Stripped Bung

[cody]

So I installed a new gasket between the UP and ex. man. today. It went fairly well (the exhaust leak is fixed) except when I was reinstalling my EGT probe, I think I tightened it too much. Everything was good and tight but I guess I gave it just a touch too much torque, because it started to spin more easily when I gave it that last 1/4 turn. So I just stopped and left it.

I figured that it would leak on my test drive but it didn't. I got into full boost a few times and it sounds perfect.

I'm tempted to just leave it but I feel like that could bite me later. What should I do? I think I've heard that the best thing to do would be to tap the hole to the next size and put a hilacoil or something like that in it to restore it. Is that right?

This is the DIY I followed like 4 years ago when I originally did the install except I did the passenger side for some reason: http://www.scoobymods.com/forums/mod...=egt+probe+tap He suggests that you can check for a leak with soap and water. I suppose I could try that, but I'd think I would hear it under boost if it leaked.

The tap I used is labeled as "1/8 27 Pipe". The gauge (and probe, I'm assuming) are Omori. The gauge hasn't even worked right for a while but I had just emailed JspecTuning on Friday afternoon asking how much a replacement probe would cost, as I believe that may be what's causing the gauge to read incorrectly.

I'm tempted just to tap it to the next largest size and put a short bolt into it since the gauge is most useful after a tune or maybe at the track, things I have no plans to pursue any time soon. Thoughts?

[van]

is pipe thread what most exhausts bungs use? doesn't seem right to me (although I'm wrong most of the time).

[cody]

I seem to remember that it was recommended for my application and it seemed perfect before today.

[cody]

Maybe I should use this opportunity to get PP&C'd OEM headers.

[A1337STI]

Pull it out, get it fixed by having a peice of metal cut to match and welded in. and put your probe on the otherside this time? or you could place it back in the same spot it is now, though it would be harder to cut though. you could even just get a small bead of metal welded in around it and retap .

[van]

You could try cleaning up the threads inside the bung with the tap and then the threads on the sensor with a diamond file or die. If you're sure its not leaking just leave it alone.
Did you do the standard leak test?
-stuff the tailpipe with bananas or a potato (bananas might work better with your yellow car).
-start your car
-spray soapy water on your "bung" and see if it bubbles/leaks gas

[cody]

I like the way you think Van.

It'd be great if I could simply add a layer of teflon tape but obviously I'd need something much more heat resistant. Any other solution requires that I remove the header to avoid getting metal shavings into the turbo.

Well, a short bolt that's a touch wider than the probe or welding it shut are options too I imagine.

[Kevin M]

Personally, I wouldn't do anything until you can hear a leak or your EGT readings get wacky.

[cody]

My EGT gauge displays nonsense and has for a while. Part of the reason for that was a faulty vampire connector that I replaced but I think the last time I had the probe out, I damaged it because although the needle doesn't jump around to the beat of the music I play like it used to, it still reads way low and intermittently reads zero. That's why I emailed to get a quote on a replacement for the probe on Friday. I could really live without the gauge, I think.

[Dean]

Check that the gauge is getting a good ground and a filtered +12. More aftermarket gauge problems are due to incorrect wiring than anything else. They, just like ECU sensors, have to share a good reference ground and regulated power.

[cody]

It uses ground and hot from the OEM clock wiring, just like my Omori electronic boost gauge which has always worked perfectly. I guess the EGT may just be more sensitive. But I really don't value the EGT gauge nearly as much any more. It'd be cool to fix it, but there's too much uncertainty regarding the real issue and it's just not worth it to me anymore.

I've got it all taken apart again. Soapy water revealed that it was leaking. I have confirmed that the threads I cut into the ex. man. are what stripped. I really wish I had a slightly oversized bolt I could just plug it with and be done.

[sperry]

Do you have a full-on bung welded in there or just a tapped header? If you don't already have a bung welded on the header, you can just drill out the hole a little and get a bung welded over the top of it.

If you do already have a bung on it, you could have it grinded off and a new one welded on. I wouldn't try to heal-a-coil an EGT probe... lots of those heal-a-coil solutions use the equivalent of JB-weld. A full-on repair insert might work, but even that's going to add yet another layer of metal that has to heat cycle over and over w/o loosening up.

[cody]

...

[cody]

It's just tapped. Can you just weld in a bung? Jeremy of Crucial Racing posted that you have to heat up cast iron to 500*F before you can weld on it. I didn't think that helacoil required any JB Weld type stuff. I actually considered JB Weld, but at least the "Quick" version I have says it's only good to 300*F. No good.

In the interest of saving me from typing two updates, here's the latest update I just typed on WRXFanatics:

I've had it out so many times over the years because it has to come out any time I remove the heat shield to get to various pre-turbo leaks I've had. Once I got all OEM gaskets back in, I thought I'd be good, but the stupid UP to Ex. Man. gasket started leaking again so I took the heat shield off to diagnose if that's where it was really leaking and when I saw that it was, I didn't have a new gasket so I simply tightened the bolts which cured it for a few months but the leak, unsurprisingly, came back so this weekend, I put in a Grimmspeed gasket since they come highly recommended and Ed gave it to me last time he was up. They're basically OEM but a touch thicker. This time I loosened all of the bolts I could get to for the UP to Turbo connection and the bolts that secure the turbo in place. That got me a touch of play, but not as much as I expected. I guess there were some bolts that I couldn't get to but it did allow the UP to flex a bit. I also loosened the Ex. Man. to head bolts. Then I put in the new gasket and torqued it down as hard as I could with box end wrenches and a rubber mallet. Then I retightened the Ex. Man. to head, then tightened up the UP to Turbo bolts, and lastly the turbo bracket bolts. This is the order I’ve seen recommended in a few places.

So that leak is now fixed. No more rape whistle turbo noise and my boost response is noticeably better. I really don't want to take it all apart ever again, but the EGT probe is still leaking. And no, it doesn't work. I'm 80% sure I just need a new probe but it could be a problem with the gauge or the wiring.

So, yesterday, in an attempt to fix the issue, I looked for a helacoil at Kragen and True Value but neither had one in the correct size for the probe so I may just drill it out to the next largest size and plug it with a bolt since it doesn’t work and it’s in the wrong header anyway.

What I ended up doing as a temporary fix is I used this Screw Hole Repair stuff I had picked up at Harbor Freight a while back. It’s just thin sheet metal that you cut into strips and put into the hole to act as a shim. I experimented with it to ensure it held up to the screwing back in process and it seemed to. But I couldn’t get the hole to seal completely and pass the soapy water test.

I’m tempted to just leave it since I really don’t think it’s losing much exhaust, but I won’t be happy with that. What if it blows the probe out at an autocross or somewhere else because the hole repair metal just melts…or whatever.

What sucks is that you’re supposed to remove the Ex. Man. Before you drill and tap it since any tiny metal fragments that you leave in there could destroy the turbo. But I’m tempted to just tap the hole with it on the car. The casting button I’d be tapping is on the bottom side of the Ex. Man. and the metal fragments are magnetic so theoretically between a magnetized screwdriver (with extra magnets attached to it for good measure) and a vacuum, I should be able to clean them all out and then just plug it with a bolt. If I destroy my turbo, I have another one I bought used for $100 shipped with only 10K miles of stock boost on it so it’s basically new, and how much longer can my current turbo with 102K miles on it (much of them at max boost of 16-17 PSI and lots of autocross and spirited driving…) really last?
That sucks that you can't weld on cast iron without removing it. I still wish I could just score a bolt that's slightly oversized to plug it. I think I'll call our local fastener shop which has awesome hardware and see what they suggest.

Jeremy, please go ahead and PM me a price for that replacement passenger side manifold, but is there any danger to running only one PP&C'd manifold? I'm guessing no.

http://www.wrxfanatics.com/index.php?showtopic=60022

[sperry]

When I had a shop weld a bung to my old headers, they just welded it on... I'm pretty sure there was no oven involved.

Also, if the EGT probe uses the bung as a ground, there's a chance your readings are crappy because of the loose threading.

If you really want this taken care of once and for all, get a bung welded on, and get a stainless plug for it so you can run w/o the EGT probe if you need to.

[cody]

Yah, it seems like if you had to heat the pipe to 500, you could just do so with a blow torch. It's on the wrong side so if it can be welded, I just want it welded shut.

[AtomicLabMonkey]

You don't have to preheat cast iron, but it's definitely helpful. And if you preheat a part, you want to do it uniformly.. not just focus a blowtorch flame on the spot you're gonna weld.

http://www.lincolnelectric.com/knowl...ronpreheat.asp

[cody]

Would you recommend that I tap it for a bolt and use a bolt to plug it instead?

[AtomicLabMonkey]

I'd rather not make a specific repair recommendation like that, since I don't own one of these cars and I've never even seen the part in question.

[cody]

Well, if it helps, it's a heavy cast iron OEM exhaust manifold and the probe regularly saw temps upwards of 1500*F. The hole that needs filling is tapped into a casting button (small raised bump on the surface) and it's nowhere near any existing creases or welds.

[Dean]

In cast, I'd try a NPT plug of the right size. they are often slightly tapered and might bite. if not, tap one size larger and plug rather than welding.

[Kevin M]

Yeah, I think threading in a plug is probably the better idea.

[cody]

Originally Posted by Dean

In cast, I'd try a NPT plug of the right size. they are often slightly tapered and might bite. if not, tap one size larger and plug rather than welding.

I held one of the correct size (if the threads weren't stripped) in my hand at True Value yesterday but figured it'd be useless.

I called R&E and they said they'd be able to fix me up with a tap and a bolt for $20-30. I think I'd rather buy a tap on the cheap and then go there to grab the bolt to plug it.

Any recommendations for a single tap? I'm thinking Sears since I could grab a pair of shorts while I'm at the mall anyway, and that's where I got the first tap years ago.

Shit, for $12.99 maybe I should just grab this set: http://www.harborfreight.com/cpi/cta...emnumber=39384

[cody]

Oh, and Jspectuning says Omori went out of business and they were taken over by Omori USA and they no longer support the "old style" gauges. The new probes may work if spliced in but no guarantee. He said he'd sell one to me at cost if I wanted to try it ($50 shipped) but this just enforces my desire to say fuck the gauge.

[Dean]

I have that or a similar HF kit in both English and metric. You are welcome to borrow it. And NPT plugs can be had at lowes, Home Depot.