Wet Sleeve O-Ring Lube/Sealant

[arlen]

So I was talking to the local expert on antique tractor rebuilding today. I asked him what I should use on my cylinder sleeve o-rings. I know soap is a poplar choice. He said for decades he has used blue RTV! He said he installs the O-ring in the groove, then smears a bead around on top of the O-Ring. He said it acts as a lube, and squeezes around the ring groove and helps with the imperfections that these old blocks have.
He said he has not had a single problem doing that in countless rebuilds in gas and Diesel engines.
I did a little googling, and I found a few people that swear by it.
Just curious if any of you fine people have did that? If not, do you use liquid soap?

[Gary Dotson]

I've never used RTV but I see no reason not to. Back in the day, when I was doing some of this kind of work, the engine blocks were not as old and pitted (old guy here) we lubed them with tire mounting soap. You need something slippery, for sure, and RTV is slippery. I wouldn't put big gobs of it in there, just enough to lube and seal it.

[arlen]

I've never used RTV but I see no reason not to. Back in the day, when I was doing some of this kind of work, the engine blocks were not as old and pitted (old guy here) we lubed them with tire mounting soap. You need something slippery, for sure, and RTV is slippery. I wouldn't put big gobs of it in there, just enough to lube and seal it.

Thanks for the feedback Gary. I think I’m going use the RTV.
My grooves look pretty good I think, but there is 1 spot about .020” by .060” right in the middle of one groove. Doesn’t look like rust pitting, but more like a casting defect.
I will feel a little better giving the o-ring just a little help.
I will be a little annoyed if after all this work and expense I have a leaky sleeve

[arlen]

The sleeves pretty much dropped right in. I was able to easily seat them by hand. I used 9 1/2 bolts and fender washers to hold them at bottom until the silicone set.

[Gary Dotson]

I'm glad they went in easily for you. Leave the bolts and washers in place till you're ready to install the head.