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NE ND | Rebuilt waterpump and replaced manifold gaskets on tractor this winter. There was orange rtv silicone on the old intake gaskets. Also every gasket on the waterpump had been siliconed the last time it had been apart. I admit i siliconed everything when i put it back together as a precaution.
But it got me thinking. Am i just wasting silicone when i am using a new gasket? What is SOP when using a new gasket? Do you just use silicone instead of gasket? |
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| A mechanic friend of mine told me to put them on dry if possible. Even use a bit of weatherstrip adhesive if it needs to be held in place. |
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South west of Winnipeg MB | Why did he say that? |
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Janesville | When I first worked in a shop when still in high school, all the older techs that helped guide me in the right direction always said "If they wanted you to use silicone they wouldn't have made a gasket". Well 27 years later I still go by that saying and it really is true. The best use on a gasket would be if you are going to reuse one in a pinch or something, or a rough and pitted surface. |
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| I will tell you my experience with gaskets and glue.Have an IHC 656 DSL and valve cover was leaking,installed new gasket dry and a month later leaking.Took it off again and someone said try this gasket glue called the RIGHT STUFF. I cleaned surface and layed a bead of this glue,kinda like silicone but black,grey color on the head and installed valve cover with no gasket and a year later no leak .I swear by this gasket glue now. |
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Between Omaha and Des Moines, 7 miles South of I80 | monse - 3/31/2017 19:20 Rebuilt waterpump and replaced manifold gaskets on tractor this winter. There was orange rtv silicone on the old intake gaskets. Also every gasket on the waterpump had been siliconed the last time it had been apart. I admit i siliconed everything when i put it back together as a precaution. But it got me thinking. Am i just wasting silicone when i am using a new gasket? What is SOP when using a new gasket? Do you just use silicone instead of gasket? Normally, if you have nice dry and flat surfaces, then "dry" gaskets should be absolutely fine.(and considered normal procedure) But there are few times, when using a "very thin bead of silicone" (or just a film of silicone, rubbed on with finger and thumb, over sides of new gasket) can be helpful. I've done it on my "over 30 year old" Toyota engine water pump's gasket, because I know I'll be the next guy to change it = easy to remove old gasket; but you need to carefully and evenly snug your mounting bolts, little by little. I also lubed some CAT 3406 timing advance cover gaskets, with regular grease, because those were very time-consuming to clean around all those 3/8" studs, with a razor blade, when they got installed dry. (note: it only has to hold back "splash oil"; so there isn't any pressure on that particular gasket, anyway). Also, used a film of grease on 3116 valve cover gaskets. Again, it is only getting "splash oil" against it. The thing, I really dislike, is the type of guys that put on a silicone bead, like they were using a chalking gun and sealing up their bathroom tub = way, way too much! (I've seen an engine's oil passages totally plugged up with silicone before, when people do this)
Edited by 4WD 3/31/2017 20:27
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| His experience had shown mixed results whether it actually did any good. It made it harder to take apart the next time, and if it was set wrong and had to be taken apart for an error it was a pain. I think it occurred to him when he realized most OEMS put their gaskets on dry.
I can tell you from personal experience when using a gasket, I have had less problems than with silicone. I used to get leaks every now and then myself.
Right or wrong, it works for me and him. |
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North Central OH | I normally use high tac gasket adhesive to hold in place or install dry. Used never seize when working in a green house once, main guys instruction. |
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WCOH | I was raised, Never use silicone on a cork gasket. The silicone causes the gasket to move around and not grip. High tac is ok to hold it still if needed. Silicone is more for making a gasket instead of supplementing. I was taught this way and still follow it myself.
I do agree if they wanted you to put it on they would have supplied it with new gasket.
Take the time and clean it right and you don't need silicone. |
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NW Iowa | I have cut way back on silicone use. Usually a tube will get hard before I use it up. A few years ago one of my tractors suddenly lost oil pressure one day. After much investigating and head scratching it turned out it still had oil pressure but a little glob of silicone had plugged the line going up to the oil pressure gauge. I have been the only wrench turner to work on that tractor for the last 45 years so I am to blame for over use of silicone on that one. Another time I found a heater core neck plugged with silicone. Again, I was the mechanic to blame. The plugged heater happened forty years ago. When silicone is goobered on a gasket and the clamping bolts are threaded into an open ended hole that is open to the inside of the engine, the end of every bolt might have a drop of silicone on it from being pushed through the thick silicone covering the bolt hole. That drop of silicone might drop off and end up plugging something years later. That said, I will still use a light coating of silicone on some gaskets, like valve cover, oil pan or other light metal surfaces. Flat cast iron to cast iron mating surfaces usually don't warp or distort enough to prevent a dry gasket from sealing. A thermostat housing is one place where I almost always use silicone on the gasket unless the two mating surfaces are good and heavy and flat.
Edited by Iowajim 3/31/2017 21:15
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NE KS | If gasket is hard to hold I use a very small amount, just enough to hold it in place. Otherwise I go dry. |
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SE MT | Working for caterpillar for a number of years I got to learn what was has been working for decades for that particular shop. The spec guys built engines day in and day out (as did us truck engine guys) that would run 15-20K hours before overhaul.
Having said that, the rule always was, use a high tack gasket cement on one side of the parts you're putting together... if it's steel and aluminum, put the high tack on the steel. NEVER put high tack on aluminum, you'll ruin the surface trying to buff it off next time.
So, you high tack the one side, and gasket, let dry, put gasket on, use a light film if silicone on the other side of the gasket surface before mating the two together.
NEVER use silicone on both sides of the gasket, the gasket will slip and slide all over the place instead of staying put and clamping down.
Another substitute for the high tack is Copper Coat (in the copper spray can). This works really well for head gaskets since it's a light film. It gets costly to use for everything, but I believe it's one of the best high tack sealers out there. love the stuff. All the old timers in the spec shop swore by it as well.
running a gasket dry can do two things. with nothing holding it in place, a gasket can slip, and may not get a complete seal, or may seal just well enough to blow up later down the line. Also as the gasket gets old the silicone and cement helps hold it in place and prevent leaks by better filling surface imperfections in the steel/aluminum.
Places I would never use any sealer would be on like an automatic trans pan... don't need anything there, or anywhere where buffing a part could leave the area you're trying to keep clean dirty. |
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farmland indiana | I was told by the older guys when I started at the dealer ship. Grease is the only thing to use on a gasket. Unless it's a cork valve cover gasket or oil pan gaskets. Than use weather strip glue on the valve cover side or pan side. It holds it in place and keeps it from working its way out over time. It's worked for me. But the right stuff works great if you don't have a new gasket. |
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| Aviation Form-A-Gasket is my favorite for cork and 'paper' gaskets unless no sealant is called for such as some Cummins oil pan gaskets. |
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Pilot Grove, Missouri | Silicone is a gasket maker, not a gasket sealer. It is intended to be used in certain uses, without a gasket. It can be used in certain applications where there is pitting or other surface imperfections, though. Most GM vehicles built in the mid 80's came from the factory with silicone only for valve cover gaskets. Patrick |
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South Central Kansas | DrZhivago - 3/31/2017 22:26
Aviation Form-A-Gasket is my favorite for cork and 'paper' gaskets unless no sealant is called for such as some Cummins oil pan gaskets.
X1000; Silicone has it's place but not on a gasket of any kind.
Edited by Super 65 3/31/2017 22:55
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SE MT | PatCMO - 3/31/2017 22:43
Silicone is a gasket maker, not a gasket sealer. It is intended to be used in certain uses, without a gasket. Patrick
Does that include multi piece gaskets, and paper pan gaskets that cover engine block, front plate, front cover, rear cover? lol
Silicone is a useful tool.. It works well alone but makes paper gaskets better. There is no good reason not to use it to aid with sealing as long as the person doing it does not get carried away. Just like any other tool, if used properly can make repairs better and longer lasting. If used by an idiot, well, you can probably figure that out. |
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Pilot Grove, Missouri | Nice how you only quoted the first half of my post. Patrick |
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Southern Alberta Canada | Gaskets or silicone, never both. Sometimes a dab of silicone is used where gaskets connect, that's it. |
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South Central Kansas | dieselfume1 - 3/31/2017 23:03
PatCMO - 3/31/2017 22:43
Silicone is a gasket maker, not a gasket sealer. It is intended to be used in certain uses, without a gasket. Patrick
Does that include multi piece gaskets, and paper pan gaskets that cover engine block, front plate, front cover, rear cover? lol
Silicone is a useful tool.. It works well alone but makes paper gaskets better. There is no good reason not to use it to aid with sealing as long as the person doing it does not get carried away. Just like any other tool, if used properly can make repairs better and longer lasting. If used by an idiot, well, you can probably figure that out.
Silicone would be the last thing I would use on a gasket surface of any kind, lots of better options out there. It is ok for corners where two gaskets meet in very small amounts. See IOWAJIM's post above.
Edited by Super 65 4/1/2017 08:52
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Hemlock, Mich | My uncle use aluminum spray paint on head gaskets... probably because it was cheaper than copper coat... but he did a lot of there and always worked.... he use it on other gaskets too.... |
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Do you need silicone with new gaskets?
