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malcolm2
Samba Member
Joined: September 28, 2011
Posts: 1272
Location: Mount Juliet, TN
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 Posted: Tue Apr 28, 2020 5:25 pm Post subject: Valves are chipped |
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72 1.7 has been sitting in my garage for two years. Gotta take the heads off to fit under my house for the next project. So here we are. What caused the 1 and 3 ex valves problems? #1 piston has a nick. #3 is good. Not sure why this bus had not moved on it’s own power in 30years. These nicks would not stop it.
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SGKent 
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Tue Apr 28, 2020 5:32 pm Post subject: Re: Valves are chipped |
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valve stuck open due to many causes and tagged a piston. That made a hell of a racket and scared the owner who parked it. Or the seat came out, held the valve open and the piston hit the valve, then the seat dropped back in and it is like you see it. That made a heck of a racket too if it happened. The heads have to be rebuilt and there aren't too many people who do a good job of that anymore. The piston set will get replaced, and the rod checked to see if it has any bend to it.
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malcolm2
Samba Member
Joined: September 28, 2011
Posts: 1272
Location: Mount Juliet, TN
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| Posted: Tue Apr 28, 2020 5:36 pm Post subject: Re: Valves are chipped |
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Strange to me that it is 1 and 3. Across from one another.
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busdaddy
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Joined: February 12, 2004
Posts: 51121
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Tue Apr 28, 2020 6:03 pm Post subject: Re: Valves are chipped |
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| malcolm2 wrote: |
| Strange to me that it is 1 and 3. Across from one another. |
Not strange at all, they are the furthest away from the fan and most starved for cooling. Add in some vacuum leaks and hippie abuse and sometimes things far worse than that happen.
There's so many little things wrong in those chambers there's no way I'd put them back on without some professional work on the heads first. And as Steve says the pistons and rods are also suspect too.
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50336
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| Posted: Tue Apr 28, 2020 6:05 pm Post subject: Re: Valves are chipped |
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I am going to guess that your two damaged exhaust valves are some kind of cheap aftermarket crap. Doesn't look like the valves contacted anything to me, but that they couldn't stand the normal conditions to be found in a VW aircooled engine.
Two of your cylinders have one brand of exhaust valve that is junk and your other two exhaust valves are a different brand and seem to be holding up well from what little we can see of them.
Last edited by Wildthings on Tue Apr 28, 2020 8:30 pm; edited 1 time in total |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Tue Apr 28, 2020 6:07 pm Post subject: Re: Valves are chipped |
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| malcolm2 wrote: |
| Strange to me that it is 1 and 3. Across from one another. |
Maybe he was headed down a mountain grade at the time it happened. You know what they say, Sh_t rolls downhill............. 
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raygreenwood
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Joined: November 24, 2008
Posts: 21510
Location: Oklahoma City
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| Posted: Wed Apr 29, 2020 1:58 pm Post subject: Re: Valves are chipped |
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While I agree...the ding in the piston is similar to what a valve striking the piston can make...I have NEVER seen a steel valve chipped by an aluminum piston.
And...I have ever seen a valve that has struck a piston that has NOT gotten a bent stem.
However....if the engine "swallowed" something....like a nut or stud....you "could" chip a valve AND ding a piston. But...usually that results in many little dings in the piston.
I am betting it was detonation. Ray |
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SGKent
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Wed Apr 29, 2020 2:36 pm Post subject: Re: Valves are chipped |
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| raygreenwood wrote: |
While I agree...the ding in the piston is similar to what a valve striking the piston can make...I have NEVER seen a steel valve chipped by an aluminum piston.
And...I have ever seen a valve that has struck a piston that has NOT gotten a bent stem.
However....if the engine "swallowed" something....like a nut or stud....you "could" chip a valve AND ding a piston. But...usually that results in many little dings in the piston.
I am betting it was detonation. Ray |
Everyone assumes it was one thing only. Could be really cheap metal in the valve along with something else. I didn't see classic detonation damage on the head or piston - but in all my thousands of heads worked on I have never seen damage to a valve like that - where it flakes off in areas. More like someone prying on it to get it open.
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TomWesty
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Joined: November 23, 2007
Posts: 3482
Location: Wyoming,USA
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| Posted: Thu Apr 30, 2020 6:59 am Post subject: Re: Valves are chipped |
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| busdaddy wrote: |
| malcolm2 wrote: |
| Strange to me that it is 1 and 3. Across from one another. |
Not strange at all, they are the furthest away from the fan and most starved for cooling. Add in some vacuum leaks and hippie abuse and sometimes things far worse than that happen.
There's so many little things wrong in those chambers there's no way I'd put them back on without some professional work on the heads first. And as Steve says the pistons and rods are also suspect too. |
Out here we have more dead Volkswagens parked on farms and ranches than anywhere else, so if the hippies were abusing them, they were sneaking on to the old German farmers’ homestead at night to do it. 
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raygreenwood
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Joined: November 24, 2008
Posts: 21510
Location: Oklahoma City
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| Posted: Thu Apr 30, 2020 7:19 am Post subject: Re: Valves are chipped |
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| SGKent wrote: |
| raygreenwood wrote: |
While I agree...the ding in the piston is similar to what a valve striking the piston can make...I have NEVER seen a steel valve chipped by an aluminum piston.
And...I have ever seen a valve that has struck a piston that has NOT gotten a bent stem.
However....if the engine "swallowed" something....like a nut or stud....you "could" chip a valve AND ding a piston. But...usually that results in many little dings in the piston.
I am betting it was detonation. Ray |
Everyone assumes it was one thing only. Could be really cheap metal in the valve along with something else. I didn't see classic detonation damage on the head or piston - but in all my thousands of heads worked on I have never seen damage to a valve like that - where it flakes off in areas. More like someone prying on it to get it open. |
Yep....never seen damage like that. Agree....could be a combination of things. But....you can take an exhaust valve (or intake).....anyones valve. Use it as drift with a hammer....to beat holes in "aluminum" pistons all day every day.....and you will never get a "steel alloy" valve.....much less a stainless alloy valve.....to "CHIP"....beating it against any alloy of aluminum on the planet (well.....maybe hard anodized, forged 7030 or similar).....except where the steel hammer strikes the valve.
See what I'm saying?
So.....I think the term "chip" is a poor one. But yes. I have never seen damage like that. Ray |
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alaskadan
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Joined: January 09, 2013
Posts: 1857
Location: anchor pt. alaska
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| Posted: Thu Apr 30, 2020 7:29 am Post subject: Re: Valves are chipped |
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| No engine building expert here, but the two valves with the most chips look to be a different brand, maybe. They look to have a deeper recess, the bevel down to the recessed area looks to be a larger bevel. No? |
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jtauxe
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Joined: September 30, 2004
Posts: 5780
Location: Los Alamos, New Mexico
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| Posted: Thu Apr 30, 2020 8:36 am Post subject: Re: Valves are chipped |
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| malcolm2 wrote: |
| Strange to me that it is 1 and 3. Across from one another. |
50/50 chance...
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50336
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| Posted: Thu Apr 30, 2020 8:41 am Post subject: Re: Valves are chipped |
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| jtauxe wrote: |
| malcolm2 wrote: |
| Strange to me that it is 1 and 3. Across from one another. |
50/50 chance... |
He is numbering his cylinders wrong, the bad valves are on #1 and #4, so they are not directly across from one another. |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Thu Apr 30, 2020 8:47 am Post subject: Re: Valves are chipped |
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| Wildthings wrote: |
| jtauxe wrote: |
| malcolm2 wrote: |
| Strange to me that it is 1 and 3. Across from one another. |
50/50 chance... |
He is numbering his cylinders wrong, the bad valves are on #1 and #4, so they are not directly across from one another. |
They were if he was parked at a 45 degree angle..... 
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malcolm2
Samba Member
Joined: September 28, 2011
Posts: 1272
Location: Mount Juliet, TN
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| Posted: Thu Apr 30, 2020 8:51 am Post subject: Re: Valves are chipped |
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| Wildthings wrote: |
He is numbering his cylinders wrong, the bad valves are on #1 and #4, so they are not directly across from one another. |
They were the closest valves to the flywheel. I just looked at the tins on my 914... 1 and 3 are stamped in the tins and they are the closest cylinders to the flywheel.... both are EX valves and use the same cam lobe. truthfully it does not matter the number. I think the white paint will remind me, or the next guy that those valves are damaged.
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Wildthings
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Joined: March 13, 2005
Posts: 50336
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| Posted: Thu Apr 30, 2020 9:09 am Post subject: Re: Valves are chipped |
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| malcolm2 wrote: |
| Wildthings wrote: |
He is numbering his cylinders wrong, the bad valves are on #1 and #4, so they are not directly across from one another. |
They were the closest valves to the flywheel. I just looked at the tins on my 914... 1 and 3 are stamped in the tins and they are the closest cylinders to the flywheel.... both are EX valves and use the same cam lobe. truthfully it does not matter the number. I think the white paint will remind me, or the next guy that those valves are damaged. |
Set your heads so that they face each other as they would if installed on the engine and see where the bad valves end up. |
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