I have a Megan Racing 3" turbo back exhaust. Everything fits fine and the downpipe has a flex section. Well Friday I went to a road race at the Autobahn Country Club for a lapping day. After 2 hours of track time I noticed the sound of an exhaust leak coming from the O2 housing area. I jacked up the car and HOLY CRAP my Dowpipe was missing one bolt and the other wasn't even hand tight! I tightend the one bolt, called it a day, and headed home.

I replaced the missing bolt and double checked the existing bolt for a lock washer. All appeared to be fine so I tightened them back up and took the car for a beat run. After an hour of abuse I brought the car home and check the torque spec (45ft/lbs) on the bolts.....they had come loose again.

Now I dont know if this is because I am not using the factory spring loaded bolts or if there isnt enough flex in the exhaust system but it certainly isn't a good thing.

I suggest everyone double check their downpipe bolts.

ANYONE ELSE HAVE THIS PROBLEM? ANYONE SOLVED THIS PROBLEM?

 

just put some locktite on if ur really worried

 

It probably gets hot enough to melt loctite......that....and.....I used antiseize on the bolts so I doubt it would work now.

 

did you have anti-seize compound on there? Also are the springs still on there, the compression helps keep the bolt / downpipe on tight

 

First time i heard of this! Good luck DONT LOOSE ur DP

 

I suggest keep checking them, anti-size good.

 

lol took to long to type the msg. just degrease the bolt and hole with acetone and keep them bone dry...it should stay on...

 

I used grade 8 bolts with lock washers not the factory spring bolts (though I still have them). I may give loctite a try and if that doesn't work then go back to the stock spring bolts.

 

45 ft/lbs seems too tight to me. The factory specs are 37ft/lbs for the O2 housing to downpipe and 45 ft/lbs for the cat bolts.

 

So use antiseize or not?

 

Using Anti-seize will just help it loosen easier when your taking it out. Thing smells to when it burns up.

Thighten them up a little more. Those are 10mm bolts so another 20ft.lbs shouldn't be a problem. Or re-use the factory bolt and springs.

 

Should've stuck with a downpipe that uses the spring bolts and donut gasket. That is what the car came with from the factory that is what you should've stuck with. It is funny when people deviate from what professional Mitsubishi engineers designed for the car and then wonder why there are problems.

 

Um you can use the stock spring bolts and it does have a donut gasket.

Many people told me to not use the spring bolts....so I didn't. If they come loose again I will try the spring bolts.

 

I've used anti-seize from day one, and will not put anything in an exhaust component without it. Period.

As for the bolts, I highly suggest to people that they NOT use the OE spring bolts to mount to flush flanges together as that is not their design. I suggest people do as I did and go buy you two 10mm 1.5" 1.25 thread stainless steel bolts. Put a stainless flat and lock washer on there also. I've not had one fail on me yet. However, I do "hand tighten" them probably well over the OE torque rating. Just the same, with the testing I do, and the bolts going in an out, I've had no issues.

In the above case, I would suggest that either they were not tight enough, and the lock washers might have failed. I use the good old fashion Ace Hardware store bulk stainless hardware for the bolts and washers.

 

PS, with the Megan downpipe, you are supposed to take the OE donut gasket off! Otherwise the two flanges can not mate. I just used the cheap, crappy gasket supplied by Megan... and it still has not failed even with all the removal cycles.