Exhaust Manifold Installation

[tnfastback]

Ok since this is my first ever Chrysler build and I guess the first Muscle Car build ever without headers, what is the best gaskets and/or sealant to use??

 

[Nate S]

For manifolds just stock gaskets from the parts store. From the factory most of the 60’s mopars had no gaskets at all. Any warpage in the last 50+ years and that approach will leak though.

 

[chtampa]

Use a straight edge on all surfaces first.

 

[Demonic]

I had the HP manifolds on my Charger planed at a machine shop. I used all new studs and sleeve nuts, and a see-through thin bit of high temp anti-seize as a gasket. No gasket, just like when I took it apart, and no leaks.

 

[davek]

felpro gaskets for me at your local store

 

[Pistol Pete]

I don't use any gaskets, just Hi-temp RTV sparingly.

 

[RJRENTON]

I don't use any gaskets, just Hi-temp RTV sparingly.

A colleague of mine insists on using RTV on his cars as well. Unfortunately, GE's Silicon RTV 108 (red color) high temp, is only good to approximately 450° F. The metal temps of the cast iron manifolds approaches 600° - 650°F, so after about 2-3 weeks, the leaks reappear. I've suggested that he have the manfold sealing surfaces checked for flatness and corrected if not. My friend just glops on more RTV and keeps on going.....oh well. I hope you have better luck....
BOB RENTON

 

[Nate S]

A colleague of mine insists on using RTV on his cars as well. Unfortunately, GE's Silicon RTV 108 (red color) high temp, is only good to approximately 450° F. The metal temps of the cast iron manifolds approaches 600° - 650°F, so after about 2-3 weeks, the leaks reappear. I've suggested that he have the manfold sealing surfaces checked for flatness and corrected if not. My friend just glops on more RTV and keeps on going.....oh well. I hope you have better luck....
BOB RENTON

Good point. A straight edge should tell you enough. If you can fit a .005 feeler gauge under it you’re probably too warped for no gaskets. Gaskets will likely work up to .015 or so. After that, plan on a quick fly cut on the mill.

 

[rich hourigan]

not to high jack, i know he asked about a gasket and sealing the manifolds for leaks but if he's going to use new hardware to mount the manifolds i believe some of those go into the wet areas, maybe some one could advise the OP and myself on what kind of sealant should be used on the ends of the studs or bolts to prevent the coolant from leaking.

 

[chtampa]

I have always used "Yellow Death" weatherstrip adhesive. It keeps the studs from coming out when you remove the nuts. I have used it since the 70's.


(3M Weatherstrip Adhesive, Yellow)
Also use Anti-seize for future tightening

 

[Frank Mopar]

One tip to prevent leaks Is to check the bolts after a couple of heat cycles Do this a few time until they are staying tight

 

[dla4567]

A colleague of mine insists on using RTV on his cars as well. Unfortunately, GE's Silicon RTV 108 (red color) high temp, is only good to approximately 450° F. The metal temps of the cast iron manifolds approaches 600° - 650°F, so after about 2-3 weeks, the leaks reappear. I've suggested that he have the manfold sealing surfaces checked for flatness and corrected if not. My friend just glops on more RTV and keeps on going.....oh well. I hope you have better luck....
BOB RENTON

My manifolds are warped so I put on a thin coat of high temp RTV. no leaks for 4 years now.

 

[Longknife]

If you go with Fel pro, the header pipe gasket may not work with your 2 1/2 exhaust! See thread below,,,Ed
https://www.forbbodiesonly.com/mopa...nge-one-manifold-gasket-arrrrrggghhhh.196922/

 

[Pistol Pete]

A colleague of mine insists on using RTV on his cars as well. Unfortunately, GE's Silicon RTV 108 (red color) high temp, is only good to approximately 450° F. The metal temps of the cast iron manifolds approaches 600° - 650°F, so after about 2-3 weeks, the leaks reappear. I've suggested that he have the manfold sealing surfaces checked for flatness and corrected if not. My friend just glops on more RTV and keeps on going.....oh well. I hope you have better luck....
BOB RENTON

I've been doing this for several years now and have to experience a failure. I believe the key is proper application.

1) Apply RTV
2) Assemble
3) Tighten nuts to snug
4) Wait 60 minutes
5) Torque to spec
6) Re-torque after a few heat cycles

 

[RJRENTON]

I've been doing this for several years now and have to experience a failure. I believe the key is proper application.

1) Apply RTV
2) Assemble
3) Tighten nuts to snug
4) Wait 60 minutes
5) Torque to spec
6) Re-torque after a few heat cycles

My colleague has progressed in a similar fashion..... but to no avail. I believe that the exhaust manfold sealing surfaces and perhaps the head's mating surfaces are out of flat to the point that resurfacing is the only option. If the head's surfaces are out of flat, this involves a teardown. BTW....the application is a '70 Chrysler 300 Hurst with a 375 HP 440 TNT engine....the exhaust manifolds are of a different configuration, especially the driver's side.
Thank you for your insight.
BOB RENTON

 

[tnfastback]

I will check the manifolds trueness with a straight edge for sure. The heads being new shouldn't be a problem, but I will check them also. Thanks everyone for the suggestions and help.

 

[Frank Mopar]

Seeing as it has not been said, Remflex gaskets will seal up even warped manifolds.

 

[Billccm]

Remflex is the only exhaust manifold gasket I would ever consider.