terryk

After 13 years my hot side pipe (turbo to IC) split. I'm shopping the GM replacement (25912407) but figured I'd check on my other options. Any input is welcome. I prefer to stay stock since I doubt I will have the car in another 13 years but aftermarket is fine too. Now if someone has a good GM original, message me.

Thanks for any suggestions!

Edit: I went ahead and ordered the OEM part. The price was good and I'll have it in a couple of days. Good enough. I do like keeping this SS stock.

The symptoms were - no boost immediately after boosting for a few seconds. You could drive it mildly but any big throttle caused it to buck and eventually threw a P0101. I have a spare set of both boost solenoids and a MAF. Tossed them in, no change. Did the leak test and the pipe split along the seams with another crack going up over the top. You couldn't hear the leak though. On my Duramax, it was a trumpet but on this LNF, nothing.

Edit2: I rescaled the pic and added one showing the length of the crack and another showing the fix. While I wait for the new one, I decided to try and repair this one. I drilled holes at the ends of the cracks and then held it open a bit to allow the epoxy to flow in. I'll pressure test it again to confirm and then install it. It's just temporary but I was curious if JB Weld. Plastic Bonder would hold up.

Terry


Initial crack I found


The actual length of the crack held open with screwdrivers.


JB Weld Plastic Bonder applied.

Oldblue

Seems you have the seam crack problem fixed!

donbrew

If you decide to try to fix it AVOID silicone, it will kill your O2 sensors and cat.

terryk

I pondered fixing it but at 22+psi and it being split along the long seam and then the crack ... well ... ya know. :)

Edit: Removed the snark and I decided to try and fix it for fun. See above.

Edit2: I suspect the JB Weld won't adhere well enough to the plastic. It's curing right now and is certainly rock hard but I am suspicious. If it doesn't then I might break out my plastic welder and see how that goes.

Edit3: Yup, few things will work with PA66-GF25 Nylon ...

It appears the pipe has been split slightly for a period of time along the seam and with expansion and contraction a crack started outside the seam eventually traveling to the center of the pipe. It finally opened enough to pretty much kill all of the boost. In hindsight, I have watched the boost go to 22 or so (depending on a lot of factors) and then sag off a couple of pounds. I'll be curious if that goes away with the new pipe.

PulpFriction

I would be inclined to bandage it with fiberglass cloth and epoxy resin. If I was stingy I would etch the plastic and prime it with plastic-compatible epoxy, and after that set, apply a patch. But a foolproof and very strong fix would be to just wrap the whole thing in a single layer of light fiberglass cloth. Polyester resin would probably suffice but I would use epoxy.

I keep glass cloth and marine grade epoxy around for a boat but fiberglass muffler bandage kit might work.

Same principle would apply to the other various crack-prone plastic induction parts.

Oldblue

Possibly a fix while pipe is still in place , to get you home!

terryk

Ah, that gleaming smile of success! (tm FST)

I bought and just installed a new replacement GM pipe. It doesn't appear they made any improvements in the pipe.

I noticed a couple of performance changes from before it finally split. I believe (and I believe a lot of things) that the pipe was leaking for a long time:

1. The fuel trims are now nearly 0 vs being slightly negative (around -5) I remembered I disconnected the battery so I don't know yet what the final trims will be.
2. The boost builds quicker and holds without any sag. I do see it go to 20-21 psi and then rise to 23 in 2nd and 3rd gear as it used to when the weather is cool as it is now. Boost varies with weather.
3. I pressure tested to 30 PSI for a couple of minutes and it held with very little drop. I didn't blow the ends off the intercooler either!
4. Amazing how small drops in performance can get by you. It feels like that original rush when I had the GMTU installed. Whoa!

I am considering just getting a ZZP pipe for daily driving and save this pipe for emissions testing (pass visual) but I was also thinking a very tight wrap of of plastic section would be good to limit the ballooning which leads to cracking. Something to ponder.

To PulpFriction and Old Blue - After messing with various solutions I think the only viable one is a nylon solvent and patch applied to the inside of the pipe which would be nearly impossible to achieve. Many things will stick to Nylon but few will stick well enough to hold 25PSI of pressure.Anything on the outside would just flex under boost and leak. The Flex Seal tape might get you by to get you home as Old Blue suggested though! My crack was long but in a section you could easily wrap on the side of the road. Don't tempt fate with a lot of boosting. You'll lose.

So, once again P0101 with major bucking was was a boost leak due to a cracked hot side intercooler pipe. For the archives.

donbrew

You don't think wrapping fibreglass/epoxe would withstand 50 psi (I wanted to be an engineer, always double parameters when testing)?
Plumber's GOOP would probably stick, but I don't know if it has silicone in it. I know it sticks to HDPE (drywall compound bucket) without roughing it up.

Greybeard999

I'm pretty sure GOOP products are silicon based.

terryk

I recall seeing a video of the upper pipe ballooning under boost. It might have been a Cobalt rather than an HHR but it was interesting to see. Does anyone remember it and have a link? Actually, it wasn't ballooning but rather changing shape.

When I pressure tested mine at 30psi, you could see it but I want to see that video.