Piston melted

[aspira]

Hi Guys,

I thought i might have dropped a valve or ring so dropped the engine and took off the heads. #3 piston has melted and the rings seized inside the piston. The barrel doesn't look bad.

What do I do now. I know a friendly machine shop, do I take all pistons and barrels down to them or just the broken one? Do I replace all the rings or just the broken ones?

Any help or thoughts much appreciated.

Here's a couple of pics;

 

[RICH-I-AM]

Any idea how this happened?
What caused it?

 

[Anonymous]

looks like fueling problem if it were my engine I would put on a new set off barrels and pistons the cost of a machine shop is no cheaper imo

 

[aspira]

Yes, completely my own fault unfortunately.

Got stuck in a long traffic jam at stonehenge, then running late I stupidly pushed it too hard onto Devon. It was a 6 hours trip! Puff of smoke and loss of power so limped off and got relayed back to London.

It's a 1641 and T1 btw, the engine has less than 5000 miles on it.

Is it always better to replace all 4 pistons and barrels then rather than just replace the broken piston?

 

[Anonymous]

its cheaper to replace all four its very hard to get just one new barrel and piston unless some one on here has a spare 1641 b/p

 

[aspira]

Do I need to replace them with a 1641, any recommendations where to buy from?

 

[lhu128l]

Running to lean /air leak will cause that , so will incorrect ingnition timing

 

[Anonymous]

1600 or 1641 not much difference vw heritage do them or jk or volkspares or gsf or veewee or you get the picture

 

[Anonymous]

148.00 cheapo set or 250.00 forged jk forged are the best but if you drive like a nutter you can kill the best set just as qwick

 

[aspira]

right got it - thx

 

[the_troupster]

How's the head? Valve seats ok? Pour some fuel in the combustion chamber n see if it leaks out...

I agree with above, keep it all equal and buy a set. You'll make a chunk of it back selling the other remaining 3 on second hand.

Jim

 

[aspira]

The head looks fine Jim. I noticed the electode was missing on the spark plug (the bottom bit under the gap). When it happened I lost a little oil. On removing the engine I couldn't see any evidence of it coming up through the plug, the head or the bottom of the cylinders so I guess it came up through the overflow.

Tried your test with fuel and no leaks btw so I'm hoping the head is okay.

Thx

 

[Trikky2]

Dont blame yourself. Your "pushing it" just made it happen sooner.

If all is well with the engine it will happily run flat out all day. This is because they are over engineered eg. 1600 cc only producing 58 bhp. So even flat out, its only the equivalent of about half throttle on most engines.

That damage is from overheating. The fault that caused this overheating would have caused the engine to fail fairly soon anyway, such as when you have to climb a long hill for instance.

Thoroughly check for all the causes of overheating when you do the rebuild.

Also dont forget to check the valve stem and guide for wear, especially on the overheated cylinder.

 

[Alex VW Heritage]

Dont blame yourself. Your "pushing it" just made it happen sooner.

If all is well with the engine it will happily run flat out all day. This is because they are over engineered eg. 1600 cc only producing 58 bhp. So even flat out, its only the equivalent of about half throttle on most engines.

That damage is from overheating. The fault that caused this overheating would have caused the engine to fail fairly soon anyway, such as when you have to climb a long hill for instance.

Thoroughly check for all the causes of overheating when you do the rebuild.

Also dont forget to check the valve stem and guide for wear, especially on the overheated cylinder.

Awesome advice as always,

I would be replacing 4 barrels and pistons and checking over the cylinder heads.

Repro £121 then your EB discount on top(Due in the next week or so, AA Performance):

http://www.vwheritage.com/vw_spares_Barrel-piston-kit-1641cc-87mm-repro-AC198870R_act_shop.product_pID_19649725_lang_EN_country_GB.htm" onclick="window.open(this.href);return false;

Or Mahle £204 then you EB Discount on top:

http://www.vwheritage.com/vw_spares_Barrel-piston-kit-1641cc-87mm-AC198870_act_shop.product_pID_116337_lang_EN_country_GB.htm" onclick="window.open(this.href);return false;

 

[sweat69]

What oil cooler is it running the single port or the twin port one.
As the twin port does not stop air flow to no 3 piston.

 

[aspira]

It is running a twin port cooler - didn't know they were interchangeable!

On stripping the engine I've found that the two heads are different. One's a Mexican VW head with short reach plug holes, the other's an aftermarket with long reach plug holes.

I'm taking the heads to a machine shop for testing, they look okay but since I'm rebuilding the engine I thought it wise to have them tested properly.

Do you think it is okay to use two different heads?

 

[Anonymous]

Have you got the same short reach plugs in both heads or long reach in both heads probley why the plug tip melted long in a short or visa versa I would get a pair the same other wise you will have to have two sets of plugs

 

[aspira]

Sorry for my ignorance here or if I misunderstand

Are the plugs either short or long reach or the plug-holes in the head?

 

[Resto-raider]

That depends on the heads. What is the number on the head?
I have had a similar issue and can sell you a piston and a cylinder if you want, because I have 3 good ones left.
I don't see the use of throwing 3 good cylinders away, although they are likely to have damage as well, because they have probably been hot as well although a little less than the number 3

 

[aspira]

I'll check the number later. I did consider replacing only one p&c but after plenty of discussion thought it better to replace all of them.