Author Topic: Etches G40 (2)  (Read 26425 times)

Offline Etches

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Re: Etches G40 (2)
« Reply #15 on: October 15, 2012, 04:31:32 pm »
Couple of teething problems atm . Tappets are making a racket with plenty of oil in which could mean they need a service or replacing. Also it burned a fair amount of oil on the way back from Santa Pod which is worrying considering it didnt do that before the turbo went on, I suppose it could be the turbos oil seals?

Offline Etches

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Re: Etches G40 (2)
« Reply #16 on: November 11, 2012, 05:46:34 pm »
Right if you've read the other thread then you know some of the problems i've been having here the suspected diagnosis...



head off, cylinders 2,3,4 looks like overfuelling massively.

cylinder 1 closer look



hello melty



Been speaking to PeteG40 and he reckons i'd probably get away with a hone new piston and rings. Although I reckon i'd like to get some forged items.

Offline Etches

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Re: Etches G40 (2)
« Reply #17 on: November 12, 2012, 08:07:36 pm »
At the min I'm abit puzzled to the source of the melted piston, Phil J lead me to this post on here;

Anyway, thought this should be useful. A definitive checklist on how to avoid melting your engine for anyone who has built, restored, recently bought or just had a G40 laid up for a while.

First one which has prompted me to write this, Mark’s G40 started misfiring recently, easy fix – unplug the lambda and sorted. The lambda was new a year previously so something has killed it, running too rich or lean. The car had an issue where the fuel pumps wouldn’t prime, turned out the connector for the relay had corroded just enough to stop the contact. Had that not been driven like a vagina, rather than the lambda probably would have taken the engine out. Worth a look for any 40’s that have been laid up.

Another one sometimes forgotten is the wiring in the top of the fuel rail, again corrodes, goes brittle etc.

Fitting a smaller pulley/upping the boost without the fuel to suit a quick way to achieving an extra oil pump. IE a chip for a 68mm pulley and fitting 65mm toothed belts will do it on about the 3rd 145mph run.

Injectors, fuel pumps, shit in the tank and blocked filters will all lead to the same. Easily done with how the tanks corrode. Can you still get the accumulators (yellowish box by fuel pump) from vw? Haven’t asked in a while…

Timing’s always worth a check, both of.

Realistically a G40 shouldn’t melt if its right and it’s always a shame to see them go down.

Sure everyone else can add their bit, might save a few engines.




My injectors were apparently cleaned not long before I got them and the pump always seem'd to work fine before the conversion. The timing did skip afew teeth but I dont think its down to that. I filled the tank up to the brim for the trip down to pod so I think shit in the tank has come up and blocked it somewhere.

I reckon I'm guna get a new tank,filter and clean the injectors before shes running again. Maybe even get some metal fuel lines.

Ordered a set of pistons off phil, hoping to be up and running before christmas

Offline Andy

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Re: Etches G40 (2)
« Reply #18 on: November 12, 2012, 09:43:45 pm »
Lambda is extremely unlikely to melt a piston - it's not used on full throttle (i.e. full load). Even on partial throttle where lambda correction is applied there's a control limit applied to how much fuelling correction is permitted. This is supposed to ensure that an utterly fucked probe doesn't cause component damage.

Lift pump failure will cause lean-out at higher fuel flows (high load), but also makes the car harder to start so I think you'd know about that - and it's easy to verify with a fuel pressure gauge.

Inline pump failure seems to cause significant missfires even on lowish powered cars, so I think you might've noticed that. Again, that is easily verified by sticking a pressure gauge on the end of the fuel rail.

Injector failure is a possibility, as is injector wiring harness as Phil said.

Incorrect map for spec probably accounts for some failures too I'd imagine, but that shouldn't be the case here.

Was your car pinking at all? Can't see any obvious det damage on the piston - but Yoof's the person to ask about that.

Offline cheys03

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Re: Etches G40 (2)
« Reply #19 on: November 12, 2012, 09:58:03 pm »
sorry to see you've had this problem. It's something we all fear happening.
Purely out of curiosity, which map is it running?

Offline Yoof

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Re: Etches G40 (2)
« Reply #20 on: November 12, 2012, 11:17:31 pm »
Drop the oil into a clear container- see if it seperates, will know if it's bore wash then,

Having said that, if it's bore wash, I'd expect a lack of lubrication on all cylinders, not just one. Without removing the piston I can't really see but it looks like a crack rather than something melted from the top angle.

Piston is free from det and otherwise looks in good shape, what injectors do you have, presume it's a known map from PPP (normal K03) so that's a known quantity- you deffo need to find the root cause, otherwise it will happen again  :'(

I'd get a new knock sensor too  ;)

Offline Yoof

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Re: Etches G40 (2)
« Reply #21 on: November 13, 2012, 09:33:12 am »
Tom, here’s a quick list of things to check that should help you find the root cause:

1)   Drain oil into clear container (note some types of plastic will disintegrate with fuel/oil mix) and see if there’s any separation, you can usually smell fuel content in oil, and it will light too (much more easily than oil)

2)   Take pictures of the bores on all cylinders- if a lack of lubrication caused by bore was has led to a melted piston, you’ll see this in the ring on all cylinders, if No.1 has gone first, the other 3 won’t be far behind.

3)   Check injector part numbers, and for cracks on their bodies and the fuel rail, and for any debris in them (they have small filters in the top)

4)   Photograph cylinder head

5)   Check wiring (your knock sensor looks dead) check boost switch (Chris has written an FAQ on this) and that your wiring is correct, this is key- if the 6psi switch is engaged on cruise, then the ECU will assume you’re at a full throttle condition for a given MAP & Speed site, so it will be too rich- lambda won’t correct on WOT either, check CO pot values, you can’t check cam timing or ignition timing now- can you remember what they were?

6)   Check all coolant passages and the pump impeller (although you said it was running normal temp?) usually if the coolant temp is too high expansion tank and then a head gasket after that.
 
7)   Injector clean/test again (post results)

8)   Fuel pump check- G40 will run quite happily without a lift pump until 3500-4000rpm and then will go lean, you can check both are working and their flow rates very easily with a 5litre jerry can and a stop watch, off the top of my head a stock G40 lift pump is 75lph

That should give you enough to go at  :)

Pete

Offline Etches

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Re: Etches G40 (2)
« Reply #22 on: November 13, 2012, 06:57:46 pm »
Andy , I dont think the car was pinking. Seemed to run ok on idle but didnt enjoy part throttle too much.

Chris, the map was a ;
Map #G40008- 1341cc chip- As above with altered parameters to suit a 6psi boost switch replacing the standard G40 WOT switch, giving a smoother more progressive drive.

Pete, Separated the oil and its clean as a whistle with no separation. Im using G60 greens injectors which I bought off someone on here. The knock sensor has looked pretty banged up for a while so I'llk defo be replacing that.

I'll crack on with the list asap inbetween dissertation hell! Wossners are in the post ( read plenty of threads with comments from both you and Andy to decide which to go for)



Offline Etches

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Re: Etches G40 (2)
« Reply #23 on: December 14, 2012, 02:02:28 pm »
Right an update on this finally! Took the head off to get some work done where PeteG40 mentioned (skim, new valve guides, stem seals, 3 angle valve and seat cut and a pressure test) then also took the injectors to be flow tested and cleaned.




Head is getting done today but got the results back from the injectors.

Turns out all of the injectors had good spray pattern, 4 of them had flow of 260cc and one of them had a flow rate of 240cc . The guy reckons  i should chuck the "knackered" one and find a new one. They also do turbo rebuilds for 200 so i may also end up going up again!

So i'm looking for a G60 injector now!

Also got the main and big end bearings on order from Rotherham Engine servies, picking up all bottom end seals off Pete next week. Just got to wait on the pistons now from Phil J!
« Last Edit: December 14, 2012, 02:05:45 pm by etches69 »

Offline Andy

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Re: Etches G40 (2)
« Reply #24 on: December 14, 2012, 04:33:59 pm »
Don't just focus on the injector flow at 85% or 100% duty cycle, did the guy give you an idea of how they flowed at lower duties too? In your car they'll probably not get above 75% duty even on max boost/full throttle, so it's worth knowing what they do across the opening range.

Offline Etches

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Re: Etches G40 (2)
« Reply #25 on: December 15, 2012, 08:41:29 am »
Cheers Andy, I've messaged him so hopefully he gives me some info. I didn't get a print out as it was either £30 for the verbal results or £50 for a print out (rediculous I know).

Offline Etches

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Re: Etches G40 (2)
« Reply #26 on: January 12, 2013, 09:20:40 am »
Bit of an update now;



Bottom end totally ripped apart and to the engine shop for a full  clean and  for a 2mm overbore for the wossner pistons

The heads come back RES where its had

head skim, 8 valve guides, stem seals, cam oil seal, three angle valve cut 3 angle seat cut



I've got to get some 315cc injectors and some big end bolts.

Offline Etches

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Re: Etches G40 (2)
« Reply #27 on: January 16, 2013, 08:25:39 pm »


Got these in the post today - Cheers Phil!

Means they can be given to RES for the bores to be matched!

Offline gaz g40

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Re: Etches G40 (2)
« Reply #28 on: January 16, 2013, 09:19:17 pm »
Just had my bottom end done the pistons look too good to fit lol you going for rods aswell? I got the PEC ones
Nice build thread too got mine to start soonish

Offline PeteG40

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Re: Etches G40 (2)
« Reply #29 on: January 16, 2013, 09:55:24 pm »
showed my K1 rods to yoof... he thinks they're probably just same as his PEC, but with a different logo...