Brickheads,

I have to replace 4 broken manifold studs in the 84 Turbo project car. I plan to follow the procedure laid out in the FAQ. I'll be using a rt. angle drill (millwaukee)and cobalt bits.

I want to re-tap the holes for a 10mm. stainless allen cap screws.

Is there anything I should be aware of outside of the advice given in the FAQ? I am worried that there might not be enough clearance to drill the studs in the front and back of the head.

Any tips on keeping the holes perpendicular to the head? I don't want to remove the engine if I don't have to.

As always, thanks

almost any stainless alloy is going to be weaker than a good steel alloy...it's only advantage is it's supposed to be proof against corrosion. But you're not a marine enviro, so I'd go with stock steel studs. Helicoil the heads if you must, but you'll get higher clamping forces with the stock studs.

Randolph,

Randy is making sense. With 5 pop the head....new head gasket alone is worth it...the hardest part is the turbo/ex. mani removal and you are already there.

And believe me I'm a guy that's done them in the car. Yes cobalt bits are critical....as are diamond bits...and moto tool.

I do question the socket head cap screws....I don't know if these are that great of a choice for this application. (weak at the head) Stainless maybe with the right alloy...

Randolph,

I don't want to throw a wet blanket on your party, but personally I haven't had much luck when it comes to drilling out broken exhaust manifold studs. Alignment is critical as you indicated. The hardened stud in a soft aluminum head adds to the difficulty (my opinion). A machine shop deals with these problems everyday and are actually pretty good at it. They are not always able to deal with them however if a lot of molestation (for lack of a better word) has occured prior to their attempt.

You would have to remove the head to take it to a machine shop. That isn't all bad. While the head is off they can go through it and check for plane, worn guides, replace the seals on the intakes and lap or grind the valves ("valve job"). You would basically have a rebuilt head when finished.

Either way take your time and enjoy the learning experience. If you are successful in removing the broken studs by drilling be sure to share your tips with everyone here as it is a common occurance.

Randy

Thanks guys, I appreciate where you are going with this. Believe me, not wet blanket here--I need to do this right.

I have taken compression readings in all four cylinders and they read between 118 and 125 psi. I never saw the engine smoke badly, the little smoke I did see led me to think the the crankcase ventilation system is clogged (and from all indications it seems to be fouled up and needs cleaning).

Since I will likely pull the head, have the valves looked at, and replace the head gasket what else should I be looking for?

The low compression worries me a bit. Should I be condsidering a ring job at this point also?

Thanks for the input,

Someone with more knowledge and experience will have to help you here. Low compression can be one (or a combination of) several things. The valves and rings (along with the head gasket) contain the compression. A valve job could very well bring the compression up, but you should determine if the lower than specs compression is a result of rings or valves. Squirt a tablespoon of motor oil into the cylinder and run another compression test. If the results are significant higher then it indicates that the rings are somewhat worn and the oil is temporarily sealing up the leaking. No significant difference and it would indicate the leaking is between the valve and seat. You should make a new posting with a "compression test help needed" subject line so someone can give you the fine points of conducting the test and diagnosing the results.

Addition things to have done when the head is off:

1. The machine shop should check for electrolysis damage. If the car hasn't had its antifreeze changed regularly electrolysis can damage the aluminum head creating cavities in the surface that can cause problems of sealing against the head gasket. These can be welded before any planing of the head is done.

2. Your turbo head doesn't have exhaust valve stem seals (because of the heat they endure). The guides need to be checked to see if they are worn. If they are worn they will allow oil to seep by and you get smoke- most often at initial startup (only a minor embarassment) but also possibly when down shifting or pulling away from a stop and idle period (slightly more embarassing).

3. Your intake valves do have seals and they need to be replaced.

4. They will remove the years of deposits that have built up on the under side of the valves.

5. They will resurface the valve seat (in the head) and resurface the valve face itself. They will then using lapping compound to help insure a good seal between these two surfaces.

6. They will grind a small amount of length from the valve to make up for the additional distance the valve extends into the head after completing #5.

7. They will check the head for plane. If it is OK they will take a small clean up cut on the head to give you a nice new surface to seal up with the head gasket. If it is warped they will remove enough (there are limits) to make it plane again. Volvo heads have a lot of tolerance to milling as there is little if any possibility of the valves contacting the head, but at some point the compression would be high enough that you might need to run aviation fuel in your new weekend warrior :- )

All of these acts of labor on the head should only be undertaken after a competent person has examined the head for damage. Overheating is bad for any head but especially aluminum ones. Warping can occur and cracks can form. Warping can be dealt with by milling, but cracks usually mean you need to post in the classifieds for a good B21FT head.

Randy