Removing a seized/broken captive nut/bolt - advice please

[007singh]

Guys,

Need to replace a battery on a Fiesta. I thought it was the starter playing up, but when the RAC came out, he confirmed it was the battery. He offered to supply and fit one for £90, but seeing as it is a simple job, I said its ok mate. I picked a new battery from Halfords for £50 this morning.

Problem is trying to get the old one out of the battery box. There is a bar on the top, across the battery to keep it in the box. It is held in place by what seems to be two captive bolts fixed from under the battery box, bar put on top, then two nuts holding it down.

The back of the captive bolt is hidden within the battery box, and the damn bolt keeps turning when I try to remove the nut. It must be rusted on (nut to bolt), and broken free from inside the battery box.

I tried to file down two sides of the bolt so that I could hold it still with some grips whilst turning the nut to try to break it free, that is not working. Liberally applied WD40 for a few hours too, still no joy.

I should have paid the RAC guy and left it as his problem, lol, but I had no idea it would not come out.

So, any ideas on how best to remove this?

Very last resort is to break the battery box and get a new one.

[eltax91]

WD40 is not a penetrating fluid. It's not what you need for this application. PlusGas or "shock and unlock" are the one's that come recommended. Hopefully one of these will help

[007singh]

eltax91 said:

WD40 is not a penetrating fluid. It's not what you need for this application. PlusGas or "shock and unlock" are the one's that come recommended. Hopefully one of these will help

Cheers mate, will see if I can get hold of some. However, if I cannot grip the bolt securely enough, I might still have an issue even if I can break the rust bond. Just wondering if cutting vertically into the bolt to create a slot with a hacksaw might allow me to put a screwdriver or such into it to get better purchase to hold it in place whilst trying to move the nut.

[TheRealFingers99]

A photo would help.

GT-85 is pretty easy to get hold of and is as effective as Plus Gas.

But if the captive nut is turning, any long term solution will involve welding.

How much is a new battery box?

[VinceFox]

Cut it off, remove the clamp pieces and replace them.

[OldBuoy]

Or take battery back to Halfords for a refund and get RAC to do it.

[007singh]

Not my photo, but the same engine bay, and you hopefully get the idea:



The two nuts can be seen on the right the photo, locking the bar down on the battery. The bolt is a captive bolt (or is meant to be!), and the bolt head is not accessible.

[VinceFox]

If you cut the top off, the bolt can be removed.

[007singh]

OldBuoy said:

Or take battery back to Halfords for a refund and get RAC to do it.

RAC won't come back out free of charge for the same issue, they will charge a call out of £85.

cutting the top off might be an option, but it is recessed in the clamp plate, so will be awkward if nothing else. I am going to grab some PlusGas and try that, also try to cut a slot with a dremmel in the bolt to put a screwdriver in. Will see how that does.

I think that if I cut the nut off (and cut through the bolt), and could get the broken captive nut out, I could secure it back together with a bolt and wing nut and washer - only needs to hold the battery in place after all.

[TheRealFingers99]

Just a thought -- some cars -- smaller FIATs are an example, have a bar in the shape of an elongated J, the hook of which locates into a hole in the battery box. Might be possible to adapt one (visit the scrappy, peek at Seicentos, Puntos, etc.).

[one eyed mick]

Pair f self grips hold the long bolts and undo the nuts at the top ,lift of stap undo battery terms lift out battery clean every thing replace battery and clamps job done !! took longer to type than do !"!!!!!

[S0 What]

Undo the one nut that will undo then bend the battery clamp bar up to get the battery out, then you can get mole grips on the loose bolt shaft.
You can't get to the bolt shafts with the battery in as the bolts run inside the battery box between it and the battery, once off you will need to straighten the clamp bar but a hammer and or vice will sort it out

Edited by S0 What on Wednesday 20th August 21:39

[007singh]

Both the captive bolts are buggered.

I cannot hold the threaded shaft and undo the nut, nothing seems to hold well enough, can't get purchase on the threads. I have filed two sides down to help, still no joy. I cut a slot in the top for a screwdriver, that didn't work either.

I got some WD40 penetrating spray, have soaked it all in that now, leaving it till tomorrow. Will then most likely end up cutting both nuts with a hacksaw, prise them open with a big screwdriver and a bit of force and then remove the clamp. That allows me to change the battery, and leaves me to see what I can to fix the clamp back down again.

[S0 What]

Ahh bugger
When you try it again hit the spanner/ratchet with something, the shock may help free it, i've done this on a few wheel nuts when the stud is spinning in the hub ?? a DIY impact driver(ish)?

[007singh]

After all the buggering about, with penetration fluid etc, hammering, spanners, wrenches, sockets and a bit of crude drilling, nothing wanted to work.

I ended up cutting the nut with a hacksaw, then using a hammer and chisel to force the nut off.

What a stupid design!

Once I got one nut off, I could swing the clamp round and get the battery swapped over. The new battery is a bit taller than the old one, so having pulled the clamp back over, it actually holds it in place a reasonable amount. Might just be tempted to leave it like that for now.