Common Fault? Front A/c Bolt Seized Solid. Be Warned!

[Titch LS]

HI everyone, I took my Mk4 LS in for an a/c re-gas recently and two days later a small leak showed up (bright green uv dye) from an 'o' ring connection right at the front next to the receiver/drier,-- where the ally tube meets the condenser. This is held by a single 10mm bolt. Easy peasy.... NOT!! The a/c chap (whom I've used a few times with other cars) said he would not touch it because on the LS these particular bolts ALWAYS seize solid after so many years and undoing it can twist the tubing and damage the condenser. ( Apparently, using steel bolts in aluminium fittings is not a good combination). He de-gassed the car and told me to come back when I've got the bolt off myself. He would then replace the 'o' ring. You can guess what happened... he was right of course! The head of the bolt snapped off. 'They all do it ' he said. Now I have to drill out the bolt somehow, after removing the front bumper and front impact bar (which is HUGE by the way). I suppose I could always use one of those sealant/ refridgerant kits from eBay and save myself some hassle but, if I did that, the a/c tech said he would not touch my car again!. Be warned -- if you ever have leaking a/c, fixing it might not be as straight forward as you think.

[ipwn]

Did you first use some sort of plusgas a couple of days earlier? Was there any space for some heat? Once the head snapped you can drill in and use a screw extractor.

Would replacing the pipe be easier?

I assume you've looked at all the options :)

[Titch LS]

Sam, I tried heating it up first as you suggested, but to no avail.The combination of corroded aluminium and steel together seems to set it like concrete. I'm going to drill it out with a left- handed (reverse flute) HSS drill. I hope the concentrated heat/vibration will start to undo it a little. Then i'll try and use one of those 'easy-out' gizmo's. Then off to the a/c place for the replacement 'o' ring and re-gas (if all goes well). I'm not looking forward to removing the bumper and front impact bar though. With the present Monsoons I'll probably have to do the job in a wet-suit. Could put it off till later, but if I do that I'm a bit concerned about future seal leakage as there is no gas in the system at all at the moment.

[steve2006]

Hydrogen peroxide is good at removing the crud around the threads on steel to aluminium fixings.

[abs66]

That's exactly where mines leaking too. Not happy to hear about problems with the bolt as I was going to tackle this job in a couple of weeks! What a shame.

Tell me more about the hydrogen peroxide trick Steve please.

[ipwn]

[steve2006]

That's exactly where mines leaking too. Not happy to hear about problems with the bolt as I was going to tackle this job in a couple of weeks! What a shame.

Tell me more about the hydrogen peroxide trick Steve please.

I have read in the past that if you soak the joint between the bolt and the threaded hole with Hydrogen Peroxide solution then wrap it in a rag soaked in the same stuff and leave it overnight it actually penetrates the threads and dissolves the crud.

Now I haven't tried this so no warranty given or implied.

[abs66]

Sounds like a plan. I don't know much about hydrogen peroxide, is it dangerous ie does anyone know what precautions need taking. I will obviously Google it but I really do believe the advice from this forum is second to none.

Thanks Steve for all your help and advice recently its very much appreciated.

Cheers

Pete.

[abs66]

Seems quite safe from info found on tinterweb, so I will give this ago when I get a chance and report back. I assume the o ring is available from Toyota / Lexus.

As ATS are doing £29.99 ac recharge at the moment I had better get a move on.

[TigerFish]

I use hydrogen peroxide to nuetralise potassium permanganete when I treat my pond, never had any issues with the hydrogen peroxide, although I would wear gloves when using it just to be on the safe side.

[abs66]

It does seem to have many uses!

Thanks for the advice, which I will of course heed.

[Cotswold Pete]

HI everyone, I took my Mk4 LS in for an a/c re-gas recently and two days later a small leak showed up (bright green uv dye) from an 'o' ring connection right at the front next to the receiver/drier,-- where the ally tube meets the condenser. This is held by a single 10mm bolt. Easy peasy.... NOT!! The a/c chap (whom I've used a few times with other cars) said he would not touch it because on the LS these particular bolts ALWAYS seize solid after so many years and undoing it can twist the tubing and damage the condenser. ( Apparently, using steel bolts in aluminium fittings is not a good combination). He de-gassed the car and told me to come back when I've got the bolt off myself. He would then replace the 'o' ring. You can guess what happened... he was right of course! The head of the bolt snapped off. 'They all do it ' he said. Now I have to drill out the bolt somehow, after removing the front bumper and front impact bar (which is HUGE by the way). I suppose I could always use one of those sealant/ refridgerant kits from ebay and save myself some hassle but, if I did that, the a/c tech said he would not touch my car again!. Be warned -- if you ever have leaking a/c, fixing it might not be as straight forward as you think.

Sounds like the engineers did not remember basic physics, and you get electrolytic flow between different metals which causes a build up of 'crud'. The very reason why Land Rovers get their allloy panels all mucked up as the steel rivets react. But I suppose tensile strength of steel was the important requirment?

Would have thought the lexus lads would have used a stainless steel bolt (which will have same problem, but just takes longer), but then a stainless bolt would be be a real drill bit killer to get out when it did corrode

As for the peroxide, sounds like a neat trick, and beats using it to turn what little hair one has, to grey.