How do you seal joints?

[Ed T]

In my experience, plain teflon sheet creeps under load so probably not too good for a gasket that is under compression where the TEFLON is not fully captured by the mating parts. TEFLON also has a fairly high rate of thermal expansion which needs to be considered if heat is part of the puzzle. There are a number of reinforced teflon materials that have worked well for me. One brand name is Rulon which comes is several flavors depending on the application. AFA laser cutting TEFLON or other similar materials, I'm not sure if they would get hot enough, but burning TEFLON produces noxious gasses (fluorines I think) so water jet or exacto knife might be better.

 

[HMEL]

Just wondering if anyone has used teflon (PTFE) sheet like this for high temp gasket material? The thickness is 0.1mm (0.004") which meets my requirements. Its something I could obtain & hand over to a local decal cutting shop. They told me their machine uses a laser so I image should be able to cut them.

https://www.amazon.ca/Transfers-Resistant-Protects-Thickness-×1000mm/dp/B078N3WN32[/QUOTE
Teflon begins to deteriorate at 500 degrees. It also has a tendency to compress and move. So it depends on what you define as high temperature. Its a good product but not for everything.

 

[petertha]

Thanks, EdT & HMEL. The gaskets I was intending this material for are front & rear faces of my radial engine crankcase (to the nose case flange & the induction manifold flange respectively) and under each cylinder flange. So not a high temperature environment like a head gasket. Basically keeping oil/methanol residue inside. And I need it to be thin so it doesn't disrupt the mechanical assembly geometry too much. And ideally cut from a 2d cad file that I would provide. They are relatively thin circular profiles various arrays of 3mm holes for bolt passage. Really, those paper type gaskets would be fine but I haven't seen a convenient supply in that thickness. I know McMaster Carr sells everything but they don't ship to individuals outside USA unless they have a business.

There might actually be a similar thickness film that the decal cutters have on hand, PET possibly? I'm just checking into that now. It would be nice if it was 1-stop shopping.

 

[Sprocket]

10K - This is what I was using, and it reminded me of aviation form- a- gasket . I thought this was #2 when I bought it, but it doesn't say that on the package

 

[ICEpeter]

Thanks, EdT & HMEL. The gaskets I was intending this material for are front & rear faces of my radial engine crankcase (to the nose case flange & the induction manifold flange respectively) and under each cylinder flange. So not a high temperature environment like a head gasket. Basically keeping oil/methanol residue inside. And I need it to be thin so it doesn't disrupt the mechanical assembly geometry too much. And ideally cut from a 2d cad file that I would provide. They are relatively thin circular profiles various arrays of 3mm holes for bolt passage. Really, those paper type gaskets would be fine but I haven't seen a convenient supply in that thickness. I know McMaster Carr sells everything but they don't ship to individuals outside USA unless they have a business.

There might actually be a similar thickness film that the decal cutters have on hand, PET possibly? I'm just checking into that now. It would be nice if it was 1-stop shopping.

Hello petertha,
If you would like to use Teflon for gaskets and cant find a service for cutting the gaskets, take a look at the Polulu website (the robot part supplier, etc) here in the USA. They offer a service for gasket cutting where you or a supplier of your choice (McMaster) send them the material and gasket info and they cut it for you. Don't know whether Polulu ships to Canada but I assume they will. The service is not inexpensive but a last resort if everything else fails.

Peter J.

 

[stevehuckss396]

Just wondering if anyone has used teflon (PTFE) sheet like this for high temp gasket material? The thickness is 0.1mm (0.004") which meets my requirements. Its something I could obtain & hand over to a local decal cutting shop. They told me their machine uses a laser so I image should be able to cut them.

https://www.amazon.ca/Transfers-Resistant-Protects-Thickness-×1000mm/dp/B078N3WN32

Yes I have! I use it on all my engines. .020 for my heads and .010 for everything else.

 

[petertha]

Thanks Steve, that's encouraging. Do you have the gasket shapes cut by a service or make them manually yourself? Just curious if there is anything I should pass on.

 

[ranger]

Happy new year everyone, I don’t know if this would work for you, Rover “K” series engines used a special sealer compound between the cylinder head and the camshaft carrier. It relied upon both surfaces to be machined. No gaskets so no chance of “creeping” between components. I’ve always found with silicone sealants that they squeeze out when fasteners are tightened fully, which is not something you want inside an engine. Sorry I can’t give you a brand name for the sealer, but I’m sure “google” will know. I’ve also used a “loctite” P.T.F.E. Pipe thread liquid sealer for similar ( r/c engine”) joints.

Doug.

 

[el gringo]

you might want to check out the specs on Loctite # 518 aluminum flange sealant.
Ray M

 

[Brian Rupnow]

I don't care for any of the "gasket in a tube" sealants that available, because on very small engines, this stuff extrudes into the passages when the bolts are tightened up, causing blockages. I buy 0.030" thick fiber gasket material from my auto parts dealer and use it for all joints which require a gasket. This is a simple "waterpump" type gasket, but I find that it works equally as well on head gaskets. I buy it by the roll---it's not expensive. I use a leatherworkers punch to put any bolt holes in it, use a surgeons scalpel for cutting out any required larger holes, and cut the outside to size using scissors. ---Brian

 

[el gringo]

I don't care for any of the "gasket in a tube" sealants that available, because on very small engines, this stuff extrudes into the passages when the bolts are tightened up, causing blockages. I buy 0.030" thick fiber gasket material from my auto parts dealer and use it for all joints which require a gasket. This is a simple "waterpump" type gasket, but I find that it works equally as well on head gaskets. I buy it by the roll---it's not expensive. I use a leatherworkers punch to put any bolt holes in it, use a surgeons scalpel for cutting out any required larger holes, and cut the outside to size using scissors. ---Brian

I simply asked if you looked at the specifications...you might even try some between aluminum flanges Brian...has anyone that has used it have any comments? I am sure the person that started the thread would be more interested.

 

[ranger]

If you have reasonably wide flanges and don’t want to use gaskets, you could possibly try a shallow groove in one flange, (like an “o” ring groove) but not as deep. A small bead of sealant in the groove, which then shouldn’t extrude out everywhere but should seal ok. I’ve done this to good effect on Iveco Diesel engine lift pumps which used an “o” ring seal between the pump and housing. The “o” ring caused the pump body to distort due to fastener locations, ( and forces from the pump operating pushrod, which worked in the vertical plane). I used to throwaway the “o” ring and fill the groove with “Delta” high temp black silicone sealer. The pump was then in full contact with the housing with no rubber ring trying to distort the flange. This mod was actually ok’d by Iveco, it saved them money on warranty claims with the engines, (2.8l, pre-common rail), we used in equipment we produced.
Blue Hylomar sealer is another decent product, especially for cork gaskets,which shouldn’t be over tightened, thinly applied to all surfaces, left to “ cure” like contact glue, you only get one go at assembly but no leaks! The disadvantage is the cleaning required on disassembly.

 

[petertha]

Not to detract from OP's original question, but maybe of interest. My gaskets are relatively simple shape so in this case, think I've saved myself using a computer cutting service. I made a paper cad template of the shape, 3M sprayed that on scrap 1/8 hardboard, cut to the outline. Then 3M sprayed the 0.005" PTFE material to the template with some slight excess. Then just used an Exacto blade to cut out the internal & external shape. Really quite easy.

While on an experimental roll I just drilled the holes again with template still intact & pressed to a backing board. I thought the holes would come out ragged edged, but came out not bad. For the holes I think I'll make either a rudimentary bevel ended punch or maybe a rotating drill blank with a ball end milled relief in the bottom so the tool does more slicing action instead of drilling.

The rear crankcase gasket is shown. For the few of these I have to make, I think making by hand will be fine. If the gasket material was thicker or tougher, might be a different story. At least now if I put goop on one side, I think disassembly will be easier. I have some other Loctite gasket maker goop to try, I'll report back on that.

 

[Steamchick]

Having worked in Engine Design for 6 years, particularly looking at some of the sealing arrangements of Japaese engines - which differed somewhat from European (Leaky?) engine experience from my previous 15 years... - and I learned a few things.
Almost every joint on the engine has a "unique" parameter that must be resolved for the joint to work - foerever. (2 years, 5 years or 10 years isn't good enough). Paper gaskets, (dry) are good for some joints, but not all. Viton O-rings - correctly installed in correctly design joints are perfect. In fact they were preferred for must applications on an air-cylinder actuator for a HV circuit breaker that I designed in a previous job. (40 year life requirement - 10 year maintenance interval - ZERO air leakage in 1 year!). Viton is also oil and chemical resistant, and very long-lived. O-ring grooves allow a very high precision compression without excess local pressure, and with metal-to-metal mechanical loading. I'm very suprised at Ranger's experience with the diesel engine lift pumps, but he does mention the flange loading/bolt arrangememt being significant. Maybe good seals but bad installation design? (Flange stiffness and bolting arrangement, relative to dynamic loading?). Gasket designers particularly are challenged to get the right combination of seals on cylinder heads. I remember (vaguely) that there were at least 5 different sealing regimes built-in to car engine cylinder head gaskets - that took some development time to get right. But the requirement was "zero failures in 10 years/250,000 miles". The cylinder seal must withstand high pressures and temperature, and vacuum loading, at engine cycle frequencies and for engines from -30C to +130C. Water channels must contend with hydraulic and chemical conditions. Oil pressure and drain passages have different conditions to coolant passages. Gaskets must be hard enough to resist the dynamic loading between block and head - and in some cases apply a clamping force to Iron liners in an Aluminium block where the block may not fully support the liner at the top.
But a useful lesson was that a simple (not high tolerance groove in a flange - with the correct FILLED silicon seal - with an ACCURATELY applied section of the gasket material will form an excellent seal for oil pans, timing covers, etc. especially where the 2 parts are of different materials, temperatures and expansion coefficients. Excess silicon will cause leaks, insufficient silicon will cause leaks. But the key was that Japanese silicon was heavily filled with stabiliser powder, but European silicon was not. After a few years we stopped trying to develop a system with "un-filled" silicon, and reverted to Japanese (3M) silicon of various grades for various applications. (They need different production plants and the commercial quantities required for different technology are huge!).
Hope this is of interest?
K2.

 

[ranger]

Having worked in Engine Design for 6 years, particularly looking at some of the sealing arrangements of Japaese engines - which differed somewhat from European (Leaky?) engine experience from my previous 15 years... - and I learned a few things.
Almost every joint on the engine has a "unique" parameter that must be resolved for the joint to work - foerever. (2 years, 5 years or 10 years isn't good enough). Paper gaskets, (dry) are good for some joints, but not all. Viton O-rings - correctly installed in correctly design joints are perfect. In fact they were preferred for must applications on an air-cylinder actuator for a HV circuit breaker that I designed in a previous job. (40 year life requirement - 10 year maintenance interval - ZERO air leakage in 1 year!). Viton is also oil and chemical resistant, and very long-lived. O-ring grooves allow a very high precision compression without excess local pressure, and with metal-to-metal mechanical loading. I'm very suprised at Ranger's experience with the diesel engine lift pumps, but he does mention the flange loading/bolt arrangememt being significant. Maybe good seals but bad installation design? (Flange stiffness and bolting arrangement, relative to dynamic loading?). Gasket designers particularly are challenged to get the right combination of seals on cylinder heads. I remember (vaguely) that there were at least 5 different sealing regimes built-in to car engine cylinder head gaskets - that took some development time to get right. But the requirement was "zero failures in 10 years/250,000 miles". The cylinder seal must withstand high pressures and temperature, and vacuum loading, at engine cycle frequencies and for engines from -30C to +130C. Water channels must contend with hydraulic and chemical conditions. Oil pressure and drain passages have different conditions to coolant passages. Gaskets must be hard enough to resist the dynamic loading between block and head - and in some cases apply a clamping force to Iron liners in an Aluminium block where the block may not fully support the liner at the top.
But a useful lesson was that a simple (not high tolerance groove in a flange - with the correct FILLED silicon seal - with an ACCURATELY applied section of the gasket material will form an excellent seal for oil pans, timing covers, etc. especially where the 2 parts are of different materials, temperatures and expansion coefficients. Excess silicon will cause leaks, insufficient silicon will cause leaks. But the key was that Japanese silicon was heavily filled with stabiliser powder, but European silicon was not. After a few years we stopped trying to develop a system with "un-filled" silicon, and reverted to Japanese (3M) silicon of various grades for various applications. (They need different production plants and the commercial quantities required for different technology are huge!).
Hope this is of interest?
K2.

For this (Iveco fuel pump) application, imagine a round - I can’t remember the exact shape, flange with three fasteners arranged, not equally, but positioned as if there should be four but with one missing. The seal (“O ring”) never failed, the pump flange distorted on the unsupported side allowing oil to leak out. After replacing the seal with silicone we never had the problem again. Reading all of this reminded me of the cylinder head sealing method used on a motorcycle I had in the late 1960’s, a 500cc Velocette MSS. Rigid frame, “Dowty” pump up telescopic front forks, the barrel was cast iron with a tapered spigot, this spigot fitted into a matching recess in the cast iron head. The two were then lapped together like lapping in valves. This method could perhaps be used for a “farm”type engine with steel or cast iron liner and head?

 

[stevehuckss396]

Thanks Steve, that's encouraging. Do you have the gasket shapes cut by a service or make them manually yourself? Just curious if there is anything I should pass on.

I had a bunch of Demon engine sets laser cut by a member of the forum. Most all my other gaskets I make templates and cut them using them. Some of the templates for the original Demon gaskets and a shot of the laser sets. Teflon also comes apart easily even after being in use for years. You wipe it off with a paper towel and reassemble. Cant do that with lok-tite or form-a-gasket in a tube.