"DynamicWeight" (dynamicweight)
10/25/2016 at 14:24 • Filed to: None
0
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"DynamicWeight" (dynamicweight)
10/25/2016 at 14:24 • Filed to: None | 0
| 22 |
So this weekend I tussled with my miata. She really didn’t seem to want to let go of her engine mounts, but I finally convinced her. Now, to be spiteful, she has a really bad exhaust leak. So bad that she’d sputter and die upon any application of throttle.
So I went and bought her a shiny new manifold gasket, and it’s still not enough. WHY WON’T YOU LET ME LOVE YOU!?
Here’s some pictures, because we all love looking at pictures of old cars being taken apart:
crowmolly
> DynamicWeight
10/25/2016 at 14:29 |
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Damn, that is a SERIOUS header flange.
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DynamicWeight
> DynamicWeight
10/25/2016 at 14:32 |
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Oh, I almost forget, shiny new engine mounts! The idle is so nice now right before it sputters and dies.
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DynamicWeight
> crowmolly
10/25/2016 at 14:33 |
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It’s all stock. I know the miata motors are a naturally aspirated version of a turbo motor so a lot of it is overbuilt.
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crowmolly
> DynamicWeight
10/25/2016 at 14:35 |
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Did you do the heat cycle/re torque on the nuts?
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DynamicWeight
> crowmolly
10/25/2016 at 14:45 |
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It starts leaking exhaust gas pretty much immediately as soon as I start it. Do you think I should run it like that until it heats up? I mean, it’s leaking so badly you can see the smoke and it’s undriveable.
I am currently doubting my torque wrench’s accuracy since I left it set for a long time (years) and learned later that can ruin the spring. So I’m going to try torquing down the bolts more and see if that helps. When I took it all apart the third time and put it back together, it did seem to get slightly better so I’m hoping that’ll fix it.
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crowmolly
> DynamicWeight
10/25/2016 at 14:58 |
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1.) You are following a torque sequence, correct? Good quality gasket, not a parts-house special?
2.) Go up in steps if you can. So 15->30 lb-ft, etc
3.) The car won’t stay running so you haven’t really heat cycled it. But once you get a good seal and can run it for 10-20 minutes, let it cool off completely and then re-do your torque procedure.
And I’d borrow/rent a different wrench if you think yours is out of spec.
nerd_racing
> DynamicWeight
10/25/2016 at 15:16 |
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I thought that was a mazda B series exhaust flange in the picture! Most of my experience is admittedly fwd though.
brianbrannon
> DynamicWeight
10/25/2016 at 15:44 |
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I think you should recheck your diagnosis. Exhaust leaks don’t cause stalling
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DynamicWeight
> brianbrannon
10/25/2016 at 16:46 |
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Okay, I agree with this. But small leaks cause bogging right? So couldn’t a really big leak (which this seems to be) cause it to bog so hard it stalls?
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DynamicWeight
> crowmolly
10/25/2016 at 16:53 |
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1.) Fel Pro exhaust gasket. It looks nearly identical to the one I pulled off.
2.) Yup, that’s the plan.
3.) Will do.
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DynamicWeight
> nerd_racing
10/25/2016 at 16:54 |
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Good ol’ B series. My first introduction was FWD, in a protege 5. The 1.6L in the miata is a really great engine. Lots of people seem to prefer the 1.8L though.
Nimbus The Legend - Riding on air like a cloud
> DynamicWeight
10/25/2016 at 18:46 |
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Id look for an engine vacuum leak before id continue messing with the exhaust....
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DynamicWeight
> Nimbus The Legend - Riding on air like a cloud
10/25/2016 at 19:29 |
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Okay, that’s what I thought too. That maybe while I was fiddling near the hoses I knocked something loose. But I was thinking if a small exhaust leak can cause bogging, couldn’t a big one cause such a large bog that it stalls?
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brianbrannon
> DynamicWeight
10/25/2016 at 20:42 |
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Nope. No burned valves, no bogging, maybe a check engine light.
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nerd_racing
> DynamicWeight
10/26/2016 at 07:05 |
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I thought the protege 5 had an F series...
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DynamicWeight
> brianbrannon
10/26/2016 at 11:30 |
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Okay, well, I tightened everything down, the leak went away, and it doesn’t stall any more. So either the leak was causing the stalling, or there was/is another problem that got better all on it’s own that just happened to coincide. No CEL.
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DynamicWeight
> nerd_racing
10/26/2016 at 11:34 |
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You’re right. I was confused because the previous generation protege used a B series motor. Well shit, that’s embarrassing.
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Nimbus The Legend - Riding on air like a cloud
> DynamicWeight
10/26/2016 at 12:25 |
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It could if there wasnt enough back pressure throughout all the cylinders, but its less likely if you have the header attached at all. Just think about the individual exhaust runners on a hot rod. I would look at vacuum leaks and make sure the throttle body sensor is plugged in all the way (if you have one)
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DynamicWeight
> Nimbus The Legend - Riding on air like a cloud
10/26/2016 at 12:53 |
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Well, I tightened it down another 10 ft lbs which seems to have sealed it. It did seem like it was leaking from all cylinders. Now the leak is gone and I can rev it again. The current plan is to get the heat shield on it, drive it around the block ten times, retorque everything again. I’m not adverse to looking for vacuum leaks, it hasn’t been running 100% perfect anyway. I’ve just never done an vacuum leak check and my visual inspection hasn’t turned up anything glaringly obvious.
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nerd_racing
> DynamicWeight
10/26/2016 at 15:06 |
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It’s all good, I didn’t want to say something but I thought maybe you were in a different market and there was some untapped source of B series goodness available.
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DynamicWeight
> nerd_racing
10/26/2016 at 16:37 |
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I’m really glad you’ve corrected me. That wasn’t the first time I’ve said that to someone.
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nerd_racing
> DynamicWeight
10/27/2016 at 07:24 |
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