push rod tubes

[Johns]

Hi Guys, So I figured out my high oil pressure problem. There was a pressure adjustment on the rear relief valve that was set to high. I fixed that. Now I have leaks from some of the pushrod tubes on the right side. I'm guessing as a result of the high pressure. Anyone have quick fixes or does this mean replacing them.

John

[vwglenn]

On a regular VW with stock tubes you can pull the head and stretch the tubes a bit. Install new seals and squish everything back together.

Or you can get aftermarket spring loaded aluminium pushrod tubes like these...

http://www2.cip1.com/ProductDetails.asp?ProductCode=C26-109-351-SET

...Pull the rockers off and the pushrods out. Cut the stock tubes out. Then these spring loaded tubes can be put in place without pulling the head. I'm not 100% on the quality of these tubes. I've heard both good and bad about them. They potentially add another leak point because they're sealed with O rings. but, since they're spring loaded, They would make it easier to service in the long run. Much quicker than puling the head off.

[Johns]

Thanks Glenn, that looks like a quick and easy fix. What about those screw kind, anyone have any experience with those?
John

[gammaxy]

There was a pressure adjustment on the rear relief valve that was set to high. I fixed that.

Is that something that Great Plains added to your engine or is it from a previous owner? The stock Aerovee doesn't come with one of those, but some people add them for fine adjustment of the pressure. It's surprising to me that someone would have it adjusted bad enough to blow your oil cooler unless there was something bad wrong with the oil pressure that got fixed during the rebuild and no adjustment was made to the adjuster.

Now I have leaks from some of the pushrod tubes on the right side. I'm guessing as a result of the high pressure.

Those tubes don't contain high pressure oil--they drain oil from the heads back to the case, so they were going to leak either way. Again, did Great Plains assemble this for you? The "How To Rebuild Your Volkswagen Air Cooled Engine" book mentions stretching the bellows so the length between the far sides of each bellows is 7 9/16". I've had my heads off a couple of times and I haven't noticed any leaks, so I think that dimension is correct.

[Onex107]

I had leakers on one side. Bill Larson had the problem and used the spring loaded tubes and wasn't happy with them. Either the spring wasn't strong enough or the O-rings leaked, or the seats in the block and head were rough. Don't know which, but, I decided to replace my standard tubes with the adjustable tubes. They are threaded with and O-ring and double nuts. I had to seal the threads to prevent leaking at the nuts but they do allow you to tighten them up if you still have leaks. Bill went back to standard tubes during an engine rebuild.

[mike.smith]

I recently installed the 2-piece tubes. My stock tubes were leaking on the right side so I decided to try these. The left ones have been fine, but the right ones were still leaking at the base.

The issue with the stock tubes appeared to be twofold. One, the tubes were making contact with the super tin and that was pushing the tubes slightly out of alignment at the case seats. And two the seats just never seemed to seal properly on that side. I "dented" the super tin where the tubes went by so they could run straight, but that didn't seem fully solve the leaks. I re-installed the tubes after being careful (again) to extend the bellows for good pressure, and that didn't help.

When I installed the two-piece tubes I did not experience any leaks from the point where the two pieces come together, nor from the seats at the heads, but I was still getting leaks at their bases, where they contact the case. So I took out the new tubes (easy to do with the 2-piece tubes), cleaned everything, and used Permatex on the white seals at the case. It seems to have helped, but I don't think it's fully "solved." The left side has no leaks. Go figure.

[Johns]

Thanks everyone, I have a set of the two piece( the screw together kind) on order.

Mike, I was thinking of using Permatex when putting things back together. You just made up my mind.

Any suggestions on the easiest way to remove the existing tubes without removing the heads?

John

[vwglenn]

Thanks everyone, I have a set of the two piece( the screw together kind) on order.

Mike, I was thinking of using Permatex when putting things back together. You just made up my mind.

Any suggestions on the easiest way to remove the existing tubes without removing the heads?

John

The quality of aftermarket VW parts is always suspect. Many parts are low quality poor fit made in China. It's almost always better to lean towards German or OEM stuff. You usually get what you pay for. I try to avoid anything that says EMPI. I prefer Scat when I buy the less expensive aftermarket stuff.

The white pushrod gaskets are better than the red ones in my opinion. They stay softer and seal better.

Pulling the pushrod tubes without pulling the heads is easy when you're going to install spring or twist tubes. Just pull the valve cover, the rockers, and poshrods. Then you can cut the tubes out with tin snips.

[John Usher]

If your pushrod tubes have a longitudinal seam, install them with the seam facing UP. (Towards the top cowling.)
JU

[mike.smith]

It's almost always better to lean towards German or OEM stuff.
The white pushrod gaskets are better than the red ones in my opinion. They stay softer and seal better.

My "stock" pushrod tubes were the OEM type. I've never used the red seals, only the white ones. They all worked well together for the first 120 hours, but after taking the engine apart for new cylinders and a couple of other things, the tubes (even new ones with new seals) have never sealed tight. Not sure why. Everything *looks* tight and well seated, but I have oil on my cowl and beads of oil at the bases of the tubes (but only the right side). I removed and reseated several times with no change. The recent Permatex attempt has only about an hour on the engine, so I'll need to fly it some more to see if I'm still getting the leaks.

By the way, these leaks are minuscule in terms of quantity. After 5 or 6 hours of flight there isn't a discernible drop in oil volume. But there is enough that it coats the bottom of the engine and the bottom of the interior of the cowl, making enough of a mess to be quite irritating.