Report from Valter about head works (VVC) to the MGCARS BBS 22 June 2005

Valter, Lisbon, vnoivofernandes at mail.telepac.pt
Hi all.

After 4 months my saga is over. My F is running again. Top down motoring is so much fun!
If you can't remember my problem, here goes a small brief: VVC cambolt unscrewed, pin sheared and inlet pulley became loose.
Result: 4 inlet valves bent, revealed by a compression test.
Now I'm certain of what caused it. During last timing belt change the official MG dealer removed the inlet pulley for access (not strictly necessary) and didn't torque the bolt properly. There wasn't also traces of loctite, fixing material. Since they screwed up I vowed to tackle the job myself.
Car is a June 1999 VVC, so after the famous cambolt recall. 59000km on the odo.

What I did is NOT an easy DIY. But it is feasible with some skills, top tools, K series engine technical manual (ABSOLUTELY necessary), nice jacks, garage space and a friend wishing to help.

I'll try and share some of my experiences with you. I'm sure I will forget many things, but I've got loads of pictures and you are always free to pose questions.

First thing to do is remove the head, following instructions on the manual. The key is: do as much as you can outside the car. That means head should be removed and installed as much complete as possible. Access to engine bay is just your worst nightmare! Several tips that will ease this job:

- You won't need to remove the inlet manifold. Only the plenum and air filter are necessary to be removed;
- You won't need to remove the fuel injectors or the fuel ramp. Just disconnect the wiring and fuel lines (in and return) on the left of the car facing forward. Everything will came off attached to the manifold and head;
- You won't need to uninstall completely the alternator. Remove the top bolts and ease the bottom one. This will allow you to rotate it forward, i.e. clockwise seeing from the RH side of the car;
- The exhaust manifold needs to be free from the underside as well as exhaust protection covers. It will not be taken off;
- I removed the crankshaft pulley, but you don't need to if you are using the same timing belt. I used it since it was only 10 months old;
- To torque the crankshaft pulley bolt (210Nm) you won't need to remove the starter motor as the manual says. From the bottom of the car you can look up and you'll find an open spot where you can clearly see the flywheel. I just inserted a suitable tool there and asked a friend to torque the bolt;
- You will need to remove the front timing belt pulleys, but not the ones on the back (VVC only). However you won't need to remove all the front black plastic timing belt covers;
- Before removing the head, make sure the crankshaft is in the position shown on the manual. There's a mark on the black pastic cover, where the TDC is also shown;
- You won't need to remove the VVC hydraulic control unit before taking off the head. It will clear the bodywork, just...;

Then I started dismantling the head to remove the valves. Head bolts were in perfect condition and so was the head gasket. I changed the the plastic locating dowels for the new stainless steel ones. I removed all valves and used paste grinding on all.
Exhaust valves had some nicks and roughness that were cleared using this method. Afterwards I did another compression test and it was everyting perfect.
Disassembling the head and puting it back together is very well explained on the manual.

If you don't have the tool (like me) to lock the combustion chamber floating liners, pay extra attention not to rotate the crankshat while head is off. This is critical!

When assembling the head I used the same bolts but renewed several gaskets (head gasket included :) ).

In my case front VVC mechanism had to be taken apart. It was damaged on the surface that matches the inlet pulley. Sadly I didn't take note of the small little "cubes" positions. So I was left all the bits lying on the table... The VVC unit internals are assembled starting outwards to inwards. That is, from the pulley side to the camshaft side.
Assembling is starightforward, you CAN'T go wrong. The problem is the tight tolerances of the "cubes". I thought they were exactly the same but they aren't. So my only option was a trial and error fit. Some will fit the slots, some won't. After all is back together, oil it and check for the free movement using your fingers. It took me 5 minutes all together.

If don't have to do this, keep VVC mechanism always bolted to camshaft carrier. To change the VVC gasket you'll need to remove these bolts. If you do this, try not to separate VVC mechanism from inlet camshaft. I achieved this supporting the VVC casting on the hand and holding the camshaft vertical. This will prevent "cubes" to fall off from mechanism.

To synchronise front and back VVC units I engaged the control shaft on the same tooth on both VVC eccentric wheels. There's also a slot on both units that when aligned will prove if both are synchronised.

I also ported the waterways on the head as per David Andrews instructions. I opted not to port the head, because from what I've read the VVC head is a much superior design already compared to the MPI, so few things still to be done.

Installing the timing belt can be easier if you completely remove the bolt that runs on the slot of the belt tensioner device. This will allow the tensioner to rotate further down and you won't need to remove the inlet pulley to install the belt. Then install bolt and connect spring to pillar bolt. When everything is bolted together and torqued, including allen bolt (that is hard to access. In fact this part of the job can be desperating!) discard spring as it can break loose and cause tremendous negative effects to your engine. Mine was of course left there before by the "clever" MG dealer's mechanic...

Since all this I drove it for 400km and car revs happily to 7200 and pulls like it used to.

Hope this is of some interest.

Valter.