Engine/Transmission (1998.5 - 2002) Cracked turbo exhaust housing (warning, big pics)

[snowracer69]

I sent off my exhaust manifold, exhaust housing, compressor housing and elbow, and intake horn and had them ported/polished. When he started working on the exhuast housing, this is what he found:



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Which is on the wastegate hole. Then this:



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Then 5 more crack around the webbing that all look like this, cause that's all you can see of them due to their location:



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Sooooooooooooooooo, I'm waiting on Ken to get in some single entry housings and am supposed to be first on the list for one. The cracks are obviously from too much heat, and the housing is only about 5 months old now. We believe it is being caused by shock-cooling it from +1600*F to 600*F almost instantly... that thin webbing cannot handle the temp change and expansion/contraction.



Just thought I'd brag a little Gonna cost me some $$$ to learn a lesson.



BTW, I am still running the housing until Ken gets the new ones. he said it wont fail (I don't agree however) and that he's seen many of these before. Oh well.....



Josh

 

[lmills]

That does look like a costly lesson.

 

[snowracer69]

Originally posted by lmills

That does look like a costly lesson.

Not as bad as I thought it'd be, but still, there are other things to spend my $$$ on.

 

[DGFoster]

Looks as though you caught it before it became catastrofic.

 

[GFrance]

Boy Josh good thing you decided to port & polish. That could have been even more spendy if it all grenaded.

 

[snowracer69]

Yeah, Dave caught it, but I still have to run it. I try to tell myself "You don't need to go to 5x5 and smoke that Dmax or PSD", but that rarely happens! I'm hoping Ken is right, in that it won't destroy itself in the next month or so.



How many ways can you guys say "twins"?

 

[Forrest Nearing]

it ain't gonna hurt anything... run it!

 

[John - K5AWO]

I presume you are exercising a cool down cycle before shutting the engine off?



But a shift from 600-1600-600 is even worse than the shutdown too quick syndrome.

 

[snowracer69]

Yes, I always cool to a minimum of 375 pre turbo... most of the time below 350. It's not a matter of not letting it cool down properly, it's the shock and stresses caused from the extreme temp changes when I'm racing on 5x5 and stay in it till the top end of 4th gear and then let off real quick and coast down to a slower speed. It probably goes from 1800*F to 800*F in about 1. 5 seconds. I'm not sure what the housings are made of, but assuming a steel of some type, that's taking it from one atomic structure to another almost instantly.

 

[Cooker]

Just a thought... Is it right to assume that because the EGT got up to 1800 that the turbo housing also reached 1800? I would think there would be a slight delay in heating the steel to EGT temps. And in the same regards the steel would hold the heat much longer than it took for the EGT's to drop back down the 800 degress. In any case I am sure it is the extreme changes in excessives temperatures that the steel was not designed for that caused the cracks.

 

[snowracer69]

Originally posted by Cooker

Just a thought... Is it right to assume that because the EGT got up to 1800 that the turbo housing also reached 1800? I would think there would be a slight delay in heating the steel to EGT temps. And in the same regards the steel would hold the heat much longer than it took for the EGT's to drop back down the 800 degress. In any case I am sure it is the extreme changes in excessives temperatures that the steel was not designed for that caused the cracks.

Well, probably not good to assume that, no. However, if you hold 1800*F for 10-15 seconds, as I often do (that's about a 1/4 mile run) then it's probably safe to assume that the housing itself is well over 1500*F. Then assume that outside air temp under the hood is around probably 200*F and you let off and EGT's inside the housing go to 600*F... . can you say fast quench?



I'm not sure most of you are taking my original post in the right manner... . I'm sure what caused my cracks, not wondering why they are there. There's no doubt in my mind that I lead my turbo to this demise (well, my right foot did, and my need to beat every other car on the road to the next stop). Just thought I'd let you guys see what a "bad" housing looks like. I'm gonna run her till I get a new one.



Josh

 

[willyslover]

GEEEEES. . we introduce ya to a fast truck at the sled pulls and now look what ya goo and do LOL

looks like we need another beer / fun day to straighten ya out



so now twins Eh