aaddpp

I have been trying to pull the water bridge to fix a coolant leak and oil filler leak, but the rear bolt on the diver side of the bridge will not budge, and looks to have been partly stripped from prior attempts. WD-40'd the heck out of it, but still nothing. Even when I got a hex key onto it, it would not budge. I even tried to tighten it to get some budge. One on the pas. side eventually gave with a 3/8 hex socket and a breaker bar.

Since the bolt is stripped and will not hold the key, I have started to dremel a couple of channels into the top of the bolt to get a flat, screw driver like grip on the bolt with something that can take the torque. I have included a photo the bolt in case my description is not clear.

Any thoughts on how else to go after this SOB of a bolt that it completely stripped now, and will not take the hex-key it was supposed to?

Thanks,
Dave

Dave H.

if you can get it down in there, you might try a bolt extractor...

Bill Ball

Another good way with Allens is to slot them, as you are doing, and smack the edge of the slot with a chisel and hammer to drive it loose. This exerts more force then you can with a screwdriver. I think there may be a clearance problem trying to do this in that location, as well as that external extractor, which is a great tool if there is enough room for it. It helps to drill away most of the bolt head to weaken it so it will give up some of its grip. You may just as well drill the whole head off.

Tails

I know it is a bit late for this advice, however, for future reference, ensure that penetrating fluid enters the thread area of set bolts by either building a small dam around the head to hold the penetrating fluid or wrap a small piece of cloth around the head and apply the penetrating fluid to fill up the dam or to the cloth and keep it wet.

Before you try to undo the bold, give it a couple of sharp hits, with a brass dolly and hammer, on the head and it may help to break free the threads. When you use an allen key of spanner on these type of bolts you should try to give it a sharp push with your palm of your hand to get a shock loading torque into the bolt and it should break free. It is imperative that you have the allen key firmly seated fully into the slot and use an extension bar on the shank or you can use the ring section of a ring spanner or a ring and open ended spanner to give you more leverage.

If you have a small chisel and there is sufficient room, do as Bill suggests, I usually sharpen the chisel before trying this so that it gets a good bite into the head of the bolt.

In some cases I have used a centre punch to peen the head of the allen set bolt slots back into the hole and I have ground the end of the allen key with a small taper and hammered it into the head.

You will note that there is a lot of shock hammering (small hammer) in the processes described above, it all helps to get the bolt moving.

In addition I also have a small set of allen headed driver bits that I can use my 1/4" socket set on. This give me the option of using a small universal driver onto the extension driver and by using my a "T" handle, most anything is possible to remove. You can use an extension piece on the T handle to increase leaverage.

If this does not work as a last resort if the bolt extractor wont fit , I agree with Bill, drill the head off with an drill that is a slightly bigger diameter than the allen head. A left handed drill will also assist, however, do not have the drill with too much angle of cut at the cutting edge as you want to take the process slowly so as not to damage the bridge.

Once the bridge is off you will be able to get at the threaded area with a set of vice grips of a very small stilson wrench and it should come out.

When you reassemble ensure that you use an anti-scuffing or anti-seize paste with no carbon content, as any carbon will cause corrosion with aluminium, and you should not have this type of problem again.

Keep us informed as you proceed.

Tails 1990 928S4 Auto

Mike Frye

Great advice, all, but I'm surprised no one mentioned this: WD40 isn't the best penetrating oil. Try some Kroil or some other kind of powerful stuff.

Put in on there and let it soak in overnight or even keep applying it for a few days. Put some oil on, tap it with a hammer, tap-tap-tap. More oil, more tapping. You need to get the oil int between the threads, but it needs to be one that will really seep in there deep. Heat works too although it might be tough getting a torch in there without cooking anything important.

Those bolts are always a PITA and once you get it out (and you will, or at least get the head off) take your time putting the new one back in. Chase out the threads (I make a thread chaser by cutting two grooves up the sides of a sacrificial bolt and just turning it all the way in and out over and over again). Take your time making sure all of the corrosion and metal burrs are out or you (or the next owner) will have the same problem in a few years. +1 on the anti-seize or anti corrosion paste. I also replaced those bolts with hex-head stainless bolts rather than playing around with the allen head ones next time.

I had to cut down one of them because the stock bolt was an odd length, but knowing I'll be able to get the bolt out again if I need it was the priority.

Just my $.928

NoVector

I had the same problem (freak'n cheese heads...) After I rounded out the inside of the cheese head, I tried clamping a vice-grip to it, but it still didn't work. In the end, I used a cutting blade on my dremil and cut off the top of the head--the bridge will slide up and over what remains. Like Tails siad, use antisieze when you put it back together.

FWIW, I'm finding that PBR works better than WD-40. Good luck! / Bruce

M. Requin

Cheese head screws take a flat blade screwdriver, but your advice on PBR is right on. A six-pack always helps... And removing the head with a dremel to get access to the remaining shank of the screw is good. Anyone ever used the (expensive) SnapOn collet-type removers in this kind of situation?

Lizard928

Remove the intake and do it right will be the best way.

AO

Atthis point, I'd invest in some Kroil, a set of bolt extractors like the one pictured earlier, and a hand impact wrench. You could try drilling the head off the bolt, but I don't think you'll be able to lift it up and off the shaft with the oil filler in place - which will necessitate removal of the intake - about a 2 hour job if you take your time.

Tom in Austin

Having just done intake refresh, I'll bet you end up taking off the manifold to get a good angle of attack on it. That is really a tight spot down in there.

Be patient and good luck with it!

hagen454

Try some heat, either a small pencil torch or just get the car up to operating temp. Get those alloys to seperate. Think SMOKE WRENCH.

sharknoob

I have had good luck with a set of these
I find one that just starts to go in the hole then hammer it in
I Put a socket on a my 1/2" impact that fits the end
Take your time start off slow let the gun hammer on it a while with spray
also sometimes I need to hit the end on the grinding wheel if it doesn't look like a tight enough fit.

SharkSkin

If you are suggesting use of that tool or similar on the allen head, that often works out... For anyone considering use of easy-outs on bolts, especially small ones like this one on the bridge, I have one word of advice: DON'T.

They are very brittle and like to break off and leave a piece of easy-out in there that is very difficult to remove. One reason for this is that easy-outs tend to expand the stuck bolt into the hole, adding to the difficulty of turning it out.

chewy8000

DON'T get involved with the bolt extractor route. Dremel the bolt head off remove the bridge soak the remaining bolt in PB blaster over night, torch it nice and hot and grab the remaining section with some channel locks and remove it. Your just going to make a mess drilling and using an extractor and right when you think your getting somewhere the extractor will snap leaving HARDENED steel in there and your really screwed. I only know this because it happened to me on my coolant bridge nightmare...

StratfordShark

When you advise to dremel the head off do you mean making several vertical cuts to remove the head in pieces, or something simpler which I'm overlooking?