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Re: Case 680E
Posted: Fri Feb 24, 2023 11:03 am
by Eugen
Small update. Cleaned up and decarbonized the head main surface to measure warpage with a sheet of glass. Seemed to be within spec. Not having to resurface this half of the head is a relief.
But the valve seats must be cut fresh.
Re: Case 680E
Posted: Fri Feb 24, 2023 2:33 pm
by Eugen
I'm slightly confused about something, and I'll think aloud here in the hope that you guys can confirm or otherwise. This shows how little experience I have with such things.
When I took the valves off, there were seals on the intake valve guides (inner two guides) but none on the exhaust. In the picture below you can see one seal on for illustration purposes. You can also see the mark on the other inner guide where the other seal was.
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The parts manual for this tractor does not show any such seals. But other tractors have used this particular engine, and other parts manuals for this engine do show such guide seals in a kit being available. The parts manual particular to this tractor has something named a "STEM SEAL" , a square profile o-ring type of seal that slips into a groove on the valve stem. Each of the valves did have this seal. It looks like this:
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Sooo, there are clear signs that someone has opened this engine up before, for instance, orange silicone gasket maker on the oil pan gasket. Why have they decided to put this type of valve seal in addition to the original stem seal? And why only on the intake valve guides?
Re: Case 680E
Posted: Fri Feb 24, 2023 3:00 pm
by Eugen
Measured the valve stems and they have absolutely no wear, therefore new valves are not needed.
Re: Case 680E
Posted: Fri Feb 24, 2023 4:15 pm
by DavidBarkey
Stem seals are only needed on the intake valve due vacuum drawing in oil , where as the exhaust has pressure and the heat would kill them anyways . Only "umbrella seals" (square o rings at the top to keep oil from running down the stem from the spring keeper .
Re: Case 680E
Posted: Fri Feb 24, 2023 4:16 pm
by DavidBarkey
How big are those valves ?
Re: Case 680E
Posted: Fri Feb 24, 2023 4:47 pm
by Eugen
DavidBarkey wrote: ↑Fri Feb 24, 2023 4:16 pm
How big are those valves ?
1.75 ex
2 in
O.4025 stem diam
I'm taking the other head of now.
Re: Case 680E
Posted: Fri Feb 24, 2023 5:53 pm
by DavidBarkey
Eugen wrote: ↑Fri Feb 24, 2023 4:47 pm
DavidBarkey wrote: ↑Fri Feb 24, 2023 4:16 pm
How big are those valves ?
1.75 ex
2 in
O.4025 stem diam
I'm taking the other head of now.
I double checked ,Sorry I do not have anything that big.
Re: Case 680E
Posted: Fri Feb 24, 2023 7:21 pm
by Eugen
DavidBarkey wrote: ↑Fri Feb 24, 2023 5:53 pm
I double checked ,Sorry I do not have anything that big.
Thanks my friend, I appreciate it! It's the neway cu645 I need and a thicker pilot. It's pretty big $$ for just a one time use. Will think of something.
There was not a lot of carbon on this head, just like the other one. Does anyone know if these two seals are normally part of the head gasket? They are circled in yellow here. The head gasket remained stuck to the block.
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Here's a close up.
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I'd like to know if they are a separate seal to order it. Seems to be around a coolant gallery. Nothing shows in the parts diagram.
The pistons looked decent. Recall that compression was weak but over 340 psi in both these cylinders.
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Cleaned and measured for warp. This one's good too.
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What next?
1. Get the valves out and measure it all
2. clean both heads and the valves
3. resurface valves
4. cut seats
5. pull out the other pistons
6. order kit
Roughly that's the list. Probably forgetting something.
Re: Case 680E
Posted: Fri Feb 24, 2023 8:10 pm
by DavidBarkey
@Eugen @10 oclock on the first piston pic. the piston is signs of the piston deteriorating due to compression leaking past. It will fail like the other one .
Re: Case 680E
Posted: Fri Feb 24, 2023 9:39 pm
by Jancoe
Both pics show signs of detonation. First pic 10oclock second pic 2 oclock.
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