PD Melted piston

russ_tdi · Mar 18, 2010

hello all
Iv got a pd130 with 17/22 turbo WI and all the norm bits to go with it. Was making 268bhp and 412lbft for over 2 years (22k miles) up untill a couple of weeks ago. Was going along at 85mph when it started running on three. so did the norm compression check and no4 was down, so thort head gaskit. when i ripped the head off i found that no4 piston has what i can only describe as melted the top on one side it has got very hot and saged. found no damage to rings or bore

Anyone had this or any ideas what it could be corsed by? was thinking if my injectors spray pattern was very bad it would only cool some parts of the piston with the fuel duse this sound right?

thanks

vwmikel · Mar 18, 2010

russ_tdi said:
hello all
Iv got a pd130 with 17/22 turbo WI and all the norm bits to go with it. Was making 268bhp and 412lbft for over 2 years (22k miles) up untill a couple of weeks ago. Was going along at 85mph when it started running on three. so did the norm compression check and no4 was down, so thort head gaskit. when i ripped the head off i found that no4 piston has what i can only describe as melted the top on one side it has got very hot and saged. found no damage to rings or bore

Anyone had this or any ideas what it could be corsed by? was thinking if my injectors spray pattern was very bad it would only cool some parts of the piston with the fuel duse this sound right?

thanks

Perhaps it was a leaky injector causing preignition or it streamed...

silver_tdi · Mar 18, 2010

I would guess it would be your injector spray pattern. They operate at extremely high pressure. I have seen diesel injectors on C15 Cat's blow a hole right through a piston. Your PD injector runs at a higher psi than the Caterpillar engine does about 2050 bar or 29 750 PSI according to this source. http://www.langleyvw.ca/tech/pd.html
So even if your spray pattern was off just a bit it would make the top of the piston look almost melted. Is the point completely gone off of the top of the piston where the injector sprays if it is, that would be a good sign of improper spray pattern.

hatemi · Mar 18, 2010

I just wonder it lasted so long with the claimed turbo and powerlevel. EMP->EGT->Molten engine.

tdi_davy · Mar 18, 2010

With this turbo i would not go higher then 215hp....

vwmikel · Mar 18, 2010

hatemi said:
I just wonder it lasted so long with the claimed turbo and powerlevel. EMP->EGT->Molten engine.

I don't even think that power level is even remotely possible with the hardware given, but with all of the dynos out there that defy logic and mathmatics you just have to give up.

ArturCosta · Mar 18, 2010

hatemi said:
I just wonder it lasted so long with the claimed turbo and powerlevel. EMP->EGT->Molten engine.

x2

Maybe it was never pushed hard for a long time... and when it was cabum.

I also own a melted piston in my garage

Back to topic , maybe the high PCP and EGTs where the reason the piston melted.

russ_tdi · Mar 18, 2010

cheers for the quick replys and input

I did find it wird that it was making that much power. I just thort it was a fluke as i was told the turbo had bin built a wee bit difrontly from the norm

iv had it on 4 diffront rolling roads came out as 259.8, 262.3, 265.1 and 268.2 so just went with it

Running at such a push i always thort something was going to give but i thort it would be the turbo 1st

now im re building it and going a step up with head work, race injectors and a bigger turbo i would love to get to the bottom of the problem so i can stop it from going agen

will try and get pics up asap. Think it will help a lot more than me trying to explane

DanG144 · Mar 18, 2010

Verify that your piston oil squirters are all good and clear, and aimed correctly.

This sounds as if it could be a contributor.

Dan

russ_tdi · Mar 18, 2010

one of the good pistons looks very sooted up

the bad one no4

The Shootist · Mar 18, 2010

Be sure to check that injector. The melted spots match the spray pattern.

The sooted piston has a pattern that stretches a ways out onto the piston crown. I'm not that familiar with what that pattern normally looks like, but a deviation in timing could be an issue too.

ocshaman · Mar 18, 2010

In your first post you mention WI, would that be water injection?

russ_tdi · Mar 19, 2010

yes running a water injection as well

mojogoes · Mar 19, 2010

russ_tdi said:
yes running a water injection as well

Was/is that water only or W/M mix?

russ_tdi · Mar 19, 2010

water meth with a 40-60 mix. 40 meth 60 water

Farfromovin · Mar 19, 2010

I'm going to go out on a limb here. By running high concentrations of methanol, you can take the timing control of the combustion out of the ECU's hands. Lot's of people run 50/50 with out problems, and then there are people with cracked/melted pistons. If you have a stock intake, no matter where the W/I nozzle is located you are going to get a concentration of spray in cyl 4. Is it possible that the burn started in #4 too early due to methanol? Maybe I'd say...

Either that or a bum injector... You need to have your current injector setup tested prior to disassembly for the race nozzle swap. All your answers lie there!

ryanp · Mar 20, 2010

I have a good place to send injectors for testing/fitting as Phil knows!

The intake will definatly send more meth to the 4th cylinder. at the claimed power lever the SOI and duration must be way beyond specs for definate!

devonutopia · Mar 20, 2010

I've been running 50/50 water meth for quite some time and all 4 pistons were fine when removed for my new rods to go on. I also run a stock pd150 intake, only mod to it is porting out.

My W/M injector is also in a boost pipe a good 3 feet from the inlet manifold so the shower spray should be evenly dispersed in the air by the time it reaches the intake - It's just a question of how it distributes into the cylinder head then

ocshaman · Mar 22, 2010

I am confused about why your piston is so dirty even though you have been running WMI

PD Melted piston

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