Cracked Valve Guide Pillars - OK to Use?

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BillGrissom

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I have the heads off on my 1965 383 and noticed a possible problem from peering thru the valve springs. On one head, all of the exhaust valve guide pillars (correct name?) are missing chunks or at least cracked. I wasn't planning a valve job and just had the heads off to mill a smooth surface to better seat the valve covers and stop oil leaks which drove me nuts for years (done). 1st photo shows the worst one, where I removed the spring. It seems the valve guide sits in enough meat to secure it well, and it protrudes past the cast-iron pillar (keeps oil away). The second photo is the same PN head (2406516, "L", closed-chamber) I found for sale on ebay, which has even worse pillars , several cracked off completely. I can't tell about my intake valves since the shop used seals which have a wire spring to secure them to the pillar (instead of umbrella seals).

Is this head OK to use as is? Does anyone know the purpose of these pillars, and if they exist on later PN heads? Is the purpose to help keep oil from pooling against the valve guide? To provide structural support to the guide? Hard to imagine since fairly thin brittle cast-iron. Could the pillars have broken when the shop installed new valve guides and just didn't tell me? I haven't pulled the oil pan yet to look for debris, though that could be inconclusive since it could have come out with the oil. I didn't find any debris in the valley, so wonder if the heads were like this when I installed them in 2001. The shop which did the head job was a high-volume place in south Atlanta. The mechanic exclaimed, "lucky you have the desirable L heads", so seemed like he appreciated working on them. I'm now in CA. Haven't driven the car but ~5000 miles since then. Haven't noticed any blue smoke or oil loss. I mainly worry if the valve guides could get loose or more cast-iron cracks off to put debris in the engine. Any comments appreciated. I am sure some will say "toss the heads", because no cost for them. I have considered aluminum heads, but that can cause new issues (valve-train geometry, risks of warpage, high cost).

Cracked exhaust valve guide pillar - small.jpg
Head w cracked valve guide pillars on ebay.jpg
 
That one where you have the spring off has had the guide replaced. When that was done, the shop should have milled the rest of the factory guide off, but they did not. If all you have is the factory guide like in that last picture, you can dress the top of the guide with a file to make sure there are no sharp edges on it. That will help it from not cracking or breaking any further. If they are cracked really bad though, like all the way to the spring seat for instance, the guide(s) should be replaced and the old guides milled down to the spring seat. Then you can run the valve seals that press right onto the ends of the guides.
 
Like Rusty said someone just did a half *** job and didn’t take the time to clean up there work. There is probably nothing wrong with your head unless the new guide is worn. If I see the top of the guide chipped like in the picture of the eBay head if the guide is still good I just machine the top of the guide down and put a positive seal on it. Sometimes depending on the cam and springs used the top of the guide has to be machined for clearance between the retainer and the top of the guide anyway so it’s no big deal
 
Some smart guys here. If i would have seen this, for a moment i would think its junk. but it makes perfect sense now.
 
Thanks for the very competent replies so fast. Many issues bring concern when a little experience can alleviate fears. So the purpose of those pillars was that they were the OE guides, just a hole bored in the raw cast-iron, just like the cylinders. In a "valve job", they bore a larger hole and press in separate tubes as guides, similar to sleeving a cylinder. That leaves the walls of the OE guide thin and easy to break as the new guide is forced in. Seems they don't know that until it cracks and hard to backup at that point, so some shops just leave as is.

Perhaps they could first mill down all the pillars. That appears to be how aluminum heads are cast, without pillars, since they use separate iron guides from the start; but would be more costly and this was a very active shop. I was surprised how inexpensive this valve job had been, ~$90/head, which included repairing a few small cracks.
 
Thanks for the very competent replies so fast. Many issues bring concern when a little experience can alleviate fears. So the purpose of those pillars was that they were the OE guides, just a hole bored in the raw cast-iron, just like the cylinders. In a "valve job", they bore a larger hole and press in separate tubes as guides, similar to sleeving a cylinder. That leaves the walls of the OE guide thin and easy to break as the new guide is forced in. Seems they don't know that until it cracks and hard to backup at that point, so some shops just leave as is.

Perhaps they could first mill down all the pillars. That appears to be how aluminum heads are cast, without pillars, since they use separate iron guides from the start; but would be more costly and this was a very active shop. I was surprised how inexpensive this valve job had been, ~$90/head, which included repairing a few small cracks.


Those "pillars" are called valve guides. Or you can call them valve guide bosses. Or pillar.

It doesn't hurt anything they say it was done, just shitty work. At this point, I'd make sure all the guides are good and if not, replace them. While they are in there, they SHOULD cut the guides down for a positive seal. I can't imagine a shop today not doing that. Ive been doing it since 1982. No reason EVER to not use a positive seal.
 
Thanks for the very competent replies so fast. Many issues bring concern when a little experience can alleviate fears. So the purpose of those pillars was that they were the OE guides, just a hole bored in the raw cast-iron, just like the cylinders. In a "valve job", they bore a larger hole and press in separate tubes as guides, similar to sleeving a cylinder. That leaves the walls of the OE guide thin and easy to break as the new guide is forced in. Seems they don't know that until it cracks and hard to backup at that point, so some shops just leave as is.

Perhaps they could first mill down all the pillars. That appears to be how aluminum heads are cast, without pillars, since they use separate iron guides from the start; but would be more costly and this was a very active shop. I was surprised how inexpensive this valve job had been, ~$90/head, which included repairing a few small cracks.

Yes, you got it spot on. That's how we used to do it when we replaced original cast in guides. We never left the top portion of the guide intact for the very reason they could crack later and cause mayhem.
 
Yes that is a good way of looking at it. And I know you said the work was inexpensive but, if you paid someone for the work and then took it some where else and said take these apart and tell me what you think and they said looks like a cheap job done in a hurry is that what you want on your car. My point is when people do work in any industry where there are the experts I think they should do work that everyone would say that's a nice job. If you didn't have someone to explain it you have had to worry about it or replace the heads at great expense maybe to you. Not to get on my soap box to much on your post but work in the automotive industry has to be better than anywhere else because of the reputation of the industry and anyone doing poor work maybe shouldn't be in my industry anymore.
 
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Yes that is a good way of looking at it. And I know you said the work was inexpensive but, if you paid someone for the work and then took it some where else and said take these apart and tell me what you think and they said looks like a cheap job done in a hurry is that what you what on your car. My point is when people do work in any industry where there are the experts I think they should do work that everyone would say that's a nice job. If you didn't have someone to explain it you have had to worry about it or replace the heads at great expense maybe to you. Not to get on my soap box to much on your post but work in the automotive industry has to be better than anywhere else because of the reputation of the industry and anyone doing poor work maybe shouldn't be in my industry anymore.


It's not just that it looks bad. The guide should be cut for positive seals and lowered for lock to guide clearance. Or the retainer.
 
Yes that is a good way of looking at it. And I know you said the work was inexpensive but, if you paid someone for the work and then took it some where else and said take these apart and tell me what you think and they said looks like a cheap job done in a hurry is that what you what on your car. My point is when people do work in any industry where there are the experts I think they should do work that everyone would say that's a nice job. If you didn't have someone to explain it you have had to worry about it or replace the heads at great expense maybe to you. Not to get on my soap box to much on your post but work in the automotive industry has to be better than anywhere else because of the reputation of the industry and anyone doing poor work maybe shouldn't be in my industry anymore.

That's not a soap box. That's expecting people to do the work right. Either they are a machine shop or they aren't.
 
It’s half assed work.

It’s nice to think all shops would do equal work, but just as in any other profession........ that’s just not how it is.
Some people are better at their jobs than others.

In your situation....... while the appearance of the work there leaves something to be desired, if you weren’t having any problems with the heads before...... and there is nothing mechanically wrong with them....... you can keep on running them.

Honestly......... I see **** like that all the time.
 
I was surprised how inexpensive this valve job had been, ~$90/head, which included repairing a few small cracks.

The heads would never have left my shop looking like that.
But then again....... they would be considerably more expensive than $90/head.
A lot of what machine shops charge has to do with what region they’re in.
I started in this business in 1989, and the shop I worked at had a basic valve job(disassemble, cleans heads and parts, reface valves, grind seats, reassemble) on a V8 at $100/pr.
The owner had it as a “loss leader”.
It was a huge loss.
I ended up managing that place at one point, and immediately did away with that loss leader pricing.

It’s pretty easy these days to have $1000+ tied up in reburbishing a set of 40-50 year old iron heads.

And that’s before the porting happens.
 
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The heads would never have left my shop looking like that.
But then again....... they would be considerably more expensive than $90/head.
A lot of what machine shops charge has to do with what region they’re in.
I started in this business in 1989, and the shop I worked at had a basic valve job(disassemble, cleans heads and parts, reface valves, grind seats, reassemble) on a V8 at $100/pr.
The owner had it as a “loss leader”.
It was a huge loss.
I ended up managing that place at one point, and immediately did away with that loss leader pricing.

It’s pretty easy these days to have $1000+ tied up in reburbishing a set of 40-50 year old iron heads.

And that’s before the porting happens.


Any machine shop using loss leaders to drive business usually don't last long.

The other thing that happens when you price like that, you get the tire kicking coupon clippers who look to cut corners, and when you do, it ends up on the internet making your work look bad.
 
If it was me, I'd take a punch and carefully bust the rest of that off. It'll still look like hell, but you don't want that remnant thing coming loose inside a running motor.
 
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