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Piston slap and damaged rod; engine replaced

In June '10 my 06 Explorer twice idled down very low in traffic. Happened again within 1,000 miles; took to dealer: throttle body and spark plugs/wires replaced. Within day noticed constant very rough idle. I returned Dec. '10; was told could not “replicate the customer’s complaint”. Rough idle continued. Feb. '11 took to another dealer: #3 piston slap, damaged rod, new engine, $5600. Did first dealer cause this or mis-diagnose? Do I have an actionable claim? Thanks.

Sounds like they fixed it. No claim that I can see (not that I’m a lawyer, but I did sleep at a Holiday Inn Express).

One question first, did you hear piston slap? It is audible. A little is harmless but a lot will eventually be a problem. It typically happens with a cold engine and goes away with warmup. GM had a problem with piston slap in several engines in the past but it was taken care of by 06 with a tighter assembly fit.

If you heard no piston slap, then the answer leans toward a mis-diagnosis and it is very doubtful that a dealer’s helper would cause a ruined engine.

DID YOU PAY THAT MUCH or was this under warranty? I would think you had it under warranty…NO?

My first question is did the first dealer mis-diagnose the problem to begin with, and, therefore, was the replaced throttle body and spark plugs and wires not the correct fix. Second question is, in replacing the spark plugs and wires, could that have actually caused the piston slap and damaged rod?

Not mechanically knowledgeable so I can’t say I heard a slap. I noticed the constant rough idling right after the dealer replaced the throttle body and spark plugs/wires in Dec. '10. The first two “idle down” episodes in June '10 were very brief and did not continue after I re-started the car each time.

First question - who knows? Maybe, but (second question) it could not have caused the problem.

How might you have been damaged financially?

What I see getting mixed up here are drivability concerns(the rough idle) and an internal engine concern (the piston slap). Your Explorer (or any other vehicle for that matter) can have a very noticable pistion slap but not have a rough idle. I give “altomarie” an opportunity to explain this situation before I lable the story a fail.

Please see my response to Wha Who’s reply. Does that clarify? I don’t know this stuff so my language may not be clear enough in describing what happened. I just want to know if replacing spark plugs/wires can cause the piston slap that has now been diagnosed. Thanks.

At most you might have a complaint that you may have paid for something at the first dealer that you didn’t need. You and everybody else who goes to dealers (and actually most mechanics).

Other than what would be seen as a routine and minor complaint, no - you’ve go nothing and certainly no “actionable claim” - I mean, I guess unless you can show that the first dealer dumped a handful of BB’s in while the spark plug was out.

What I want to know is how the second dealer figured out that you had a damaged rod and what piston slap has to do with it. I’d also like to know (similar to Honda B) why an engine would be going for $5600. At the moment I’d be more worried about the second dealer.

Nope, it can’t. Are you out $$?

It appears from the replies I am getting that the throttle body replacement in June 2010 by the first dealer was not necessary and did not solve anything.

Last week, I took the car with the constant rough idle to the second dealer. In investigating my complaint (running diagnostic tests), the second dealer saw something that led the service manager to call me and say they suspected the problem was in the motor and stated the engine department needed authorization to tear down the engine to properly diagnose (up to several hours of labor to do so). From the repair papers I have: "Power balance test showed #3 cylinder misses at idle; ignition test found bent ground electrode in #3 spark plug… Rechecked and confirmed electrode bent… Found that “vehicle has internal concern casuing internal engine component to contact spark plug. Sent to engine dept.” Engine dept said “#3 plug has piston slap. tear down found damage to either rod or bearings. As per mileage (129K), necessary to install new engine.” Engine with core return was $3400; labor was $1545 and included oil change and tire rotation.

I can assume this was the very first time you gave it a tune up??? Piston movement does occur, for it to bend an electrode and not make noise is alittle fishy. A band aid would have been the old spark plug fouler for cylinder #3 and some washers. No the dealer did not cause this issue, you did by wearing the truck out.

If in fact the #3 electrode was bent, and installing a new spark plug also resulted in a bent electrode, we have no option but to assume that something inside the engine failed and is contacting something it shouldn’t be–namely the spark plug.

Hard to say if the first dealer dropped the ball. If you had over 100K miles and had not yet had the plugs and wires changed they certainly were due. Throttle body replacement is questionable–a good cleaning will usually suffice. As for whether they should have diagnosed the internal engine faiure, well, maybe. Spark plugs and throttle body issues are a common cause of your original complaint. Internal engine failure like you describe is quite rare. So it’s logical that they looked at ignition and intake systems first; when you hear hoofbeats, you think of horses and not zebras, right?

As for the price, labor charge sounds right on the money. Price for the engine itself sounds reasonable for a new Ford engine. Were you given options, like new, rebuilt, or good used?

It’s at least reasonable to consider plugs, plug wires, and a throttle body (electronic) as a cure for the complaint of idling down and a rough idle.
What is not stated is the steps involved leading up to those replacements and none of those would cause a problem inside the engine.

Offhand, it sounds to me like the engine was prematurely worn out (possibly from lack of regular oil changes) and the Number 3 rod/piston was moving on the crankshaft journal too much. This could allow spark plug electrode contact and especially so if the wrist pin is loose in the piston or the connecting rod.

Maybe this piston slap is not piston slap at all and the noise was a rod bearing rap, wrist pin rattle, or a combination of the two.

If you bend a rod, the distance the piston travels will be less–the piston will not make it up as high in the cylinder, leading to reduced compression. It’s hard to imagine how the plug could have been damaged unless they used the wrong plugs that are too long. If they put a plug in that was so long that the piston really hit it, that could possibly CAUSE a bent rod though. Another way to cause a bent rod would be if they cleaned the old throttle body first and used too much cleaner, ‘hydrolocking’ the engine.

If a rod bearing was so worn out the there was enough “slop” so as that the piston could move far enough to crush the center electrode of the spark plug the vehicles owner would be complaining of much more than a “rough idle”.

You obviously have assigned way too much credit to the average car owner. When I was doing this type of work, I saw cars come in that should have been immediately impounded and the owners insisted everything was OK and just needed a little fixing. Brake rotors cut completely through the circumference riding around on the hub, frames rotted so bad and visibly sagging we wouldn’t put them on the lift, etc. Haven’t you seen those pictures of the guy who came in complaining there was a shimmy on the highway and they found 75% of a mattress wound around the driveshaft/differential? You’ve led a sheltered work life if you think a little engine rattle from a worn bearing/wrist pin and maybe some carbon chunks floating around in the chanmber would be obvious to everyone…

A bearing that is in a condition that allows a piston to contact the sparkplug is way out of the “worn” catagory,it is in the “gone” catagory.

Again the use of the ad-hominem logical fallacy, compounded with the strawman fallacy. Not a good example of logical thinking.

Man, you are a piece of work. I seem to recall you’re the one who thought piston travel distance was constant regardless of engine RPM. You obviously don’t possess the type of knowledge or experience to be arguing this subject so let’s leave it at that…