Sealing Cylinder Sleeves

mts5154

New User
I'm presently overhauling my TO30's engine. The old engine had been "overhauled" by the previous owner, but the block had cracked lower webs that he welded, but which distorted them and resulted in coolant leak into the oil system. I found a replacement block with no cracks, had it prepped at the machine shop and am now about to install the sleeves. I cleaned up the lower sealing surface for the sleeve o-rings with a hone and I'd like to ensure that they don't leak any coolant into the oil. The manual says to use vaseline or light grease to lubricate the o-rings for installation, but I wonder if there is a suggested sealant that would both lubricate as well as provide additional sealing when it sets. Has anyone used something other than silicone sealant for these?
 
2 ideas. Dow Corning makes a pricy O Ring dressing. #77 (222 maybe??) by my recall. Bit pricy- industrial uses in tubes. Pinkish. At home I have a tub of (green) "Liquid O- Ring". General stuff- Grease + Sealant + Anti-Seize. Think Liquid Teflon for cool people. Agree- RTV is for the sloppy ones in this application. IF REQUIRED ONLY, I/d use Permitex 2 before rtv. Best Luck.
 
Note 95% Shure I meant Dow 55. Industrial / marine duty / military buy it. Works- "rich man's" Vaseline. Will not harm the O ring, but will keep it pliable. May Slightly swell- that is what it is for. Last note I don't work for Dow- just used it for decades in "expensive" applications. "The Green Tube".
 
I'm presently overhauling my TO30's engine. The old engine had been "overhauled" by the previous owner, but the block had cracked lower webs that he welded, but which distorted them and resulted in coolant leak into the oil system. I found a replacement block with no cracks, had it prepped at the machine shop and am now about to install the sleeves. I cleaned up the lower sealing surface for the sleeve o-rings with a hone and I'd like to ensure that they don't leak any coolant into the oil. The manual says to use vaseline or light grease to lubricate the o-rings for installation, but I wonder if there is a suggested sealant that would both lubricate as well as provide additional sealing when it sets. Has anyone used something other than silicone sealant for these?
So, I’ve rebuilt 4 or 5 of these engines and originally used grease on the sleeve O rings. I’ve then used water based lubricant (KY jelly) with very good success. It’s about getting the O rings to easily find their seat and seal.

let us know how you make out.

ps, when you go to reinstall, lube the o ring, push sleeve down as far as you can (they may push right in). If needed use a block of wood and hammer to seat.

Tom
 
Thanks Tom, my concern is, if there is any pitting or irregularities in the o-ring seating area, that may compromise the sealing of the sleeves. As I've mentioned already, I've cleaned up the sealing areas and used a hone to finish them, but my confidence in the sealing of those o-rings is somewhat lacking. I don't want to teardown this thing again if there should happen to be a leak. I used to work for a helicopter company and we had a two part sealant that I know would work, but good luck if you ever needed to get the sleeves out again. It would be nice if there was a way to pressure test the wet part of the block before reassembly.
 
Thanks Tom, my concern is, if there is any pitting or irregularities in the o-ring seating area, that may compromise the sealing of the sleeves. As I've mentioned already, I've cleaned up the sealing areas and used a hone to finish them, but my confidence in the sealing of those o-rings is somewhat lacking. I don't want to teardown this thing again if there should happen to be a leak. I used to work for a helicopter company and we had a two part sealant that I know would work, but good luck if you ever needed to get the sleeves out again. It would be nice if there was a way to pressure test the wet part of the block before reassembly.
I think you will be fine with Vaseline.
 
Unlike a water based lube, the petroleum jelly will not move from the O rings. Again, I have rebuilt many of these engines with no problems.

Tom
 
1 more idea- kind of thought experiment stuff- I have a Qt. can of some black goo, made in Germany for the O-rings on my Military truck 2 piece rim O rings. A "bead sealer," non hardening liquid rubber sold at any NAPPA. Holds up (with Oring) on a tires that can hold 10000 lbs. ea. at 100 psi as we speak. Might work- See little down side as it doesn't hurt O-rings. Fills rim pits + lubes. Your fight- off label uses have to start somewhere, right? Good luck. Otherwise, I in general, do agree with Tom H ,. above.
 
As mentioned, the Vaseline or similar O-ring lubes allow the o-ring to find its happy home without getting pulled or cut as it slides into place. But as you note, it won't help with a pitted/scored block that the o-ring can't perfectly seat against. You'll probably be fine if you've cleaned and polished the block well. But there are lots of folks with pitted/corroded blocks that can't be sealed with the o-ring alone. It's quite common on several of the Waukesha's used in Olivers and Whites, and several of the three digit Allis's. In these cases, most people use a flexible, high temp gasket sealant smeared lightly around the o-ring (some folks even use pipe dope). It usually works just fine. If the grooves and block locked clean, I'd probably just use a lube on the o-rings, but if there's any question about it, you could smear some sealant on there.

The only problem with using sealant on o-rings is that once it sets/hardens, it's no longer allowing the o-ring to resume its natural sealing geometry under pressure: The reason simple, cheap o-rings work in things like hydraulic quick-connects and other applications with crazily high pressures is because the pressure acting on one side of the 'O' cross-section acts the right surface area at the right geometry: It tries to deform the o-ring in such a way that fills the groove and seals better: You'll actually get better sealing under pressure than you would at no pressure (up to a point). Once you've stuck it in place with some RTV or similar goop, however, the o-ring can no longer deform, and you've messed with the surface area that the pressurized fluid acts on, so it can't deform under pressure. You're relying strictly on the goop's adhesive properties to seal, and the goops can't handle very high pressure. An engine block should be quite low pressure, which is why the goopular fix works. But it's the reason (or rather: one of the reasons) you definitely don't want to use any goops/gasket makers on o-rings in high pressure pneumatic/hydraulic applications.

We used to repair a lot of pneumatic video pedestals for new crews that had slow leaks due to amateurs rebuilding them: Rather than take the trouble put new, lubed o-rings in and polish the sealing surfaces, they'd re-use the old o-rings and goop them up.
 
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Thanks to everyone that came up with options for sealing up the cylinder sleeves, it's given me lots to think about.

Thanks again!
 
So whichever lubricant you use, push the sleeves in as far as you can with you hand, then put a piece of wood on top of the sleeve and tap down with a hammer.
Tom
 
Finally got things back together, with just a few things left to sort out. The rear axle seals look to be leaking a bit and the brakes, although adjusted well, must have some oil on them, because they take their own sweet time stopping. What are the aftermarket seals called, something like SureSeal? Those and some dry shoes and hopefully that can be sorted out. The tractor has a Howard aux gearbox and it seems to be working well. The levelling box shaft is bent, but I have a new one coming
 

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Thanks Jim, do you know where to buy them? (besides YT. They don't like to sell to folks in British Columbia. There is no way to pay on the online order page)
 

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