exhaust manifold question

kilbrethj · Oct 10, 2007

i was putting a new water pump in my 94 3.0l yesterday and noticed that my exhaust manifold was leaking. after further investigating the issue i notice that a stud had broken off the passenger side manifold. i got to looking and it looks like if i pulled the head off i could pull the manifold off and drill out the stud. and if any more broke off i could do the same. i was wondering if i could drill out the hole a little larger in the head and then just re-tap the holes. would this be the best way to get rid of the broken stud? i realize if i did this i would also have to drill out the manifolds to. i plan on trying to rebuild the motor in a few months anyways so this would be the perfect time right? thanks

MAKG · Oct 10, 2007

To be honest, in a few months would be the perfect time.

Some people like to drill out broken studs with the manifold in place, as the manifold holes serve as a kind of drill guide you wouldn't otherwise have. You can expand the bit (away from the tip) with masking tape and grease the outside to fit the hole nicely. It would help a lot if you removed the manifold completely and ground the broken part down flat if possible before reinstalling the manifold.

If you can, the best thing to do is drill the stud out to (or near) its current tap drill size ALL the way through, centered directly on the stud. This is not easy. Sometimes you can collapse the now-hollowed-out bolt with Vise Grips before you get to TDS (BTDT on a heat riser bolt). You can instead drill the hole straight through and just use a nut on the back of the flange (no tapping).

If you're good with an oxyacetylene torch, that is the fastest way out. I'm nervous with that much heat around cast iron.

Just some ideas.

85_Ranger4x4 · Oct 10, 2007

If it is broken off flush with the head you are stuck drilling it out. Sometimes if it is broken off aways away from the head you can put two nuts on it and turn it out with a wrench on the inside nut, it has worked great for me in the past in similar situations.

RobbieD · Oct 10, 2007

I've had to drill them out before, with the motor in the truck. Best advice is use the sharpest-assed drill bits you can find, and be sober when you're doing the drilling.

kilbrethj · Oct 11, 2007

yeah... sober would be the best bet but weekends in a small town get offly boring sober!!! lol.... i think drilling them out completely and just putting a bolt with a nut would almost be the best bet.... it seems logical and i bet it would hold then manifold very good! i am still up in the air with it though.. i am thinking of trying to rebuild the motor. i have never rebuilt a motor before and i only paid 800$ for the truck and the only things wrong with it are it has a headlight out, cracked windshield, and the exhaust leaks.

RobbieD · Oct 11, 2007

Heh heh; I know that it's asking for true dedication and a lot of sacrifice, but maybe you can drill early and drink later to celebrate. Just kidding with you, and I found that the tapping part was really easy compared to drilling them out. I went back with new stock-size bolts, since I had to repair 4 of the 6 on the one side. Whichever way you go, good luck with it. Seriously, though, new sharp drill bits, and oil, are the ticket.

exhaust manifold question

kilbrethj

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