The Portal Hub: All things Pinzgauer, Haflinger, Volvo 303 and more.

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 Piston swap question 
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Joined: Mon Dec 18, 2017 3:18 pm
Posts: 4
Location: St. Helena, California
Post Piston swap question
So I bought a '74 710 which had zero compression on cylinder #4. All other cylinders have 130-150. With the engine in place I removed the valve head and cylinder thinking it maybe a bad valve or broken rings. Well it is definitely broken rings but also a cracked piston sidewall. So easy enough, buy and install a new 93 or 93.5mm cylinder and piston, but...

Can I swap the #4 piston with the engine still in place? And if I can, any tips or tricks to pass along?

Cheers
Joe


Sun Dec 24, 2017 10:31 am
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Joined: Thu Oct 06, 2011 4:25 pm
Posts: 788
Location: Mount Vernon WA USA
Post Re: Piston swap question
I've done it. Can't think of any tricks required. Be sure to get exhaust studs as they usually butlst off.


Sun Dec 24, 2017 1:40 pm
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Joined: Sun Sep 25, 2011 11:19 am
Posts: 622
Location: Woodside, CA
Post Re: Piston swap question
Yes, you can tear down the top end and rebuild in place,
for any one or all of the cylinders needing an overhaul.

Tricks, yes. First recommend while #4 is out, replace the
push rod and oil return tube gaskets and O-rings. Note that
the washers on the push rod tubes are special and have a
very subtle concave shape. You want the "domed" part
facing the rubber washer to provide proper force from the inner
radius to the washer getting the higher part of the dome so that
there is a lateral force across the washer to seal properly. Make
sure you get the Silicon (orange) O-ring and not a substitute. Scott
at EI stocks the proper O-rings.

Replace the push rod housing gasket as well. The head will have
to be hand lapped to the steel cylinder since there is no head gasket.
Get some course and fine grit lapping compound, rotate the
head over the cylinder (on a bench) until there is a clear sign of a polished
surface 360 degrees arounf the head.

When reinstalling the cylinder into the block us a liberal amount
of Aviation grade shellac inside the engine wall and on the bottom
portion of the cylinder that fits into the block -- with the cylinders near
horizontal you will leak oil otherwise.

Assemble head snug not tight. Get a straight edge on the exhaust
ports and make sure the head is rotated in alignment with the other
ports, otherwise you may leak exhaust. Once reasonably aligned
snug up a bit more, add exhaust and intake, snugging them into
position. Now you can go back and torque the head proper -- it's
a relatively low torque given Aluminum heads. Tighten the header
and intake manifold. Now your in the home stretch.

_________________
Puller: 710K 2.7L EFI
Follower: Sankey MK 3, 3/4 Tonne
Driver: Ron // KO0Q


Sun Dec 24, 2017 2:27 pm
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Joined: Mon Dec 18, 2017 3:18 pm
Posts: 4
Location: St. Helena, California
Post Re: Piston swap question
Thanks for the tips and guidance.
I haven’t work d with Circlips before.
Any good video showing the process?


Tue Dec 26, 2017 10:18 pm
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Joined: Tue May 26, 2015 2:30 pm
Posts: 245
Location: Houston, TX
Post Re: Piston swap question
jw_in_Cal wrote:
Thanks for the tips and guidance.
I haven’t work d with Circlips before.
Any good video showing the process?


It's super obvious once you look at them, you won't have any trouble. Piston has a little recess, stick anything narrow in there. Pick, awl, tiny screwdriver, and just pop the circlip out. They are meant to be one time use. Just have new ones on hand.

_________________
1977 Austrian 710M


Tue Dec 26, 2017 10:48 pm
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Joined: Mon Dec 18, 2017 3:18 pm
Posts: 4
Location: St. Helena, California
Post Re: Piston swap question
Great thanks


Tue Dec 26, 2017 11:21 pm
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Joined: Sun Dec 22, 2013 5:53 pm
Posts: 126
Location: Melbourne Australia
Post Re: Piston swap question
Thanks rmel that is some great info...you just answered me a few questions that I've long wondered about. In particular I had previously thought that an alignment plate (Factory tool?) was required across all four heads to do this work. I suspected one (or all) cyl's could be aligned properly without the factory tool but it's great to KNOW it can be done....Awesome explanation of the process. Thanks for sharing.

_________________
1985 pinzgauer 712K factory 2.7lt civilian (RHD, 4 door K)
1979 Volvo tgb 1314a (under construction to om606 diesel/722.6 trans. Dual cab/tray)


Tue Jan 02, 2018 7:55 am
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Joined: Mon Dec 18, 2017 3:18 pm
Posts: 4
Location: St. Helena, California
Post Re: Piston swap question
Ok, I finally have the parts. Everything else is removed and I'm ready to go. Since I'll be installing the cylinder onto the piston (I'm use to installing the piston into the cylinder) would the same piston ring compressor work or is there a specialized ring compressor tool I would need?

And as luck would have it as I'm doing this outside, it's suppose to rain the next few days so I have some time.

Cheers,
Joe


Sun Jan 07, 2018 7:24 pm
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Joined: Sun Sep 25, 2011 11:19 am
Posts: 622
Location: Woodside, CA
Post Re: Piston swap question
No special ring compressor, Just use plenty of lub or Vaseline.
Gonna get pretty wet starting early in the morning. Good luck
and don't hesitate to PM me if you have any assembly questions.

cheers,

ron

_________________
Puller: 710K 2.7L EFI
Follower: Sankey MK 3, 3/4 Tonne
Driver: Ron // KO0Q


Mon Jan 08, 2018 12:00 am
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