Engine/Trans noise woes. Miata gurus hellp?

[xjdesertfox]

So for the past couple months, I've been trying to figure out what this noise is that my car is making. I cant really describe aside from the sound of a bearing with a pit in the race that makes a "tap tap" added in with a rattling washer.

I've tried to eliminate variables, but I just cant figure it out for the life of me.

My car is a 95, all stock drivetrain + K&N drop in filter and a Jackson racing header.

- When the sound happens. -
The sound does not occur until the motor is warm, and it seems like it happens on warmer days.

Sometimes it slightly makes the noise if i let the clutch out at around 1300 rpms. Higher rpms it does not.

In third, fourth, and fifth gear, at or above 3.5k RPMs. But not first or second.

If I climb a big hill on the freeway, it will make the noise throughout the whole pull.

- What I've tried. -

My first thought was speedo cable, I threw a new one on and it seemed to fix the problem. Until the weather got hot again.

I've removed my A/C belt and tensioner(car has no P/S) thinking it was the A/C clutch. No dice.

I've looked for any type of loose bolt/washer or the like, but it doesnt sound like its just a loose washer, theres an RPM related "tick" associated with it.






Someone mentioned clutch pilot bearing, or TOB, but I've never had one go bad so I dont know what that feels like.

You can hear the sound in this video as my car drives by. I cannot replicate the sound unless the car is under load, it does not make the sound while revving in neutral.



Is my motor gonna asplode?

[xjdesertfox]

Also, someone told me it might be detonation. I havnt checked the timing on the car, and it seems like my problem came back after putting in some 87 octane arco gas. But I topped off my tank with 3 gallons of 100 octane, and the sound did not go away.

[— kung fu jesus —]

would love to help, but that video isn't offering any clues. It's too short.

possible to make one from in the car? if you suspect detonation, check your timing. If you are too far advanced, 87 octane is tearing it apart. You shouldn't be at anything above 14* at idle.

[xjdesertfox]

Will try to make a video as soon as I have time. I'll grab a timing light and go to town as soon as I get a chance too.

I just drove it with the speedo unhooked, same problem so that rules the speedo cable rattle out.

Ill probably get a vid this weekend, thanks KFJ

[— kung fu jesus —]

If it is under load when this happens, it could very well be detonation. Check your plugs in the mean time to see if they are burnt. It could be a pulley (idler) going bad.

[atlnb]

Does sound weird. I wouldn't suspect engine though. When was the last time you changed the clutch?

[xjdesertfox]

Does sound weird. I wouldn't suspect engine though. When was the last time you changed the clutch?

I bought the car in February with 156k miles on it, "supposedly" the clutch was changed 3k miles before I bought it. When I test drove the car I tested it for slippage and it felt real good. But whatever clutch and pressure plate thats in the car doesnt feel that great.

i have an ACT stage 1 pressure plate and exedy HD friction discs sitting on a shelf collecting dust because it was given to me, but whether or not its usable is another thread altogether.

Took some pics to show you guys my plugs are unevenly colored? One side is lighter than the other. Also, I stared down the spark plug holes and my pistons look heavily carbon coated. I also discovered a leaking valve cover gasket, and a belt material covered idler.




My number 4 plug had this weird black burn on it?



Idler



Tensioner

[— kung fu jesus —]

Wow. Those plugs definitely don't look right. The darker ones, especially. If you have heavy carbon build up in the combustion chamber, the carbon can heat up to the point of causing detonation, it can also raise your compression in some cases.

The idler pulley is OLD. It makes me think it is the original one. You shouldn't see pitting and discoloration on the surface like that. I changed mine, as I normally do, when I did the TB service last spring. It had 70-80k on it and still looked new.

Just my opinion, but I would still check the timing first. If I were you, I would recommend plans to "reset" the car by updating the routine maintenance. I would look into a complete TB service (timing belt, ilder pulleys, seals, hoses, coolant flush, etc.). This will help you start to pinpoint potential compounded issues and will give you a clean slate of sorts to help you get the car's performance back. Forget the clutch for now. Start with a good, thorough tune up.

I might also suggest you start running 91 octane or at least buy fuel from a GOOD source, like Chevron, Shell, or Mobile until you get the timing checked. Buy fuel with good detergents. Hell, just go BUY a timing gun, they aren't that expensive $40-50. Small price to pay for irreversible engine damage. I would probably pick up a can of Seafoam and dump it straight in the fuel tank with a full tank of fuel if you suspect heavy carbon build up.

[xjdesertfox]

I got a timing gun yesterday, those plugs only have 3k miles on them btw.

I won't be able to work on the car for awhile, I'm thinking of just buying tony pham's motor that's for sale right now. This motor also leaks all over the damn place, so at this point calculating cost, it might be cheaper and less headache to swap another motor in.

In the meantime I'm gonna drop some MMO down the spark plug holes while it sits, from my reading doing an mmo piston soak cleans the carbon off pretty damn well.

I'm running a mix of 2 gallons of 100 octane from alliance, 6 gallons of chevron 91 and the rest is arco 89 and its still pinging.

[WASABI]

I got a timing gun yesterday, those plugs only have 3k miles on them btw.

I won't be able to work on the car for awhile, I'm thinking of just buying tony pham's motor that's for sale right now. This motor also leaks all over the damn place, so at this point calculating cost, it might be cheaper and less headache to swap another motor in.

In the meantime I'm gonna drop some MMO down the spark plug holes while it sits, from my reading doing an mmo piston soak cleans the carbon off pretty damn well.

I'm running a mix of 2 gallons of 100 octane from alliance, 6 gallons of chevron 91 and the rest is arco 89 and its still pinging.

I agree that those plugs look bad, especially for only having 3k on them. Had the car been sitting before you bought it? I ask, because my idler pulley looked the same on a car I bought that had been sitting for a couple of years.

I suggest you buy a timing belt/water pump kit (that includes cam, and crank seals, new belt, water pump, pulleys, and gaskets (valve cover gasket too). Also, pick up a CAS o-ring as well (and maybe plug wires).

Once you change your timing belt, and everything else, adjust your timing, then you'll have a base to judge how you engine is really behaving. This is basic maintenance, and will more than likely fix your leak, and performance issues.

-Jim

[xjdesertfox]

I agree that those plugs look bad, especially for only having 3k on them. Had the car been sitting before you bought it? I ask, because my idler pulley looked the same on a car I bought that had been sitting for a couple of years.

I suggest you buy a timing belt/water pump kit (that includes cam, and crank seals, new belt, water pump, pulleys, and gaskets (valve cover gasket too). Also, pick up a CAS o-ring as well (and maybe plug wires).

Once you change your timing belt, and everything else, adjust your timing, then you'll have a base to judge how you engine is really behaving. This is basic maintenance, and will more than likely fix your leak, and performance issues.

-Jim

My motor is currently leaking pretty badly from the rear main. The car was indeed sitting for awhile, the previous owner said he drove it about 2k in the year prior to me purchasing it. Supposedly the previous owner changed the timing belt and water pump before it was sold to me, which I believe because my belt looks brand new, and is goodyear branded. Im guessing he just didnt replace the idler/tensioner while he was in there.

Right now I just feel I should just try and swap in a lower mileage motor which has been maintained, I have to pull the motor to change the rear main anyway right?

But if it doesnt seem financially viable to do a motor swap, I will indeed change the TB/WP/seals.

[adamvanxxx]

It is easier to pull engine and trans together but you can just drop trans and change the rear main.

But with the engine out we still had a hard time getting my buddys out.

As for the engine, without a better video there is no telling, but I would not just suspect it to blow. As stated to some tune up stuff maybe seafoam it before hand and get some carbon out. If you can try to look in those spark plug holes and see if you have any damage on the pistons.

[xjdesertfox]

Looking inside, all I could see was a ton of carbon.

Looks like I'm gonna reseal the motor and try to get it running right, the motor I wanted to buy sold.

[adamvanxxx]

Try seafoaming it and breaking some of it up?


If you can afford to taking the head off and giving it a good clean would be awesome too.

[xjdesertfox]

I would take the head off, but If I did, I know Id want to just rebuild the whole motor, I'm willing to bet my block's surface needs to be refinished if I pull the head.

I'm going to soak the pistons with MMO, then again with amsoil powerfoam. Then i'll run seafoam in the gas.

I checked the timing, and im at 12degrees BTDC. I backed it off to 10 degrees to hopefully stop the pinging for now. I think i've found the source of my pinging, I think its a combination of the carbon deposits on the pistons and running lean from my header/exhaust/intake combo. I remember pulling my plugs before I put this stuff in, and my motor wasnt detonating at the time...but it was also february so who knows.

I do plan on rebuilding this motor completely next summer when I have all the money and parts I want to put into it. So i just want to keep it running well for now. I am taking all of your guy's advice though, and I really appreciate the help.

Only reason progress has not been made yet is because its finals week next week and i've been studying.