Valve train noise

Well, maybe. One thing you should know is what sort of push rods you have. If alloy (whatever that means; others here can be more specific)you may have just set the gap too big. The alloy push rods expand at same rate as the case/valve combo, so need no big gap to save the valves. They say (zero) gap, but always good to have a little, say 0.001 in. If you have "ordinary" push rods (steel??) then proper "lash" is in order. The exact dimensions to use escape me at the moment, but a call to the engine builder should reveal all. If there is no reliable data, I do not know how one would determine which type of push rods you have. Perhaps the use of a magnet would reveal. Would have to rely on Dr. Clock, Wolfgang, Gordon (of Five Cent Racing fame), Pip, or other sharp air-cooled guy to 'splain about that... If you have the alloys and set 0.012 gap, I'd say no wonder you have some noise. That the noise is all from one cylinder/valve would be troublesome, I'll grant you that. If an exhaust valve is burned, a quick compression check would reveal that. I toasted an exhaust valve on my old S90 Coupe many years ago, and it makes a very distinctive noise. Do not assume the worst, and do the easy troubleshooting first. Seems to me if compression on 1 out of four is bad from exhaust valve leaking, then power should be down noticeably -- how about that? Engine still have spunk?? All else fails, then might be time to drop the engine and look at the heads. Aside from being real careful about the order in which you remove and replace head bolts (and mind the torque settings), that job is not too hard. If you need to have the valve replaced, chances are the seat might be in trouble too -- a proper AIR COOLED shop will be able to help you w/ that: diagnosis and fix too. Worst case, you'd need a new head as well as a new valve. Tiffs, or Cory's favorite place in Annapolis should know the particulars about that. Were you running the engine w/ valve covers off?? That would be messy . . .

OK East Coast brain trust, chime in and tell us where we've gone wrong here.

*Valvetrain Noise

This past Saturday I went for a drive to the eastern shore of Maryland. While in traffic I dropped from 4th to third in order to pass. While accelerating in third a new noise sprang from the engine bay. It sounded like what I thought was an exhaust leak. Made sense to me as I had just tightened a couple loose exhaust nuts to quite the motor down. Temp fix to get me going down the road a little quieter.

Sunday I get under the car and pull the exhaust/heater boxes replacing all gaskets. even put on the new clamps from the heater box to exhaust. Started the car up and still heard a ticking sound. Checked the fan shroud by disconnecting the belt, no change, sound still apparent. Checked the points in the 'new to me' 019 distributor i installed last week. .016 exactly. Checked the timing. was at 30d BTDC, timed it to 28d. Let engine cool and checked the valves this evening.Found #1 to be a little tight on the exhaust. Same as #3. #4 exhaust was loose. It was at about .012. I tightened it up to within spec. Turned the engine over and still have the higher pitched ticking/knocking sound.

I grabbed a 3' length of fuel line and put one end to my ear probing the motor with the other while at idle. I can hear the noise extremely clear about 1" right (standing at back of car facing front) of the #4 exhaust port.

My non-expert opinion is i have trashed a valve. Sound Right? Anything else I need to do in order to trouble shoot?

So, if it does indeed sound like a bad valve, where do I go from here?

Engine specs are as follows:

AS41 Mag. Case - Full Flowed
SCAT C35 Camshaft
69mm Counterweight crank
5.4" I-Beam Rods w/ 5/16" ARP Bolts
94mm Pistons/cylinders
New VW 043 heads w/ 40mmx35.5mm Valves
1.1 standard VW rockers
Shadek 30 mm oil pump
12 lb flywheel 8 dowel
deep sump
40mm Dellorto's

Hey Paul how many bhp's do you have with that spec?

If you have aluminum (VW stock push rods) normal lash would run around .006".....Steel push rods run "zero"(when adjusted the push rod can be spun easily but has no in/out play)
All push rods are adjusted stone cold.....

If you have aluminum push rods, you may have had one bend....(a sudden increase in valve lash)......Steel rods are not bent as easily, but they too can be bent......

Lastly, if the rods are straight, you may have a cracked or damaged lifter/cam lobe....Very rare.

Hope its simple and this helps....

if u have hydraulic lifters one of them might not be pumping up fully

I do have aluminum Pushrods, I do not have hydraulic lifters. Ill check compression between No. 3 and No. 4 tonight. Do I pull the coil wire in order to do so? I am assuming in order to take a look at the pushrods I will be pulling the rocker arm assembly. Anything I should be aware of prior to doing the work? Leon, you make it sound as if its either or. Either the pushrod is bent or i am splitting the case. Is that right?

Yes,the Valve covers were on... that would get really messy really quick.

Burak, not sure about the bhp. I can be sure in saying it is less this week than last.

Murpy's Law... I really splurged and purchased a custom Vintage Speed exhaust last Monday. That money would have bought me two new performance heads if need be. Go figure!

Paul.....Its not strictly one or the other......After reading your engine specs, I thought you might Massage the gas pedal every so often......If you get over about 4500/5000 rpms, the aluminum pushrods are a definite suspect.....You stated the clearance had opened up to .012"......That sounds about right for a bent rod.......

You will have to pull the rocker shaft to pull the rods in order to check them....When you pull them mark them as to which side and their orientation.....There are probably shims under the rocker shaft stands....keep them with the stand they were used on......

Check the rods by rolling them on a FLAT surface...( a plank of the correct width helps)

After reassembling the shafts to the heads crank the engine over by hand several times then recheck the valve lash.....Never assume it will be correct the first time......

If you do find a bent aluminum rod, now is the time to install steel units......

Didn't mean to give you cause for alarm,...just giving you my best educated SWAG. ;-)

or go with chromoly and forget about setting valve lash. zero lash for those requires a screwdriver and a 13mm wrench.

I have read that the chromoly pushrods can be very loud??

Eh? What's that? I can't hear you...

Seriously, I've got 'em, and they seem quiet to me.

The chromoly PRs are the way to go, if you ask me. Al sounds like they are not stiff enough for high revs, and steel, while stronger, require a proper lash that will make a bit if tick-tick when working. I have heard nothing about the chomoly PRs causing noise in and of themselves, given they are adjusted correctly.

My brand-new CB engine has chromoly pushrods. Valve lash is supposed to be set at .002". There is no valve noise.

I got it wrong, it was the Steel Pushrods that apparently make the noise.

Paul, if you have aluminum, and get the engine up higher in the revs, it is very easy to mushroom the pushrods. The round portion of the rod mushrooms, and the tips push in, making the pushrods shorter. The only solution is to replace them. Aluminum are set at .006 and .004, if I remember correctly.

Chromoly steel are set at .002 or zero lash, and are extremely resistant to mushrooming.

BTW, the steel ones when set to zero clearance don't really make much noise, at least I cn't hear it over the exhaust!

So, would a broken head stud, the one closest to the back of the car (No. 4 Cylinder) make a noise like described earlier? I noticed the nut and washer floating out away from the head. When I went to tighten it with my fingers the entire stud spun. One good pull and I completely removed the stud from the head. It has sheared at the threads, I am assuming the rest of the stud is nice and snug in the case.

1. Am I correct in assuming the engine is coming out of the car to make the repair

2. What else could have gotten screwed up because of this? I drove the car a good 100 miles after the initial noise.

3. What could have caused this

4. How do I keep it from happening again

5. Finally, what questions aren't i asking that i should be (leaving myself open with this one)

Thanks for all your help thus far. I think ive got a couple weekends worth of work ahead of me. Main concern is that I double check everything that could have been damaged prior to putting the engine back together.

Paul:

Well, that one got me....I thoughnt it might be a loose rocker arm stud, but it turned out to be a broken head stud - I'll be damned.

On to your questions: BTW: The good new is that it's a LOT better to have the stud break off as it did than have it pull out of the case! ;>)

So, would a broken head stud, the one closest to the back of the car (No. 4 Cylinder) make a noise like described earlier? Yup - sure thing. Compression pressure pushing out at the head. Sounds just like a "tick".

I noticed the nut and washer floating out away from the head. When I went to tighten it with my fingers the entire stud spun. One good pull and I completely removed the stud from the head. It has sheared at the threads, I am assuming the rest of the stud is nice and snug in the case.

1. Am I correct in assuming the engine is coming out of the car to make the repair That would be easiest, but I've removed broken head studs with the engine still in the car. You WILL need a lift - it's a PITA to do it on your back on a creeper. Still......for the 45 minutes to pull the engine, it makes it a whole lot easier.

2. What else could have gotten screwed up because of this? I drove the car a good 100 miles after the initial noise. Don't worry about it. The head nuts might have been over-torqued during assembly or after break-in, or you might have had a weak stud (it happens). Pull the engine, get the remains of the stud out and replace it with a new stud. Hopefully, your case has case savers installed so the stud remains should come out with an EZ-out extractor.

3. What could have caused this See #2 answer. Possible weak stud or an over-zealous assembler or later-on mechanic.

4. How do I keep it from happening again? Torque head nuts to the proper amount. Apart from testing all head studs with a tensile strength tester (not a lot of those around), you'll have to have faith.

5. Finally, what questions aren't i asking that i should be (leaving myself open with this one) No....You're doin' OK. You'll have to pull the head and barrel on that side to replace the stud, then, since you have the mill out on the floor, I would remove and check all stud-to-case points for cracks and/or use of case savers, then I would remove all studs and check the threads on both ends for stretching and replace if found, then I would loosen and then re-torque all head nuts, just to make sure they're torqued right.

All this may be moot - it may have just been a weak stud, but it's always best to check other possibilities while the engine's out.

Now....If you have never done all this on an air cooled VW engine, I might strongly suggest that you let someone with appropriate experience tackle it. Getting the stud remains out without damaging the case can be tricky, especially if the stud were installed with Locktite or some other locking agent. There are tricks that can be done to get it out easier, but which ones used depends on the circumstances. If you damage the case, then it becomes a BIG DEAL!

Good luck!

gn

Gordon, thank you for the response. Makes complete sense to hear the exhaust forcing its way out between the cylinder and head. For what its worth I am posting an image showing the stud. It definitely looks as if it sheared from tension, for whatever reason.

Thanks again.

I agree with Gordon on this one.... looks like it was a weak one and or, over torqued at some point.

I assume there isn't all that many miles on it, don't expect much but, I would still drop a dime to Thunder Ranch and let Tom know what's up and your concerns. ~Alan

Paul....It looks like the broken end of that stud has started to rust up, indicating a crack that migrated through the stud.....If another stud is found suspect, I would replace all of them....

There were some "Made In CHINA" pieces on the market some time back, and they may still be out there......

C B Perf, Scat and other known builders carry the required parts....

As Gordon says, "If you aren't comfortable working on this yourself, find an air cooled shop."

Glad you found the problem, and good luck with the repair....

You know.....thinking on this a bit more, I would pull the engine and replace and retorque ALL head studs. They're cheap, and the peace of mind later on would be worth it to know it's been done right with good parts.

I wonder if someone assembled that engine with an impact wrench.......

I could not agree more w/ the wise heads (a**es??) about the "while you're at it" syndrome. Fool me once, shame on you. Fool me twice, shame on me. I'd repace all the studs. As to getting the rest of the broke one out, that will be a challenge. I'll bet it is off right at or below the case surface, and so getting a grip on it to get it out is going to be a double BEE-atch. I have NEVER had any luck w/ E-Z outs, despite all the glorious claims. Gordon says pull the barrel, well I'd guess so, since you need to get to the thing w/ tools ,etc. and the barrel is clearly in the way. Pull the barrel means new rings and hone the barrel to me -- once seated and then separated, rings can't be put back EXACTLY where they were, and if you don't, they will never be right again. So there would be that item: trip to the machine shop to hone the barrel (or get a drill motor and a bottle brush and do it yourself -- best not), and new rings. Not to mention needing a ring compressor and the "touch" needed to get it all pushed on right. I guess you can do that to one cylinder only. Not sure if the barrel can be just partially extracted, keeping the rings in place and letting you get to the troublesome parts too. I'd bet not. Gordon seems to say he's been here, done that, and if so, he needs to tell you what all you will need to do. Me, I'm just guessing.

OK, some technical BS: "sheared off in tension" is a perfect oxymoron, to us technical types. Can't be both, has to be one or the other. Either the stud was overstressed in tension, or was overstressed in shear. Looking at the fractured surface (something rocket scientists get to do a lot), I see an almost pure shear failure pattern there. Would have to look at the thing really up close to be sure, but looks like the material could not take the shear of torquing. Pure tensile failures look a bit different. Might have just been a clinker (small flaw in the metal) that weakened it, or maybe it was knicked during handling/assembly, or, if it was really an OK part to start, it was overtightened.

Good luck -- since what you've had so far has been pure shit, if you ask me. First the suspension all but falls off, now this?? Bum deal, to say the least. Thunder Ranch is just about at zero on my quality meter . . .

I sent TR an email this morning. Received a phone call shortly after they opened (west coast) from Tom, very quick repsonse time. He was genuinely concerned. The motor was purchased as a long block from SCAT. Tom will be sending a new head stud to replace the broken one. He took at look at the pictures and thinks it was just a bad stud. The longblock did come with chromoly studs.

Funny you should mention re-honingcylinder walls. I asked my father and Tom whether or not I should re-hone the cylinders and replace the rings. I was told not to... just to put everything back exactly as it came off. At the same time i get your point as to why it would be a good idea to do it. shit.

I was told to check the head, that the blow by could have eroded the aluminum surface and it will never seal back to the cylinder the same. If I have to resurface the one head... i definately have to resurface the other to the same spec in order to keep the engine balanced.

Geez! this is just a failed head stud. It's not the end of the world as we know it!!!!

I would NOT re-hone the barrel, nor would I have the head(s) machined unless there is some obvious wear at the blow-by point (which I doubt - you weren't driving it all that long and it's pretty rugged aluminum. Besides....It's gonna blow out along a portion of the head-to-barrel intersection, not at a precise point to cause significant errosion). For the number of miles you've got on this engine, the barrel honing cross-hatch is just about getting worn in - leave it alone and just re-assemble.

I WOULD mark the barrel as to which side is up when removing it to replace it in the same orientation. I would also gently remove the barrel and then mark the positions of the ring ends (openings) vis a vis the piston (a simple magic marker will let you mark the opening positions of each ring (#1, 2, 3) versus the piston as you dis-assemble) and then re-assemble with the ring slots in the more-or-less same positions (You're not assembling one of Kelly's rocket engines here - being off a few degrees isn't the end of the World). Then, when you've removed the barrel and can easily access the stud remains, get it out (gently heating the case area around the stud saver should help) and replace it with a new stud (Thanks to Tom McBurnie). I would still advocate replacing ALL of the studs, but that's up to you - they're cheap and you're already in there, so what the heck?)

As an aside, a good VW shop will know that you can't re-assemble the barrel to the piston with a "normal (read that, American-style) ring compressor. Why? Easy - not enough room AND you can't get an American-style ring compressor out after sliding the piston in to the barrel -think about it....you'll see the light). A VW shop will know enough to use a big hose clamp as a ring compressor so it'll get the rings compressed and seated into the barrel (with appropriate assembly lube), and then you can open up the clamp and slide it out between the head studs. Larry Jowdy knows this, but the young guys at B&T Machine in Beaufort didn't.

Now, to your latest queries:

Funny you should mention re-honingcylinder walls. I asked my father and Tom whether or not I should re-hone the cylinders and replace the rings. I was told not to...just to put everything back exactly as it came off. Yeah, me too, if that means anything.....

I was told to check the head, that the blow by could have eroded the aluminum surface and it will never seal back to the cylinder the same. If I have to resurface the one head... i definately have to resurface the other to the same spec in order to keep the engine balanced.
While that's true (doing each to make them match) I really doubt that it has eroded that much in that short a drive time. Weeks of driving, maybe, but a few hours? Naaah. Anyway, take it to a good automotive machine shop and tell them what's happened and have them check it out - They'll know what to do, and if they need to address the opposite head they'll know and should talk to you about it.

I still would let a knowledgeable shop do the heavy lifting on this. Everything I've mentioned should be second nature to a good shop and they should also be communicating with you as they go along with facts found and what their next step should be - it's your money, after all.

Isn't speedster ownership FUN????????

gn

Paul, Gordon's got it EXACTLY right. Every word. I removed my pistons and cylinders to reset the deck height. I went lower on compression ratio to tolerate all the alcohol in our gas. I didn't hone or replace anything. I never took the rings off the pistons either. Just new cylinder base shims, that's all. Car runs REALLY well, did that somewhere around 10-12K miles.

OK, I'll stand corrected by the wise-guys who have been there and done that, although I would run the hone and get new rings. Maybe I'm just remembering how it was done on other kinds of engines in another era. But the rings do "seat" during break-in which is to say they wear groves up and down in the cylinder walls and the ring edges themselves. Think of a really fine scale key in a lock. The little microgrooves are like finger prints, at least in my mind -- no two are alike. Once you undo 'em, you'll never get the same ridges/valley in the rings to match w/ their mates in the bore. It's just how I would do it. Maybe the materials used these days will "re-seat" and all is fine -?-

And you will need a close inspection of where the exhaust gas got out. If the metal in the head is affected (it is only Al after all), or the edge of the barrel too, you will not be a happy camper to put it all back and then have it leak there. That seal is VERY important, and dressing both surfaces so they are flat and well mated is essential. Recall my mention of burning an exhaust valve in an old S90. Alloy barrels and Al head, of course. Heat distribution in an air-cooled combustion chamber is very important, and the reason (told me by the mechanic who fixed it) that the valve burned was that the seal around the barrel at the head probably warped just a smidge and so the heat conduction pattern in the head changed just a little, and now the head was a little hotter right near where the exhaust valve was, and so the valve seat was a little hotter than it should be, and so the valve that sat on that seat was a little hotter than it should be (the valves cool while in contact w/ the seat), and so when I was climbing that mountain for 20 minutes solid in the summer of '68, the freakin' valve burned. I do not think it takes very long for hot exhaust right out of the CC takes very long to work on Al, if it is not well cooled. Longish story short, I got all new barrels, and had the head "sockets" trued.

Cool idea about the ring compressor hose clamp thing. That would work.

Not too sure if dressing up the head so the mating surface is just right (what would this take?? a few 0.001" at most??) would indicate the need for doing same to other cylinders. Seems one might use a proper spacer/shim at the barrel to case joint the make it all right and maintain comp. ratio, if had to. I understand they make different thickness gaskets to go in this place for just this reason.

And let me say once again -- SH**!!! -- you are up against it here. I'd also follow Gordon's advice here and solicit the help and advice of a reputable AIR-COOLED shop on this one.

OK, I'm done. Pls keep us posted on how it goes.

About to put a large order into CIP1 for parts. Anyone close to me need anything? Thanks again to everyone, all the posts are helpful one way or another. Ill take some pictures to post as i break the car down and find out more.

Do I need to replace the pushrod tube seals after pulling the head or can I reuse whats on the car?

Yes.......They are cheap.....

And not the PR tube "seals", per se, but the pushrod tubes complete, seals and all, as I understand it.

Yeah, go for the whole echilada - get all new pushrod tubes and o-ring seals for both ends. As someone said, they're cheap (of course, all things are relative, aren't they??)

Cip1 should call you "Mr. Rich" after this, no?

My .02
I'll recommend replacing the push rod seals and..the push rod tubes as they get "crushed" when installed and are inexpensive to replace them...... I always go this route and they don't leak".
Also best to replace all of head studs and by doing so, you'll have piece of mind knowing you did the job was done right the first time and you will not have to redo this again in the near future. ~Alan

I was Mr. Rich prior to owning this speedster... need to run down to Social Security and see if Mr. Poor is available. Dont get me wrong, im not complaining. This keeps me out of the bars.

Will get new tubes (windage tubes?) and new studs. Any sealing (stuff from a tube) I need to do to prevent oil leaks?

RTV Silicone rubber, if you really feel the need. I use it on just about everything.
The High Temp. version is good to 425F. if i remember correctly. The regular is around 325F.
Surfaces must be oil free.

On pushrod tubes no sealant is needed. Make sure you have new tubes and new silicon seals. Surfaces on head and case must be clean, smooth, and dry.

I used Scat spring-loaded tubes. That way, if one ever leaks, it can be replaced without pulling the head. No leaks in almost two years.

10-4

In the process of pulling the motor. Took a couple shots of the stud broken off in the case. There seems to be very little clearance between the cylinder and the stud... would this have caused the failure?

Also, I plan on cleaning up some of the plumbing. I have had oil leaks from day one. Prior to putting the motor back in I will be venting the valve covers to a breather. Not sure what all is leaking around the oil pump. Maybe the fittings at the S.S. hose, maybe the oil pump cover. Its really hard to tell. I purchased some LOCTITE thread sealant. Is this ok to use on the oil line fittings? I also have a leak between the extended sump and the case. Also seem to be leaking oil at the temp sender on the side of the case above the tin.

I have some oil accumulation on the outside of the cast just below the hole in the back (see photo). Is this cause for concern?

My first guess would be over torqued at which time it had the initial crack and over time, it failed.

Well, the fractured stud due to initial over-torquing is the failure mechanism, but that doesn't address Paul's stated concern, which is; Is the oil seepage from that area of the case/cylinder intersection cause for concern??

Nope.

As the stud was failing, it allowed that corner of the head and it's respective corner of the cylinder to lift just enough to allow a bit of oil to seep out at the case (doesn't look like much, either). That's to be expected and nothing need be done about it other than clean up the area when the engine is dis-assembled (I would use carburetor cleaner on a rag) and then just put it back together correctly.