Gasket Sealant on Exhaust Manifold

[TowerDog]

Just installed a BYO 787 from SES. Do I need gasket sealer on the exhaust manifold gaskets at both ends ? They sent me nice 1.50mm gaskets and are a lot better than the paper ones that I have used before that have failed and killed motors.

If I do use gasket sealer which I have no problem doing either way, I have ultra copper and black, but both are RTV and RTV is not known for being fuel resistant. Where can I get fuel resistant sealer?

 

[96spxpos]

There is a thread on here that was a nightmare from the Previous Owner using copper sealant.Def don't go that route. If you go to seadoomanuals dot net and look up the "PARTS CATALOG" for your specific year and model, look up the exhaust section, and itll show you teardrops near the gasket if it does require any type of sealant/adhesive.

 

[wabash]

I use ultra copper on exhaust all the time. Now I'm concerned. What was the issue? Also usually no sealer is required on these but if you want them to come off easier you can use a very thin coat of never seize.

 

[mikidymac]

The manual says to install them dry and that is the consensus here too. If you are going to put anything on them use ThreeBond 1211. Don't put antisieze on gaskets, it is for bolts.
Like you said, no RTV or Copper spray.
I have only ever had one leak dry so a very thin coat of 1211 did the trick.

 

[Mekanix]

NO!
Any excess will get stuck in the water jacket or splooge out the side.

Just install it dry and make sure the two mating surfaces are clean.

THE TRICK to this is to follow the manual exactly!
Certain bolts get anerobic sealer on the threads.
Blue locktite all the bolts except the ones that say to use the sealer. (the ones with the sealer go into the water jacket and will leak if not done right)

Torque it down exactly as it says and in the right sequence.
Too little and it leaks.
Too much and it leaks.
Wet slippery gaskets with sealer on them can slide out while torquing and leak.

I've never put gasket sealer on any gaskets on these engines except the cases mating surfaces where it call's for that. But for what your doing. Just dry is the best.

Also if you see a machine with gasket sealer splooging around the exhaust or anywhere. Be weary of that machine!

I've seen one machine overheat constantly because of the gasket sealer covered 90% of the water jacket ports at the exhaust flange.


Another good thing to do on anything like this that vibrates is to make a sharpie mark on the side of each bolt and on the manifold and check it after the first hour of use to see if any bolts backed out.

 

[wabash]

Ok I get the RTV splooge. But that's not a fault of the RTV. Regardless it's not needed on these gaskets. I can rest easier now.

 

[wabash]

Also I will back up what Mekanix said above. Follow the OEM instruction on these engines. My reference to ultra copper and never seize is from other applications and has specific circumstances and requirements that don't apply here. If you follow the manual you can't do it wrong. Btw the manuals are available for free here. I know it sounds like brp has stock in Loctite but use what they call for where they call for it. It just works. I do use Permatex equivalents depending on what's available. and I think they are just as good. But I do research and make sure it is a true equivalent.

 

[nickj718]

I put a thin coat of Permatex high temp red sealant on every exhaust gasket i have ever installed. Never had a problem and gives me the confidence that it will never leak.

 

[wabash]

Nickj718 the key word being thin. With any gasket sealant it should be a thin coat. And I coat a lot of gaskets with different coatings for different reasons. But always a thin coating. Which I don't think some understand. They think more is better in which case no coating is better

 

[TowerDog]

Thank you everyone. I used a gasket before with no sealant and it failed. It was a paper gasket though. The paper part of the gasket deteriorates and water went right into the cylinder and killed the motor right away. Flooded it so bad I couldn't even get it running so that's why I asked. I guess if it's a paper gasket I would use some sort of sealant if need be but in this case I do not need to. I appreciate everyone's input.

 

[mikidymac]

All good info and Permatex, Loctite and threebond are all good products.

The only place I suggest not following the manual are the cases. 518 flange sealant has no place in that environment.

In your case the cheap paper gaskets were probably the issue, (cough , cough Wonderosa, SBT).

 

[nickj718]

Thank you everyone. I used a gasket before with no sealant and it failed. It was a paper gasket though. The paper part of the gasket deteriorates and water went right into the cylinder and killed the motor right away. Flooded it so bad I couldn't even get it running so that's why I asked. I guess if it's a paper gasket I would use some sort of sealant if need be but in this case I do not need to. I appreciate everyone's input.

This is exactly why i use a thin coat of exhaust sealant. I use it on all my builds and customers never had a problem and its so nice when you have to take it back apart. Just use your finger and spread a thin layer staying away from the cooling passages

 

[wabash]

Mikidymac. Why do you say that about 518. And did you mean 515?

 

[racerxxx]

This is exactly why i use a thin coat of exhaust sealant. I use it on all my builds and customers never had a problem and its so nice when you have to take it back apart. Just use your finger and spread a thin layer staying away from the cooling passages

^^^^^


I'll go + 1 with Nick. I will not assemble a 787 WITHOUT putting sealant on the cylinder to manifold gasket. I have them fail leak tests before on the cooling side. You guys know me, I use all OEM gaskets and NEVER stray from them. Every cylinder and manifold I see is very "porous" and I like to make sure all those nooks and crannies are filled in, to get to an even sealing surface. I put a SKIM coat on the gasket on both sides. SKIM, just a smidge, a SKIM, a tiny bit, not too much just JUST enough, a SKIM. Did I mention BARELY ANY, just enough, LOL. I use Permatex Ultra Copper. I use so LITTLE you can't even see it squeeze out. Just like in the pics below. As far as the hardware, yes certain ones get Molykote 111 synthetic grease the other get Loctite 515, not the blue thread locker. I know for sure several guys on here use the copper spray on their gaskets for the mani. Now, for the mani to head pipe, no way, that goes on dry for me. I smeared the red on the cylinder to show the porosity.

 

[mikidymac]

Mikidymac. Why do you say that about 518. And did you mean 515?

The sealant that seadoo calls for on the case is 518/515, one is a Permatex number and one is a Loctite number but they are the same thing. It is an anaerobic flange sealant so without oxygen it hardens. On cases with vibration once it hardens it can crack over time and fail. The other big issue is that it is not fuel resistant at all. Try cleaning some of the old stuff off with gas and it comes right off. I will let you in on a secret, there is fuel in the crankcase of a 2-stroke.

What you want to use it the same thing that all other 2-stroke manufacturers use, a non hardening, fuel proof liquid gasket like Threebond 1211 or 1194, Hondabond 4, Yamabond or Motoseal. Do not use RTV silicone either.

 

[racerxxx]

Actually 515 and 518 are both Loctite products they is ever so slight a difference in them. I know you might remove it with gas, but there is almost no chance gas is getting between the case halves. once that seals and dries its not going to break down. Now, I only use 518 on the threads of screws, I use Threebond 1211 on everything else.


Permatex has these equivalent which is blue 51531 and 51831
https://www.permatex.com/products/g...e-sealants/permatex-anaerobic-flange-sealant/

https://www.permatex.com/products/g...nge-sealants/permatex-anaerobic-gasket-maker/


https://www.zoro.com/loctite-anaero...YSGkf4AJ7MQ01GcR6Yl4-xoC1V7w_wcB&gclsrc=aw.ds

https://www.zoro.com/loctite-flange...dT3dl054cX6wJsmzweSBkxoCir_w_wcB&gclsrc=aw.ds

 

[mikidymac]

You can use what you like. I have seen how the 518 looks when splitting cases and I personally don't trust it. I have no experience with the 515 and got the permatex and loctite numbers confused.
I have always used 1194 on cases and never had a leak. Just my preference.

 

[Matt Braley]

You mean 1184 right? I love that stuff.

 

[mikidymac]

LOL Matt. You got me to walk out to the garage. Yes 1184, I think it has changed numbers 3-4 times since I started using it in the 90's. How about 1104D?

 

[racerxxx]

You can use what you like. I have seen how the 518 looks when splitting cases and I personally don't trust it. I have no experience with the 515 and got the permatex and loctite numbers confused.
I have always used 1194 on cases and never had a leak. Just my preference.

Heck no I won't use the 515 or 518 on case halves. When I did my first 787 I couldn't get it to seal. I called GroupK and they turned me on to 1211. I only use 518 on the threads where required. I wasn't calling you out on the permatex. I figured you got mixed up. It's nice for other guys to see the other brands out there.

 

[mikidymac]

No problem at all racer. We are on the same page. I use the 518 on threads, pump and head orings and air cleaner base to carb like the manual too.
I use 1211 on gaskets and if you look at the application the 1184 is more suitable for cases like all the Japanese skis and dirt bikes where I started on 2 strokes. Although don't tell Harry Klemm I don't use 1211 on cases:thumbsup:

 

[nickj718]

I use this when assembling the entire motor. Again skim coat like racer put it. I even use it on the case. Best sealant in the world

 

[wfo speedracer]

I use Honda bond 4, it's the same consistency as the old Yamabond 4 but it's cheap as hell.

https://www.amazon.com/Genuine-Honda-Marine-Hondabond-08717-1194/dp/B0083BWULK

 

[wabash]

Well I have been using 518 or the equivalent Permatex anaerobic as per the book. That might explain a small oil leak I have in one rv gear cavity.

 

[pwgsx]

I always spray the gasket with copper spray and have never had a issue. NEVER use any kind of sealant as it will clog the water jackets.