3.8L Splitport project Q: Leaks between heads and exhaust manifolds - TCCoA Forums
 
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post #1 of 5 (permalink) Old 09-26-2012, 12:30 AM Thread Starter
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3.8L Splitport project Q: Leaks between heads and exhaust manifolds

Hi:
It appears that my use of Exhaust manifold gaskets was a bad idea. I've just about finished my splitport upgrade and when I started up my tbird to warm it up to operating temp (needed to bleed air from the cooling system, set the idle/IACV, and set the throttle position sensor), I noticed some smoking from the exhaust manifolds that prevented me from warming up the engine completely.

I originally thought this was just oil burning off the manifolds but then I noticed that the amount of visible smoke varied with engine RPM (push on the TB, more smoke). I then resigned myself to the fact that yes, the leak is from where the manifolds mate to the heads.

The bolts are tight so therefore using exhaust manifold gaskets wasn't a good idea.

Q: Since I plan on unbolting the each manifold and pulling out the exhaust gaskets, is there anything else I should consider using before bolting the manifolds back on?

For example, a friend mentioned copper gasket spray. Is this a good idea? I'm not sure I'm going to get enough room to spray the heads/manifolds without unbolting the manifolds from my downpipes so unless you guys say this is a GREAT idea, I'd rather not create more work for myself here.

Thanks in advance for your response. once I have this licked, my splitport upgrade will be complete (at least until I decide to DIY the Windstar Intake manifold and/or swap in a 4.2).

-g

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post #2 of 5 (permalink) Old 09-26-2012, 02:11 AM
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I used felpro gaskets with mine and have had zero problems so far.

Which manifolds are you using?

I have also seen the mating surface of exhaust manifolds warp. This could also be your problem.

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post #3 of 5 (permalink) Old 09-26-2012, 07:18 AM
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Ultra copper RTV on the mating surfaces should help you seal it up. Just don't start it for 24 hours after you install it to give it time to cure.

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post #4 of 5 (permalink) Old 09-26-2012, 09:39 AM Thread Starter
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Quote:
Originally Posted by Bay_Bird93 View Post
I used felpro gaskets with mine and have had zero problems so far.

Which manifolds are you using?

I have also seen the mating surface of exhaust manifolds warp. This could also be your problem.
I'm using my old 3.8N/A manifolds that didn't leak before. I had to remove and seal up the manifolds one time before when I did the auto to manual swap so I suspect my manifolds are OK.

The only thing that changed was the inclusion of the gaskets so I suspect they are the culprit.

I'll do as you suggest Mike and pickup some ultra copper RTV. This make require more work (disconnecting the manifolds from the exhaust). Sigh. Yet another gooey substance in my inventory. I believe this might complete my collection of autozone adhesives and aerosols....

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post #5 of 5 (permalink) Old 09-30-2012, 11:51 PM Thread Starter
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Hrm. I wonder what I'm doing wrong here.

* I'm using the splitport heads from the Mustang
* I'm using the exhaust manifolds from my tbird.
* I know the exhaust manifolds can bolt straight to my old singleport heads w/o any leaks b/c I had to remove the manifolds and reinstall them once already when I did the auto to manual swap.
* Right now, I pulled the manifolds off, cleaned the surfaces, generously applied ultra copper RTV around all the exhaust holes, and allowed the RTV to cure for 24 hours.
* I'm still seeing exhaust seeping from the manifolds near the heads.
* Plus, there's this crazy deep drone sound (whooooooong) from the engine
* The engine seems to idle OK (hesitates a little but has no problem running w/o any throttle once the engine warms up slightly).
* The drone sound goes away (or diminishes) with more revs; I'm not sure if it's from the catless true dual exhaust (cherry bombs for downpipes plus a crossover X and then 2 flowmasters) but it's quite loud.

I thought for sure that I had solved this issue with the application of RTV. This splitport project is almost done so if any of you folks have any ideas as to why I'm seeing exhaust seeping out (kind of like steam coming up), I'd love to hear your thoughts.

-g

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