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Anyone ever break a valve like this?

Dashnizzle

Proven Member
129
93
Jun 5, 2021
Montana
Suffered a pretty major valve failure a while ago and I've been trying to sort out the cause for a while now. The head (aside from cams and lifters) was assembled at a machine shop with a full valve job, deck resurface, etc.

I'm more curious than anything about the actual valves that were pulled from the head. One valve has a perfect shear at almost 90 degrees right at the point where the valve stem tapers down before the valve 'head'.
I will also note that none of the valves were binding in the guides. Everything was still loose and pulled easily.

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Anyone ever see this? The Machine shop said they weren’t familiar with valves breaking like this and even considered that it may have been as simple as the valve itself randomly failing. Like a manufacturer error of some sort.
 
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1990TSIAWDTALON

Moderator
10,172
6,156
Nov 14, 2013
Independence, Kansas
I have bent dozens of valves but never sheered one off at that point unless it made contact with the piston, and still those just bent. There is a first time for everything I suppose, and manufacturer quality may have something to do with it I would say also.
 

Thecarfixerguy

Proven Member
33
9
Dec 13, 2022
Idaho
I’ve seen it happen lots of times when there’s piston contact on other types of vehicles. The valve head usually punches through the piston and sometimes the cylinder wall. It can mash the head pretty bad too. I bought my Audi TT with a broken timing belt and it had two exhaust valve heads embedded in the #1 piston.
 

dwb

Proven Member
403
223
Sep 9, 2021
Broomfield, Colorado
When researching valves for my 1g head rebuild, I read some posts/reviews that mentioned the Topline brand valves are a two-piece design which has resulted in an occasional one breaking in half. I can't identify the OP's valves, but kind of seems like what's going on here.
 

1990TSIAWDTALON

Moderator
10,172
6,156
Nov 14, 2013
Independence, Kansas
When researching valves for my 1g head rebuild, I read some posts/reviews that mentioned the Topline brand valves are a two-piece design which has resulted in an occasional one breaking in half. I can't identify the OP's valves, but kind of seems like what's going on here.
It appears that he has that "2 pc" design NOW.......
 

Dashnizzle

Proven Member
129
93
Jun 5, 2021
Montana
Yeah so these are the supertech nitride coated valves. They were recommended to me by someone trustworthy and I cant confirm or deny if they are a 2 piece construction but that would seem silly to me!
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I’ve seen it happen lots of times when there’s piston contact on other types of vehicles. The valve head usually punches through the piston and sometimes the cylinder wall. It can mash the head pretty bad too. I bought my Audi TT with a broken timing belt and it had two exhaust valve heads embedded in the #1 piston.

Yes One of the valve heads was embedded in the piston and the other shot through to the oil pan.

Call me crazy but I am going to use them again. Manufacturer error never really occurred to me, I just assumed it was an installation error so I didn't think twice when re-ordering. I'm nervous now.
 

Dashnizzle

Proven Member
129
93
Jun 5, 2021
Montana
Update: I called supertech and confirmed these are one piece valves. He told me that if you have a bend in your valve and you continue to run the motor, they will try and straighten out in the guide and over time develop a crack that will eventually give a knife-like break like what I have.
I'm not ruling the possibility out that something got bent during assembly or in the first few miles while we figured this engine out, but yeah thats what they told me.
It begs the question: Are other manufacturer's valves stronger in the sense that they will bend more without breaking? This guy was very familiar with my issue and so far you guys are telling me its unusual so once again im nervous LOL
 

danl

20+ Year Contributor
726
117
Apr 8, 2002
Severn, Maryland
If you can slide the broken valve stem out of the guide easily, I have a hard time believing that it was ever bent and “straightened “ out when running. Furthermore if one pair of valves hit a piston, then you should see witness marks on the other pistons.
 

Dashnizzle

Proven Member
129
93
Jun 5, 2021
Montana
If you can slide the broken valve stem out of the guide easily, I have a hard time believing that it was ever bent and “straightened “ out when running. Furthermore if one pair of valves hit a piston, then you should see witness marks on the other pistons.
Exactly what I was thinking. Broken stem was loose and everything happened on cylinder one.

I do believe one thing he told me on the phone which is that if a small crack forms on the valve it will eventually work it’s way across like it did to give that knife like cut. I guess the question is if we should avoid Supertech valves and if this characteristic is not found with other valves on the market.
 

EC17PSE

Freelancer
5,696
3,057
Nov 1, 2008
London, UK, Europe
I have only seen this on 2 piece where they join the 2. sometimes its from high pressure valve springs and it yanks its off as it seats again. on a DSM i have never seen this but best to call some DSM or 4g63 machine shops and ask them their knowledge is on this exactly and if they seen it.

maybe it could be a faulty valve or it just was slightly bent and micro fractured, it looks like a very clean break though which is odd
 

CKOPOCT

Proven Member
185
98
May 27, 2017
Odenton, Maryland
Not familliar with the brand, but "Supertech" sounds a lot like some other highly trusted brands with similar naming conventions:
Hypertough
Great Value
Everstart
...
 

danl

20+ Year Contributor
726
117
Apr 8, 2002
Severn, Maryland
Exactly what I was thinking. Broken stem was loose and everything happened on cylinder one.

I do believe one thing he told me on the phone which is that if a small crack forms on the valve it will eventually work it’s way across like it did to give that knife like cut. I guess the question is if we should avoid Supertech valves and if this characteristic is not found with other valves on the market.
I would be inspecting all the other valves at that machining line under a microscope. If you see cracks on other valves, then you will be able to make an informed decision on what to do next. If you don't see any other cracked valves, then you need to keep investigating to find the root cause.
 

turbomister2

Probationary Member
9
17
Jan 7, 2014
Massachusetts
Supertech valves did this twice once to me and once to a friend. Was in a Honda but same catastrophe

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bastarddsm

15+ Year Contributor
5,550
1,360
Aug 26, 2003
Mendota, Illinois
Pretty common. Valve float, seats were not concentric to guides, slightly bent valve, or sometimes it just sucks to suck.

I've seen many times they new fancy machines that cut the seats are not for shit and leave the seat off center. You can feel it with a bare head clean not lubed stems, the valves sort of stick shut, it's just a very slight feeling. Usually they are lapped in to check, but lapping compound is thick and hides a lot of sin. I paint them with permanent marker and give em a spin to see. Still can hide, but nowhere near as bad. Need to inspect it all. See what the condition of the seats are, see what the locks and retainers look like ect.

Supertech stuff is pretty high quality.

Also, just because it was done at a shop, doesn't mean it was done right. Most shops can't seem to figure out how to do these heads right.

I do mine with stones, and most will tell you that's a hack way..... It's not it just takes about 100x more attention/patience/skill to do it. You have much more feel and control over what you are doing.

There's a video floating around on the fb groups from some shop local to me that ruins a lot of stuff. like media blasted the cam journals on a head. Anyway they are cutting seats on some sort of a live pilot setup and you can see the whole thing flex like hell, it's gonna be not round, or at least off center. When you do new guides the valve ends up not centered to the seat anymore. The guides are not coencentric from factory. So when you cut with a single point cutter (serdi newen ect) there is a lot of unbalanced cutting forces. You have a pilot the size of a valve stem trying to hold the cutter in place, and it's driven by what is essentially an expensive drill press. Floppy and unrigid as hell. It's dumb. But they cut all 3 angles at once and are fast.

When you grind seats there are hardly any cutting forces so they are easy to keep coencentric, as long as you don't side load the grinder. But you have to cut all 3 angles independantly and get them right. Grind a little far on the top/throat cut and start over. It's a cocksucker. Then our seats seem to load up and wear the stones a lot, so I spend a lot of time truing the stones. I use a diegrinder with an adaptor to drive the stone vs the sidewinder deal. Easier to not sideload. and slower so you can sneak up eaiser.
 

Dashnizzle

Proven Member
129
93
Jun 5, 2021
Montana
Yeah I don’t doubt that the shops get it wrong and often. I did my best to mitigate this by using a machine shop that has experience with our cars and shipped it to IL from my home state of MT. That being said I was told they gave it a 3-angle valve job but I have no idea how exactly it was done. I could ask i suppose. They took tons of measurements to see if anything would point towards a failure like this with no result either.

Here is what they were able to do with the head:
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As you can see the new Supertech valves are installed. They made the guides a tiny bit looser this time but otherwise gave it the full valve job and checked it with lapping like last time. I do remember at one point he explained his machine to me and was pretty proud of it. What it does exactly? Couldn’t really tell you. This is where my knowledge and skill (and tools) fall short and I have to rely on others.
 

We're on Boost

15+ Year Contributor
1,698
494
Aug 25, 2007
Seattle area, Washington
I do mine with stones, and most will tell you that's a hack way..... It's not it just takes about 100x more attention/patience/skill to do it. You have much more feel and control over what you are doing.

when you cut with a single point cutter (serdi newen ect) there is a lot of unbalanced cutting forces. You have a pilot the size of a valve stem trying to hold the cutter in place, and it's driven by what is essentially an expensive drill press. Floppy and unrigid as hell. It's dumb. But they cut all 3 angles at once and are fast.

I had no idea people would be trying to do valve seats with a single point cutter these days. It does seem dumb. I only remember one way to do valve seats, and that is grinding with stones, with frequent re-truing of the stones. In 1966 (my year of auto shop LOL) that is the only way we were taught.
 

turbomister2

Probationary Member
9
17
Jan 7, 2014
Massachusetts
Yeah I don’t doubt that the shops get it wrong and often. I did my best to mitigate this by using a machine shop that has experience with our cars and shipped it to IL from my home state of MT. That being said I was told they gave it a 3-angle valve job but I have no idea how exactly it was done. I could ask i suppose. They took tons of measurements to see if anything would point towards a failure like this with no result either.

Here is what they were able to do with the head:
You must be logged in to view this image or video.

As you can see the new Supertech valves are installed. They made the guides a tiny bit looser this time but otherwise gave it the full valve job and checked it with lapping like last time. I do remember at one point he explained his machine to me and was pretty proud of it. What it does exactly? Couldn’t really tell you. This is where my knowledge and skill (and tools) fall short and I have to rely on others.
Both times it happened we used two different shops …. So I know things can happen but only one thing stayed the same and that was the manufacturers. With that being said I still run Supertech just not their valves
 

bastarddsm

15+ Year Contributor
5,550
1,360
Aug 26, 2003
Mendota, Illinois
@Dashnizzle that this head before and after the repair? They actually sent it out with the gnar job on the chamber? Did they put new seats in? what size valves? Have you checked piston to valve clearance? most pistons do not have clearance with oversize valves, you need to cut the reliefs.
 

bastarddsm

15+ Year Contributor
5,550
1,360
Aug 26, 2003
Mendota, Illinois
I had no idea people would be trying to do valve seats with a single point cutter these days. It does seem dumb. I only remember one way to do valve seats, and that is grinding with stones, with frequent re-truing of the stones. In 1966 (my year of auto shop LOL) that is the only way we were taught.
Yeah it's all the rage nowdays.
 

Dashnizzle

Proven Member
129
93
Jun 5, 2021
Montana
@Dashnizzle that this head before and after the repair? They actually sent it out with the gnar job on the chamber? Did they put new seats in? what size valves? Have you checked piston to valve clearance? most pistons do not have clearance with oversize valves, you need to cut the reliefs.
Yes same head, I have a new block on the way so nothing has been checked for compatibility. These are standard sized valves not oversized by the way. And yeah the machine shop welded and that’s the result. I still have some work to do to make sure everything still works.
 
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1990TSIAWDTALON

Moderator
10,172
6,156
Nov 14, 2013
Independence, Kansas
I have 2 DSMs running Supertech valves. The ONLY time I had a problem is when the front timing pulley worked it's way loose and I bent all 16 but didn't break any of them. Now I do what @bastarddsm suggested to me and use plenty of locktite. That set of valves all did a good job of NOT ruining a piston as I was able to reuse all 4. I will run Supertech again. They dont scare me.
 
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