Exhaust manifold leak: deferrable maintenance?

"With-a-G is back to not having anything written after his username" (with-a-g)
04/04/2016 at 01:04 • Filed to: None

Title kinda says it. I just discovered an exhaust manifold leak in my ‘91 Miata, thanks to the magic of Seafoam (ultra smoke formula). How urgent should I make the repair of this? I might be able to get new headers in several months, and if I go that route I’d rather not replace the gasket right right now. It’s not like I ever sit and idle in a closed space where the exhaust would build up, but is there a solid reason to treat this as an imminent hazard vs. a nuisance?

DISCUSSION (27)

The Crazy Kanuck; RIP Oppositelock > With-a-G is back to not having anything written after his username
04/04/2016 at 01:30

Just an costly excuse for a nice ceramic coated header.

TheHondaBro > With-a-G is back to not having anything written after his username
04/04/2016 at 01:57

Just out of curiosity, what does it mean to seafoam a car? I’ve heard it all over and never really understood what it meant.

atfsgeoff > With-a-G is back to not having anything written after his username
04/04/2016 at 01:59

You want to fix exhaust leaks that are in front of the cabin sooner rather than later, or risk carbon monoxide poisoning.

Flynorcal: pilot, offshore sailor, car racer and panty thief > TheHondaBro
04/04/2016 at 02:18

http://seafoamsales.com/

Snake oil.

AMGtech - now with more recalls! > With-a-G is back to not having anything written after his username
04/04/2016 at 02:42

Where does your HVAC system take in outside air? Firewall area somewhere? Where is the exhaust leak? In front of the firewall? Maybe the fumes have already started affecting you...

Also, 500+ degree air blasting directly at other underhood components such as wiring. Great!

And don’t forget! Incorrect readings on your oxygen sensors causing incorrect A/F ratios, decreased power, decreased economy, increased wear and carbon accumulation (all potentially, not a given, of course).

Last but not least, erosion! All of that hot air and hydrocarbons blasting out past your gasket can create wear tracks on the gasket sealing surfaces on the head and manifold. This could make the engine susceptible to premature gasket failures in the same location in the future, or cause a new gasket to not seal at all. Admittedly this is unlikely, but I have seen it.

AMGtech - now with more recalls! > TheHondaBro
04/04/2016 at 02:48

Basically it’s a chemical to clean carbon out of engines. Snake-oily in nature, but surprisingly effective in practice. Some of these types of products don’t really do anything, some work incredibly well, sea-foam is one of the better ones IMO.

Sovereign, Purveyor of Coupes > AMGtech - now with more recalls!
04/04/2016 at 03:23

Sums it up. The deal breaker for me would be incorrect O2 readings. You can run rich all day....

6Cylinder > With-a-G is back to not having anything written after his username
04/04/2016 at 04:32

Like a crack in the manifold? Find someone with a wire feed welder and just pile up a bunch of beads till it doesn't leak anymore.

SidewaysOnDirt still misses Bowie > Flynorcal: pilot, offshore sailor, car racer and panty thief
04/04/2016 at 07:47

Not really. It works pretty well.

SidewaysOnDirt still misses Bowie > 6Cylinder
04/04/2016 at 07:51

I’d think that the different rate of expansion will cause this to break and possibly make it worse.

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 07:52

Yes. Fix it. You don’t want fresh air coming into your exhaust system. Depending on where it is, they make a wrap for sealing exhaist.

With-a-G is back to not having anything written after his username > 6Cylinder
04/04/2016 at 08:48

No, just at the gasket where it bolts to the head.

With-a-G is back to not having anything written after his username > SidewaysOnDirt still misses Bowie
04/04/2016 at 08:49

I would think the pressure would always be positive and there is no chance of fresh air coming on to the exhaust.

With-a-G is back to not having anything written after his username > AMGtech - now with more recalls!
04/04/2016 at 08:50

Thanks for the comprehensive response. This is why I needed to hear.

With-a-G is back to not having anything written after his username > TheHondaBro
04/04/2016 at 09:03

I had to remove my throttle body to change a leaky hose underneath it and while I had it off I noticed how bad the carbon buildup was inside of it, as well as inside my intake manifold. My car is 25 years old with 150,000 miles on it and could use some cleaning, no surprise there. Once I reassembled everything I ran a bottle of Seafoam through the intake vacuum hose while revving the heck out of it (plenty of YouTube videos of people demonstrating this process), and it has made a substantial difference in throttle response. There used to be a noticeable hesitation between pressing the pedal and getting more torque but that’s gone now. A side effect of the Seafoam running through the engine is that it combusts into a thick, white, James Bond-worthy smokescreen coming out your exhaust. In my case, it also spouted out of the gap between my exhaust manifold and engine.

With-a-G is back to not having anything written after his username > 6Cylinder
04/04/2016 at 09:04

No, just a gap at the gasket.

Steve in Manhattan > With-a-G is back to not having anything written after his username
04/04/2016 at 09:20

As Tom and Ray say - if you find yourself having difficulty doing simple math problems, get it fixed.

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 09:21

It’s not positive when the valves are closed :)

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 09:22

If it’s coming from there, is it the manifold itself or the gasket?

With-a-G is back to not having anything written after his username > SidewaysOnDirt still misses Bowie
04/04/2016 at 09:49

I haven’t fully probed it, but my guess is that a new gasket will do the trick. I just don’t want to do a gasket now and then re-do it all when I put a new header on later this year. Maybe I should just bite the bullet and do it anyway.

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 09:51

I’d just do it. You don’t want hot cases escaping there, and you don’t want clean air getting pulled in between exhaust pulses. The gaskets are what, like $20 tops?

With-a-G is back to not having anything written after his username > SidewaysOnDirt still misses Bowie
04/04/2016 at 10:12

Yes on the minimal cost. But it would have to be a one-weekend job because I can’t be without my daily driver right now. I’m pretty sure I could do it in a day, but there’s always that chance that something would go wrong. At the end of the summer I’ll have a third car again and I’ll be able to wrench the Miata without time pressure.

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 11:36

Just unbolts and comes off. This is how clear your access is. I’d say a couple of hours tops unless you start stripping bolts, but I think it will be fine.

Kinja'd!!!

With-a-G is back to not having anything written after his username > SidewaysOnDirt still misses Bowie
04/04/2016 at 12:34

That is indeed how clear my access is. You’re a tad low on brake fluid.

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 13:39

Haha, not mine. I have an MR2. I.... do not have that access to my header, lol. It’s like working on a FWD car but worse.

With-a-G is back to not having anything written after his username > SidewaysOnDirt still misses Bowie
04/04/2016 at 13:46

Dat reduced yaw moment doe

SidewaysOnDirt still misses Bowie > With-a-G is back to not having anything written after his username
04/04/2016 at 13:47

Izz sexy.