Changing piston, cylinders and cylinder heads

[Hugues]

How to remove the diffuser ?
I removed the central bolt, sprayed a bit of wd40, but it's not budging, don't want to force it

diffusder.jpg (770.19 KiB) Viewed 9776 times

[Hugues]

and these seems to be rivets that hold the gasket in place
but the hole in the new gasket is much smaller than the rivet's head.
Do i need to pop the rivet out with a blade first then put it back ?

rivets for gasket.jpg (815.43 KiB) Viewed 9773 times

[Hugues]

Got the engine out, built a stand for it.
Tomorrow I will be removing the cylinder heads, cylinders and pistons.
I'm not re-using them. Only things i will re-use are:
-push rods tubes
-oil return tubes
-bolts

Anything I should pay special attention too when i remove the parts ?

IMG_20240815_184019.jpg (936.91 KiB) Viewed 9638 times

[Hugues]

Ah ! I probably found the reason why my cylinder #3 was giving a higher leak reading on the tester:
https://pinzi-forum.de/viewtopic.php?p=116133#p116133

The first compression ring was broken in 2
Cylinder #3 does not look very different from #1 and #2

IMG_20240816_161122.jpg (809.08 KiB) Viewed 9606 times

[Hugues]

Well, all heads, cylinders and pistons are out.
Apart from the broken compression ring, I didn't see any obvious damage, but I would need to measure the parts.

Now how do I remove these long bolts? They are quite stiff, I don't want to break them into the crankcase.
But I think it's better to remove them so I can better clean the surface that received the cylinder?

I think I will use 2 nuts held together? I sprayed WD40 at their base, but....
Should I apply heat around the bolt on the crankcase if necessary?
Can I use an impact drill? Or just manually?

IMG_20240817_164332.jpg (43.03 KiB) Viewed 9580 times

[rmel]

The the long cylinder bolts should be removed.
Double nuts work sometimes. I have used Visegrips
on the shaft close to the base -- use two to increase
surface ares to minimize marring. A plumbers
wrench can also be used.

When you put them back make sure you put the FLAT
surfaced end into the block -- the ends are different.

[Hugues]

Thanks Ron,
I'm starting to think about how I'm going to reassemble the pistons, cylinders and heads. The Pinz manual doesn't give too many details.

There must be a specific order in which you have to do it, I think I'm doing it in this order, is that the right ?

I'm going to use Loctite MR-5923 as a sealant between the cylinder and the crankcase. It doesn't dry immediately, but I can't let it dry for too long either. The cylinder and head are of course metal to metal connections.

1.Piston #3 on connecting rod with both clips
2.Piston #4 on connecting rod with both clips
3.Piston #2 on connecting rod with both clips
4.Piston #1 on connecting rod with both clips
5.Slide in Cylinder #4 on piston
6.Slide in Cylinder #3 on piston
7.Slide in Cylinder #2 on piston
8.Slide in Cylinder #1 on piston
9.Apply sealant on cylinder #4 base
10.Install cylinder head #4 and slightly tighten 4 nuts
11.Apply sealant on cylinder #3 base
12.Install cylinder head #3 and slightly tighten 4 nuts
13.Apply sealant on cylinder #2 base
14.Install cylinder head #2 and slightly tighten 4 nuts
15.Apply sealant on cylinder #1 base
16.Install cylinder head #1 and slightly tighten 4 nuts
17.Install both air intake
18.Tighten cylinder heads to specifications

[rmel]

I have no experience with Henkel's Loctite #5923.
Permatex makes a very similar sealant Aviation #3, which I
have used but not with the best of results.

I have found it to have insufficient viscosity. Loctite #5923 also
has a low viscosity, ~10K mPa.s.

If you use it, I'd suggest applying on both mating surfaces, allow
a little time for the sealant to set up than apply a wee bit more
before assembly. If your getting advise on use of this product just
make sure they actually use it and what tricks they use for best
results.

As far as assembly, #4 first, #1 last. Piston cylinder head then next
position -- DO NOT TIGHTEN just snug. Intake manifold next to
align #3/#4 then #1/#2. CHECK the planarity of the exhasut ports
with a machinists straight edge or similar good flat reference. It
does not need to be perfect but close enough so that the exhaust
seals. If it's not true enough something is not seating properly. If
good add your exhaust again don't tighten -- snug. Get your heads
torqued, next intake, then exhaust. Wait an hour or so and re-torque
your heads.

[Hugues]

ok clear,
I will assemble everything first without sealant to see how parts fit together, also the exhaust,
as for the sealant, the shop who checked my new parts is working with Loctite and i happened to have bought it recently for another job,
but he did not know about Hylomar,
i checked their High Viscosity version, looks great.
Where did you order it from ? I just can't find it online, only a shop in Texas, but the picture they show is not the HV one,
I called Hylomar, too early ion the UK, I sent them an e-mail,

[rmel]

Just for the record, my experiences with sealants are not necessarily
the best to use -- it's just what I have dialed in from my own experience.

That said, I just find that the shellac type of sealants from Permatex is
just not viscus enough straight out of the bottle.

That's why I started to experiment with other brands e.g. Hylomar.
And at that I tried a couple of their products to finally sort out which
is best for certain types of sealing.

The Hylomar "Advanced Formula" series does not require wetting
and curing before assembly as does Hylomar "Blue". I have moved
to AFHV for higher viscosity yet it is still a Zero gap sealant, which
means under torque there is very little material on metal to metal
surfaces with material only in the gaps.

So that's what I use and your results will all depend upon how well
you do the assembly -- that is -- if it leaks don't blame me !!

As one other possibility for a 2'nd opinion, give S-tec a call or email,
and ask them for a recommendation. What do they use?

Incidentally, I source from the UK at silmid.com they may also have
a distributor in the EU. https://www.silmid.com

[Hugues]

Don't worry, I never blame people. You're the only one I know who has first hand experience with this job on Pinzgauer.
I asked Werner at S-Tec a while back, but he never wanted to answer this question somehow.
I spoke to Hylomar, indeed the HV version is better as my surfaces stand vertically.
I called Silmid earlier, they don't have it on stock before 30 days.
Hylomar gave me another address in Germany but they don't have the HV version.
But I found it at luboseal.com in Texas, they should ship it soon.
Thanks again,

[rmel]

Yes, the HV formulation is viscus enough that it does not run
even when the engine is hot. Thanks for the pointer to Luboseal.
That's a new source and a wee bit closer for me

[Hugues]

So just test fitting the parts today, lubricated but no sealant.
I'm a little stuck when it comes to push the head completely against the cylinder,
as shown in this video:
any guidance appreciated, i don't want to force anything and break stuff,


https://www.youtube.com/watch?v=lyU3xjRpWiE

[rmel]

Spring force wants to keep the head/cylinder apart.

But there also could be burs on the head side preventing seating.
These are new heads I believe so they were machined and never
mated to a head -- unless hand lapping was performed which
would help to remove any burs or fit fit. Even new out of the
box lapping is necessary for a tight fit and again to open up the
mating surfaces.

[Hugues]

Thanks Ron,
I managed to install pistons, cylinder and heads for #4, #3 and #2 today, without sealant, indeed it was the springs holding up.
I did lap the cylinder on a flat surface, and the cylinder with the head. I posted about this in the VW forum, while I could not post to the forum here some weeks ago for some technical issue.
https://www.thesamba.com/vw/forum/viewt ... 9#10259899

Tomorrow I will install #1 and test for the air intakes and exhaust.