I am trying to remove the water bridge, one of the bolts has been rounded off by the PO. How can I remove this bolt? The Allen key just spins in the bolt head.

 

I had a rounded water bridge bolt which I removed using the type of tool shown in the link:
My bolt happened to be the rear drivers side bolt (left hand drive) which was hard to get to, so I had to wait until the intake was off before I could reach the bolt with the tool.

 

I use a torx bit around the same size or just a little larger. Tap it in with a hammer and it will cut grooves into the head. You will need to get a replacement bolt but sounds as if you need one any way.

 

Drill the head off the bolt and stop when the head spins. You'll probably find that the bolt is corroded stuck in the bridge and not in the bock. Once you get the bridge off the headless bolt it will probably unscrew with pliers.

 

Vise grips if you can get them in there. If not then a bolt extractor that grabs from the outside. If not that then drill the head off, remove bridge, and then deal with it.

 

Try vise grips as advised above or i had luck with heat then knipex pliers. you can also try using a dremal to cut a slot in the head then use a screw driver.

Good luck

Steve

 

These work well. Just be sure a really snug fit. May have to use a slight tap.

 

left handed drill bit..... most of the time it will bite into the bolt and back it out... if it doesn't then drill until the head is loose.

 

Thanks guys, I'll try the above in the morning.

 

If you can get in to make the slot, you may be able to get to whack it with one of these:
http://www.jpcycles.com/product/150-341

The best penetrating oil is a 50/50 mix of acetone and ATF.

 

+1

 

Your PO did it completely wrong - everyone knows you're supposed to snap off the water bridge bolts. Rounding is for oil drain plugs...

My usual order of things to try (after liberal application of penetrating oil):
1. torx bit( hammered in to cut it's own teeth)

2. left hand drill bit

If the head snaps off, I've found the K-D tools 1708 cam style stud remover works wonders.

HTH,
-don

 

It may sound too good to be true, bit I have had very succesfull results with "ez grip friction drops".

A friend of mine works at Martinair, and they use it for work on their aircrafts.

Really great stuff (no affiliation)

 

The easiest way to remove a rounded allen type bolt is by mig welding an allen socket in. The heat from the mig aids in removal and there is no mess from drilling. Hopefully you have access to a mig.

 

Try this: take a 12 point regular hex head socket (it has to be 12 point - the 12 points are going to supply the grip) and get some valve grinding compound. I'm not sure about the size of the socket, I think its going to be either 11mm or 12mm. You did'nt say what engine you have but that will determine what you have to move for access. Try to get as straight of an angle to the bolt as possible. Put the 12 point socket on an extension, put the valve grinding compound on the inside edges of the socket (for additional grip) and hammer the socket over the outside of the allen bolt. PB Blaster is the most effective lubricant for freeing seized and rusted fittings I have used - available at Home Depot in my area, hopefully some auto parts store, but this will probably not do any good for this situation. Applying heat to the bolt will help, but access is probably limited - maybe you can get a soldering gun on the bolt and hold it on there for a good while before attempting this maneuver. This is the technique I use and I have fixed cars for a living for 32 years. Hope this helps. I just did the same job on my 83 and the bolts gave me a little trouble and I was the first guy to take them apart - you do have to be very careful or you see what happens.