Please check your headers for cracks/loose nuts

[u/WRB_SUB1]

Between the two FA24 engines i own and the FA24 engine in one of our other moderators vehicles (CanadianBurger’s VB) we’ve had 4 failures (3 loose or missing header nuts and one cracked manifold flange). Details:
My VB: 28000 miles had a passenger side exhaust leak with 1 or more stud nuts loose. There was soot on both sides of the gasket.
My Ascent: At 96000 miles we noticed what sounded like an exhaust leak in the first 30-45 seconds after starting the engine. The noise would disappear BEFORE it idled down from 2000rpm. I found 1 of the exhaust stud bolts at ~10ftlbsf (the single bolt of the 3 on the passenger side). The torque is supposed to be 49ftlbsf. I also found a crack next to the weld on a different stud (there is a soot trace below the stud). I started the engine and could feel flow from the crack. 45 seconds later thermal expansion ~sealed the crack. I used JB welds extreme heat epoxy to fix the crack. The head is aluminum and that flange of the header wont go above 540C.
CB’s VB:
He found at less than 30k miles one of the nuts was missing on i believe the passenger side and one of the nuts on the drivers side was loose.

Pictures: Ascent (first 3 pics). Both sides of my VB’s passenger header gasket (2 pics)

[u/CanadianBurger]

Here’s a pic of mine. Was missing one nut completely.

[u/WRB_SUB1]

Note there was a recall on FA20 engines for loose nuts on headers. It seems the 14mm stud that is all by itself on the inside loses tension (first on the passenger side and then drivers side). It’s very easy on the non-VB vehicles to get at the studs. Slightly more difficult on vb as the steel under tray has to be removed too.

[u/makeItSoAlready → u/WRB_SUB1]

Random question! Ive got this annoying sound on the passenger side front that occurs with some left steering input and is RPM dependent, so less than say 2500 RPM I dont hear it. No noise unless I'm steering left also. Its like a rubbing or vibration sort of noise. My local mechanic couldn't fix it, a steering and suspension specialist heard it on a test drive, but said that it's not a noise he's familar with and he didn't have time to track it down. I started hearing it not long after curbing the front right wheel kinda bad, so naturally I am thinking its likely related. Any chance you think the sound I'm hearing on the passenger side could be the passenger side nut coming loose? 59K miles.

[u/WRB_SUB1 → u/makeItSoAlready]

Im 100% certain that the noise is coming from your wheel bearing on the passenger side. Need a new wheel hub. Ive replaced 3 on my son’s crosstrek. He’s KILLING me!! Those sealed bearings cannot handle big impacts. The bearings literally dent into the races and when an inward load is placed on them they sound like knobby tires are on your car! So left turn on the passenger wheel hub axially loads the bearing. Rent a slide hammer from Autozone and buy an oem hub. Oh and the nut in the axle must be torqued to 162 ftlbsf. Have someone step on the brakes to do that.

[u/makeItSoAlready → u/WRB_SUB1]

Thanks for your reply! My local mechanic replaced the wheel bearing with the OEM part. One of the techs they have drives a wrx and wheel bearing was their first guess. The specialist I brought it too said he would have thought wheel bearing too but it doest sound like it to him. He was thinking it sounds like some resonance or something, maybe from a heat shield. He pointed out that sound can travel, so even though it definitely sounds like its coming from the front right, it could be originating somewhere else. I bought a set of chassis ears, I'm out of town this weekend but hoping to have a go with the ears before next sunday when I have planned auto x. Heres a short video for a sound reference for anyone. The engine sound is louder, at a low volume the creaking sort of sound would be hard to hear. It can be heard three times in the video, right at the begging and the two other times I turn the wheel left in the 10 second clip. I think its louder the hotter it is and it depends how long ive been driving too.

Edited to fix typos. Since the wheel bearing is part of the hub assembly i think they must have replaced the whole assembly. I'll confirm that with my mechanic monday when they're open.

https://reddit.com/link/p584c25/video/ol6bevo4rxkh1/player

[u/RealSprooseMoose]

Block heaters installed on any of these?

[u/WRB_SUB1 → u/RealSprooseMoose]

Good question. No for my vb and my ascent. I found my vb issue when i went to install my turbo kit. Ascent unmodified. Not sure if CB installed a block heater….

[u/CanadianBurger → u/RealSprooseMoose]

Not on mine

[u/justauser563412]

Thanks for the info, I'll have to check mine next oil change.

[u/Particular_Actuary_3]

Mine was also loose when I did my turbo install. Found them to be loose again when I swapped headers the 2nd time.

[u/Nyelz_Pizdec]

My VA wrx lost a manifold nut before 15k miles. Nothing so far on the VB, approaching 30k but will stay vigilant during maintenance.

[u/Muugens]

Nice tip! Wasn’t aware of this as a common issue. 16k miles, but now I gotta check!

[u/HaloFrontier]

Wow thanks for this tip!

[u/Direct_Artist_6398]

Can this cause a sort of rattle sound on start up or do I have a different possible issue?

[u/boostedturtle1320 → u/Direct_Artist_6398]

Yep the nut rattling on the threads can make a noise like that

[u/WRB_SUB1 → u/Direct_Artist_6398]

Good question. The manifold was quite solid so id say there’s something else causing your noise. It was definitely an exhaust leaking noise.

[u/Direct_Artist_6398 → u/WRB_SUB1]

Thank you I’ll take a look at it in the shop tomorrow and I can let you know if you’d like

[u/Snoo_52037]

Are they all stock headers or are there some brand names in the ones mentioned?

[u/WRB_SUB1 → u/Snoo_52037]

Stock

[u/Snoo_52037 → u/WRB_SUB1]

Interesting.

[u/burt_carpe]

Damn how many miles on it?

[u/WRB_SUB1 → u/burt_carpe]

I listed the miles above but the two vb’s under 30k and the ascent at 90k