WBX Cyliner heads reseal

[itchyfeet]

I have just acquired this 1.9 DG engine which has a blown compression seal, symptoms are a blown hose and now constant bubbles into the cooling system.

Rather than posting loads of pictures I have a slideshow on Photobucket ( now moved to flickr) and I will write some points here that may not be clear from pictures ( next few posts reserved for that)


http://s1145.photobucket.com/user/paul_ ... ead%20seal" onclick="window.open(this.href);return false;

As I finish it over the next week or so I will update the slideshow and this thread.

I hope these pics will give some people the confidence to tackle repairs, it would be nice to save these engines for the next generation, once they are removed and melted down to make beer cans we can never bring them back, there are no more new engines.

[itchyfeet]

Time is the biggest cost in a garage.

1 hour to clean it
3 hours to get heads off, they were stuck on and two barrels came off with one head and had to be separated
2 hours to remove pistons, gudgeons were stuck in tight.
2 hours to clean up pistons and barrels and water jacket.
2 hours to fit new rings and hone barrels because rings were shot and barrels a bit marked from the seal failure letting water in.
1 hour to drill out a snapped stud by alternator bracket and fit helicoil
1 hour to remove measure and set end float
1 hour to clean up lower barrel seal surfaces on crankcase , remove oil pump cover, check endfloat and replace.
1 hour to clean heads externally and remove valves.
2 hours to grind valves on both heads and clean compression seal, water jacket seal and green oring surfaces
2 hours to refit valves, tap out all threads in heads, tap out head nuts and clean head studs, fit a few helicoils, clean and stretch push rod tubes
2 hours to refit heads

Total 20 Hours


Costs so Far

Gasket set £100
Piston rings x 4 sets £50
Set of end float shims £20

[itchyfeet]

I have found heating the studs with a blowtorch for a about a minute is very helpful is ensuring the release but I now shield the valve springs as I don't want to heat them too much incase it changes their properties ( shield now shown in pics)

Broken head studs are always a worry, the studs corrode and getthin, in this case they may well snap but I have found many studs I have snapped look fine, they snapped because the nuts were rusted to the studs and I didn't heat them, I just forced them.

If, when you start turning you feel spring tension then stop and another 1 minute of heat.
Even once they have moved they can seize again so after the initial release, for which which I use a breaker bar, I then use a shorter socket handle to remove them, if heat does not work you can do the nut back up to help release rust, I personally would not do this on the initial release.

When you heat the nuts under the rover cover you will get smoke form burning oil so needs a ventilated area, don't heat the valve springs keep the flame away, you risk changing their properties if you heat them.

Once the nuts were off these heads were stuck on, the steel studs in close proximity to the aluminium head creates bimetallic corrosion, I managed to move the heads a bit with a wooden block and a lump hammer, just enough to pull the water jacket seal out and get better purchase.
I then pushed the heads back on and off again repeatedly until the came off, each time removing the corrosion around the studs.

On one side the barrels were stuck to the heads, I tried some plus gas an a bit of gentle prising on the barrel lugs but no luck, just have to pull them off pistons. One of the rings broke doing this.

Using heat on the barrels didn't shift them either so moved the assembly into the vice, I shifted the corrosion between barrels then using a floor board removing tool I pushed the barrels apart slightly, then with a hammer pushed it back, repeat this and they separate. Second barrel was removed from head but tapping side to side.

[itchyfeet]

Gudgeon pins were tight, the pins can hit the circilps and create a burr in the piston.
VW recognised this problem and made a reamer tool but I can't find one for sale.

I purchase a spiral hand reamer for £25 and while the end is tapered ( so smaller) it can still be used with the pin in place to remove the burr by placing pressure in a circular motion.

Once the pins are out the piston can be reamed, don't go too far you just want the pin firm not tight and not too loose. Need to be clear and remove swarf

Pulling the gudgeon pin is done with a home made tool, It's an M8 Rawlbolt with 18 inches of studding, 60mm of M8 washers, a nut to clamp the rawl bolt, a large socket to use as a slide hammer if needed, a large washer to hold the socket and two nuts tightened together to allow you to hold the studding while you tighten the rawl bolt.

Use wooden packers while slide hammering to prevent damage to con rods.



Because one ring was broken I checked some others and discovered they were nearly on the wear limits, I could have just fitted new rings to one piston but seems better to do the lot barrels need honing with new rings so they bed in.

[itchyfeet]

Flywheel oil seal was leaking alot, when I removed it I found the shim retainer that should be fitted to a late engine was missing, I have a suspicion this is really an oil thrower as it doesn't retain shims and the flywheel wasn't badly scored, not much explanation I can see for the leak other than this shim missing.

Also the larger diameter 0.4mm shim that should be on a late engine was missing
Endfloat was quite alot over spec and so shims were worn and damaged, needed all new shims.

Replaced seals from the Elring kit.

[itchyfeet]

Fitting pistons and barrels best done with engine on flywheel.
Rotate each circlip with just one hole to be sure it's seated, if not it can ping out later.

[DoubleOSeven]

Good Viewing. I think the pictures say it all.


Sent from my iPhone using Tapatalk

[itchyfeet]

Thanks Martin

Cleaned up heads next, could not get the compression seals out of the head that had the stuck barrels, just too corroded in so had to take the dreaded screwdriver to it and left some small scratches

This gave me a chance to test the grind with an old barrel technique suggested by Andrew of Campershack but Sarran uses it too so must be an Aircooled thing.

It worked well and removed the scratches, I did both sides equally so any material removed was matched.

Then I use 600 wet and dry with paraffin to clean up the green seal mating surface and take to harshness off the ground surface.

Water jacket seal was cleaned up too but I used 400 grit for this on one side because it was very corroded.

I wanted to check valve guide play because one head felt quite bad, I made a little bracket to keep the valves level with guides as stated in Bentley, then used a piece of square tube bolted on as a guide and checked with a caliper, 0.8mm on one head approx and 0.5mm on the other, well with in 1.2mm tolerance.

Valves are ground with a battery drill for speed but you don't want to be rotating much, pull on the drill to give lots of force rather than too many turns. Make sure valve stems and guides are clean and oiled.

[mm289]

Good work Itchy and well done for posting it all up

Cheers,

MM

[itchyfeet]

Thanks.

Fitted heads today, cleaned all seal surfaces with meths first.

Getting the push rod tubes in is tricky as you need three hands, a couple of pieces of wire makes it easy.

First I squashed push rod tubes by tightening the bolts gently

I torqued heads to 25Nm, then 40Nm then 50Nm

I prefer to turn 1/6 of a turn at a time when I'm doing the higher torque.


I have not refilled tappets, they will likely just drain down again, three are a bit spongy, these are likely to be the three under compression when the engine was stopped last time.

I'm not fitting push rods until the engine is ready to be fitted because more will drain down.

Finished

slideshow updated
http://s1145.photobucket.com/user/paul_ ... ead%20seal" onclick="window.open(this.href);return false;