lilredpo

How hard is it to replacing a broken head bolt with the engine in the car?

Thought I blew a head gasket, smoke out the back and a milk shake in the dipstick. Fortunately, no oil in the antifreeze. Shut down right away.

Never taken a Porsche engine apart, but have some wrenching experience, so I followed Clarks and Haynes and have it disassembled to the point where the head is off.

When I got to removing the head bolts, I found #4 head bolt was already snapped about 1 1/2 inches below the cylinder surface.

Gasket looks good, no signs of giving out. Probably seeped when the bolt went.

Engine was running strong with about 110K on it as far as I know.

Any suggestions? Thanks in advance!
Ray

Yabo

drill (perhaps they make self cleaning drill bits?) and a tap, and a new bolt. maybe. if you can get that stuff to where you are

Devia

REPLACE THAT GASKET! You've GOT a headgasket problem, you should always replace it when you yank the head. What's the big deal about paying $80 for the gasket, and other seals!? I wouldn't take the chance. You can have a leaking headgasket, yet it not be visible to the naked eye.

I believe you can drill that bolt safely out, ask some of the other guys around here about that. Since that one bolt went, I'd suggest replacing al the bolts, just in case. Someone may have overtorqued them, I don't know.

I've been driving around nearly a year with oil in my antifreeze, that would be the oil cooler and seals. Not too worried, just a teaspoon a month.

I'm probably going to have to dig back in there, when I replace the camshaft gaskets over the next month.

No, I don't think your engine is toast.

- Julie

Tom M'Guinn

Wow. Bummer. That's a tough one. Studs can be a real pain to remove, even when they are not broken. They tend to be loctited into the block, which sometimes requires heating the block to loosen the loctite so the studs can come out. People can spend hours removing un-broken studs. If the stud is broken down in the well of the block, I feel for you. Every now and then a stud will spin fairly easily in the block. Can you get needle nose vice grips on it? That might give you a .1% chance of success. The only other thing I can think of is to see if you can get an EZ-out in the stud?I kind of doubt you will ever get the torque you need with an EZ-out, but it is the only thing I can think of short of pulling the motor and taking the block to a machine shop. The hole is too narrow to get anything on the stud down there. Wish I could be of more help.

abduln

You are going to have a tough time getting the remainder of the bold out. Ideally, you'd have the block clamped to a mill table, and you'd machine a hole into the bolt so you could use an appropriate sized extrator.

To get the bolt out with the block installed, you'll need to worry about several things. You need need to know if the broken surface of the bolt is relatively flat, which will reduce the possibility of a walking drill bit. If the surface is good, you can get a hardened punch and punch a good centered divet (the bolt is probably pretty darn hard even in the center, so this may be difficult), and drill it with a small pilot hole. Then you can drill a larger hole and use a screw extrator, or a reversed tap to get the bolt out. Drilling freehand like this is dangerous, as if the drill walks, or drills crooked, you can easily, and most likely will, damage your block.

Another possibility is having a bush made to use as a jig for drilling the hole. A machine ship could do this really quick and cheap. This is basically a piece of steel that can be used as a drill guide. It's shaped like a mushroom or a Champagne cork, but it has a hole drilled through it (from top to bottom). The hole is just big enough to let a drill bit pass through it and easily turn. The small diameter portion (the stem) is just small enough to slip into the bolt hole. The large diameter is just a bit bigger (maybe 1/2" to 1") larger in diameter and just acts as a stop and stabilizer for the bush. You place the bush into the bolt hole, stem first. and make sure it's squarely seated with the cylinder deck. Then you insert the appropriatelly sized drill bit through the bush and drill the hole into the screw for the extractor.

Just some notes:

1) Spray penetrant into the bolt hole for a few days, to make sure it soaks, and allows the bolt to hopefully free up.

2) Don't do anything risky, which will potentially damage the block.

3) Take your time drilling into the bolt, don't press so hard that you snap the drill bit off, and it's stuck in the bolt... you'll be screwed unless you have a broken drill bit extractor. In a blind hole, it's easier to get a broken scew out than a broken drill bit.

3a) Use the right sized screw extractor. If it's too small, it will break, and that is impossible to get out without sending the block to a machine shop.

4) Try to use reverse twist drill bits when possible; they help loosen up the broken bolt.

5) Realize that if you damage your threads, you can always Helicoil the hole, so it's not the end of the world.

Sorry, it's not good news or easy advice.

Good luck,
Abdul

Bri Bro

Are you saying the head stud broke? If that it the case, remove the head and replace ALL the studs. Sounds like someone in the past overstress the studs. Were did the remainder of the stud, nut and washer wind up?

lilredpo

Thanks everyone. I don't feel as bad now.

Julie - You are 100% correct, I already have the new gasket set. When I said it looked good, I meant that it did not appear to show signs of being cracked or broken, so the leak must have come as the head lifted.

Brian - to answer your question, when I removed the intake, the 5 exposed head bolts on the right side looked ok. Each showed a few threads, a washer and a nut. Nothing out of the ordinary. unitl I touched #4 and realized it was snapped. It probably stayed in because it was long enough not to pop out while the intake was on.

I'm going to start soaking, look for a reverse bit and easyout.

Please keep your fingers crossed for me.

Thanks again,
Ray

Devia

Fingers and eyes crossed for you, Ray! Just be patient...remember, it's an aluminum block, and the bolts are steel. Like I said, you should replace all bolts, due to stress issues, regardless.

Good luck! Er, patience I think will win this one, heh.

- Julie

jonnybgood

Abdul has given you the correct advice. I would start with reverse drills. There are specially hardend head bolts for the 944. There must be an ongoing problem here. They are expensive and are available from Pelican Parts. Something like 240 for a set. Don't know what your budget is but you might consider these once you get that broken one out.

Peckster

Are you talking about bolts or studs? How could you see exposed thrads on a bolt?

MHT

you might clean out the hole before you put the penetrating oil in it. There is often a lot of oil in the bottom of the hole, spray in some brake cleaner and flush it out and then blow it dry or absorb the solvent with strips of paper towels, the penetrating oil will have a better chance of working if there is nothing else in the way. Abdul's idea of a bushing to center the drill is a good one, once you are ready to remove the stud, try to apply heat to the area of the block where the the stud is threaded in.

Good luck

lilredpo

To be clear- it is a stud not a bolt. When you remove the cam housing, you expose the 5 studs (on the left, looking back) and when the intake is removed, the 5 studs on the right are exposed.

Thanks again!

Granite 944

Wow! that sounds like a good challenge there!
I have never removed a broken stud from a 944 block, but have had to remove some from other engines before. I believe most of those were fairly flush with the top of block also.

My personal opinion, I hate easy outs, though this is probably your only choice of extractors long enough to reach down to the broken stud. Try to find the four sided type easy out/reverse tap, not the spiral type. Might want to look at this post, especially the inside extractor tools that rennlister Magown shows/talks about. But I don't think any of these will reach down far enough.

https://rennlist.com/forums/showthre...ght=extractors

Good advise given in your post. I would emphasize the statements:

If your not careful here, I agree, your in real trouble. I would center punch it, use a small drill, like maybe a good, sharp 3/16" drill for the initial pilot hole into the broken stud, especially if you decide to freehand it. That way, if it does run off center slightly, you can still step it up using a larger drill pulling it back more to center ( easier said, than done, I like the bushing idea ). If it truly is broken off 1 1/2 below surface of the block, you shouldn't have much stud left to drill thru.


Same is true with a broken easy out/extractor. Much harder steel. Drill stud using a low rpm (less than 1000 rpm) and plenty of lubricant. Keep it out of cyl. bore of course.


Very important IMO. You might really need to apply heat to the block surrounding that stud (don't melt/distort the aluminum). Don't force the extractor to much. Make sure you match the final sized hole you drill to the proper sized easy out/extractor. Leave enough stud material in the hole so as not to expand the stud outward while trying to extract it up and out.


Good luck!

lilredpo

Ken,

Thanks for the input.

This extraction is going to be a nail biter. Not sure if you've seen inside the block, but the head stud is inside a 'chamber' approx 5/8" wide. 2" deep. Not sure why it's designed this way. But my stud snapped leaving approx 1/2" exposed, 1 1/2" below the deck surface.

Can't get vise grips or extraction sockets in there. I picked up the Sears/Craftsman set and they are nice if you have the room.

I am planning on setting up a drill holder / stand and going to clamped it to the block. First I will use a smaller drill bit, reverse cut 3/16 for a pilot hole, then a larger bore to fit an extractor sized for a 7/16 bolt.

I checked with a few local shops, nobody will touch it in the car and if removed, I must strip the block.

I figure if I can't get the pilot hole straight, then I'll stop. Otherwise the cost of sending the block to a machine shop may be prohibitive and I might as well get a short or long block.

I'm trying to figure out my options and gather the courage to start the drill.

Thanks again for your insight.

Ray

Danno

Hmmm, I wonder if there's an acid we can use that would dissolve steel and not aluminium...