Exhaust manifold leak

[AresROC]

So I put some SeaFoam in the intake manifold last night. Found out I had an exhaust leak! I took the exhaust manifold cover off so I can visually inspect for any smoke coming out it. Turns out I see fluids coming out of it!

Car has been running rich during idle, with high HC hydrocarbon. This leak between the exhaust manifold and down pipe, upstream of the O2 sensor, may just be the cause! This may also explain the rough idle due to loss of power caused by the leak.

Does anyone have any suggestions about how to fix this? I was thinking either J-B weld, exhaust sealant or new exhaust gasket? (if there is one)

[Tercel GTS]

Manifolds are cheap and plentiful at salvage yards.

[AresROC]

The SeaFoam came out right at the joint between the exhaust manifold and the down pipe. Maybe the exhaust manifold is cracked underneath? I hear the manifold is going to be a b!tch to remove so hopefully I can avoid that. The 93' Paseo has 170k miles on it.

[96paseo]

The cone shaped gasket that lies in between the header and down pipe may be your problem. Remove the header flange bolts and lower the downpipe. Check the condition of the gasket and header flange before you go hunting for a used header.

[Tercel GTS]

Check the flange on the downpipe as well. The one on my 92 Paseo is broken off.

[AresROC]

Finally checked on the manifold to downpipe flange. At first it looked weird to me, after a closer look it appears both bolt's hex heads are broken off. There is a bolt stud without the heads sticking out on top, and the rest of the bolt and a nut on the bottom.

No wonder it's leaking, the thing is only loosely held together!

Since I can't get those bolts out, does anyone know the size and thread on them by any chance? I plan to put some high-heat sealant on it, and find some reverse nuts from a specialty hardware store and see if I can tighten them with the studs that are sticking out.

[96paseo]

Those bolts are flanged and have retaining springs to hold the pipe flange against the gasket. Order new bolts and springs from the dealer and save yourself the headache. Use some penetrating spray on the old bolts and let it sit overnight. Remove the downpipe and try removing whats left with vise grips. If that doesn't work, start shopping for used manifold. Order a new cone gasket, manifold gasket and bolts/springs to go with it. Your rubber exhaust hangers are probably shot so get two of those too. Spray the manifold bolts and let sit before trying to wrangle them out. Good luck.

[AresROC]

So I tried to remove the bolts, no dice. I tried WD-40, thought about using a propane torch or just saw it off. I also bought an air ratchet for it (probably should have spend the money and get an impact wrench), but didn't end up using it.

I did end up discovering the reason of the leak! One of the flange bolts didn't even have a nut on it! I got this car from my sister-in-law, and I know she only takes it to one shop in town to work on it. I even know the auto shop's owner for a long time. Can't believe their quality of work on this Paseo... if I can't trust them, I can't trust anybody... all the more reason to work on it myself.

So I bought M10 1.25 nuts from AutoZone, tightened it with a retaining spring washer, and put on some high-temp silicon gasket maker for good measure. Still didn't pass the smog test, but no more leaks!

[Tercel GTS]

Does your car have an EGR?

[AresROC]

Yes it does have an EGR. I took out the EGR valve, and found one of its tubes block-filled with carbon deposits. I cleaned out that tube, and rinsed down the EGR with throttle cleaner. The car idled better after that (but still far from smooth), at least it won't stall when I jam on the brakes.

I haven't checked on the EGR valve yet while idling. (I forgot to test it) And I haven't checked the exhaust tubing to the EGR valve, 'cause I couldn't get if off the exhaust manifold... but since it is a larger diameter tubing I hope it won't get plugged...