Megan the Merlot M edition

[ViPER1313]

Explain to me why it ran before, you altered the timing, then it didn't run.

[*insertusernamehere*]

Explain to me why it ran before, you altered the timing, then it didn't run.

Question answering a question isn't a good answer to the question.

[Senor_Taylor]

Explain to me why it ran before, you altered the timing, then it didn't run.

Since you failed to answer my question, I'll answer yours. The answer is simply the fact that I have the uncanny ability to ruin whatever I touch. Efforts will be made to fix the crank being off by 4 degrees tomorrow after work. Maybe 4 degrees is enough to cause it not to start.

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[D_Eclipse9916]

D W
#1 150 180
#2 150 180
#3 120 150
#4 140 190

Not awful, but they don't seem too good either on #3.

"dont seem too good"???

Edit: Nicer Alumni tone this time..

You are low in compression by 20%. Anytime compression is off by now more than 10% something is typically wrong. Especially since you have some of the symptoms of low compression. That is too big to ignore and is not a vacuum leak or spark plug fix away. Sorry to hear about the bad luck pawned off to you on this car. I would borrow a leak down tester and air compressor and figure out what is leaking (and confirm the issue).

I hate to say it, but based on your project threads, your mechanical ability combined with young eagerness has gotten you in a bit of trouble. I would suggest leaving the job of taking apart and putting back together the motor to a professional or something with more experience and patience. I just don't want to see you keep getting burned as this is more than a $50 repair if you get it wrong.

[Senor_Taylor]

Yeah, I hear you, DJ. I'm going to re time it today after work and see if I can get it running. I would pull the heads myself but I have nowhere to keep the car with the heads off and that seems like a bad idea. I didn't mind driving it with the miss, so if I can get it back there, I'll do a leak down test and see what's happening. I'm sure it's not rings, but valve related. I'm sure paying someone to do a valve job would be near $1000, no?

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[Senor_Taylor]

Okay, pulled it all apart again today. I'm befuddled. It seems that the timing marks are aligned correctly at TDC, but with them like this, both the intake and exhaust valves are open at TDC of the exhaust stroke. How is that possible unless the alignment marks are incorrect? I would appreciate some kind of real feedback instead of telling me to give up and sell the car, thanks.

Pictures are of TDC on the exhaust stroke, not the TDC where the plug would fire. Is it possible they flipped the cam gears or something when the PO did the cam seals?

[Senor_Taylor]

Someone on Miata.net agrees that the cam gears are not lined up correctly.

"The cams appear to be assembled 90° out of phase. At TDC, the cam lobes on the #1 cylinder should be 180° apart. The intake should point to the left, the exhaust to the right. The lobes seem to be pointed in the same direction, ie down.
Remove the belt, remove the cam gears, align the cams properly, reinstall the gears with the marks in the right places."

[navin]

I'm no Miata expert, or if its just the picture... but is the intake cam off by a tooth?

edit -- did you verify if the marks are lined up on the "seal plate"

[navin]

Oooh, I didn't even pay attention to the third picture you posted. Sucks man, but we've all done it.. (yes, even DJ probably).

[Senor_Taylor]

I'm happy to say that none of this seems to be my fault. I'll know more tomorrow, but it looks like the shop that replaced the cam seals put the cam gears back on aligned incorrectly so I aligned it right according to the marks, but the marks are wrong.

[Scott]

Someone on Miata.net agrees that the cam gears are not lined up correctly.

"The cams appear to be assembled 90° out of phase. At TDC, the cam lobes on the #1 cylinder should be 180° apart. The intake should point to the left, the exhaust to the right. The lobes seem to be pointed in the same direction, ie down.
Remove the belt, remove the cam gears, align the cams properly, reinstall the gears with the marks in the right places."

I agree with that statement.

. I'm sure paying someone to do a valve job would be near $1000, no?
k

Well north of $1000......

[quote="Senor_Taylor" I aligned it right according to the marks, but the marks are wrong.[/quote]

Which marks are wrong?

[Senor_Taylor]

[quote="Senor_Taylor"]Someone on Miata.net agrees that the cam gears are not lined up correctly.

"The cams appear to be assembled 90° out of phase. At TDC, the cam lobes on the #1 cylinder should be 180° apart. The intake should point to the left, the exhaust to the right. The lobes seem to be pointed in the same direction, ie down.
Remove the belt, remove the cam gears, align the cams properly, reinstall the gears with the marks in the right places."

I agree with that statement.

. I'm sure paying someone to do a valve job would be near $1000, no?
k

Well north of $1000......

Which marks are wrong?

The ones on the cam sprockets since they are not aligned to the cam properly.

[Scott]

So the marks are stamped correctly, just aligned wrong. As above, "Remove the belt, remove the cam gears, align the cams properly, reinstall the gears with the marks in the right places." and see what damage has been done up to this point. You will at least need to do another compression check and go from there, however I'm guessing the head will need to come off. You are looking at a $1500 machine shop bill to go through the head (not including the labor of taking it off and putting it back together) by someone who know's Miata's.

[Senor_Taylor]

Why do you suspect head damage?

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[Scott]

Why do you suspect head damage?

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Mostly based on your previous luck with cars and I'd be scared of what else has happened since the previous mechanic had no idea what he was doing. Once you get it together, do another compression test and see where you are. If you luck out, it might be perfect. Or you could need a new motor.

[Senor_Taylor]

Success! Whoever did the cam seals on this thing last put the cam gears on the wrong way. I took them off, turned the cams over to the correct position, reinstalled the cam gears, then timed it and buttoned it all back up and she purrs like a kitten. No stumbles, idles PERFECTLY, revs all the way through the rev range smooth as a whistle. Even changed the CAS O-ring while I was in there. Took for a long drive to stop by everyone who helped me out on the car in the last week and snapped this photo at my sister's house. I'm too tired to do another compression test, but I'll do one soon. I'm sure the results will be good. Lesson learned: Don't be afraid to dive in... again.

Edit: Compression test

Dry

140,145,120,135

Wet

150,165,155,155

[rherold9]

Everyone has to learn somewhere. I even have no idea how to take cams out of my car or anything so you gathering quite the knowledge

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[Senor_Taylor]

Compression numbers from the most hasty test ever.

Dry

140,145,120,135

Wet

150,165,155,155

[Scott]

Success! I'm too tired to do another compression test, but I'll do one soon. I'm sure the results will be good. .

Edit: Compression test

Dry

140,145,120,135

#3 isn't "good"

The specification from Mazda for the 95 with 9:1 compression is:
Max 182
Min 128
Max difference between cylinders 28

Wet

150,165,155,155

None of these are where you want to be. A 100k 1.8 should be in the 170-185 range for a "healthy" motor.

Park the car until you can do the test again, but you are going to need to replace the rings.

[Senor_Taylor]

Does it really matter to park the car? There's 0% chance on this earth I have the money to replace rings on this until I graduate. It's made it this long and runs fine. Hell, I'm using a Harbor Freight gauge, so maybe it's reading low.