Bad luck with the BXE - depressingly common.

Excluding gross neglect or damage, VAG diesels don't suffer from bore wear. It's difficult to generalise on an unseen engine, but I would take a very non-invasive approach and simply de-glaze the bores with emery to give a helical cross hatch. Also relieve the top ridge with a scraper if you cannot get a stepped top compression ring set.

You're "over a barrel" with oil. You can't run in the engine on mineral oil as none will meet the film strength spec. I would try to find some 505.01 for running in which should be SAE 5W - 40, and after run in, change to 507.00 which is 5W - 30. Both specifications are valid for this engine if there is no DPF, but 505.01 is now hard to find. If there is a DPF, you must use 507.00.

On assembly, apply "Molykote" paste sparingly to the valve actuating cams and followers, keeping it really well away from the injector cams, whose followers have to roll - not slide.

Be meticulous in the assembly of this engine, renew fasteners as specified and measure the piston protrusion accurately so that you can select the correct head gasket. Check the injector loom for condition and connector preload before full assembly. You need quite a few special tools to do this job properly.

659.

Don't apply any American "snakeoil" to this precision engine. The production engines operate on VAG spec. 507.00 from assembly.

Edited by 659FBE on 14/05/2016 at 00:28

Hey guys,

Many thanks indeed for the detailed replies. I was away for the weekend but really appreciate the advice.

Focussed, I did a good bit of research in to the flexhone and alot of people issues with it appear to come from using it with out of spec cylinders, although I'm open to correction on that also. I measured each cylinder long/lat at top/middle/bottom with a dial bore gauge and the greatest wear from factory was +0.025mm which is well within service man. limits. I removed the carbon 'ring' on top of each bore and there is no visible ridge (or to the feel) and crosshatch is still visible on all bores. I would post a picture but its very hard to get a good picture of it for some reason.

However, if emery cloth is a good way to go with it, I would of course go with the more practiced method such as 659FBE suggests. (I know he has a lot of experience with VAG cars) Any ideas of a grit# for emery cloth and is it done by hand or some tool and dry/wet oil/water? I'd be very happy to go this route if it has merit. Only problem I see is that the hone might get the hatch easier to the 45 degree cross pattern.

Sorry I know that is alot of questions, but it really is hard to find the method most used to successfully get these walls ready for new rings. I would go the machine shop route but the closest one to me is 2 hours away and also a quote from them was just way of the scale (just to hone) so I would prefer to get this over the line on my own steam (if I can without being silly about it).

Thanks very much for that info on the oil 659FBE. I did see today that halfords have castrol 505.01 5W-40 so I'll take your advice on this and use this as the run-in oil. No DPF thankfully and point taken re snakeoils.

I haven't really gotten into the head yet as was focused on the bottom end but it was working perfectly on the previous engine and I will give it a good go through before reusing. I have been building up a lot of VAG tools over the past few years as I have two of these cars. I did purchase the rear seal installation tool during the week from Laser and that seriously hurt the wallet but too crucial a part I thought to skip and will use in future no doubt. I am replacing all gaskets/seals/stretch bolts with Elring/Reinz/OEM as I really don't want to open this back up for a while :)

Either way I'll have to find a half-way point between running the camshaft and rings in on first cranking. (Haven't received camshaft yet to see the run-in procedure) But I did order that book your suggested Cyd, so will take a read through before I begin assembly.

The help is really, really appreciated. I'll keep you posted with how matters progress but I'm sure I'll be back with more questions before then ;)

Edited by brianthnach on 16/05/2016 at 01:51

I wouldn't use a crank with .0035" runout if I had the option of one with only .0008" runout.

Hi guys,

Back again with another query. I cleaned up all the pistons in the new block and found this on piston #4;

i.imgur.com/XkiFPfK.jpg

The pitting is pretty deep and as you can see one of the pits on the right hand side has caused some of the crown to deform outwards on the side of the piston.

Now, whether I'm right or wrong, I am considering taking the no. 4 piston from the other damaged block (piston 4 is perfect in it) and putting it in place of this piston. The only difference is that this (pitted) piston is marked 79.48mm while the good piston is marked 79.45mm, even though they are both BXE blocks.

I'm assuming I should just swap pistons alone and not con-rods, which leads me to my next question.. Which wrist/gudgeon pin should I use? Both rods/pins are in perfect condition with little to no play in the small end bushings/pins.

I would weight the good piston to get it close/shave to the weight of the pitted piston if need be, or I could replace both #3 and #4 to keep them balanced. Is this workable or is the 0.001" difference in piston diameter a problem?

Thanks again for all the help. The wealth of experience here is like gold-dust

Jim

Edited by brianthnach on 23/05/2016 at 03:53

I only obtained this as a replacement block so I never saw the head although I would think it would have been similarly damaged. I think you could be right. There is much lighter pitting on piston 3 but not on this scale so I think the glow plug theory is very likely indeed.

Just don't know if I am doing more harm than good replacing this piston with another BXE piston that is in good condition?

Jim

If it was me, I'd use the better (smaller diameter) piston with it's pin. 0.002" over the diameter of the piston is nothing.

Hi,

Well took out the scales and did weighed up. Surprisingly enough the 79.45mm piston is 20 grams heavier than the 79.48 piston. The former has more material inside the base. Would I be foolish to install one piston 20g heavier than the other three?

Jim