Oh POO! My head gasket just went pop! 56k GTFO, no chance!

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davebmw
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Oh POO! My head gasket just went pop! 56k GTFO, no chance!

Post by davebmw »

Bad news! my head gasket has given up the ghost, a little too much advance and no knock sensors on MS2 not a good thing.

The engine now overheats as combustion gases are leaking into the coolant and coolant into one of the cylinders.

Runs reasonably at idle with the radiator bleed valve and cap open, close those up and the pressure builds within a few minutes and I get a misfire and lots of steam out of the tail pipe.

Looks like I'll be in for a weekend of damage investigation and stripping down. :cry:

Maybe even some time off work! :D
Last edited by Fred on Sat Oct 18, 2008 10:06 pm, edited 1 time in total.
Reason: Add mega 56k warning
93'BMW 325is M50B25TU, Rebuilt 06/06, JE10.5:1, polish&port. Scorpion BB, K&N CAI, TEJ21 WBO2, '07 M3 Evo 18" 225F, 255R, EBC Kevlar, Bilstien Sprint, Polyflex. Head rebuild Oct'08, OEM+FSE FPR, MS2v3.0_DJB Custom, Extra 2.0.1
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Fred
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Re: Oh POO! My head gasket just went pop!

Post by Fred »

That's a bugger Dave, but even with a sensor you should be listening to the engine directly with headphones or similar. How much advance had you given it? What is the compression, and what was it stock? Lastly, which fuel do you use? Curiosity killed the cat :-)

Time off work does sound good though!

Fred
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Re: Oh POO! My head gasket just went pop!

Post by davebmw »

Thats the thing I was listening very intently, i heard the tinkles of early knock so i retarded the timing and tuned the AFR to 12.5 which is what the AFR would have been with the stock ECU on at that load and RPM. when we came to the end of the 9 mile stretch of road, i noticed a slight misfire, went round the round about to go back down and the temp gauge started to soar at which point we rapidly pulled over and switched it all off.

I have been running with Shell Super unleaded nothing else touches my tank!

The advance at 6000 rpm was 37 deg but that seemed to be the point of optimum power at a safe AFR with no knock and further retarded and the engine just hit an isupassable mountain of retardation.

I'm thinking that there is either me being stupid and have totally balls'd up the tune and there fore the engine, or there was a weakness in the head gasket before hand.

The other really annoying part is that i didn't logfile it all! twat!

Tell you what though, when this is all repaired I won't be so eager to do flat out tuning on anything other than a rolling road!
93'BMW 325is M50B25TU, Rebuilt 06/06, JE10.5:1, polish&port. Scorpion BB, K&N CAI, TEJ21 WBO2, '07 M3 Evo 18" 225F, 255R, EBC Kevlar, Bilstien Sprint, Polyflex. Head rebuild Oct'08, OEM+FSE FPR, MS2v3.0_DJB Custom, Extra 2.0.1
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Re: Oh POO! My head gasket just went pop!

Post by Fred »

37 at WOT?? with a high quench fast burn modern 24v head? dude, that is asking for trouble. When piston meets head it rapidly accelerates the burn so big advance usually isn't needed at all on a modern engine. even worse, the further forward you have it the more reverse work done by the pressure on the piston btdc.

don't dismiss the street tune so quickly, many a good street tune has been done on many a car. basically the only reason not to do that is when your car weighs 5kg and has 3999hp.

I'd be surprised if you needed to go past about 32. Mops has to retard back to around 25 or so at peak torque in his older bmw. at cruise with light load and lean mixture he runs in the 40's but cruise is different to 100kpa.

sucks that shes dead :-( good luck with the fix.

Fred.
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Re: Oh POO! My head gasket just went pop!

Post by Fred »

The other thing I meant to say is that if you can hear knock, it is reasonably significant. If it seems loud, it is dangerous. It is there when you can't hear it without instrumentation too. Using a headphone setup or similar will allow you to detect the ones that both you and any electronic box have no show of detecting otherwise.

I guess I have half a show of having the rina running sooner now. Always looking on the brighter side :-)
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davebmw
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Re: Oh POO! My head gasket just went pop!

Post by davebmw »

Yes now I have looked back over everything I have done to get to this point, I have realised I had the ignition map arse backwards. I had way, way too much advance at WOT.

Hell those poor pistons must have had hell, good job they are forged! With a bit of luck its just the head gasket! cos if I have to strip another 24 valve head or get that big ass lump out of the car..... well... I'll shlt a cactus! :mad:

What I must have been doing is getting the wrong combo of VE to Ign and tricking the WBO2 to give me the reading I was looking for, this must have produced knock that I couldn't hear or the knock i did hear for the second or so dealt the fatal blow.

Not to worry though, its a good excuse to have a look inside the engine after 2 years and see what has gone on, hopefully nothing too drastic as the head has been skimmed and the block ground during the last rebuild in '06, if I can get away with just the head gasket that will be outstanding.

I have this glimmer of hope inside, as the motor still runs quite smoothly, so there shouldn't be too much damage to the head. fingers most fucking enthusiastically crossed.

The major PITA is that this engine is the best part of a days work to get the head off, its a well complicated bit of kit with loads of bits in awkward places.
Having had the bitch out before is going to help a shed load though, especially as I made all the special tools to set the timing correctly.

But on the up side the exhaust manifold has to come off so its an ideal opportunity to fit the stainless equal length manifold, and at the same time the FSE fuel pressure regulator can go on. and measurements for the supercharger bracketry can be sorted and if there is any damage to the pistons (which I doubt) than I could change them for the dished 8.3:1 forged set I have in the loft and get the SC bolted on there pretty damn quick.

So even though the shit has hit the fan, or rather the coolant has sprayed all over the MS2 there is always an up side. yes I fucked up, but hey that's all part of a learning curve, I won't make the same mistakes again.

And in fairness it would be all too easy to blame the MS2 but that would be total bollocks! It did exactly what i told it to, right up until i disconnected it and chucked it in the passenger footwell. This is a prime example of operator error and inexperience, creating a very valuable lesson in how not to do it. :lol2:

Oh and while writing this Fred posted and commented on him having the rina running sooner now, so... I hope you do my friend, but I will have the bitch up and running in a week at the outside as I have to get back and fore to work 20 miles away so the motivation is there. this is, in some peoples books a major thing, for me its a fucking big hiccup, but a hiccup all the same.

I may have the same episode with FreeEMS but its not going to be down to the firmware or hardware it will be the human element which is the let down.

Learning curve, what more can you say eh? just a kick ass ski slope for some and a white knuckle snowball effect MOFO event for others. :lol2:
93'BMW 325is M50B25TU, Rebuilt 06/06, JE10.5:1, polish&port. Scorpion BB, K&N CAI, TEJ21 WBO2, '07 M3 Evo 18" 225F, 255R, EBC Kevlar, Bilstien Sprint, Polyflex. Head rebuild Oct'08, OEM+FSE FPR, MS2v3.0_DJB Custom, Extra 2.0.1
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Re: Oh POO! My head gasket just went pop!

Post by Fred »

davebmw wrote:With a bit of luck its just the head gasket!
Worst case is probably some salt n pepper effect. I doubt you cracked ringlands or melted anything, but it is possible I guess. Headgaskets make a nice "engine fuse" much like clutches make a nice "driveline fuse".
if I can get away with just the head gasket that will be outstanding.
You shouldn't need to touch the block, but it's good practice to skim the head. Then again, you can probably ignore that and get away without touching either if you are lucky.
yes I [fizzle] up, but hey that's all part of a learning curve, I won't make the same mistakes again.
It takes a real man to say that! good on you!!
And in fairness it would be all too easy to blame the MS2 but that would be total bollocks!
Ditto the last comment. I'm all for giving ms shit where deserved, but too many people try that trick.
I may have the same episode with FreeEMS but its not going to be down to the firmware or hardware it will be the human element which is the let down.
Don't put too much faith in my code just yet LOL. It could give us trouble.
Learning curve, what more can you say eh? just a kick ass ski slope for some and a white knuckle snowball effect MOFO event for others. :lol2:
Even as a beginner I liked the black slopes :-)

Fred.
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davebmw
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Re: Oh POO! My head gasket just went pop!

Post by davebmw »

Fred! we must have a pint/glass of rather nice wine!
93'BMW 325is M50B25TU, Rebuilt 06/06, JE10.5:1, polish&port. Scorpion BB, K&N CAI, TEJ21 WBO2, '07 M3 Evo 18" 225F, 255R, EBC Kevlar, Bilstien Sprint, Polyflex. Head rebuild Oct'08, OEM+FSE FPR, MS2v3.0_DJB Custom, Extra 2.0.1
davebmw
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Re: Oh POO! My head gasket just went pop! No 56K!!!

Post by davebmw »

Good news everyone! ( in the voice of prof Farnsworth of futurama fame)

My head gasket is shot but the head and block are intact with no visual erosion or warpage, i will take the head for a professional examination though just to be sure. Pheww!

I started at 12pm today and had the head off by 3pm. not bad going eh?

I have included some pics of it all, and the evidence that knocking has battered the head gasket.

Before:
Image

Image

Image

Image
And with the intake manifold out of the way:
Image

Image
The offending article:
Image

Image
Cylinder 3 blew through to the water jacket
Image

Image
Cylinder 5 blew through to the water jacket:
Image
Notice the dents in the steel gas rings!
Image

So thats pretty damn conclusive then...... knock is really bad!!

apologies for some of the fuzzy pics, i had to use the camera on my phone!
93'BMW 325is M50B25TU, Rebuilt 06/06, JE10.5:1, polish&port. Scorpion BB, K&N CAI, TEJ21 WBO2, '07 M3 Evo 18" 225F, 255R, EBC Kevlar, Bilstien Sprint, Polyflex. Head rebuild Oct'08, OEM+FSE FPR, MS2v3.0_DJB Custom, Extra 2.0.1
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Re: Oh POO! My head gasket just went pop! 56k GTFO, no chance!

Post by Fred »

If I was a more grumpy bastard I'd tell you off for the size of those pics :-)

As it happens, the detail was nice, but you might wanna drop them back to image links and/or post some smaller 1024/768 or so ones instead/aswell?

Your call, I relabeled the thread to try to help people out anyway.

About the pics...

The patch on each piston where the injector has washed it clean is cool, I haven't seen that before!

The compressed fire ring is fairly expected :-) Did you check that the head was in perfect condition where it dragged across as it happened? I'd expect to see a mark there at least.

Somewhere I have a really cool pic of a hg from an engine like mine with bad detonation damage (boost).

That det of yours was clearly short lived and fairly strong. If it went on longer and/or was stronger you'd see it on the pistons and head too. Are the ring lands definitely good? I guess you'll have to wait till you get it back on as even if the top ones are OK, sometimes the second one goes instead.

Fred, typing into a huge window without enough room LOL.
DIYEFI.org - where Open Source means Open Source, and Free means Freedom
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FreeEMS dev diary and its comments thread and my turbo truck!
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