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Dreaded powerlog crossover leak

12K views 41 replies 3 participants last post by  fastech 
#1 ·
Welp I got my powerlog front and rear, installed the front this morning and now I have leak where the flange meets the crossover. Took zzps bolts out and reused the stockers and it's still leaking. I can reach directly behind the crossover from the front and feel the leak around the rear. And yes I tightened both bolts equally and as tight as possible.

I've contacted zzp since this is a known issue and some guys have returned theirs due to not being able to remedy it.

If anyone has any suggestions I'm all ears, not counting on getting a phone call back from zzp.
 
#2 ·
-slams head against wall-

Got back from work, retried the stock and zzp bolts. Neither are working, a very small leak at the rear of the plog flange. ZZP bolts even with the washers are too long to clamp onto the freewheeling flange on the crossover. I've literally got a 1/8 inch gap between the bolt head and the washers, so tightening the nuts under the plog flange does Jack ****. Stock bolts clamp it down however they pull on the front of the crossover flange more than the rear which in turn leaves a paperthin gap in the rear.

Checked on Google and numerous 3800 centered forums pointed out defects with the grind on the plog flange, mentioned funny fitment in the flange area, and also one mentioned a ceramic coated crossover fitting like a glove. It's either that or its possible my crossover could have expanded a bit, but seeing as how my stock manifold sealed, it leaves me to believe it's a quality issue. Trying copper rtv tomorrow, a few guys recommend it.

Got an email back from ZZP stating "they've never heard of this issue, are you sure a gasket doesn't fit there, it's been a while since I've worked on a 3800".

I'm beyond frustrated right now, if RTV doesn't fix it and they have no suggestion as to how to remedy this fitment issue I'm sending both back and I'm demanding a refund.
 
#5 ·
No gasket for that area. Called Mieneke and they suggested ultra copper rtv, also suggested that the crossover flange expanded like I ed thinking. Everything is back in place, just gotta wait 24 hours for it to cure, if this doesn't fix it I'll need a new crossover.
 
#7 ·
Rtv blew out after 2 days, called a dealership over 20 miles away and there IS a gasket for the front crossover. Since so many folks have this issue Ill update with the part # when it comes in tomorrow.

The RTV almost clogged my cat. Rotten egg smell after driving. Went WOT on the interstate and she backfired and the smell slowly went away. Do NOT use RTV. Luckily I didn't go nuts with it.
 
#8 ·
POS crossover pipes

Did you see the gasket in an illustration to confirm it's what you want? Where did it come from?

These POS crossovers have been a pain in the neck for a lot of years now. I've seen them get over tightened and expand flange. I've seen them get installed without positioning it properly, thus bending the flange out of shape.

Usually the only fix is to position it to where it feels "natural", tighten and drive then readjust the POS in either direction, then tightening and driving again. What a pain...

It must be a really large gap for the sealer to blow out. I've cleaned surfaces and used spray powder to find where there is and isn't flange contact. You could use gear marking compound or anything else that would leave indications of contact.

Good luck sealing it up. B
 
#14 ·
I installed THe Other Guys headers many years ago. I seem to recall installing a metallic type ring at the crossover. It only makes sense to have a gasket there.
 
#16 ·
Thanks for the pointer fastech. If there is no gasket then RTV may work. I retightend the bolts and they had come loose a bit. Ill look into some high temp thread locker as well. If I can't find that then Ill may be able to use the nuts off ZZPs bolts to clamp everything together.
 
#18 ·
Lol I may have exaggerated a bit. There isn't an 1/8 inch gap between the mani and crossover. Looking at the old manifold the contact area between the two is 1/8 inch wide. That's why I didn't use 1/4 inch thick application of rtv, had I of used that much my cat may have clogged.

After getting everything lined up properly the second night trouble shooting I tried sliding my finger nail between the mani and crossover and it wouldn't fit.

I'm not comfortable using high temp thread locker due to the heat needed to break the bond in the event she leaks after I've left it to cure. The only one I can find that would hold up is rated from 750-2000 degrees.

I've noticed Teflon paste on the bolts I reused, Ill go checking around for some later today.
 
#19 ·
After searching online it appears to be anti seize, someone feel free to educate me but I don't see anti seize keeping the bolts from coming loose, not factoring in heat cycling.

I think I'm going to pick up a pack of washers and nuts to use on ZZPs bolts. I can add more washers to take up the gap I had and add an additional nut on each bolt to keep the vibration from backing them off. It'll look uglier than hell but it may be crazy enough to work.
 
#20 ·
Got the same washers and nuts ZZP sent with the powerlogs, gonna pull it off, re rtv the mating surface and clamp everything nice and tight. I figure if I can lock the 2 nuts together they won't come loose this time. I also noticed last week the bolts at the rear of the crossover and so tight you need to push down on the crossover before putting the bolts in or it doesn't sit flush.

Ill update in a couple days, if it blows out again Ill have to get the ceramic crossover. It's $60 cheaper than an OEM crossover on rockauto.
 
#23 ·
exh crossover leak

Anti seize is used to keep the bolts from rusting and seizing. It's the clamping force of the bolt that keeps the bolt from coming loose. I think you're on the right track about using lock washers or locking fasteners. If I had an exhaust bolt that kept coming loose, that is what I would do. Large shakeproof washers usually clamp better than regular lock washers. You could put a shakeproof on the bolt head and on a back up nut.

Loctite on exhaust bolts doesn't make any difference because the hot exhaust cycles will melt the Loctite.

Good to hear your making progess. Good luck with it. :)
 
#24 ·
I've got it all back together, waiting for it to set. I'm calling permatex to speak to an engineer in a few hours. I read an article online stating that high humidity environments cause the RTV that is compressed to cure slower than the RTV that is exposed to open air.


With a dew point of 30-50 and humidity ranging between 50 to 80 percent this time of year I was reading it could take several days to a week to fully cure.
 
#25 · (Edited)
That tech article was backwards. Sounded funny since the same article said moisture is needed to cure the rtv. The tech person I spoke to assured me that he wasn't trying to upsell, but that if he were me he'd take one bolt out at a time and apply red 271 thread locker to both the bolts and nuts. I'm skeptical because the rtv has already turned to rubber texture and I'm not trying to do this again. I'm considering just using it on the nuts. Could use some input asap.

Edit: Yep he's upsellin. Tech sheet shows less than 500f is needed to dissolve the epoxy.
 
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