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Mechanic installed the wrong plugs

I took my Jeep to a mechanic for a tune-up and ended up with plugs/belts/hoses/water pump/AC fan etc. Since the work was done the Jeep surges and lags. I took it to the dealer who said that the spark plugs that were installed were the wrong ones. He replaced those and noted that I also needed a new ignition coil and radiator (which began leaking from the pipcock after the “repairs” at the mechanic). So, my question is: since the Jeep ran FINE when I took it in for periodic maintenance and ran horribly after that, could the mechanic have caused damage to the engine? Could the wrong plugs have caused the ignition coil to go bad? Could they have damaged the radiator when they drained it to put the water pump in? I feel like a fool and have now put almost $2000 into an old vehicle.

I doubt that “the wrong plugs” damaged your ignition coil. Perhaps they were the wrong heat range, which may account for poor running. I have never heard of a coil failing because of the spark plugs installed.

As for the radiator, it’s possible that it was damaged, but it’s possible that A: Damage was unavoidable in opening the radiator petcock (are you doing regular coolant system maintenance on this vehicle?) or B: The added cooling system pressure that comes with a correctly working water pump caused this weak point to fail.

Those are my thoughts. I wouldn’t feel too foolish or fault the original mechanic too harshly, but you might go back and have a word about the spark plugs because those are a pretty big part of a “tuneup” and they owe you some money if they didn’t install the right part.

I will be so bold as to assume that this is an early-'90s Jeep Cherokee with a 4.0L inline six, is that right? I say this because I’ve heard of a lot of coil failures and other ignition system maladies in this particular model.

Did installing the “correct” plugs cure the driveability concern?

Did the mechanic work off a list of replacement plugs that the Dealer labels “wrong” simply because they don’t like them?

Why did you not return to the mechanic that did the tune-up when the vehicle stsrted running poorly? Give the guy a chance to honor his warranty.

I am sure he did not knowingly release a car back to the customer thar was running poorly.

Odd to replace a entire radiator for a “petcock” leak.

Why do you think they drained the radiator thru the petcock? I never did, It took to long and you stand a chance on damaging the petcock if you don’t know which way to turn them,just pull a hose.

There is miscommunication that’s gone on between you and the mechanic, and you and the dealer, and, then, you and us.
I’ll have to echo what the others said. The dealer may not have liked the spark plugs because they aren’t the ones sold by the dealer. The brands of spark plugs aren’t that different.
Scheduled, routine maintenance has to be performed on any vehicle, and it may cost hundreds of dollars for each kind (such as a timing belt change).

I did take the vehicle back to the original mechanic. In fact, I didn’t drive it more than a mile or two before I realized it had a problem. The initial work took three weeks. When I returned it the same day, it took two more weeks to “fix” it. It started acting up again after about 5 miles. I went home and called the mechanic who told me he had no idea what else he could do about it. He suggested I tighten the belts with a wrench periodically. Have I given him enough of a chance? I am not trying to judge him harshly, in fact he was a really nice guy about the whole thing.

I have had the PMs performed since I bought the vehicle used about two years ago. It really ran just fine when I took it in but I wanted it to be in tip-top shape for winter. I will check with the dealer about which spark plugs were in the vehicle vs. what he put in. I will also ask about the specific damage to the radiator. Hopefully he will be honest with me. I am NOT a big fan of dealers but didn’t want to risk another local mechanic with my current experience.

How does one know when they need a new water pump? I had a water pump fail once so I know what the symptoms are for that but how about in a vehicle that was running well? How does one find a good mechanic? I asked locals for a recommendation and there really wasn’t a concensus. It is a 2000 Jeep SUV.

All of you are so helpful, thank you very much!

Sorry to hear that you have had such a problem with the ‘tune up’ that was done. It sounds more like a out of tune job was done. The amount of time taken to do the two jobs seems very excessive. Hopefully the dealer service department can help get things right again. If you still would like to find an independent shop here is a link to the Mechanics Files which is available from this site also.

Why don’t you post the plug manufacturer and model # so we can determine if, indeed, they were the wrong plugs.

I suspect the plugs were fine and the problem all along was the coil. As noted, dealers like to put their own plugs in. They trust what they know and there’s profit in the parts.

A leaking petcock is not all that unusual, especially if it hasn’t been used in a long time. I fail to see why a NEW radiator was needed if the petcock was leaking. The petcock is a separate part that screws into the radiator.

Personally, I suspect the dealer took you for a ride more than the original mechanic. If you had returned to them, they may have spotted the bad coil quickly and swapped it out without all this added expense.