Changing piston, cylinders and cylinder heads

[Hugues]

(sorry this is going to be a long post/thread)
So as explained in this thread:
http://real4x4forums.com/PinzgauerBBS/v ... 12&t=12661
I have some blow-by coming out of my oil filler tube and a leak-down test shows some significant loss on at least one cylinder.
So I decided that I will open up my engine head and see what is going on.

Now, some background info, I'm converting my Pinz 710M into an overland truck so i can take it around the world in a few years.
That means I will sooner or later have to deal with maintenance/repairs in the middle of nowhere and by myself.
So I would like to do this job myself (with the help of this forum) and with basic tools.
By basic tools, i mean tools that I can carry on a year long expedition.
So an engine lift does not qualify, hence I will attempt to change my rings leaving the engine in the Pinz.
It might not be the best, but i think it's feasible from what I see around, Pinz manual says even cylinders can be changed with engine "in-situ", although not ideal.

I have some questions below, I thank you in advance for any advice you may share, especially if you have performed such a job yourself on a Pinz.

TOOLS:
(only the absolute mandatory)

• A sleeve to insert rings, part 905.3.11.102.2 from the manual, found one here

• Do I absolutely need a ring filer if i need to adjust the ring gap ?

• Pinz manual mentions tool 905.3.31.103.2 to align the cylinders. They also say a simple ruler could work, I'll go with this

• Tool to compress spring to remove valve, Pinz manual says 905.3.11.101.0, not sure where I can find this and if I really need it, see my questions below

• Tool 905.3.31.102.0 to remove the pin from the cylinder, again, not sure i need this, see my question below

• Any other special tool ?

PARTS:

• New rings of course, but for which cylinder diameter ? puch.at have different sizes, see my question below

• 4 Valve seals, only for intake valve, part #36 here

• O'ring of push rod protecting pipes, how many ? part#28 here

• Gasket set , part #34 here, what is included in there ?

• Any other parts that I should change anyway ?

QUESTIONS:

1. Do I need to remove both carbs in order to remove all valve covers and possibly cylinders ?
2. Do I need to remove valves and springs to inspect them, can I simply do a leak test ? Otherwise i need to order the special tool to compress springs
3. Do I absolutely need to remove pistons to change my rings only ? This would require a special tool 905.3.31.102.0, don't know where to buy this if absolutely needed
4. Puch.at have different compression ring diameters, how do I know which diameter I need to order ? I need to open the head first and measure my cylinders ?, part#20, #21 and #22 here
5. Do I need a special tool to insert rings over the piston ? Seems I can do this manually.

Thanks in advance for your patience and help, if you answer a questions, ideally put its number so i can relate to it.

[rmel]

A little more awkward to do a top end job with the engine in place -- but no issue.

Some comments...not in order per se.

If you removed a head you should also remove that cylinder as the Cylinder-to-Block
seal my fail, and those leaks are a huge PITA.

The cylinders will have their size stamped on the top e.g. 92, 92.5, etc.

It's not uncommon for the Pinz cylinders to wear "egg shaped", if you intend to use
the existing cylinders W/O boring them, you need to check for wear, roundness, and
a topside ridge -- or you may find even with new rings engine was not fully restored.
They will require cross-cut honing for the rings to seat properly. And yes, you will
need to file the rings gap to the proper spacing. If you don't at hot the pistons can seize.

There are NO gaskets for the head or cylinder-to-block. Head to cylinder seals are done
by hand lapping the head to it's respective cylinder -or- paying a lot to fly cut them.
Cylinder sealing requires a high viscosity, zero gap sealant. I use Hylomar products,
but I suspect there's a recommendation locals can make.

The hardest part of this job is clean clean clean clean. All surface must be absolutely
free of any old sealant, debris etc. You SHOULD remove the 16 cylinder bolts to help
clean at the base.

You should get the old heads rebuilt with new seats, guides, and NEW Exhaust valves.
Especially if this engine has been using regular oil and not high anti-wear ZDDP oil.
That said, if it were me, I'd pull all four lifter housings and make sure the solid lifters
show no signs of pitting. IF the liffters are pitted they need to be replace and check
the Cam lobes.

If you want to minimize the effort and reduce risk, give S-TEC a call and see if they
have Cylinders fitted with rings and re-built heads. www.puch.at

This is not a hugely difficult job but it does involve a lot of "technique". Assembly
goes much better with 3 hands. The biggest "Oh crap" are leaks after assembly, and
more often than not the dang Cylinder to block seal.

[Hugues]

....

There are NO gaskets for the head or cylinder-to-block. Head to cylinder seals are done
by hand lapping the head to it's respective cylinder -or- paying a lot to fly cut them.
Cylinder sealing requires a high viscosity, zero gap sealant. I use Hylomar products,
but I suspect there's a recommendation locals can make.
...

Been researching this whole topic a lot in the pas few days.
Also asking in the german forum.
Hand lapping is something new to me, and there is not a lot of info on the net.
But i just stumbled onto this video:
https://www.youtube.com/watch?v=choa01fJ_E4
Head lapping for a VW engine, close cousin i guess.
I asked S-Tec how to mate cylinder to block, and head to cylinder, no answer yet,
and not a lot of info yet from the german forum on this specific aspect.

[Hugues]

Interesting video showing how a similar air cooled VW engine is assembled, start to finish.
Interestingly, the guy puts some kind of sealant as well between the cylinder and the head:
https://youtu.be/6Uuey2WuDnU?t=3175

Is this needed ? I'm quite surprised the Pinz repair manual does not say anything about this, unless I missed it.

[rmel]

The VW video is the correct approach. And NO, do not use sealant on the Head to Cylinder.
None needed when lapped properly.

If you have cylinders already fitted with pistons, clamp the head in a vise and rotate the cylinder
(upside down) to avoid getting debris inside the cylinder. If the cylinders are empty it's a wee
bit easier clamping the cylinders in a vise.

Incidentally there's a fair amount of procedures not documented in the manuals that are assumed
common knowledge for that era in the 60's and class -- Aircooled.

If you get advise lapping is not necessary -- it's bad advise. The only other acceptable practice
would be t o get the surfaces fly-cut, which is expensive and removes more material than necessary.

[eric82000]

Hello Hugues
On the VW reassembly video
I think he's using a "lubricant" to make the O-ring slide.
there's none on the pinz > dry assembly
Eric


"Google translate"

Bonjour Hugues
sur la video du remontage de la VW
je pense qu'il met un "lubrifiant pour que le O joint glisse
il n'y en a pas sur le pinz > montage à sec
Eric

[Hugues]

So finally i decided to change the cylinders, pistons and complete new heads,
because S-TEC had a 20% sale in february, and machine shops are very expensive here in Switzerland.

Here are the parts I received from S-Tec , i'm planning to do the work in May:

https://www.youtube.com/watch?v=vE50eKRVeyg

[Hugues]

As can be seen in my vide above, the cylinders are covered with a black coating,
I suppose this is some kind of rust protection ?
I certainly have to clean this off before mounting the piston and rings, right ?
What about the black coating on the outside of the cylinder, do i need to clean it off ? could be a pain to remove between the fins,

I cleaned off the black coating a bit inside one of the cylinder, picture below, is it correct that the lines we see on the surface is the normal cross hatch pattern to retain the oil film, right ?
I don't need to use a honing tool to do this, right ?
as shown in this video:
https://youtu.be/qQJ6LCOSvmI?list=PLA6a ... Z9wL&t=615

[rmel]

The protective coating must be removed. Some have reported that
soaking in Diesel fuel will dissolve the coating, followed by squirts of
Brake clean.

As far as honing the cylinders, if you look down the bore you should
see cross-hatching marks which would indicate they were honed at
the factory -- which should be the case but make sure. If your not
sure give S-Tec a call.

[Hugues]

Thanks Ron
Sorry I forgot to attach this picture to my previous post, looks like they are honed

IMG_20240316_061058.jpg (1.75 MiB) Viewed 271 times

[rmel]

Yup, and nicely honed at that.

Oh, curious, did the S-Tec heads come with the Valves seated and installed?

[Hugues]

Yup, and nicely honed at that.

Oh, curious, did the S-Tec heads come with the Valves seated and installed?

Installed yes. Seated I guess. What is the best way to check this? I have a leak down tester, wondering if I could use it while the head is on the bench. I saw someone pouring down petrol in the head and checking for leaks.

[rmel]

Most probably if the valves came installed they were seated.
It would be a very poor practice to just stick them in not grind
to the proper seating.

My last rebuild I acquired 4 new heads and they did not include
the Valves -- that's why I asked.

[Hugues]

Was inspecting the parts S-Tec sent me today, I see some scratches and dents on some mating surfaces, see pics below
what do you guys think ?

[Hugues]

some more pics