Hylomar vs Crisco & Red RTV vs Black 4 rebuild
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Joined: Apr 2008
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From: Cincinnati, ohio
Hylomar vs Crisco & Red RTV vs Black 4 rebuild
What is the up side of hylomar?
Pinapple racing wrote:
Hylomar does not help the water seals seal or have any other favorable properties to compensate for its nasty qualities. All you are trying to do is hold the seals in place during assembly. The factory originally spec'd Vaseline, which is worthy, but the best product we've ever used is Crisco shortening. We put it in a big syringe and squeeze it into the seal grooves (water seals, apex seals, side seals, corner seals, etc). When you insert the seals and springs, the Crisco hydrolics the seal in place, preventing it from falling out. The stuff is awesome. The excess that squeezes out makes a great assembly lube, as well. An odd side effect is that upon initial startup the exhaust smells a bit like fried chicken.
And any advanage to useing Red RTV on the legs instead of Black
Pinapple racing wrote:
Hylomar is one of those over-hyped products that a lot of people apparently think is good to use for rebuilding a rotary engine, for some reason. They use it in place of Vaseline or Crisco to hold the seals in place while assembling the engine. Well, it will do the job okay but (1) it is absolutely no better and (2) it is the nastiest substance on earth to work with and clean up. I hate the stuff. If you are not familiar, Hylomar is a blue gunk that never dries out. We call it smurf snot. The problem is that it is gunk that never dries out or goes away. Even 100K miles later, the engine will be one nasty pile of smurf snot that will take 5x as long to clean up for rebuilding.
Hylomar does not help the water seals seal or have any other favorable properties to compensate for its nasty qualities. All you are trying to do is hold the seals in place during assembly. The factory originally spec'd Vaseline, which is worthy, but the best product we've ever used is Crisco shortening. We put it in a big syringe and squeeze it into the seal grooves (water seals, apex seals, side seals, corner seals, etc). When you insert the seals and springs, the Crisco hydrolics the seal in place, preventing it from falling out. The stuff is awesome. The excess that squeezes out makes a great assembly lube, as well. An odd side effect is that upon initial startup the exhaust smells a bit like fried chicken.
And any advanage to useing Red RTV on the legs instead of Black
Joined: Jun 2008
Posts: 8,376
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From: Chino Hills, CA
I use hylomar on gaskets that I know I will be removing/replacing more than once, & don't want to destroy. Never did me no harm.
I'm kind of a fan of the blue RTV, for non-exhaust applications.
I'm kind of a fan of the blue RTV, for non-exhaust applications.
Little off topic but for the first time i used hylomer to rebuild my motor, it's that it's over rated or got great hype it's just that when he/she have built motors with one kind of sealing material all other sealing materials do not even come close to do the job...
For rebuilding the motor i used hylomer on my last rebuild it is reall good stuff holds the seal in place but is messy...
On the front oil cover i used indian head gasket sealer
for the oil pan i used blue rtv
but you know what there all good it just all depends on what you want to use and what the application is going to be used for...
For rebuilding the motor i used hylomer on my last rebuild it is reall good stuff holds the seal in place but is messy...
On the front oil cover i used indian head gasket sealer
for the oil pan i used blue rtv
but you know what there all good it just all depends on what you want to use and what the application is going to be used for...
Bumble Bee RX-3
Joined: Dec 2005
Posts: 101
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From: Palm Harbor, Florida
Hylomar, is a sealing agent meant for the close tolerance machined surfaces that see high temp, corrosive chemicals, sympathetic motions (vibration/expansion)... the very items the quoted poster camplains about are what makes it ideally suited to the rotary enviroment, namely, does not harden, stays plyable regardless of age, temp, chemical exposure, etc. It does not lose surface adhesion during thermal expansion/contraction, therfor does not losing it's sealing properties and will fill machine tooling marks , sanding and scrapping type surface scratches... that fact it lasts so long and is difficult to clean up only strengthens it's place on how well suited it is to this use... and with 35 plus years of use in Mazda rotaries under it's belt by the best teams and world reconized builders how could it be overrated - but like most things it is how it is used, that determines the results...
Now, the intended use is on the actual mating surfaces ( like the 'legs' or can be used between o-ring grooves), and not really to hold the o-rings... the mazda engine manuals list vaseline or a petrolatum product to be used to hold the sealing o-rings in place... the Mazda listed products are petroleum based jellies, were as Crisco is a vegetable based product and breaks down over time and with heat (becomes rancid or rotten), and can create unfairable byproducts held in the o-ring grooves...the use of any RTV type sealant between housings, does not hold up as well ( and excessive squeeze out can cause passage or filter blocking particles), but is functional for engines expecting to see frequent teardowns...
Now, the intended use is on the actual mating surfaces ( like the 'legs' or can be used between o-ring grooves), and not really to hold the o-rings... the mazda engine manuals list vaseline or a petrolatum product to be used to hold the sealing o-rings in place... the Mazda listed products are petroleum based jellies, were as Crisco is a vegetable based product and breaks down over time and with heat (becomes rancid or rotten), and can create unfairable byproducts held in the o-ring grooves...the use of any RTV type sealant between housings, does not hold up as well ( and excessive squeeze out can cause passage or filter blocking particles), but is functional for engines expecting to see frequent teardowns...
I have used hylomar in the coolant seal grooves and I have used vaseline, too. I have no doubt that Hylomar is a very good product, and as far as the cleanup is concerned, there is an excellent solvent available that is expressly made to dissolve Hylomar -- do a search for "Hylomar solvent". The downside to Hylomar, however, is that if you get it in the rotor housing, it's durable properties can wreck havoc with your rotor sealing. When I tore my first engine apart, there was a trail of this stuff in the corners, and evidence of my apex seals skipping across the surface of the rotor housing -- so my advice would be to use it on the legs, and maybe even the outer seal, but be very careful around the inner seal. Use it very sparingly there, or not at all.
Upside of Hylomar is it holds the black coolant seals in place, where Vasoline will cause them to swell and lengthen, to the point where they will no longer stay in the grooves. Having to buy a new set of seals once was enough of a lesson for me.
