Water seals

[Ricco_04]

Reading through the forums there is a great number of engines that have finially died through the years due to water seal failure.

Robbie\'s post on another thread reminded me to ask this question :

Mine died at 49,000 miles. Water seal failure. After chatting to carl he made a good point about imports being started from cold at the docks, moved a few meters then switched off. Fuel sitting in the combustion chamber soaks into the water seals causing premature failure.

How come another material is never used for the waterseals?  Could Copper not be used instead as this could stop seal failure for the above quote? (as well as possably other areas?)

[ianelvar]

I often wondered about this. We use copper for sealing cylinder covers on the steam loco I work on (full size, i\'m not talking models here!). The covers and cylinder deck both have grooves machined into them (not unlike the rotary) to accept the seals.
To make a seal, all we do is get some small (3mm) round copper rod, bend it to the right radius, cut to the right length, then lap the joint so that rather than being a straight butt joint, the ends are at 45 degress to the long axis of the rod, and when the cover is bolted down it squeezes them together.
Anyone know what the cylinder pressures get to in a rotary? We\'re working at 250 psi on the loco.
Or even better, has anyone tried this? It\'s not an easy job, and takes a bit of patience, but anyone with a little skill should be able to do it, and the seal you get is extremely hard wearing.
The only problem I can see is that the ali rotor housings may not be hard enough to squish the copper rather than distorting a bit themselves. However, provided the right grade of copper is used, and its annealed properly, it ought to be ok. Anyone got some scrap housings and plates we could use to try it out?

[ianelvar]

If I had some scrap parts to play around with I\'d fit a copper seal, torque the thing up, then section it with a big band saw from the outside to the centre, to make it into cake-like slices, with each of the bolts running through the centre of each slice. The seal could be inspected all the way round, and even hopefully through the joint in the copper, to see how well it squishes into its groove and makes contact with the plates and housings. Slices could then be dismantled to see what the effect on the housings and plates might be.



Purely hypothetical, but I think it would be an interesting experement to carry out. I seem to recall that ali Rover V8s modified by TVR had copper rings that sat in machined grooves in the cylinder head to make a sturdy seal, but I could be completely wrong. I\'ll have to rake out the book I think I remember reading this in (tuning Rover V8s or something like that) to confirm, but if that is the case it would be a good pointer that it may work in another application.

Opinions?

[Gerry M]

might find they were wills rings in the rover V8, same as most highly tuned hillman imps, head is machined to take wills rings which are gas filled and expand with engine heat to seal, no head gasket is used only an outer gasket around the water jacket

[J.j.]

There are quite a few alternative water-seals on offer in the US of A.  When Kerim rebuilt my engine, I opted for Teflon coated seals as these are in theory much less prone to heat and corrosion.

[m4drx]

if you need any other bits mate i have loads everything!

[Ricco_04]

Interesting, so at least in theory it is possable :mmmm

[RobbieRX-7]

I think age is a big factor too. So many heat cycles. My water seals were brittle as hell when i took em out. So was the stationary gear O ring, it broke into 3 pieces!

[Ricco_04]

Indeed - this is hopefully something that using copper can also have an advantage I would hope?

[ianelvar]

Doh! Looks like I forgot to post my reply before I shut the PC down yesterday. Muppetry award for me.

Anyway, cheers for the offer of parts for experimentation! I\'ll get back to the relevan people when I\'m ready to set the whole thing up.

Robbie, Ricco - Sounds pretty bad. Copper shouldn\'t do that, though. I\'ve certainly never seen steam seals give up, even after the terrific abuse they get thermally and mechanically. Can\'t wait to see how it turns out in the rotary!

[ianelvar]

Red lines on the drawing represent saw cuts from outside to inside.

The idea behind this is to gain an idea of how the seal sits in the groove after the bolts are torqued up. This can be done with only one plate and a housing.

Another valuable experiment would be to use a full set of housings and plates, leaving the rotors, shaft etc out so you we can get inside and have a good look.
Ideally, assemble it with no seals, and torque up the bolts, get inside and measure the distance between the plates at various pre marked points. I\'m pretty sure I have and inside micrometer for this. If not, I\'ll buy one.
Then take the thing apart, make up seals, install them, reassemeble, torque up, and take the measurements again from the same points. If they\'re different, then there may be a problem with the seals not squishing correctly, but we\'ll cross that bridge when we come to it.
If all is well and good, the coolant jacket can be pressure tested by bolting on a water pump with filler cap, blocking off any other passages, and pumping the thing up to pressure with a tester. Could even be filled with hot water before as another test, but i\'ve no idea how I\'d heat that much water. :rolleyes: Maybe I could jury rig the cooling system from my land rover to run through the test rig! Lol


I\'ve got a feeling my motor is coming up for rebuilding, so if this looks even promising with scrap parts I\'ll do it for real. It\'ll be an interesting experiment!

m4drx, amoungst others - you still got some bits available? I\'ve got some time over the next couple of weeks, and I\'m just dying to try this out!

[oldone]

MMMMMMmmmmmmmmm....interesting reading boys.You have to consider that when the housing and plates meet,they are in acyual fact mated together.The copper ring would have to be off exact measurements to compress into the grooves(square),then we have the expanding and contracting feature,plus the blow by possibility...........:Typing  Keep working on the theory guys........:bandit

[ianelvar]

Something like......

This....

[ianelvar]

I\'m sure you can all figure it out but i should maybe have explained those drawings a little better. They show a section through the plate and housing, dark grey for the iron plate, lighter grey for the ali housing, and orange for the copper. Number two shows what should, in theory, happen when the plates are forced together by tightening the bolts if the copper is properly sized.

[oldone]

Another factor is the chemical reaction between the copper and ally (oxidation etc )....?