Pushrod Tube Seals -- getting it right

First time I pulled the Wonderbus's engine I had major cleanup to do. It had only 4,000 miles on it but leaked so much oil that it looked like an engine with 40,000 miles on it. I replaced a leaky main seal, and replaced the pushrod tubes and seals at the same time. The engine no longer leaked from the main seal, but alas a couple of the pushrod seals did leak. I had taken a lot of care to be certain they were fully-seated, but I guess I didn't do as good a job as I might, though they passed the "eyeball" test.

Since I have the engine out now anyway, I have an opportunity to correct this problem. Does anyone have any Handy Hintz on how to get a good seal? I'm using the white silicone seals and good-quality pushrod tubes.

Reply to
Mike Rocket J. Squirrel Elliot
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...you did stretch the pushrod tubes to proper length correct? clean all mataing surfaces well (no this doesn't mean change the sheets on the bed.....nor wash the table....nor wipe down the washing machine...nor vacuum the stairs...nor does it mean wiping the showers stall down...or vacuuming the rug) I use a little bit of Aviation Permatex, or gasgacinch on them as added precaution.

...Gareth

Reply to
Gary Tateosian

Correct lenght should be between 190 and 191mm. That is, measured from end of spring to end of spring, not overall length. Also, roll the pushrods on a flat surface to make sure they are not bent.

Karls

Reply to
Karls Vladimir Peña

Aw, shoot. Well, that explains /that/!

You gotta camera in my house or something?

How about a little silicone RTV?

Reply to
Mike Rocket J. Squirrel Elliot

...umm...not on *my* engine. The base of the cylinders is the only place I will use it. I have seen too many little balls of rtv floating around in places they really shouldn't have been,....but someone else might say its fine...::shrug::... Besides you should have a botttle of Aviation permatex around handy anyway for the paper gaskets.

..Gareth

Reply to
Gary Tateosian

Squirrel Elliott"

wrote:

opportunity to correct

get a good

good-quality pushrod tubes.

correct?

the sheets on

washing

wiping the showers

Reply to
Busahaulic

It should also be neutral cure if it says acid cure or warns about acetic acid vapours when curing, DON'T use it. It causes corrosion and eventually causes it's own leaks. Also, if you have leaks you want to seal temporarily (until a proper repair is made) I use urethane sealer (like windscreen bonder or panelshop glue) on the outside after a thorough degrease (I use brake cleaner). works great!

Allan :-)

Reply to
Allan Williams

...of course it isn't....and I do use it on all 32 surfaces. However, I would like to ask.....is there any harm you can think if in using a light coating of Aviation permatex on said seals? I don't think it does *much*....and agree I had mostly leak free engines from this area before I started doing this....but somehow it makes me feel a little better. I like redundancy. And while my results are far from conclusive...so far they have been positive. While I occasionally got a weeper dry....and it always annoyed me, since this is one place that the seals seem more than adequate. I have as of yet had none with the permatex added. For the life of me I cannot think of a downside....but I'm sure there *is* one that I'm hoping I'll presently be informed of I admit I do get a little happy with Aviation Permatex at times...using it on case halfs, all paper gaskets, VC gasketes, p-rod seals...then there is the copper coat for the exhaust. I hate leaks...and have been an informal quest to banishh them for years. I like using The Right Stuff on the base of cylinders, and I smear the cardboard oil strainer gaskets with a very light coating of it as well to sela them from seepage. All this seems to work pretty well....but if any of it has and adverse affects I wouuld be grateful to know them.

.,...Gareth

Reply to
Gary Tateosian

No to RTV. Roger that.

Reply to
Mike Rocket J. Squirrel Elliot

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No.

Not if it is Permatex Aviation Form-A-Gasket #3, applied in a thin coating to a clean surface.

But it usually isn't.

The main issue here is that most push-rod tube leaks are due to improper assembly or an incompatible fit.

Compare the depth and surface finish of the push-rod sealing surfaces in the crankcase to those in the head. They should be THE SAME. But they seldom are. Some head castings are so bad that the push-rod tube socket would have to be re-machined in order to provide a leak-free fit. But instead of addressing the problem (or even trying to understand it) most of the instant experts advocate slopping on some form of sealant.

Which can lead to a whole new set of problems.

In attempting to solve a problem they don't understand, many novice engine-builders contaminate their engines with inappropriate sealants, especially when it comes to trying to resolve a leaky push-rod tube. If you tear down enough engines you'll soon become familiar with the sight of swarf and the residue of RTV sealants BEHIND the bearing shells blocking the oil gallery.

Prior to 1972 or thereabouts if you said 'Permatex' you were referring to just three formulations of a particular sealant. Type 2 was a thick paste, used for threaded fittings, Type 3 was a non-hardening brushable liquid used as the gasket between close-tolerance machined surfaces. Type 1 was a thick, high temp, hardening sealant.

Understanding of sealants is part of the core knowledge of every competent mechanic, such as knowing the 'handed-ness' of threaded fittings or the head-size and thread-pitch of common fasteners. About 85% of the foundation of nearly every occupation consists of such core-knowledge and its related vocabulary. This information is NOT included in the typical repair manual since to do so would make the description of even the simplest tasks as volumious as a telephone book.

For example, if it sez to use Permatex when assembling the crankcase, the nature of the mating surfaces defines the type of Permatex to be used (ie, #3). No further explanation is needed because there is an assumption of competence on the part of the assembler that includes the required foundation of core-knowledge is.

Unfortunately, after the Permatex company was acquired by Loctite Corporation they applied the name "PERMATEX" to everything from crazy glue to douch powder. This wasn't a problem for professional mechanics -- they continued to use the appropriate sealants. But it was a disaster for novice engine builders.

When core-knowledge is lacking, as is usually the case with novice engine builders, any mention of 'Permatex' was often taken as license to use ANYTHING having 'Permatex' on the label.

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You wanna use sealant on your push-rod toobes? Feel free. Your engine; your decision. But if the parts don't fit to begin with it may not help.

-Bob Hoover

Reply to
Veeduber

Excellent choice getting the white seals. When I did mine I made sure the bores in the head and on the case were squeaky clean, no oil whatsoever(carb cleaner on a paper towel will get it all out). I put the new seals over the ends of the pushrod tubes first, use caution so the seals do not get cut. Then I just kinda held the tubes in place against the case with one hand and put the head over the studs with another, got them all lined up in the bores and put the nuts on the bottom row of the head studs and ran them up enough to hold it all in place. From there it's a matter of tighening the head bolts to spec and reassembling.

If you are re-using the pushrod tubes, you should measure them and make sure they aren't already too compressed to put tension on the new seals. I don't have the specified length in front of me, and to be honest I've never re-used a pushrod tube, I install new ones. Always clean em first.

My engine originally came with the 'red' seals, and those did leak..almost immediately after installing the engine.

Chris

Reply to
Hal

Not that you care a bit, Bob, and I don't blame you, but the more I slow down and take the time to read your posts the more I realize that you really "know your sh*t" concerning cars. I'll never reach your level in that regard, but I'll have a lot of company I'm sure. :-) Preach on. Enough ass-kissing on my part. Time for me to get back in character.

Reply to
Shaggie

...thanks for the reply Bob, and I have burnished lightly an obvious flash or two around the seal area of the heads...but you can bet I will add this to my list of areas to be especially aware of in the future and will do more cleanup as waranted....not really sure why this hasn't occured to me as a focus area either, as I do take the time to clean the flash out of the passages through the fins for air flow...so its not like I don't have the heads in hand with metal finishing tools at my fingertips.

...Gareth

Reply to
Gary Tateosian

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It is not especially obvious. German-built heads machined the push-rod sealing surfaces at an angle about 3 degrees, which matches the angle of the push-rod between the head & cam. But after they shifted production to the plant in Spain (early 70's, I think) we started getting heads that had the sealing surfaces machined perpendicular to the valve cover's gasket rail. Still, it caused only an occasional problem.

But when we started seeing appreciable numbers of heads from Brazil and Mexico, tube seal leaks became a major headache. As it turned out, they were using a softer alloy of aluminum. It did a better job of transferring heat, of critical importance the closer you get to the Equator. But it was slightly weaker than the original German alloy... so they made the casting slightly thicker in some areas, one of which happened to be the floor of the valve gallery... which is pierced by the four holes for the push-rod tubes.

The thicker section is what causes the lip, the 'fix' for which is to remove it with a die grinder when you prepped the head for use, which also involved re-lapping the valves, cleaning up the casting flash commonly left down in the fins, adding the missing air deflector plate, chamfering the gasket rail and so forth...

As with how to prevent engine fires due to gasoline leaks, the problem and the cure was common knowledge to experienced VW mechanics, just another piece of the mosaic of core-knowledge that goes with the territory. The only reason I began posting stuff to the internet was the discovery that the magazines apparently did NOT know this stuff... and rejected numerous articles about it. Volkswagens were for FUN. No thinking required (or allowed).

The truth is, Volkswagens don't HAVE to leak any more than they HAVE to catch fire.

In earlier posts to other VW-specific groups I've mentioned the two to four hours of work needed to prep a set of NEW heads prior to installing them. It always produced a flurry of messages from shade-tree mechanics saying I was just trying to pump up the price... that they'd installed zillions of heads right out of the box and never had a problem... and everyone KNOWS VW's have ALWAYS leaked... run hot... caught fire... needed a valve job... yada yada yada.

Right.

-Bob Hoover

Reply to
Veeduber

Okay, Designated Beginner here. My local FLAPS is not likely to have a die grinder. I could order one from McMaster-Carr, but for this job that might be a bit of overkill. I wonder if a Dremel tool + proper bit would be a suitable tool for removing the lip from around the push-rod tube sealing surface.

Also: where does one go to find felt hobs?

Reply to
Mike Rocket J. Squirrel Elliot

...a dremel tool for all practical purposes is the electric powered equivalent of an air powered die grinder....there are a few exceptions...but a dremel will do most things a die grinder will.

...Gareth

Reply to
Gary Tateosian

Yee haw! Fire up that Dremel, boys, we're-a gonna do us some case modifications. Of course, /after/ the push-rod openings in the case are plugged.

Reply to
Mike Rocket J. Squirrel Elliot

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First, see if your heads HAVE a lip. A lot of them don't.

Look to see if there is a VERTICAL wall between the sloping 'cone' and the outer surface of the casting. If there is, get rid of it WITHOUT damaging the sloping surface.

A Dremel tool can do the job. So could a carbon steel rotary file chucked into a quarter-inch drill motor.

(Do you need to be told to protect your eyes and to dress for the occaison? If so, have someone else do the work.)

The casting flash restricts the flow of cooling air, makes the heads run hot. So you get rid of that too. Usual tool is a pneumatic riffler. (rifflers are a special kind of file; a pneumatic riffer is an air-powered thingee that provides a reciprocating stroke whereas a die-grinder is a rotary tool)

But you don't have any of that stuff.

So use a coarse wood cutting blade -- like for cutting tree limbs, not plywood

-- mounted in a sabre saw -- an electric, hand-held 'jig saw'. That will do fine for getting the flash out of the fins (Most of it will be on the ends of the heads near the exhaust stacks... which are the hottest parts of the heads.... which is why the flash needs to be removed.)

There will also be some flash in the air HOLES down through the head in the vicinity of the exhaust valve GUIDES. Hold the head up to the light with the top fins toward you. You can see light through the holes (or should). Use long drills, Swiss files, rifflers or whatever to make sure the air can pass freely. (DO NOT try to 'improve' things by drilling NEW holes. Just clean up what's already there.)

The gasket rail around the valve gallery should be perfectly flat, smooth, free of any scratches or gouges, and have a smoothly chamfered edge -- a neat little angle on each side of the flat portion, a bit like a Mansard roof (lookit up if you donno).

The perfectly flat part is what forms the oil seal. The chamfered edge is what allows the gasket to be compressed ONTO the flat surface. The gasket get glued to the valve cover, hopefully before being installed onto the vehicle.

Novice mechanics don't know how to adjust valves and often damage the gasket rail sealing surface while attempting to do so. So it leaks.

Flat is good. Shiny is better. And no scratches. Ever.

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Buyem from a Felt Hob dealer, such as McMaster-Carr, Enco, MSC, Travers.... or any of a dozen other industrial supply houses.

(Real FLAPS usta carry them -- they're used to polish-out chips & scratches from glass. But the typical consumer-grade FLAPS, like Kragon, Pep Boys, et al, is similar to Home Depot -- Yuppie junk at inflated prices.)

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You don't need a lot of tools to fulfill the preventative maintenance and minor repair requirements of an air cooled Volkswagen. Maybe five hundred bucks worth, which you don't need all at once. Using the normal maintenance schedule as a guide you've got about two years to tool-up so you can maintain the vehicle. This inexpensive simplicity is one of the hall-marks of the original VW design, along with the robust, over-built nature of its components. Alas, following the death of Nordhoff in '68 the management of VW was high-jacked by the bean-counters who cheapened the product in exchange for a short-term enhancement of the bottom line. It virtually destroyed the company but by the time sales began to slump they'd already paid themselves fat bonuses and bailed out.

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You wanna pay yourself a bonus? How does a quarter million dollars sound? That's the LEAST amount of the 'hidden income' you'll realize by simply learning to maintain your own vehicle and then keeping it for as long as you can keep it running. (Max is over half a mil, based on 1980 prices... around THREE MILLION based on 2004 projections.)

Not kewl of course. And no fun at all, since you have to subject yourself to about 1300 hours of hands-on education in the mechanical arts. Very VERY unkewl in today's society of instant gratification and No Thinking Required.

No, I don't mind if you tell folks about it -- it's no secret. You can even work it out for them on a chalk-board. But the typical American has been dumbed-down to the point where 99% of them simply won't believe you.

Tough darts (he sez, as he climbs into his 1965 bus and roars off for... wherever he wants to roar off to. Because he's got a stone reliable set of wheels that gets the PM it needs to keep from breaking down... and he knows how to fix if it does).

-Bob Hoover

PS -- Doesn't have to be a VW. The 'Forever Car' philosophy applies to any vehicle. The key is doing the maintenance & repair yourself, and keeping the vehicle for as long as possible, with ten years being the minimum. Projection is for the years of your working life, typically around 45 years for most Ameicans.)

PPS -- yeah, I know... you're already thinking gas prices. Would you believe that the cost of fuel is less than 10% of your bill for 'personal transportation?' Most of the cost goes to buy the thing, then to rent the money you used to buy it with, then for insurance and licensing and registration and inspections and so on. Fuel, oil and tires doesn't even make a pimple on the ass of the statistical curve. Now figure out what happens if you STOP pissing away that 90% and start salting it away in Widow & Orphan funds.

Surprise!

Reply to
Veeduber

On Thu, 27 May 2004 18:12:49 -0700, "Mike Rocket J. Squirrel Elliott" scribbled this interesting note:

Harbor Freight has die-grinders. Cheap. And they are relatively reliable.

-- John Willis (Remove the Primes before e-mailing me)

Reply to
John Willis

"Hobs" does not ring a bell at Mcmaster.com -- but "felt BOBS" they have on page 2505 of their online catalog. Same thing? I have an account and can order some post-haste.

Reply to
Mike Rocket J. Squirrel Elliot

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