Push rod tube seals. Dry, oiled or sealant?

[Who.Me?]

Hi

Sorry, I know this has been discussed before, but I've not found a definitive answer - When fitting spring-loaded push rod tubes, should the case and head seals be fitted dry, oiled or should I use a sealant?

I fitted Scat big-mouth tubes about 18 months ago, and about half of them leak at the heads or the case.

I saw a tip on here of tapping them home with a screwdriver on the seal-retaining washer, which helped, but a couple of them leak a fair bit, so I'm going to take them out and replace the seals tomorrow.

When I put them back in, what can I do to avoid further leaks?

When I took the old, fixed tubes out (they leaked too), there was sign of grey sealant in the seating sockets in the case and heads that I cleaned off, but the sockets looked slightly rough/uneven, so should I use a sealant, or should the seals conform to any irregularity?

I'm not going to pull the heads and use fixed tubes because whoever built this engine used blue hylomar between the barrels and the case. I don't want to disturb the barrels and have further problems.
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Andy


Looking for info on my truck's history. Are you from Campbell California or nearby. Do you recognise it? ... http://www.thesamba.com/vw/forum/viewtopic.php?t=636786

[Danwvw]

I have been using the CB-Performance Racing tubes the Stainless are nice! Wide mouth. I use silicone grease on mine. Some say dry. I find the grease keeps them able to move with the engine over time. No leaks on 3 engines so far.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Split 66']

I bought a set of Jaycee PR tubes about 7 years ago, not one drop of oil has leaked from them since. Just lubricated the included silicon seals with the oil I'm using (VR1), on installation. That was the last time I thought about my PR tubes.

Seem like they'll last a lifetime:
https://www.cbperformance.com/Original-JayCee-Push-Rod-Tubes-s/127.htm
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"OG = Original German" -- TheSamba.com dictionary

[Joey]

I've always used a thin coat of wheel bearing grease.
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Joey

‘60 Kombi - '74 Bus - '79 Panel - '65 Beetle

[Eric&Barb]

Oil and make sure the case/head seal surfaces are smooth. Wet/dry 300 grit sandpaper if need be to polish those areas.
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In Stereo, Where Available!

[easy e]

Is 300 grit really a polishing step?... seems coarse.
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aka: Evan
Spreadsheet for Bus RPM, based on gearing & tire size (Excel format)
Searchable, click-navigable 1958 Bus Parts List

[Danwvw]

Yeah it is course! But it would be perfect for this job. You could follow up on the 300 with 400!
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Eric&Barb]

[easy e]

Heh.. ok. I didn't really think you left off a zero.
3,000 grit seems like it would be overkill (and I don't think I've ever seen wet/dry that fine of a grit)
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aka: Evan
Spreadsheet for Bus RPM, based on gearing & tire size (Excel format)
Searchable, click-navigable 1958 Bus Parts List

[Danwvw]

You could polish it to a finish but that would make it sticky to the silicone seals.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Who.Me?]

Thanks all. I used some grease and so far so good. One of the No.4 cylinder tubes might be weaping, but I need to clean it again and run it some more tomorrow. The tube sockets were actually pretty good. I must have cleaned them up more than I thought when I fitted these tubes the first time.

I also realised that the metal washer on these tubes which acts as a 'back stop' for the seals needs to be manipulated to get it square to the head.

The tube sockets in the head and in the case are offset relative to each other.

With stock tubes; the concertina must make up the offset so the end of the tube can sit perpendicular to the case or head (another reason to expand the concertina before fitting).

On spring-loaded tubes, they can't flex like that and the washer wants to stay square to the tube, not the head, so it pinches/pushes the seal in more on one side than the other.

Once in place, a gentle press on the foremost side of the washer at the head end and rearmost side at the case end with the end of a screwdriver squares them up to the case or head, so they press evenly on the seal.

While I'm updating this, I asked Scat to confirm which way round the tubes should go (I've seen people saying fat end to the case or fat end to the head to give more clearance for the pushrods on bigger engines). They said...