93' Plymouth mini van ( piston slap.. doh ! )

[awsomeears]

Just wanted to start a thread about my mini van as I know some mopar nuts are in here, so 3 days ago I pulled out of a parking spot and instantly heard " Tap tap tap "

Pulled over as that was never there before, it will only come around 1800 rpm and up if I remember right. I took it into my buddys shop so the top tech there could futz with it, at first said is was possibly a lifter as he's replaced them before on the 3.3

Turns out he diagnosed it as Piston Slap, on one of the rear two cylinders :wow

I will have one more shop diagnose it just for the hell of it as this could lead to a engine replacement. The Van is in great shape and has all new suspension, brakes, tires and killer Red interior :shades

Thoughts ?

Any tech you know of that really knows his shit about these 3.3's ?

[Prince Valiant]

Generally something like a lifter, if it's a single lifter, it's going to have a rather slow sound to it relative to the engine...

My guess would not be piston slap but probably a bad wrist pin...

loud deep sound would be a rod knock...these often will start out quiet if not completely silent, then get louder as the engine heats up and the viscosity of the oil decreases---which doesn't take long. Loudness can vary with throttle too.

Get an auto stethescope or use a large screw driver held against your forehead and start trying to pinpoint the location.

The presence of either means sourcing a new 3.3 or upgrading to a 3.8. iirc wrist pins were a known weak point of these engines though they are generally reliable units.

[Russ Jerome]

Piston slap does not just "start slapping", more and more pronounced on cold start up.
Lifter, wrist pin, bearing can start all at once. Disconect one wire at a time and listen is first step.

[Car Guy]

Generally something like a lifter, if it's a single lifter, it's going to have a rather slow sound to it relative to the engine...

My guess would not be piston slap but probably a bad wrist pin.


Piston slap does not just "start slapping", more and more pronounced on cold start up.
Lifter, wrist pin, bearing can start all at once.

Spot on guys, I talked to B-rad last night and these were my exact thoughts......



The presence of either means sourcing a new 3.3 or upgrading to a 3.8. iirc wrist pins were a known weak point of these engines though they are generally reliable units.

Assuming a wrist pin is the cause I suggested pulling the piston assembly and repairing. Normally I would not suggest this with a 200k mile engine but this 3.3L uses NO oil, was dead quiet before this noise, easily has >90% of original power output, etc. I am curious to hear both your thoughts on this repair (opposed to a long block replacement) from a sensible and financial point of view. Keep in mind Brad's plan is to drive this van until the wheels fall off and an aftermarket reman’d 3.3L is $1,500.....

[-stew-]

The stands that hold the rocker shafts on those like to break. I'd pull the valve covers off and take a look.

[Russ Jerome]

A guy posted earlier to start pulling plug wires while running, that will isolate the cylinder to confirm the issue....or continue to wildly guess and theorize on possible outcomes.....but he drinks a lot.