"Blown Head Gasket" sound

[Y2KRKNG]

Alright fellas, I've got one that's stumping me. It's a exhaust leak noise in the front cylinder along with the tell-tale sharp crackling on decal. It all points to exhaust gasket leak or even HG leak, But I just cant find it. I've R&Rd the Thunderheader and then smoke tested the gasket seal, No leak. I've also did a good visual and a soap test on the HG and cant find anything. I've CCPd it and it's still right on 200psi. I've also replaced the lifters.  Any suggestions?

[les]

Do you have manual compression releases?

[Y2KRKNG]

Do you have manual compression releases?


yes, I've activated them while riding but haven't done more testing. I WILL! TY

What's the best way to take them out of the equation? Possibly remove and plug with a bolt?

[Y2KRKNG]

It's not the compression releases. The sound is right at the exhaust post and present (but slight less noticeable) at the rear cylinder. It follows the exhaust "cadence".   Am I just hearing the ext valve slam shut???  I'm going to R&R the pipe(again) and put new tapered gaskets and new split rings in.  I just cant ignore that the sound is right at the pipe and that the decel crack is telling me air in getting in.

[dirty jim]

A long neck BBQ lighter found my leak, after I took the heat shields off. Pipe was cracked due to a lowside crash. Looked like a hair line scratch, until you torqued down the header flanges. Happy Hunting.

[Hossamania]

My thought was also to check for a cracked pipe.

[chaos901]

Note to self:  Remember the BBQ lighter suggestion for finding exhaust leaks.

[Y2KRKNG]

Note to self:  Remember the BBQ lighter suggestion for finding exhaust leaks.

So I'm guessing that you're looking for a change in the flame pattern

[Boe Cole]

back in the day, used to find them by introducing atf fluid into the intake.  The smoke really pinpoints the problem and does not hurt anything internally.

[Y2KRKNG]

Well by golly it's the ext gaskets!

[chaos901]

So I'm guessing that you're looking for a change in the flame pattern

Certainly.  I don't smoke so I can't use that, strips of thin paper don't work so good, trying to feel for it burns my hands, need to be more careful.  Seafoam sprayed into the intake smokes too, that may wok.  Just wanting options.

[86fxwg]

So I'm guessing that you're looking for a change in the flame pattern

Certainly.  I don't smoke so I can't use that, strips of thin paper don't work so good, trying to feel for it burns my hands, need to be more careful.  Seafoam sprayed into the intake smokes too, that may wok.  Just wanting options.

Stethoscope,but remove the solid pointer & install 5/16 steel brake line in its place works for another option.
Also find vacum leaks too.

86

[dirty jim]

Yes flame pattern changes. Looks like someone is trying to blow it out.

[Hossamania]

Well by golly it's the ext gaskets!

We like cheap fixes!

[Y2KRKNG]

She's fixed. Rock solid! No more SE style gaskets! Ever! I figured I could double stack them and they'd suck less, but nope.

[BVHOG]

If you want an SE style gasket that actually works, seals up and doesn't squish into the port then the Cometic C9247  Drag no 0934-6318 work extremely well.

[jamminhd2000]

 

[Y2KRKNG]

If you want an SE style gasket that actually works, seals up and doesn't squish into the port then the Cometic C9247  Drag no 0934-6318 work extremely well.

I was using the one that came in my Cyco top end gasket kit with the MLS style HG paired up with my Thunderheader.