanks for all the input. Turns out it was the water pump. I took it to my local Dodge dealership and paid them $35 to diagnose it. The mechanic put it on the rack, removed the belt and cranked it up. No ticking noise. He isolated it to the water pump and then quoted me $380 to replace it.

I bought a brand new pump from the local parts store for $38 and had it installed in just a little more than two hours.

On removal of the old pump, I found the plastic impeller was broken into two pieces almost right down the middle. There was just enough of the center left to hold one half of the impeller on the shaft. The other half had lodged in a recess in the wall of the pump housing. The noise was coming from the connected half hitting the disconnected piece.

Apparently, it had enough of the impeller left to keep pumping and would stop making the clicking noise when the broken off half would move just enough to not get hit as the other half rotated.

Funy thing was, I had to use a large crow bar to pry the engine away from a main body support about 1/4 inch to gain enough clearance for the new pump to slide into place. Evidently, there is a bit of flexibility in the mounts. Thought others might like to know that in case they run into the same dilemma.

Thanks again for all the help.

--Brad