Speaking of broken spark plugs...

[JoeSpareBedroom]

My ex's 1999 Subaru Legacy (4 cyl, 126K miles) began making some nasty noises in the motor a week ago. She drove it 2 blocks and it's been sitting in the driveway ever since, while she ponders what to do. Except for warranty work, It's been maintained by one very competent mechanic throughout its life. He's hesitant to mess with it because he says that evaluation could require major engine disassembly which could cost so much that no sane owner would want to even go that far just to find out that the car is toast. Car is in otherwise excellent condition.

So, ***if*** we were dealing with a spark plug which was broken due to incorrect length, wouldn't that have happened almost immediately after the plugs were installed? Assuming yes, what else are we left with? Right length, wrong plug (temperature)? Wrong torque? Defective plug? Seems like some things could point to the mechanic, as unlikely as that seems based on his track record. Or, manufacturer.

Any other thoughts on this?

[Jeff The Drunk]

Probably not a plug if it ran ok after the last change as a plug long enough for the piston to slam into it would have done damage on the first complete upstroke.

[Jules]

What are the oil and coolant levels like? Any oil in the coolant expansion tank?

All sorts of things can make "nasty noises" - are we talking knocking, scraping, high-pitched squeal, something else?

At the bad end of the scale, valves hitting pistons due to worn timing gear (although I'm not sure if the Legacy's engine is an interference design where that could happen), or a major bearing fault. At the other end of the scale, I had a locking tab break on a cam gear in an engine once which made a heck of a noise, but it was maybe a $1 part and a ten minute fix.

Can you get a second opinion? Maybe tow it to a garage if you have to so someone can listen to it (just keep in mind that you're free to tow it to more than one garage - don't feel obligated to leave it with the first garage you go to)

Lots of mechanics will be able to narrow it down by ear (and experience).

What makes you think it's related to plugs? Was something changed recently that you didn't mention in your post?

[Larry Fishel]

Unless one of the sparkplugs was changed just before starting it up that time, that seems unlikely.

You didn't give us very much info about the problem... Was it running badly or just making noise? Can you describe the noise at all? Are you mechanically inclined enough to at least remove the spark plugs and accessory belts and run the starter? That will narrow things way down with a minimum of effort. (A lot of horrible "engine" noises turn out to be failed alternators, water pumps, etc...)

[JoeSpareBedroom]

I thought of plugs because it's the only one of many possible causes I've read about in the past day. Misleading, but it's all I had in mind at the moment.

[JoeSpareBedroom]

Mechanically inclined enough, but not enough time, and it's winter here. These things never seem to happen when the weather's decent.

So, I'm just gathering ideas.

[JoeSpareBedroom]

Update: She had a nearby mechanic (not the usual one) take a look at the car. He pulled the plugs and in fact, one WAS broken. That's as far as it went. He said "No way to determine damage without major teardown - $1500 or so." Our usual mechanic says "More like $2500 - not worth it for a car with book value of $3000-ish". The latter guy is probably being cautious and preparing her for worst case scenario.

What a mess.

[salty]

You could probably get a guaranteed used engine installed for a lot less than a rebuild of that one. Find a junkyard that has a low mileage wreck with rear end damage. Selling and installing the engine is almost pure profit for them. Negotiate!

[Lp1331 1p1331]

I would definitely have it diagnosed to find out exactly what the problem is, rather than just guesses. If it does turn out that the engine is shot, an alternative could be a wrecking yard engine. If the car is in otherwise good shape,paid for, and she likes the car, it could make sense to fix it, even if if it does cost $1000 or so. That would be a judgement call on her part. Repairs may cost what 4-6 payments on a replacement car would be. Larry

[AZ Nomad]

Unless you're primarily interested in adding a room, or perhaps replacing a toilet, this doesn't belong in a.h.r., even if you live in the car. Try rec.autos.tech.

If the mechanic is competant, he can find out if the problem is major without doing any dissassembly at all. There's probably no way he can damage it worse than has already occured and the problem might just be the bearings of an accessory. If the mechanic is unwilling to start the car then find another.

It is insane to write off the car without even starting it again and listening for where the noise is coming from.

[JoeSpareBedroom]

Yeah - that's why when my son had two web pages full of plugs in front of him, trying to decide which ones were the prettiest, I said "Go to the Toyota dealer. Go to the Toyota dealer. Go to the Toyota dealer. Go to the Toyota dealer." He did. He's happy.

[AZ Nomad]

Whoever replaced the plugs last or perhaps the plug maker owes you an engine overhaul.

[dpb]

JoeSpareBedroom wrote: ...

A plug "broken"??? How? What broke? In 50 years w/ all personal automobiles and light trucks plus tractors and other farm equipment BD (before diesel) I've never seen a broken plug other than breaking the insulation or somesuch external damage.

Unless something like the other doofus-caused damage this seems more than peculiar it was the plug. I, like another poster, don't know the engine but if caused mechanical damage to a plug the timing or a rod or somesuch sound more proximate causes than a plug. The plug may be a symptom...

I swapped a rebuilt engine into an old Honda CRX years ago for not a lot of money...back then there was an abundant supply from Japan owing to a change in their emission requirements iiuc. Don't know what options would be at the moment for that one. Generally, if a vehicle is still otherwise in good shape one can still repair pretty major for less than what would spend on the replacement (unless one is extremely fortunate or disciplined in the process anyway).

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[Jim Elbrecht]

-snip-

Only you can determine if it is worth it to spend that much money on that car. My mechanic has recommended that I junk my daughters 99 Grand Am a couple times. Since we know the entire history of the car, it runs fine despite the 200,000 miles on it, the body and interior are in great shape, and she likes the car, we've spent the money-- and I'm glad we have.

If it was *my* mechanic telling me that about *my* car, I'd be tempted to go ahead and have it overhauled. I couldn't replace it for $3 grand. [and know exactly what is new and old on it]

Jim

[salty]

Think in terms of what it would cost per month for a new vehicle. Be sure to factor in the higher insurance and taxes. Just about any new car will cost at least $300 a month. If you fix this car for $2000 and get only one more year out of it, you are still ahead of the game.

[Tony Sivori]

A incorrect spark plug that is too long will manifest itself upon the very first revolution of the engine.

Since you have a confirmed damaged plug, my guess is that you dropped a valve. If that is the case, the valve is what damaged the plug, not the other way around.

[JoeSpareBedroom]

Spoke to her a little while ago. She's thinking they may never have been replaced. She's checking through a pile of receipts, while complaining that our mechanic should've told her to do plugs at the recommended interval. This is one instance where one of our mechanic's best selling points may be at fault: While working on our cars, he'll point out stuff that needs to be done in the future so we can plan our budgets. For instance, if he's rotating tires, he'll say "Think 6 months for front brakes, unless you start driving a lot more than usual."

BUT: He leaves it up to the customer to keep an eye on the car's service intervals and request certain things, which I like. If (and this is a big IF) plugs can fall apart due simply to age, who's at fault? The mechanic for never saying "tuneup time", or the customer, for not keeping an eye on the service schedule in the owner's manual?

And why am I in the middle of all this? :-) Don't ask.

[AZ Nomad]

It's a little weird with today's cars. Except for spark plugs, there really is nothing to tune up any more. Cars don't have points or carbs. With unleaded gas, spark plugs last at least 50K miles. I've replaced plugs after 50K miles that looked like they could have gone another 50K miles.

[dpb]

JoeSpareBedroom wrote: ...

The plug itself almost certainly had nothing to do w/ it...it's just a symptom of what went wrong. Nor would have replacing them @100k or whatever was the recommended interval likely have made any difference.

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[Stormin Mormon]

For the broken plug. Take the broken plug out, and then start the engine for a couple seconds. It will be unbelievably noisy. But, the missing plug will allow a hole for the pieces of metal, etc, to come flying out. Don't be any where near the hole, even with safety goggles.