Wagwan ma pistons? A technical query.

[Des]

Never rebuild your own engine. I tore a German watercooled flat four lump asunder a while ago, finally got around to scribbling a list of parts, getting expensive, cam just starting to pick up so that and a set of followers, all the bearings, barrels and pistons looked good but seemed to have some funny pitting just above the first ring.

 

 

Looking closely, those are little raised dimples where tiny bits of metal have become embedded, just on the thrust side and round the other side, never seen the like before, and otherwise all is in quite good order, crosshatching still visable and only minor skirt scuffing, anyone know what might have caused this? I'm guessing it was a damned good thrashing for the bedding in period as seems to be the fashion these days. Partswise, no new cams left anywhere, so a regrind will come from America, barrels and pistons have all been used up, all that's available seem to be some spurious big bore things that give an eyebrow raising 59 cc extra, but they are low compression so about a dozen HP less, not really a big deal, lifters and bearings all readily available, I suppose I should rebuild it properly while it's still possible.

 

[Squire_Dawson]

What's the age, mileage and model?

 

This damage is pretty weird. It could well be someone not giving a shit about the running-in period.

[PhilA]

Adolescent engine acne.

 

Rub in a little cream, when the engine note changes to being noticeably deeper it should be ok

 

Phil

 

 

 

 

...sorry

[michael1703]

I'd say detonation from incorrect timing but it would be more noticeable on the crown, is the pimply bit on the thrust side?

[Volksy]

2.1 Wasserboxer from a T25 bus?

[Asimo]

Is there a coating on these pistons that is seperating?

 

Assuming that this is the VW Bus engine, useful info here: http://www.gowesty.com/library.php

 

It is a bit of a bodge this engine, definately just a modified air cooled VW engine. A colleague has recently given up on his because of engine troubles. The last straw was failiure of the cylinder head bolts. They are in exactly the same place as they are on the air cooled engines. This puts the bolts in the coolant and they corrode to the point where they fail.

[red5]

Arabella engine?  

[DSdriver]

Is it too late to suggest that you give Piper Cams a call, why go all the way to 'merika when we have good people here?

[Des]

2.1 Wasserboxer from a T25 bus?

Correct, designed by Nazis and later had a water jacket added, I don't get why they did that, the diesels got the engine from the Golf with a turbo hanging off it and then rather than use the petrol Golf engine the Huns set about converting an old relic of their unsavory past to liquid. I've not ordered anything just yet so will look into a regrind of the old cam. It's an engine I picked up to replace a 1.9 that's getting a bit tappety and I wouldn't mind a shade more oomph for joining motorways. They're made of monkey metal, so if the antifreeze gets weak or is never changed things can get a bit ferric.

[fordperv]

Is it too late to suggest that you give Piper Cams a call, why go all the way to 'merika when we have good people here?

Newman cams are also good folks for one off cams

[jonny69]

No need to go to Americaland, Newman cams will regrind your old one, as will Piper or Kent. I'll drop back in at lunchtime when the work firewall isn't blocking your images so I can point and laugh at your piston damage.

[Des]

I want my bench back, sick of working on the floor, look at all this hunnish mess.

 

 

I think I might have ballsed up a bit, done nothing with this fascist lump in a Month and need to be getting on with it, so the suppliers I'd spoke to rang yesterday to say all the parts I asked for are now available, I'd not even looked into getting my old cam fixed so just ordered the lot so as to get things moving, six hunnit and fiddy squiddy for,

 

 

The low comp pistons look very low comp.

 

 

That dish is about 5mm deeper, even with the great tit poking up there's room to throw a Schuhplattler, and it gets better, the Yank cam grind has 2mm less poke outishness, so that should equate to about 3mm less valve lift. All of this is good for engine life, but I don't know how much of an effect it will have on teh OMG powah, not ever going to go much above 65 but do want a bit of the torquish stuff for cutting up lorries cause I love me the sound of airhorns. I don't suppose valve lift will make much difference there but I really don't know for sure, I should probably do some complex measurements and calculations to determine how things will work out but instead will throw it all together and then bitch and moan about it being gutless compared to the old one it replaced and then trying an induction kit / K&N / performance resistor off of that ebay.

[Des]

I've got my bench back after a year of fritzclutter it's all back together.

 

 

Didn't scrub up too bad, a bat of the wire brush and rattle can worked wonders. The pistons I'd sourced turned out to be Chinese, although they measured up ok I just couldn't muster confidence in them, low compression anyway, so painstakingly picked all the foreign bodies from the originals and treated then to new rings, then fucked off the regrind cam when I lucked upon a genuine one, and assembled with genuine Volkswanker crankcase sealant that's been in my toolbox for a little over 20 years when I last opened one of Hitlers finest. Hope it's not gone off. 

Of course when I fired up the engine that's being replaced it sounded great, well not actually great but as good as any of them ever sound, the hydraulic tappet clatter went schtum within 0.3 of a second. This after standing for a Month, In the past I tried different oils to no effect but I think this slop I put in while abroad late last summer may have helped, Soviet STP.

 

 

Oil still feels nice and slippery, been in there a very long time, I'll change it more often in future, I'm adding an oil pressure gauge as I left some spare wires front to rear when putting the LPG in, so will be a piece of piss, and great peace of mind.