Cobblers 2.0

[sarran1955]

Hello,

I've kept meaning to overhaul my engine.. but what with the Summer traffic of broken vans..and 1001 other things..

My little CT engine, cobbled together 7 years ago, thrashed around Europe, ski ing.. seaside..moped festivals..etc..

lost power on the motorway coming home, and started smoking like a wounded spitfire.....

So:..

Under the hanger in the shade:



1 man (60), 1 tractor (63), eight bolts, and fifty minutes later....



and so up into the 'new' workshop




With the tinware coming off we find a blowing exhaust clamp:



and of course nearly every 6mm bolt on the front end shears..



So, flywheel off,..




No leak from the crankcase oil seal:



But there is a 'weep' from the underside of the oil cooler:



and so onto the cylinder heads.. this one seems OK, with all the valve springs at the same height, and all the adjustment screws the same:



but on the other side..



Why is one spring higher than the others...

Here's why:




The valve seat has collapsed... at least it was into the head..and not dropped into the combustion chamber..

So, in typical cobblers fashion, I'll use my big box of bits to make good...

and shiny with new laces..

Keep watching Aircooled fans..

[sarran1955]

More?

More.... are you sure....

OK, so here we go..

Now we can look at the crankcase studs..

These are helicoiled, and so have a tendency to wind out..clamp in place and remove the nut.. DO NOT..unscrew the stud.



I have a 'nut welded on stick' tool to check for stud tightness (make what you can of that Bobster )



Then clean every thread.. big studs..



and little studs..



and while we are at it..go over the cylinder heads..



If you are using new T1 / 2 chinese heads you will need to recover this little deflector :



I will come back to the heads later..for now we will start to overhaul the exhaust and heating system..

The heating system on a CT is probably the best set up of all the aircooleds.. with a dedicated turbine and 2 sets of exchangers..

But to work at it's best, the whole thing must be air tight..

so for example I'll use NOS for this one:



The front exchangers are the most exposed, but these have held up well,despite all those broken studs..



HERESY WARNING..

The druids say you can only use CT heat exchangers (at 245€ a pop), when with a discerning eyeball



you will see that a CT only heat exchanger is a T1/2 exchanger (at 121€) with a pipe welded on ..

Which said pipe has several holes where the clamp goes..



2 ways of doing this.. either spend 1/2 the day blowing holes in the rust with welding torch.. creating something grotesque..

and then having to grind it all off to get the exhaust to fit...

or:

Secure heat exchanger:



Then cut 35 mm of same diameter tube:



Which you then slice away 2x the wall thickness:



which is then soft malleted into place..with the gap in the insert lined up with the biggest rust hole..



Then welded and sanded to finish... the old exhaust clamp ring serves as a control on the pipe diameter to check for an easy fit..

[sarran1955]

Hello,

Well,

When I removed the valve spring on the 'dropped seat' valve..This is what we see:




The valve seat has dislodged and been driven into the head, the seat winkled out with no difficulty..

So I've been looking at a few cylinder heads

T2 (what I call deep head) and here CT (shallow head):



with the corresponding difference in number of cooling fins:
T2:



CT:




and going into my CT stock:




I've chosen a pair of late CT heads (9 mm valve stem 32 mm inlet), as opposed to early (8mm 30 mm), which will need studs and valve guides.
so off come the valves:



For the valve guides I use this 70's US kit:




Simple as shooting fish in a barrel..

Step 1) tap 3/8 thread into valve guide:



Step 2) screw in threaded bar, drop on collar , washer and nut..



Step 3) wind out valve guide..




as easy as:



I had a box of bits arrive..




62 € so far.... with the valve guides that will bring the bill up to nearly 100€...

[sarran1955]

Hello,

Well, the valve guides arrived and so duly fitted..

I apologise for the lack of photos here..but I was trying out my new video glasses.. got carried away.. and had the job nearly done before I thought of photos..

So.. Step 1) clean the valve guide hole in the cylinder head..I use an old machine ream to pick up any swarf from the removal of the old guide..

Step 2) align the valve guides by hand

Step 3) Fit the insert, and a 'wobble' socket, then I use an air chisel to drive the guide in:







The guides then have to be reamed..

Reaming is needed because the guide will have shrunk slightly when it has been driven into the cylinder head..

Here is an adjustable reamer.. you start under size and wind the collars 2 turns max for each pass.. use cutting oil..



Note the grease round the top of the guide.. this is to catch swarf.. BE CAREFUL.. brass finings are VERY SHARP and will pass into your skin
soooo easily....You have been warned..

You will know when you have it right, when the oiled valve just drops in with no resistance..



So much for the new exhaust valves..

The inlet valves are cleaned up:

#

and so on to the valve grinding..

Here is the new exhaust valve lapped into its seat:



Use a plug of oiled paper (4x2 style). pushed through the bore to clean before inserting the valve..




Now all the valves are prepared.. I now polish the mating flange in the combustion chamber using a spare cylinder barrel:



Lightly ground in..:



I will not be using decompression rings..

and then last thing for tonight..

Use a peening tool .. like a fat flat punch.. to close any cracks around the spark plug hole..



................. Right that's me back up to date...more bits have arrived.. so more pics (hopefully) to come..



Cordialement,

[Titus A Duxass]

Nice to see the photos are working again.

Hello,
Use a plug of oiled paper (4x2 style). pushed through the bore to clean before inserting the valve..

That made me laugh, I wonder how many questions it will raise?

[itchyfeet]

Nice thread, great tips way above and beyond any manual as always

Why don't you use compression rings?

going to try that grinding in technique on the WBX

[sarran1955]

Hello,

Another cosy weekend in the workshop..

Outside it is maize harvesting time..

Used for silage.. very noisy machine..

disturbed my croissant..



back to cylinder head preparation..

Q why do I lap the cylinder barrel to the head..
A these heads are old, and upon close inspection you can see where the machining lines are worn away.. so to get good compression..



Once the grinding paste is in place I then use a bit of cutting oil to make the whole thing more liquid..



I am leaving the de compression rings out because although this head will run on 88 RON petrol, I will be using 98 RON or maybe E85 (in Germany).. this gives me greater flexibility when tuning..

Once you have removed every trace of grinding compound then clean out the guides AGAIN with (4x2) paper plug and oil.. do it until the paper comes out clean:



I then grease the valve with Molyslip. or CV joint grease, just to help with running in..



Then oil and make flexible the valve stem oil seal..



When fitted it keeps the valve in place for rebuild, and will settle at the end of the valve stroke to reduce oil loss and 'smoky startups'



Now we can fit the valves, springs, keepers and collets

I use grease and a magnetic pick up..(not too strong)..

Here you can see the job laid out..



The trick is to use the grease to stick the collets in place during assembly:



Once you have released the valve spring compressor.. tap the spring smartly to ensure the collets are seated correctly..



So I have now prepared 3 CT heads, 2 for the motor, 1 as a spare for my very long voyage..

So final cleandown.. and we are ready to start building up the motor..

Cordialement..

[mrhutch]

keep updates coming..
you take a spare head with you as part of your "parts that go in the van" package?
respect.

[itchyfeet]

Use a peening tool .. like a fat flat punch.. to close any cracks around the spark plug hole..

Interesting idea, I realise peening a crack slows it down, I suppose this can be done with WBX heads too , the cracks between valve seats

[sarran1955]

Use a peening tool .. like a fat flat punch.. to close any cracks around the spark plug hole..

Interesting idea, I realise peening a crack slows it down, I suppose this can be done with WBX heads too , the cracks between valve seats

No...No...

The spark plug cracks are very shallow and only go a bit into the head..

Whereas the crack between the valve seats..wbx and any 1600 twin port head.. is usually much deeper...eventually between the 2 ports..

You can 'peen'.. or use a 'staking 'tool.. like a needle punch with a step on the end.. at the edge of the valve seat..
before valve grinding.. to keep the valve seat in place

But eventually the crack will grow and you get that 'chip chip chip' misfire on tickover..

The only long term solution is to strip the head and valve seats..grind open the crack and then TIG weld to repair..you then need to re machine the valve seats and fit the inserts... very expensive

As I've said before..on the videos..Chinese replacement heads are not bad.. sand cast.. low stress..

they need valve lapping.. and the over-long exhaust studs reducing..

But good for the budget..

You can get a new pair of heads for less than a small Audi reconditioned head....


I have to confess.....

No vw today..

as we are preparing this for the offroad trophy:





Full Safari kit 10 inch lift on 22 inch rims..

BMW motor 280 BHP...

Just because we can..

Cordialement,

[mrhutch]

is the P38 yours chap?

[sarran1955]

Hello,

is the P38 yours chap?

You wouldn't believe how many of the beasts we've got..

From a series 2 pickup.. with home made body..

2 defenders for daily and farm use ...

Through various Ranges with the rear cut off at the back axle..

Better verticality .. with (my favourite) a fully blown 3.5 Buick block..

To posh Parisian stuff.. bought for a song when the supermarket car park warriors blew the auto gearbox..

Terrible for rust... but such fun..

We also participate 2 teams in the 24 hr moped marathon..

This year we came third (podium) out of 54 machines..

It's not all fun and games you know...

Any way..

Some progress..

General painting..

The hammerite finish has held up well..

For the hot spots I use woodstove paint..




The engine silentblocs were past their best..





Hopefully this and the clutch change will remove the judder in reverse..

New (branded ) engine support silentblocs..



Did need a trim to fit..



....and just when we thought all was moving along smoothly....



Despite the information coming from a reputable source.. the O ring ordered for the crankshaft pulley mount is way too small..

So then I go to order on E bay..and an advert blocks the page..remove cookies.. change pass word.. access from Google not Firefox..

all to no avail..ok so we go to Amazon UK.. Ha Ha....does not deliver to France.. ok Amazon.fr..Ha Ha this is an add on after 20€ of purchases

OMG...ring work..get the web adresse of our suppliers..Web transaction.. 2 off, by post 48 hrs 9€ inc TVA...

So.. on to the oil cooler..

cleaned and soak tested with thinners.. no leaks..



This time fit the correct oil seals..green tapered on RHS..



and seal round the outside with adhesive foam.

Flywheel and pressure plate polished then abraded..I use a high speed 50 mm air sander..

New engine studs made up..



Crankcase threads restored..



Studs glued in..

Flywheel on..



Clutch on..



That's it up to date..

Beautiful weather here... .. cows and cowlets in the field... the mushroom season will start soon..

136 varieties in the Correze

Here are my favourites..

We know them as 'Girolles'.. you perhaps as Golden chanterelles..(so says the book)..





You're welcome to come along..bring stout shoes, a cane, a pochette, a mushroom knife, and mushroom brush..( I kid you not)

Bon Appetit..

Cordialement,

[sarran1955]

Hello,

Well, while I'm waiting for the correct O rings..

We can fit the cylinder heads...



This CT engine is using standard T2 Mahle forged barrels and pistons with paper gaskets to the crankcase.

This gives me a nice deck height..(distance between piston top and barrel edge) and a deep combustion chamber
when using CT heads..

So now we prepare the pushrod tubes:



Unique to VW (AFAIK) in having beetle pushrod tubes with small and large ends..

Careful when ordering..

If you are re using stainless tubes they will have a 'set' to get the best fit..



Mount the new seals carefully using silicone grease..



As the engine ran fine before.. I am limiting playing with the hydraulic cam followers to looking to see that all the springs look nicely in place..



Now we drop the head gently onto the studs..not enough for them to stick out.. and put the pushrod tubes loosely in place held by the pushrods..





Then slip on 2 turns 1 nut (without washer) to hold the head.. and guide the pushrod tubes into place..



Make sure the seals are seated well all round..



Tap the cylinder head gently down and check that all is square..



Now put 4 nuts and washers on the outsides..



Make sure that the oils seals are well centered..



Do the initial torquing to 10 nm



Then 20 then 28..

DO EACH STEP 3 TIMES TORQUE DIAGONALLY.



Now we can start to offer up the rockers..fit the little oil seals on the studs and make sure that the base of the pushrod is correctly seated in the centre of the cam follower..



This is right..the pushrod is central..



This is wrong.. the pushrod is to the side..



Once the pushrods are ok, and all the adjustment screws are at the same height, with the locking nuts backed off 2 turns..



Torque to 28 Nms.


and then you do the same thing all over again on the other side...

Cordialement,

[sarran1955]

Hello,

As you may recollect..

I was waiting for the correct oil seal 'O ring' to arrive before I could fit the turbine base:



The seal fits into a flange, but I cleaned and greased to hold the ring in place during fitting..

the keyway is a bit imposing, and if the seal fell off during fitting it would be 'cut' like the old one.. and there is no way to
see if it has gone wrong..



apart from the subsequent oil leak...

As the turbine base has to be driven on, I decided to use the best fitting dowel and drive I had..

From my 3/4" drive set.. a perfect fit..



4 clouts with the soft mallet and the thing is seated:



Then torqued to about 150 ft lbs..24 mm socket

Haynes says the same torque as for the fly wheel.. but I will recheck later..


Now this is done I can remove the flywheel clamp and start assembling the tinware

Bottom tins on first..(if the thread in the case no longer 'holds' drill at 7mm and pass a longer 6mm socket cap and nylock) :



Then the top cylinder tin ware and try the front plate for fit..





This may have to come off again when I fit the inlet manifolds, because the screws for the heat riser feet are very fiddly

Front exhaust manifolds on..



Supper time..

Cordialement,

[sarran1955]

Hello,

Well it has been a bit 'two steps forward and then one back'....

Firstly the RHS heat exchanger tube appears too short..



so 25 mm of pipe is recovered..



and butt welded on..

Now I clean out the heat riser tube on the inlet manifold..



So.. 2 steps forward.. I offer up the engine cross bar...



but the holes do not line up..



In fact the repro part is way off..



This would not be fun to discover if you were trying to do this job with the engine in place..

Rather than die grind the holes, I decided to re use the old parts.. the new parts will get used later..

Now I recover the threads on the silencer..



Using a 35 mm m6 bolt, and a pair of tweezers to get the thing started..I manage to insert the bolt facing out..

The threads on the heat riser bit are worn..and it was the bolt coming out that created all the noise coming home..



Does not protrude into the exhaust stream..



I use silicone grease to build up the inlet manifolds..



and plenty of expanding exhaust assembly paste ready for the heat risers..



This is where it is going to be needed..



Once I am happy with my 'dry' fit of the inlets and exhausts.. they come off in 4 bits..







Ready for final assembly tomorrow...

Cordialement,