Resolved Anybody else have the exhaust bolts back out?

[rdeis]

FP manifold, 16G, STM O2 housing.

I was getting exhaust in the cabin, so I used the hose-to-your-ear trick to find leaks in basically all the joints between the head and the downpipe. Looking closely, I found that a bunch of bolts had backed off.

So I got all new stainless bolts and lock washers and gaskets, torqued to factory specs, and all the leaks closed up nicely.

For a couple of weeks.... Then it started stinking again and sure enough some of them were loose again. I retightened, closed it up again, and no a couple of weeks later I'm wondering if I'm smelling exhaust again?

Am I using the wrong hardware or something? Will AEM bolts fix this for good?

 

[BLACK'98DSM]

What torque spec did you use?

 

[SixBolt_16G]

Damaged threads, maybe? Leaving enough space for vibrations to jiggle them out..

 

[pauleyman]

Are you using the factory turbo washers? FP supplies them in the hardware kit. The factory washer isn't actually a washer. Its a Belleville spring. This is what keeps them from loosening.

 

[chrysler kid]

You should be retorquing the exhaust hardware after about a weeks worth of heat cycles

 

[rdeis]

What torque spec did you use?

Whatever the 1G FSM says, I actually got a copy of the real live book back in the day. Book says 40-47, I used 45.

Are you using the factory turbo washers? Fp supplies them in the hardware kit. The factory washer isn't actually a washer. Its a Belleville spring. This is what keeps them from loosening.

Aha! https://en.wikipedia.org/wiki/Belleville_washer
No, I am using stainless split lock washers.

Am I correct to assume that Belleville washers ought to be used on the manifold-to-head and turbine-to-O2 joints as well?

 

[pauleyman]

Just turbo to manifold. Factory repair manual shows you use two per bolt under the head and they face opposite each other. Creates tension.

 

[Justin DuBois]

Do you have a support bracket on your Down Pipe?

The exhaust system is a LONG lever - attached to an engine that flops around in the engine bay every time you accelerate/decelerate. Make sure your motor mounts are in good condition, and check the brackets that help hold the down pipe to the block.

You want the flex section of the down pipe to bend, not lift and pull on the exhaust manifolds as the engine moves under torque.

 

[rdeis]

Actually, no- I've been looking for one of those. My googling and ebay hunting has come up empty, where would I find a support bracket?

 

[19Eclipse90]

1G

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2G

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If you don’t have any luck with the part numbers, post a want-to-buy ad in the Classifieds section or your regional forum. I’m sure many members have a few of these sitting around.

 

[Justin DuBois]

In the weld up 3” pipe realm - I stopped using a welded tab on the DP cause it was the spot that regularly tore open.

Now I use a T bolt band clamp around the DP on top of a long bent bar that bolts to the block bracket.

 

[ist dwa]

IMO your problem is using split washers. Run solid flat washers between the head and manifold and those cool cupped shaped OEMS one between the mani and turbo. Torque in sequence and then come back after several heat cycles are recheck them.

 

[rdeis]

IMO your problem is using split washers. Run solid flat washers between the head and manifold and those cool cupped shaped OEMS one between the mani and turbo. Torque in sequence and then come back after several heat cycles are recheck them.

This is definitely true. I tore it apart and found the split-ring lock washers are totally flat- after being tightened and heated a few times no spring action remains at all so they aren't locking anything.