Topic: MLS head gasket question. Head gasket leaking again.

[brandEn]

My bike has developed another head gasket leak. Well I am about 90% sure its the head gasket. I can't tell EXACTLY where its coming from but everything else seems dry. I have about 1700 miles on my rebuild and this is the second head gasket that started leaking. The head gasket is a Cometic brand. When my engine was rebuilt the head and cylinder was decked. My question is : since my mating surfaces were decked will I be able to use a MLS gasket if I just clean them up when I get to that point? I know the surface needs to be smooth and flat and I am assuming it still will be.


I don't know why this head gasket wants to keep leaking. I didn't install it with copper coat. Just dry. Maybe thats why? The dowels are not the problem I double checked that last time. The cam tower pucks are new and were installed with yamabond. What about a leak from the cam tower studs? I think those threads go all the way through?

[MRieck]

My bike has developed another head gasket leak. Well I am about 90% sure its the head gasket. I can't tell EXACTLY where its coming from but everything else seems dry. I have about 1700 miles on my rebuild and this is the second head gasket that started leaking. The head gasket is a Cometic brand. When my engine was rebuilt the head and cylinder was decked. My question is : since my mating surfaces were decked will I be able to use a MLS gasket if I just clean them up when I get to that point? I know the surface needs to be smooth and flat and I am assuming it still will be.


I don't know why this head gasket wants to keep leaking. I didn't install it with copper coat. Just dry. Maybe thats why? The dowels are not the problem I double checked that last time. The cam tower pucks are new and were installed with yamabond. What about a leak from the cam tower studs? I think those threads go all the way through?

Yes...they do. I use teflon paste on them. Get the deck and head surfaces as smooth as you can (down to 400 paper). You will be OK

[killersoundz]

Question for my build, do I really need to use hondabond or whatever on the pucks that go underneath the cam tower? And you recommend putting tefflon paste on the cam tower studs? What about the bolts? hmm interesting

[Magpie]

I had a similar problem and a Honda mechanic said to use 2 washers under the nuts on the studs. He maintained that the nuts were bottoming on the threads on the studs and not able to tighten down properly. I did that and no more leaks.
Cliff.

[brandEn]

OK thanks guys, I have a game plan now. I am thinking it may be the cam tower studs or maybe the head bolts. I may have gotten the copper crush washers mixed up or something. I cleaned the engine real good and the gasket does look good from what I can tell. I will order a new one anyway and investigate the bolts in a few weeks. Got another dyno trip planned this week.

[MRieck]

Question for my build, do I really need to use hondabond or whatever on the pucks that go underneath the cam tower? And you recommend putting tefflon paste on the cam tower studs? What about the bolts? hmm interesting

Yes. Make sure the short threaded end of the stud screws into the head.

[MCRider]

"I don't know why this head gasket wants to keep leaking. I didn't install it with copper coat. Just dry. Maybe thats why? The dowels are not the problem I double checked that last time. The cam tower pucks are new and were installed with yamabond. What about a leak from the cam tower studs? I think those threads go all the way through? "

I speak from experience. The cam tower stud holes do go thru to the atmosphere, opening right above each spark plug. If they are leaking it will come out on fins ABOVE the head gasket, which makes it very weird to diagnose. (The pucks leak there too). So the question is where is your oil appearing? Above the head gasket by 2 or 3 fins, or at the head gasket.

If you have removed those studs, shame on you.    Not really, sometimes it has to be done for cleaning and machining. But you disturb the virgin seal. As Mike says, they must go back in with a thread sealer. And they should not be replaced by bolts, like the intake side has.

The intake side bolts do not require sealer as they are in bottomed holes.

My theory about the front studs is that Honda ran out of metal in the head and decided to drill and tap those holes all the way thru. Unlike the intake side where their was enough material to drill tap and stop.  Then, they put in studs which seal on first install. Then when you tighten the nut, only the threads on the top of the stud are disturbed. The threads in the head are left alone and stay sealed.

Then if you remove those studs, sealing is an "all bets are off" affair. Adding sealer should fix it, if the threads aren't otherwise sacked.

OCICBW

I just know they can leak and make an awful mess.

[Lostboy Steve]

I didn't use any sealant on the pucks. I did use a sealer for the base gasket, some sort of gasket glue, not silicone. I did not use a mls head gasket because, honestly I figured just use the one that came in the kit from APE along with my APE studs. I did however give it a nice thick spray of plain old silver spraypaint. (thats right) SPRAY PAINT. Its a trick I learned from an old hotrod builder. Something about it helps mate the gasket to the head and block. I always do it when using a regular felpro type gasket. I don't know if it actually does anything but whatever no leaks yet. I'm wondering if you have a good warp in your head or an uneven deck?

[brandEn]

I will check for warpage when I tear it down in a couple weeks. I have some 20mm shafting I figured I could use for this. Anyone else have any ideas or tips on checking for warpage?

Also I will seal all the threads on the open holes. I did remove the cam tower studs to have it cleaned and decked. I also will heli coil some suspect threads...

[MCRider]

I will check for warpage when I tear it down in a couple weeks. I have some 20mm shafting I figured I could use for this. Anyone else have any ideas or tips on checking for warpage?

Also I will seal all the threads on the open holes. I did remove the cam tower studs to have it cleaned and decked. I also will heli coil some suspect threads...

If I may, avoid helicoiling the cam tower studs if possible. It just opens another plane for the oil to wick thru. That is, the interface between the head and the coil. You can't or shouldn't seal the coil to the head, because the sealant will run out between the threads of the coil and foul the ID of the coil. been there.

If you have to, so be it. Just use the teflon paste per Mike or Locktite thread seal, when you run the studs in and hope it flows into the coil and out to the head.

[brandEn]

teflon paste? Like the stuff in the plumbing dept at Lowes?


I will seal the studs but no heli coils. I have a couple cam tower bolts that need them and at least one valve cover bolt.

[MCRider]

teflon paste? Like the stuff in the plumbing dept at Lowes?

Ask Mike, I don't know.

[brandEn]

Mike,

1. 20mm shafting to check for warpage? Got a better way?

2. Teflon Paste.... Where to get?

3. I ordered a new Cometic Head gasket. Should I use copper coat or gasgacinch with it?

[Lostboy Steve]

A good old fashion straight edge....

[Duanob]

Hey branden good to see you're still around.

I know 750s are a different animal than my 550 but on my third HG I did use the copper spray and so far so good, no leaks at the head gasket. I used an OEM Honda HG this time as well but I think yours is over-bored if I remember right?

[Doctor_D]

Mike,

2. Teflon Paste.... Where to get?

Permatex liquid thread sealer.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

[MCRider]

Mike,

2. Teflon Paste.... Where to get?

Permatex liquid thread sealer.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

"Suggested Applications: Stainless steel fittings, head bolts into through holes, oil PSI sending units/sensors, oil and coolant lines, intake manifold switches, rear axle fill plug, fuel fittings"

[tweakin]

B.  that's what I told you to use....   What, don't trust me?  Ha ha 

Mike,

2. Teflon Paste.... Where to get?

Permatex liquid thread sealer.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

[MRieck]

Mike,

2. Teflon Paste.... Where to get?

Permatex liquid thread sealer.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

That's it

[brandEn]

B.  that's what I told you to use....   What, don't trust me?  Ha ha 

Mike,

2. Teflon Paste.... Where to get?

Permatex liquid thread sealer.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

Oh no I trust you man! I just never heard of teflon paste except in the plumbing Dept.

[brandEn]

OK so I got answers to two of my questions.
Pematex= teflon paste
Machinist Rule to chech for any warping on the surfaces.
Duanob recommends coppercoat.

Anybody use coppercoat on a Cometic gasket?

[brandEn]

Do I need to change the base gasket? It was not leaking but I'm not sure if removing the head twice now will result in leaks down the road...

Got the head removed today. LOOSE HEAD NUT!

[Jerry Rxman Griffin aka MuthaF'er]

That's good news. Let's hope that's all there was to it. Base gasket would probably be OK but you won't know until you torque it back down and crank her up and ride a while. I don't think base gaskets leak very often. On the other hand removing cylinders etc can open up another can of worms if you break a ring etc.

Do you have a frame kit installed? ie did you re-torque the head? 

[brandEn]

Gordon Frame kit is installed. THANK GOD! What a lifesaver. I had my bike tore down in under 3 hours! I have checked for warpage and everything is perfect. The pucks were not leaking or any of the thru holes. It has got to be that loose head nut. Right where I was suspecting a leak too. It was so loose I just spun it off with no tool. The base gasket has me thinking though. Just not sure if its common for those to leak after removing the head once or twice.

[Jerry Rxman Griffin aka MuthaF'er]

You have the frame kit - take a chance and re-use the base gasket. Did you re-torque the head/will you re-torque the head this time? Be sure the stud is in good.