Safe to use rtv on crankcase?

9 replies to this topic
  • Mazzeppi11x

Posted May 15, 2009 - 11:26 AM


ive pulled my right side inner crankcase cover off a few times to check the shifting assembly, replaced the gasket everytime (and clean the surfaces) but it never seems to seal quite right (always a tiny tiny leak). i was wondering if it was ok to use a bead of rtv instead of the factory gasket. seems like it would be a better seal.

  • harrysmith500

Posted May 15, 2009 - 11:27 AM


hecka tight, i just put my crank case covers on after getting them Powder coated and some RTV was the only way to make the gaskets and 0 rings stay in place properly, don't be shy with it. it works great

  • grayracer513

Posted May 15, 2009 - 11:46 AM


RTV Silcone works "OK" IF you have the case joint surgically clean on assembly, and no oil drips across it while closing. There are better sealers to use.

One is an RTV-like compound that has been used at GM dealers for 15 years, known to them as GMS. It is commercially available now from Permatex as "The Right Stuff", and it is worth the extra cost. Be careful to use only the amount required, as the excess tat squeezes out can end up being somewhere that you don't want it to be.

The prescribed Yamabond is also a better choice than RTV.

  • Mazzeppi11x

Posted May 15, 2009 - 09:09 PM


ill have to get some of "the right stuff" so should i use it with the old gasket or without? im confused

  • grayracer513

Posted May 15, 2009 - 10:03 PM


The best solution is to use a new gasket with no sealer.

If you use the sealant, use it without a gasket. It won't save you any money. The tube costs $17.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Mazzeppi11x

Posted May 17, 2009 - 11:56 AM


ya im not doing it for the money, its because no matter what i do, it always leaks. and i figured if there was a nick in the edge of the case, a gasket wont seal it, so to use a sealant.

  • mxracer206

Posted May 17, 2009 - 06:27 PM


Permatex also makes some stuff called Ultra Gray and no I am not making a pun at grayracer by any means. It is made to seal aluminum parts where no gasket is used, I use that on my center cases instead of Yamabond as it is thicker and does not run. Mazz, make sure you are not over tightening the case and splitting the gasket, I think they torque to 7 ft lbs. If you do have a nick in the case use a small amount of ultra gray just in that spot along with a new gasket.

  • yz007f

Posted May 18, 2009 - 11:42 AM


Like what Grey said I would only use "yamabond" sealant. I work as a tech for a Polaris dealership and polaris uses the same stuff they call it greybond the part number is 2871557. I have sealed a ton of cases with this stuff and it has never leaked. I would just install a new gasket and a small bead of greybond sealant on both sides of the gasket and it will not leak ever again. For the RTV stuff I would not recommend using it at all. But really what do I know I guess lol.

  • William1

Posted May 18, 2009 - 03:21 PM


I have also found if the two surfaces are not completely and surgically clean, there is a tendency to get a leak. If it is impossible to get it 100% clean and dry, then I pre-soak the gasket in engine oil, ensure it is evenly wetted. So I build either 100% dry or 100% wet, not half and half. If you still have a leak, then either there is a gouge in a case/cover or something is warped.

  • grayracer513

Posted May 18, 2009 - 03:45 PM


An extremely common mistake is to leave a piece of gasket stuck to one surface or other. Guaranteed leak.

Related Content



Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies

Should I buy this bike? help....... by Numsa Hul

Dirt Bike   General Dirt Bike Forums   What bike should I buy?
  • * * * * *
  • 10 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

BIGBORE FOR YZ450F 2006? by Taattie94

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.