It's been too long since my last update, so here goes:
I bought a new piston which comes fitted with a set of new rings. I took it and the old one into work to get the gudgeon pin out and conrod off the old one then fit to the new one over a lunchtime. A funny thing happened - a great big lump of the side wall of the old piston fell off on the bench! The break-line is very durty with carbon so it had been running like this. It more fully explains the lack of compression and leak-down test failure. Going back to the photo in post # 77 you can actually see the crack in the second piston from the left, on its right hand side between the 2 compression rings. The old conrod fitted fine with assembly lube into the new piston.
The bores measured fine after honing, re-fitting the pistons was easy following a Youtube video or 2 and using a Laser ring compressor and more Lucas assembly lube. I used a set of new big end cap screws and torqued them up, even more assembly lube on the crank and big-end shells.
A note about the shells: Be really careful if this is your first stripdown of an engine: Bearing shells are very soft and easily damaged. Always bag them individually and take other precautions to stop them bashing into other parts like the big-end shells. If any are scored or worn (use Plastigauge to check) then get new shells. Mine were OK. Be sure to put them back in the same position and the same way around as they were fitted before. On this engine it is possible to fit the shells either way around. If you forget then the little audi oooo symbol and part number on the back may well have left a witness mark inside the conrod or big end shell housing and this can let you know how to orient it provided you weren't over-enthusiasitic with cleaning
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I cleaned the sump with lots of paraffin both inside and out, blew it dry and grit free with my air-duster at 90psi and repeated. Then I washed it twice with soap and water and repeated the air treatment to be sure none of the grit from the outside was left inside, (not that I had been slapdash about transferring it). Then I cleaned up the mating flange at the base of the crankcase being scrupulous about wiping from inside to outside, this despite having used my pressure washer and detergent on the engine before starting (there was still a lot of filth around).
I pump the sump back on with a new set of bolts, correct grey silicone sealant (Reinzozil or something) in a 2mm bead and torqued the new bolts to 13Nm. There was a disaster with one of the 2 bolts by the flywheel when the 5mm hex ball-end bit caught on something, slipped out and fell behind they flywheel inside the bell housing. It is at times like those I tend to give up for the evening, come in from the cold and swear at myself for taking short cuts.
After some head scratching I could see only 2 ways out:
- Release the engine-bell housing bolts and move the engine block away just enough to retrieve the hex-bit then do everything back up. A big risk in doing this would be accidentally bending the input shaft on the gearbox as the engine block would be supported only by a trolley jack under the sump...
- Treat getting the cylinder head and camshaft housing back on as a priority and the engine essentially dirt-tight, put the timing belt and right hand engine mounting back on, then take the gearbox out, retrieve the hex bit and fit a new clutch at the same time.
I chose (2). Perhaps now you'll understand why it's been a while since my last update.
I bought a new LuK clutch kit from GSF. I think it was £92 delivered the next day to work and it came with a new release bearing, sleeve and release arm. Of course, this could still be a waste of cash but I'm gaining a little confidence now...perhaps too much but we'll see.
Last week I fitted the clutch over 3 or 4 evenings. Of course I followed the workshop manual method largely but to gain decent spannering access I moved the water spout for the bonnet trumpet and thermostat housing to the front after releasing the electrical connections and all the tubes at the back and the ones that were too short to allow enough movement. This is a good first step and allows a lot of time to be saved when remving the gearbox control cables, clutch slave cylinder, starter motor etc. I split the left-hand lower ball joint taper using the Ed China method with a hammer after my scissor-tool failed to get in the gap between the top of the screw thread and the outer cv joint metal cup. It is the first time this method has worked for me. (After that I had planned to take my angle grinder to the scissor tool...). This car has the cast/forged wishbones so the ball-joint can't be unbolted separately as with the rust-prone pressed steel wishbones fitted to my TDI90 and all later cars.
The inside the clutch housing was surprisingly filthy and had signs of corrosion from water / salt ingress too. The old (Valeo) clutch had its friction material worn down a good deal but the whole thing absolutely stank of burnt clutch and there was loads of dust from the friction plate inside the flywheel too. I took over an hour to clean up everything inside the bell housing and fit new parts, lubricating the pivot points on the release arm and bearing with tiny dabs of moly grease, the same on the sleeve. I fitted the new clutch housing /pressure plate really carefully onto the flywheel. I aligned the friction plate with the centre of the flywheel by eye. Various moe reliable methods are no doubt available but this method has always worked for me,. This you can do from a few angles and its worth spending 5 minutes with a good head-torch but you may get stinky moly grease from the tied-up end of the left driveshaft in your hair if you're not careful. Moly grease always smells like a gas leak in our house.
I was very anal about doing only half a turn on each of the 6 screws in a diagonal rotating pattern so as not to distort the diaphragm spring too much and result in clutch judder. These screws are a 9mm 12 point external sline and an ordinary 12-point socket works a treat. I torqued them to spec. You don't really need to lock the flywheel to do this if you hold the torque wrench so it is tangential to the flywheel and moves inside the circle so your hand is pushing to the centre of the crank.
So, currently the gearbox is back on the car and torqued up. The engine and gearbox is sat on two trolley jacks with the right hand wheel on a ramp and the left of the car on an axle stand at the jacking point. I need to put the new death pipe back on and secure the thermostat housing in place so I can put the inlet manifold lower and upper parts on whilst the engine is still dropped down a little. I was wondering about that and feeling a bit dodgy in the heat yesterday so thought I'd tackle something easier. I changed the oil filter and pulled out the oil filler and dipstick tubes and front oil filler arrangement. I saw that the dipstick tube had broken at the bottom. Initially I thought that a trip to the dealer was going to be in order but then realised if I was careful with the length, there is a way to replace the plastic dipstick tube with rubber heater pipe. This I did. There is a possibility that it will rot but this is proper SAE heater pipe and should be OK in contact with oil. It will only get oil on it when taking the dipstick out of course...
Everything was black with gritty oily sludge so I set to and cleaned it all up with paraffin and multiple air blasting then washing, swapping from outside to inside once the outside was like new. I will only refit it once all the engine and gearbox mountings are back in. For now there is a bit of gorilla tape over the holes in the sump. I will get a pair of the green o-rings from Audi.
So, feeling OK by this point, I thought I;d get back to the main task...except I've lost that f***ing plastic C-clip that holds the death pipe to the thermostat housing... which is where I left it last night...
I've made this job excessively complicated by deciding to change the clutch in the middle of it. I realise that. But I still think it was the right decision. I am going to remove all the remaining hoses from the thermostat housing before bolting it back onto the end of the cylinder head so that I have some compromised access for spannering to reattach the clutch slave, gearbox cable brackets and other gubbins after refitting the inlet manifolds then the gearbox upper mounting.
Whilst searching through some parts I (at last) found the connector for my CAYC starter on the TDI90 with MYP gearbox. This is something I had been meaning to send photos of to
@t42 Tom. For the moment we are both running round in our TDIs with bodged crimps on the solenoid wire...
I still have a list of jobs to do that runs to 2 sides of A4 on project FSI and that's before I turn the key.... starting to have fun again and lovely to have encouragement from the family "why don't you you give up on those bangers, why can;t we get a Tesla? etc."
Some photos next time, I promise.
All the best,
Matt