Our 91 Dodge Caravan is now starting to make a "throaty" bass noise when accelerating. It also has been bucking and hesitating occasionaly, and making a larger "bump" when changing gears (Automatic tranny), however these probs may or may not be related to the awful sound. The sound usually happened before with higher highway speeds, but now it is doing it more at low speed accelerating. This engine also burns oil, and it's getting worse. We realize that eventually it's going to kick the bucket, but we're wondering what these new probs mean.

 

Ouch! Sorry to hear about your problems.

Take a look at your exhaust to make sure there are no visible holes or anything wrong.

If that seems ok, it maybe your transmission. If any of the splines in the gears are damaged, worn, misaligned, you will have noises and a rough ride.

First things first, have you checked your tranny fluid? Does it smell burnt?

 

I took a look at the exhaust system. In order, I see what must be the catalytic converter, closest to the engine, then the muffler around the middle, then another rounder shaped thing, I guess a secondary muffler or resonator. The cat. looks fine, the muffler is a little rusted around inlet and outlet and appears to be a bit dented (who knows how long it's been like that). Also, the secondary muffler/resonator has some black areas (sooty like the tailpipe from the oil burning) that are rusted through.

I also checked the transmission fluid. The engine was off and had not been driven since the other night, but the fluid level seemed to be at the hot mark? The fluid does have a smell to it, but what is this fluid supposed to smell like? It smells different then the fresh in the bottle, but does it take on a new smell from just being in the tranny? Our tranny was flushed a while ago too.

Thanks.

 

You might also double check all INTAKE related items and ducting. The bass sound might be an intake roar from a bad intake duct, which might also be affecting other engine functions.

 

Would advise:

air filter check

choke (if applicable)check

fuel filter check

taking out plugs to analyze

seeing if rotor points to #1 at top dead center

timing check

compression check

__________

Is this a 4 or 6? How many miles? HOW much oil is burned? A vehicle like this is bound to leave you stranded sooner than later. I would be afraid to drive it 'til I at least checked out things like suggested.

 

Sorry I forgot to mention. This is a V6 3.1 litre, the one that says Chrysler on top. It has 256 000 kms. I will check what is listed by everyone. As for the oil, if the engine is on the cooler side it will usually appear fine, but of course once warmed up it will be often down to add in I guess anywhere between 1-2 weeks, aprox. We blow smoke while idling after it's warmed up and when accelerating leave a pretty big blue cloud now. Thanks!

 

Did you say you checked tranny fluid with engine off? Should take it for a drive & check when warm or hot, & engine running. Over-full is not good.
Are you sure you don't have a 3.3L or 3.0L. I don't remember a 3.1L in 91's.
Can you retrieve any trouble codes? One bad or weak spark plug or wire can cause those symptoms too. I'd start with regular maintenance items.

 

I just checked it cool to smell for the burning, what exactly does normal and burnt smell like? Sorry I do believe the engine is a 3.0 litre "Chrysler/Mitsubishi" - looks exactly like the engine in this '88 on this site - http://www.robskorner.org/88caravan/my88caravan.html
We haven't got any service lights, and no fault codes, got the 55 telling me no codes to send.

 

Now that we have the correct Engine info.

Your oil burning and noise are probably caused be bad valve guides. 3.0L engines are infamus for the valve guides droppping down. Sound like yours have dropped far enough to cause an valve to hang open. It's probably so loose that the affected valve is pushing it back up at times. It will need a complete valve job to correct, but the heads maybe unrepaiable if to worn.

As far as your tranny problem, maybe cause by poor engine performance. Is it a 3 or 4 speed Automatic???

But, I could be wrong??????????????
I thought I was wrong once, but I was mistaken, I wasn't wrong!
David