My Miata's busted...
 

So, it's actually my mother in laws but I do enjoy driving it on summer days with the top down.

It's a '95 I think...

Anyway, on to the problem. It's not running on all cylinders and being a bit busy I took it to a mechanic down the street. I've used them before for stuff I didn't want to do and they had done good work at reasonable prices before. The guy at the shop this time however was different from before...

So I left it with them this morning and asked them to call me when they had a diagnosis. I knew it wasn't firing on all cylinders so I told them that. They called me later in the day to say it was oil leaking from the valve cover gasket into the spark plug holes fouling the plugs on cylinders 1 and 4.

$380 to repair by replacing the plugs, wires and the valve cover gasket.

Who and the what now? $380?

If you're not familiar with a 4 cylinder engine - it's pretty simple to replace all of those things being as they are the top most parts. The wires don't even require tools. The plugs of course only require the plug socket. Seriously... So that leaves the gasket and I believe him. It's leaky - I was planning on replacing it myself actually. Now I have to decide on if I will be having him do the repair for $380 total OR just pay him his diagnostic fee of $65 (which I have no qualms with).

I'm leaning toward bringing it home and replacing the parts myself because that will likely be less than an hour or so of work AND less than $100 in parts (total of $165 including the diagnostic fee).

Seems kind of steep for such easy work to me.

DAMMIT! The knowledge and experience of a 'shade tree' mechanic is frustrating! If I knew none of this I would have just parted with the money! Nooooo! I have to have wisdom, experience and knowledge...and tools...

The cheapest way to go is to pay the mechanic, then just replace the valve cover gasket and clean the spark plug wires. Maybe they're still functional.

This seems like good news to me. The mechanic probably doesn't want to be bothered with this small of a task so he put a little extra on the estimate to see if he could make some money. He has to send out for the parts and keep the car in the shop etc. And isn't going to make too much on this repair.

Im sure you are right. The car is due for some love so i dont mind spending the money on the parts. Also, i drive by this shop almost daily and it is pretty empty quite a lot. I figured he would want any businessnhe could get.maybe im wrong...

My biggest fear is that he is wrong and this doesn't fix it. Then it gets expensive in the labor and he is already over the line in my book. Ill just have to deal with spending time on tking stuff apart to get to the naughty bits that are failing.

If its your 911, you will pay that in a heart beat. He has to make about 70 bucks an hour just to make a few bucks. Call and get the parts and just in case if he run into any problem, he got a few bucks to soften the fall.

The miata is super easy to work on and pretty darn simple for a modern car. I say do it yourself. Consider it a Zen thing.

I had a place like that local to me. Guy seemed pretty good and always seemed fairly priced. I took a job to his place, but he wasn't there and there we 2 other guys there. I'd done the job before in about 4 hours, they quoted 8 or 10 hours and almost $1000. They didn't get my money. I think the guy had sold the place to them. I've never been back.

Miata's are really sensitive to plugs and wires, so don't cheap out on them. I'd be worried that it's a coilpack, which while seemingly simple, it actually a PITA to get out because of that third bolt underneath.

Yeah, the preferred wires for the miata are NGK blue wires. They seem to last the longest.
I know the coilpack was a week point in the '99 models. It's not as common an issue in the NAs, but it could be. Better to do the plugs and wires first then worry about the coil pack.

Let me get this straight.

Oil is leaking out of a valve cover to the spark plug area. That should be pretty easy to see.

But now we have to believe that oil is then going through the sparkplug threads, under a very tight washer, into a cylinder that is WAY above amospheric pressure mose of the time, and is fouling the plugs.

I call shenanigans. There may be fouled plugs. They might be not running right because the sparkwire is damaged. But no way is oil "seeping" into the cylinder and fouling the plugs.

get it back home. replace parts starting from cheapest/easiest to expensive/hard. spark plugs, wires and see if it's still happening. it could be just spilled oil from who knows when.

The spark plug is in a tube that goes down between the cams. There is an o-ring or gasket part way up. The ring fails, the tube fills with oil and it gets under the plug wire boot.

Once the wire shorts, I assume the plugs foul from unburnt fuel, not from oil leaking into the cylinders. But that doesn't make much sense either as there isn't enough heat. Maybe look at the plugs when you pull them. They should be wet with fuel.

What Rick-I said, it's not actually getting into the combustion chambers. It's filling the well that the plug and plug wire are in and is probably causing the spark to take another route to ground besides through the spark plug.

You can test the theory by removing the plug wires (no tools required) and thoroughly cleaning the spark plug wells. One, if the oil-leak theory is true, one or more wells will be soaking wet with oil. Two, by cleaning the oil outta there, it should run just fine for awhile. Then as the leak fills the well again, you should see intermittent misfire.

Zero tools, zero dollars.

Eventually, you should just replace the cam cover gaskets and spark plugs. Why not? It's cheap and easy.

I'm getting the car back today and will let you know how it goes. The local auto parts store has all the parts and it is less than $75 for them. I can spare an hour or so to do the work. Maybe even today.

Just picked it up. Felt a little bad; he put some used plugs in and cleaned it up enough to where it was drivable home. I appreciate that, told him so.

My heater core is probably going out on my Volvo - might take it to him.

A good, honest mechanic is a nice thing to have as a resource!

It's a no-brainer to replace a leaking VC gasket whether it's the cause or not. Then, if lucky, problem solved w/ new plugs and cleaned wires.

If not solved, you needed to change that gasket anyways.

Mikester, I'll come over and work on your car anytime if you don't have the time. You're in L.A., right? That goes for any other L.A. area Pelicans, I've been doing a bit of freelance mechanical work lately. I enjoy it and my prices are better than most shops due to lack of overhead. :)

Some Miatas have a habit of stripping the threads in the head when you pull a spark plug that's been in there too long.
It's not common but it happens enough to mention.

I might just take you up on that.