David Vizard uses a layer of sealer, a gasket, and then another layer of sealer for things like front/rear intake, timing chain cover, water pump, and the fuel pump.  Some OEMs skip the gasket and just use RTV silicone.

If I do a good continuous bead, loop all the bolt holes, and don't overdo it, can I skip the gasket?  

Maybe.

But it's hard for a home builder to get as good and consistent of a result as an OEM automated machine-applied bead of RTV.  And on a few occasions, the fit of the parts places may assume a particular gasket thickness that's hard to achive with RTV.  

That's not a problem using the time-tested Vizard method.

If you don't mind occasional "comebacks," and have a lot of confidence in your RTV spreading skills (and patience), skip the gaskets. But for us mere mortals, gaskets are a big help.  

too much RTV can get into things...  your sheet metal has to be totally clean and flat...

on many of the motors that i assemble and repair... i sometimes use 3 different sealers on the same gasket... plus antiseize on the threads...

i keep grey ultra silicone, red high heat silicone, black super weather strip adhesive and hylomar all near by...  i used to use tons of clear... but the grey ultra seems to be better...  i also keep a large squeeze tube of moly graphite assembly lube near by...

i use the hylomar on head gaskets and some intake gaskets where the exhaust passages are..

the other thing you will need are several cheep cans of brake cleaner..  this will remove oils from the surface so the silicone can get a good bite..   bite the tip of the tiny spray tube to get a fan spray...


one more tip when using super weather strip adhesive... black or yellow...   make sure that when you use it... it is on a part that comes off the motor... so you can clean it off on the work bench...    instead of bending over the fender to chip it off...

(one thing about weatherstrip adhesive... use a name brand...  the one with M's or TEX... the second one takes 3 days to get off my fingers... the first one takes 2 days... the offbrands..  30 minutes and they turn to powder..)


think of water pump gaskets... superweather strip glue the gasket to the pump... then silicone to the block... when you go to change the pump years later..   you pop the pump off... and spend 30 seconds to scrape the block..  the hardened weather strip gets tossed with the pump....

on valve covers... after making sure the valve cover flange is strait, flat and clean... put a bead of superweather strip adhesive on the valve cover... set the gasket into the wet glue.. pull it off.. let it dry for a minute or so...  then put the gasket on the valve cover and line it up.. put some bolts through the holes.. and let it dry for 20 to 30 minutes.. then silicone or dry to the head...  depending on the gasket material....  and if you have to pull it off to ajust the valves...  

Nice.  Exactly the type of advice I was looking for.

I think I will do a combination--I like the sealant on the head gasket.  For the intake manifold front/rear, I think I'm going to skip a gasket.  

hylomar is getting hard to find.... and it is not like other products...

harborfreight has gotten some in...  

I found some hylomar on eBay.  What's it like?  Can it replace a gasket or is it better as a sealer?  

hylomar is a sealer.. or gasket dressing....   it has a lot of uses....   like between the cases in a volkswagen air cooled motor...   and on head gaskets ...  i use it on exhaust crossover areas of intake manifold gaskets...

it never drys...    it is good for 600F... it does not like to blow out..  and it seals great in its uses....

i use it because i don't like doing jobs twice...     and it will take more abuse that a dry installed gasket....

the new multi layer steel head gaskets with rubber coating call for it in many engines... like turbocharged mitsubishi motors..