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  #1  
Old 07-08-2017, 10:06 PM
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I made a mistake by sending my wagon head (617.952) to a local machinist who ground an exhaust valve too deep. I don't think he knew what he was doing.

The upshot being that I can no longer get enough clearance to the cam follower on that cylinder. The top nut on the valve is turned down to where it spins the valve when tightening at the bottom of its range. The bottom nut still has a little free space to the top nut, but the top nut is bottoming out on the valve stem. I can only get about .28 clearance when I need .35.

The engine runs OK at higher rpms, -but there is a rock or miss at idle. I thought maybe I could grind down the top of the valve stem a little, but I hesitate to remove the camshaft to accomplish this. It doesn't look like I would have enough clearance by just removing the follower galley. This engine doesn't have a thrust piece on the valve to replace like other engines, so I am kind of stuck.

What would you do? I would love to drop-in a rebuilt wagon head, but they are hard to find and are expensive when you can find one.

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  #2  
Old 07-08-2017, 10:21 PM
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Can you replace the valve seat and start over?

Sixto
98 E320s sedan and wagon
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  #3  
Old 07-08-2017, 10:25 PM
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Sixto makes a good suggestion. Find a REAL machine shop and they should be able to handle that with no issue. Done poorly, the seat can come loose so you want the good guys. The only excellent shop I can recommend that's anywhere near you is Westech in Silver Lake, WI, north of Chicago. Not too close I know but Norm and his guys do it right - tell them I sent you and they'll charge you double (just foolin'). If you take the head to him it shouldn't be too pricey but it's a bummer that you'll have to do the job twice.

Dan
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  #4  
Old 07-09-2017, 01:21 AM
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Find one of the online W123 manuals and read up on rebuilding the cylinder head and then you can also print a copy of the specs to show the person who would do the rebuild.

When I changed my Valve Stem Seals if the Piston is at top dead center and the whole rocker arm assembly is removed or perhaps even with only the Rocker Arm removed and the top you you could perhaps file 20-30 thousands off the top of the Valves.

I have no Idea if the metal on the top of the Valve Stems is extremly hard or not.

They do have diamond dust coated files and sharpening stonse that you can use by hand to file down even hardened metal but they are slow.

But does anyone know any reason why the top of the top nut could not be filed instead of the top of the valve stem?
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Old 07-09-2017, 08:18 AM
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Originally Posted by Diesel911 View Post
Find one of the online W123 manuals and read up on rebuilding the cylinder head and then you can also print a copy of the specs to show the person who would do the rebuild.

When I changed my Valve Stem Seals if the Piston is at top dead center and the whole rocker arm assembly is removed or perhaps even with only the Rocker Arm removed and the top you you could perhaps file 20-30 thousands off the top of the Valves.

I have no Idea if the metal on the top of the Valve Stems is extremly hard or not.

They do have diamond dust coated files and sharpening stonse that you can use by hand to file down even hardened metal but they are slow.

But does anyone know any reason why the top of the top nut could not be filed instead of the top of the valve stem?

Filing the top nut sounds like something to look at. Are they stellite like the cam followers? a lot easier that pulling the head or reworking it. If the head is back on, of course remember and take care not to drop the valve into the cylinder. Setting (and keeping) the engine to TDC at the right cylinder would work.
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  #6  
Old 07-09-2017, 08:30 AM
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Filing that top nut is something to look at...

but also.. the type of system on has.... needs to be checked first... the kinds of followers must match the kind of camshaft or the other mechanisms up there... it is in the FSM..

but if the head can be taken off.... then new valve seats can be installed... and triple cut to the proper depth....to just start OVER ...
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  #7  
Old 07-09-2017, 08:53 AM
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member Adriel has a TD head, if you decide to buy one
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  #8  
Old 07-09-2017, 08:57 AM
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For casual members not familiar with Wagons...
Moon161 is referring to a head with the built in hydraulic pump used on the wagon for leveling the car even with variations in rear load...
Some other models have that also.. sedans... but I don't know which exactly..
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  #9  
Old 07-09-2017, 09:32 AM
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Quote:
Originally Posted by Carpenterman View Post
I made a mistake by sending my wagon head (617.952) to a local machinist who ground an exhaust valve too deep. I don't think he knew what he was doing.

The upshot being that I can no longer get enough clearance to the cam follower on that cylinder. The top nut on the valve is turned down to where it spins the valve when tightening at the bottom of its range. The bottom nut still has a little free space to the top nut, but the top nut is bottoming out on the valve stem. I can only get about .28 clearance when I need .35.

The engine runs OK at higher rpms, -but there is a rock or miss at idle. I thought maybe I could grind down the top of the valve stem a little, but I hesitate to remove the camshaft to accomplish this. It doesn't look like I would have enough clearance by just removing the follower galley. This engine doesn't have a thrust piece on the valve to replace like other engines, so I am kind of stuck.

What would you do? I would love to drop-in a rebuilt wagon head, but they are hard to find and are expensive when you can find one.
Why isn't the machine shop responsible? You paid them, right? Use your credit card and refuse payment. Most of the credit card companies have insurance fo9r this and you might be able to get a new head.
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  #10  
Old 07-09-2017, 10:31 AM
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I really don't want to pull the head again. The engine runs OK, as I said.

I didn't think it was a good idea to file the top nut, as I assumed it was hardened. If Diesel911 is correct, I can get the nut off to file the valve stem without removing the camshaft. I suppose if I have to, I can depress the valve to get it off. I figure I can get a Dremel stone in there to do the filing.

Yea, it's the machine shop's fault. They should have at least run a straight edge along the end of the valve stems. But the first valve adjustment after reinstalling the head went fine--the problem developed over a year later at the second adjustment since the re-work. So I'm sort of on shaky ground with regard to making claims.

Also, this is the only machine shop in my area, they are very reasonable, have done other excellent work for me, and I want to measure good will against any perceived liability.
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  #11  
Old 07-09-2017, 11:11 AM
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Can you file the bottom of the nut rather than the cam contact surface? I'd rather do that than upset a potentially hardened finish.

Sixto
98 E320s sedan and wagon
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  #12  
Old 07-09-2017, 11:59 AM
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Quote:
Originally Posted by Carpenterman View Post
I really don't want to pull the head again. The engine runs OK, as I said.

I didn't think it was a good idea to file the top nut, as I assumed it was hardened. If Diesel911 is correct, I can get the nut off to file the valve stem without removing the camshaft. I suppose if I have to, I can depress the valve to get it off. I figure I can get a Dremel stone in there to do the filing.

Yea, it's the machine shop's fault. They should have at least run a straight edge along the end of the valve stems. But the first valve adjustment after reinstalling the head went fine--the problem developed over a year later at the second adjustment since the re-work. So I'm sort of on shaky ground with regard to making claims.

Also, this is the only machine shop in my area, they are very reasonable, have done other excellent work for me, and I want to measure good will against any perceived liability.
Yes I agree... it is interesting that it functioned that long before being discovered... and I am not sure what the machine shop could have messed up to produce this evidence... Perhaps Steelite valve seats were not used or they were not properly heat treated...which would not be the machine shop's fault..

AS TO filing or grinding on any of those surfaces.... make provisions before hand to deal with the THREADS which will be affected... things like putting some nuts on the threads... to be taken off OVER the ground area.... and having the proper thread restorers handy ....
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  #13  
Old 07-09-2017, 12:18 PM
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Quote:
Originally Posted by moon161 View Post
Filing the top nut sounds like something to look at. Are they stellite like the cam followers? a lot easier that pulling the head or reworking it. If the head is back on, of course remember and take care not to drop the valve into the cylinder. Setting (and keeping) the engine to TDC at the right cylinder would work.
If you just remove the top Nut you don't need to worry about the Valve falling into the cylinder because the lower Nut will hold it in place.

In the Manual it only has that the later model Nuts are hardened more then the older ones.

In fact the top Nuts can be removed and a Bolt and nut with the same threads found and the normal nutr can be threaded onto the Bolt ffollowed by the top nut and then the lower can be used to lock it so it will not rotate.
After that a second or so on the flat face of a grinding wheel followed by dressing with wet dry sand paper ought to get some clearance quickly.

Personally I think I would prefer to do it by hand to control the heat and minimize how much metal would be removed.

It is clear that Stelllite can be ground by grinding wheels as quite a few larger Diesel Engines have Stellite on the valve faces and the mentioned valve seats.
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Old 07-09-2017, 12:33 PM
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In the Shop I uised to work ing we rebult the Cylinderheads on a Ford gasser from a one 2 ton truck.

The heads were warpped so the heads were surface ground.

This Engine had hydraulic valve lifters and was was not anticipated was that distance between the camshaft and the rocker arms was closer and the Push Rods were now too long for the range of the Hydraulic Lifters.

Typically you can purchase shorter Push Rods. But you need to know how much was removed from the Cylinder head and at the same time as noted in this thread how much height the Valve Stems are protruding. The Cylinder Heads were already on the Engine and the Customer was pressing us to get his truck back.

So my Boss had me remove the Rocker Arm Assembly and grind down the tops of the Vave Stems with the Cylinder Head on the Engine. It was a V8 and it took ove 2 hours.

Part of the reason for the screw up is that we were a Fuel Injection Shop that occasionally did Diesel Heads and more occasionally in frame overhauls of Diesel Engines. Like the Mechanic that overhauled the OPs head we had no books or specs to guide us.

If we had had a good manual it would have told use how much above the top deck the Valve Stems were supposed to protrude (in fact the Valve Face Grinding Machine has a facility to grind the top of the Valve Stems) and we would have noted how much was removed when the Heads were surface ground.

If we had that info we could have picked what length Push Rods we needed.

I mean we did not even know if both Cylinder Heads had the same amount surface ground off of them.
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  #15  
Old 07-09-2017, 12:41 PM
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Quote:
Originally Posted by Carpenterman View Post
I really don't want to pull the head again. The engine runs OK, as I said.

I didn't think it was a good idea to file the top nut, as I assumed it was hardened. If Diesel911 is correct, I can get the nut off to file the valve stem without removing the camshaft. I suppose if I have to, I can depress the valve to get it off. I figure I can get a Dremel stone in there to do the filing.

Yea, it's the machine shop's fault. They should have at least run a straight edge along the end of the valve stems. But the first valve adjustment after reinstalling the head went fine--the problem developed over a year later at the second adjustment since the re-work. So I'm sort of on shaky ground with regard to making claims.

Also, this is the only machine shop in my area, they are very reasonable, have done other excellent work for me, and I want to measure good will against any perceived liability.
I am sure of that because it is the same as when I changed the Valve Stem Seals except leaving the bottom Nut on mean you don't need to worry about the Valves falling into the Engine.

It does require removing that Rocker Arm Assembly and I mean the whole apparatus from the Cylinder Head.

As far as hardened goes Files are generally much harder then Steel used in most things (cast Iron is another matter). Grinding Stones can deal with any hardened Steel.
In fact it would be slow but the typical cheap knife sharpening stone with a fine and coarse side on it would work if you used the coarse side. You are not removing that much metal. Maybe 20-40 thousandths.

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