BlownV8

Don't mess with a bent crank. There is not enough upside to take the chance.

GMBALL

I have decided not to go for hybrid turbos, exactly for these reasons. I am keeping it relatively “safe” with 740 bhp. Also, I have watched quite a lot of videos from Tasos and never ever he replaced the crank with a new one even on engines running crazy numbers. I guess it’s also due to the fact that the cost is 4k+ USD for the new crank.

But yeah, strong internals, but no more power increase from this level.

The rebuild will be probably around 25k.

BlownV8

Guarantee he would never reuse a bent crank though. Get a used straight one.

GMBALL

Timestamp 24:30


and 3:10

billvp218

It sounds like he sent the crank to the machine shop to have them double-check if it was straight or not.

It didn't seem clear to me if he would have had them straighten it, and then reuse, if they found it to be not straight.

GMBALL

I watched a lot of Tasos videos. Basically he checks crankshafts for a bearing plays/runouts and if it is above permissible limits from the manufacturer, he sends them to the workshop to straighten them up. He never replaces them, or at least never did so in his videos.

Guys, could it be that this hapenned not because of a failed injector (I will replace all with new and test old ones), but because there was improperly gapped plug? I bought these colder plugs from Weistec, and drove with them for about 5 months only a few WOTs done. What I remember is then when I was starting the car, during maybe just first 2-5 seconds after the cold start when the revs are still up from the cold start there were moments of a slight drop of revs that you could barely see, but you could feel these miliseconds of revs drop and then it went back up again. Weird thing, but so minir I never did anything with it. It started after plugs were replaced from OEM to Weistec.

I have more sets of Weistec plugs but maybe I should return back to stock plugs. I had missfires on cylinder 5 with stock plugs before.

BlownV8

From what I understand, the plug indexing is critical to the health of the M157 and improperly indexed plugs can lead to engine failure. Yes, I would go back to OE plugs and use the proper torque specs for installing or make sure the aftermarket plugs are properly indexed and gapped.
Spark Plug Indexing for Direct Injection Engines QEC/ES (automotivetechinfo.com)

Robert AMG

iTrader: (1)

I think best choice for you is to send your engine to Tasos...

PeterUbers

it'll be perfectly rebuilt ... and just a few cig ash burns but hey.... first world problems 😆

CZ 75

There’s a whole thread on indexing further down the front page of this forum. The consensus is that nobody so far(from all the posts I sifted through) has been able to properly index all 8 plugs in their M157. Secondly, there are many guys who are tuned that have attested that despite not being indexed properly, they have put on tens of thousands of worry free miles on their cars.

Some guys think that running hot plugs may lead to issues such as misfires. OP did mention it in his previous post. So who knows.

GMBALL

Imagine how much I pay just to send it from Europe to UAE. And then his cost to rebuild the engine is about 50k USD. I know because I have asked his company and they have given me the estimation. The mechanic I have is very attentive to details and is known locally as a best guy for supercars. Plus I share Tasos videos with him.

GMBALL

I had misfires with OEM plugs but yeah, I don’t really trust Weistec colder plugs. That’s the only thing that was changed recently before the engine was blown. The TCU and Blackboost CAI has nothing to do with causing this imo. All the other mods 2+ years old.

GMBALL

I can't seem to find any methanol kits. Can you recommend some good and time-tested meth kits, please? Ideally with a link - I am looking hard, but don't see anything.
I have found only one from Weistec - their stuff is just too expensive.

Also, does this any good - diverter valve kit?
https://www.renntechmercedes.com/ind...-s-cl-b-detail

I will tell my mechanic to look hard for any issues mostly within my fuel system - injectors testing (will still replace with new), coils, low/high pressure pumps, plugs.

kevm14

Do we think a bad injector could really lead to a bent rod? I guess it could if that cylinder had some bad preignition events as a result of running lean.

Baltistyle

Everyone here is right on with the theory of stock vs aftermarket plugs, for heat, longevity and indexing.

You’re right that it could be a plug vs an injector, that’s why it’s so important to check the injectors. There’s services that will ensure they are clean and working correctly. From there you can diagnose whether it was a tune or plugs. Seeing that first plug issue, and your info of weistec plugs (which is well documented on this site), we can make some assumptions but no real answers. Your melted piston looks just like the one in the Mercedes indexing document.

PekkaH

@GMBALL Really sorry this happen

Maybe my question is stupid but I have to ask. Do I understand right that you have Renntech 699hp "mailbox tune" and you haven't custom tune it to match HMS Bridge pipes? You get 740hp out in dyno?Could it be that it was running lean? And the injector could also be bad flowing and it was on its max with those bridge pipes , then engine goes and said boom. I ask because when I did add 3" true cat back my car was running lean on one mile race in airport and I need to end the pull quick. I did try twice and happen twice. Now I'm waiting for new custom ECU tune to run safe on long pulls. Those Bridge pipes will add flow a lot and make get like 20-40hp more if I understand right.

EDIT: oh, you have also 3" cat back exhaust...

Im running 1/4 mile 128,6mph traps and 60-130mph 7,6s so our cars power levels are near same. (Pump gas tune in my car also, no meth) My tuner didn't want me to run any other than std. spark plugs.

GMBALL

Can you please share that document?

Yes, I have the “out of the box” ecu tune from renntech with 696bhp and 1050nm. When I was adding downpipes, turbo-backs and 3” exhaust with sport cats I have contacted renntech and asked if I need a retune. They said that these mods don’t matter and there is no need to retune.

GMBALL

I always thought that colder plugs are needed to reduce the risk of knock event and damaged engine. That’s why I have installed them.

PekkaH

Oh okey, you did your best with your tuner and they answered to you.. Im no tuner by any means but what I have experienced with my car I personally need retune.

GMBALL

Guys, please look at this video. This issue was occurring with my car for about a year before the engine damage. I showed this to many mechanics including the ones from Mercedes and they all thought that this is some way of transmission protecting itself from the increased torque. I then did Weistec TCU, which didn’t help.

Now I realize, god dammit, this was not a tranny issue, but probably fuel cut off by the ECU for some reason. Might give some clues to the overall story. I was driving with this issue for about a year, although I did change spark plugs from OEM to Weistec, thought the issue was resolved until it reappeared again. Maybe it contributed to my engine damage.

Facts:
- happens irregularly
- only during WOT
- only high speeds 4/5th gear
- only higher range of revs 3k+

https://youtube.com/shorts/kwSFMuz_H_4?feature=share

UPDATE: This probably happens, because car falls into overboost territory and probably has something to do with spark plugs. To me it happened on both ocassions, with OEM and Weistec colder plugs. Although, with colder plugs it did dissappear for some months. https://mbworld.org/forums/gle63s-gl...ml#post8791008

Baltistyle

[QUOTE=GMBALL;8790647]Can you please share that document?

https://automotivetechinfo.com/wp-co...nes-QEC-ES.pdf

Blownv8 also posted above

exhaustgases

This would be a fun project. I wish I had the correct equipment, to fix it right and improve durability.
Yeah it seems Tasos runs into a lot of bent rods, in the Merc engines he deals with.
He is not like most on the tube, he seems pretty careful. Nice guy.

GMBALL

Pistons/rods/sleeves have finally arrived.

Baltistyle

Very pretty. Something most of us would never want to go through but would love to have. Can’t wait to see the progress.

GMBALL

Well said. I would never want to go through this, but since it happened, I can’t put there stock parts and risk it all again.