Exhaust manifold studs ... replace 'em!!

[12Ounce]

Working on '97 Tracer 2.0L, ...that did not drop valve seat! I am re-learning a lesson I have learned before ... do not reuse exhaust manifold studs and nuts!!

I'm putting the finishing touches to a "regular maintenance" engine rebuild ... rod bearings, new rings, valve job, all seals, etc ... on a 175k mile vehicle. I'm fastening up the exh manifold, reusing studs, ... bringing the torque wrench up to 17 foot lbs, and the last one snaps !!! Deep in the head!!

If I can't fish it out, the head comes back off ...

How much time and money will be lost because I did not spend a little time and money for new exh studs? Exh studs get a real torture test ... high heat ... mech stress .... moisture exposure ... dis-similar metals ... you name it! There is often corrosion/cracks that occur just where the stud inters the head. They often break in normal use ... as you will perhaps discover when removing a manifold on a high mileage vehicle.

... benefit from my misfortune.

[midunno]

i just hate it when that happens.. best of luck on your "fishing" trip!

[mightymoose_22]

17 pounds isn't very tight... I would expect you could drill it out fairly easy. The deeper it snapped, the less stud there is.

[thisnametooktolong]

I don’t know the exact spot but a right angle drill can help you get in the correct spot and not pull the head. You could rent one in ¼ inch if you don’t have one. They also make (also rented) a very tiny air drill with a right angle head.

Start looking around for reverse-twist drill bits. Many times when you start drilling it will just come out by itself. It is extremely common with a fresh bolt that has not been weathered in yet. Fasten-All sells very long reverse bits that can be cut to your perfect length. (about 2 feet long to start)

[Intuit]

Thanks for the warning/suggestion. The end of the stud that broke off in the head was probably the end that was originally exposed and attached to the manifold nut. That's the side that experiences all the deterioration.

I think I did reuse my old manifold bolts as well but soaked them in oil, cleaned them up and didn't torque them into the head. Like the intake manifold bolts, after ~190k they were all loose and/or backing out anyway. I did torque the nut onto the manifold. Also packed quite a bit of engine oil down into the stud holes as was inserting them.

[mightymoose_22]

@ Intuit

Now that you mention it, I think you are probably right. One end is typically more corroded, and as I recall, one end of the stud is longer than the other (more threads). If the wrong end is inserted it might be easy to overtighten thinking that you still have a ways to go...

[12Ounce]

Thanks for all the good replys. Been on a little road trip, so the engine project is now waiting for me.

I have also reused exh studs before and "gotten away with it" ... but have also had enough failures to "know better".

These particular studs have the reduced hex/star on the outside-end for driving into the head .. so they surely were not reversed on installation. I agree with the right angle drill motor ... I have one somewhere, ... now to find it and give it a try.

[12Ounce]

..fishing expedition successful! Got about 1/2" minnow!

Found my right angle drill. Used a new-sharp 1/8" bit. Cleaned bit often of chips and relubed with Vaseline. Used mirrow to assure drill was on target. #3 Easy-Out took it right out.

Bought 8 new studs (N811313-S431) and 8 new nuts (W701706-S2) from Ford (approx $20). Interestly, these items were also in another counter customer's order ... the parts salesman pointed out.

Manifold is back on and torqued (very carefully!) to 200 in lbs.

[denisond3]

Mucho thanks for the part numbers!! I have not had any problem with the Esort studs, but this time I think Ill put a new set on. The engine, which is apart on my bench at the moment, had 187,000 miles on it, and I already replaced the two studs in the exhaust manifold at the outlet. (I sliced the threaded portion from a pair of used engine head bolts, cleaned them up with a die, and put them in). I always use a silicon/nickel based antisieze compound on ANY threaded item on the exhaust system.

I am also doing a 'regular maintenance rebuild' of the engine; new valves and seals in the head, new rings, bearings and engine seals, and of course new water pump and timing belt. I like to think of it as 'pre-emptive repair'.

[12Ounce]

I'm currently using the Permatex anti-sieze. Don't know what's in it ... but metal of some sort.

Just curious: Did you happen to notice any defect in the inlet manifold gaskets? On both '97 Escort engines I've recently worked on ... there were defects in the inlet gaskets ... tho there was never a air leak detected.