Melted Piston

[PeteG40]

the problem is that you dont know what caused the meltage.  If you just rebuild the engine, there is a chance it'll melt again - hence why people are saying check fuel pumps/injectors etc.

[grayg40]

i would agree with these lads by just going for another engine,
cos this would be more cost effective and safer than rebuilding a very damaged engine when a month down the line it could happen again if its not 100%.

Costs approx £200 per piston (inc rings and pin)(i payed 195 for one 8 months ago and never used it cos i bought another engine and put its pistons with new rings in my block)
new head is about a grandish maybe more from vw if you cant get second hand,
££££ to find out and fix what caused the problem in the first place.
£400 - £500 for a working engine and a day replacing it is far cheaper than than fixing the excisting engine,

[PeteG40]

if you want to do it as cheap as possible but retain your block, i would say a new piston, strip down, check and rebuild is needed.

Add head gasket etc and you are probably looking at £300 in parts+ labour.

Then clean/replace injectors (£35 at ppp for a clean)  and test/replace fuel pumps (£20 lift  fuel pump, £100 , replace fuel filter/strainer (£10).

Labour either way will be a biatch unless you do it yourself.

[lance]

i have a G40 piston you can have but id advise just buying another engine as you'll have to eventually anyway.

[jez1272gt]

After reading this thread and all the comments, if i were you i would take Yoof up on his offer to supply you with a ready built engine. That way you can get it in place, check the fuel system and off you go. Will save the hassel of a rebore, cleaning block after, sourcing parts and then rebuilding. Saving time your G is out of action!

Plus then you will have the damaged block as a spare to slowly build a 1341 forged bottom when time and money allows 

[Dirrt]

Thanks for the replies guys. I do see the logic but I don't know
Are you telling me, all off you in my situation would buy a new engine? I'm finding that hard to believe 

[PeteG40]

you need a new piston and a new head by the sounds of it, which will cost about the same as a yoof engine.  So its your call really.

Its gonna be quite costly whatever the outcome, which unfortunately could only be made cheaper if you could do all the labour spannering yourself

[hayesey]

I probably wouldn't buy a full new engine no, not if the bores are ok.  But I'd do all the labour in rebuilding the engine myself so it'd work out ok.  It's the amuont of money you are going to need to pay someone to rebuild the engine and inspect it for bearing damage, warp, bore size and shape etc...

[Dirty Slag]

Right you guys i had to sign up as i cant deal with being a second party anymore and trying to get info through miss DIRT!
I have the car in my workshop all pistons are out No3 is melted due to a poss fueling problem the plan is to replace this piston and fit new rings to the rest thus making it a new engine minus the bearings on the crank which are all fine as it only had a build about 10k ago!
The block is not warped and never will be as it would seize before that happened
And the fact you replaced the block because it was supposedly borewashed!!!! what a pointless exercise a simple glaze buster would have sorted that and a fresh set of rings! at worst!
The head is corroded around a water way which has gone into the sealing ring of the head gasket this also does not need replacing a simple welding job and a skim will return this back to new!
The injectors are going for a clean and pattern check and the filters and poss pump will be changed to!
Any positive comments welcome!

[PeteG40]

Block - it was suggested that waterways may be blocked, hence the poor cooling and overheating then melting

Hayesey replaced a borewashed block with another, as it cost him £50+ rings which was easier than taking the existing borewashed block apart and starting again.

Head - Dirrt said the head was fucked - if its not then good news

As for the fueling problem - well I would presume that if it has 75.5mm pistons its been slighltly overbored before, possibly due to this.  So you need to get to the bottom of this to avoid it happening again.   People have melted pistons before due to - injectors, wiring loom, fuel pumps etc.  However also some pistons also had suspect metallurgy and I've been told some g40s had their engine replaced under warranty due to melting!


As for replacing the engine - well the cost of piston+headgasket+head skimming/welding  is going to be coming towards the price of a decent secondhand engine.

Pete

[Dirty Slag]

I know its defo a fueling problem
I dont like second hand engines as you never know what they have been treated like yes they might have only done say 20k but 20k of what death? and you never get the full truth from the original owner!
Also replacing the engine is so much more work that just dropping the pistons out!
At least i'll know it been put together right and what condition everything is in doing it my way!

[PeteG40]

Agreed mate on the block, i'd prefer something I'd know was tip top.

Fueling problem maybe, but is it the ecu map, wiring, injectors, pump, filters? etc etc  Thoroughly and methodically all needs checking.

[Dirty Slag]

Hence they'll be coming off and being checked!
I'm personally going for blocked injectors as its only the one cylinder thats been affected the other 3 are tip top!
So as i said above pattern and flow check on the injectors and replace the filters as people never seem to bother for some stupid reason!
Blocked fuel filters are a major cause of engine problems!
Also its amazing the difference it makes to the performance if they are even slightly blocked and on a boosted car your relying on the fuel more than anything to stop it killing itself!

[hayesey]

lose the attitude mate.

do whatever you want with it, she asked for advice we gave it.  If you think you can repair the engine for less then do it.  From Dirts point of view, is it cheaper for her to pay you to repair the engine than it is to buy an engine that is known to be good.  Only she can answer that because only she knows what you;re going to charge her.  There's no need for the "everyone is obviously wrong except me because I'm a mechanic" attitude. 

[hayesey]

and yes I know I didn't need to repalce the block because it had been bore washed, I've still got that old block and will probably rebuild it one day and will give it a glaze break but I had a spare bottom end bought for less than it'd cost me to fix up the dodgy one.