A slight problem!

[Mm2004]

so I make a start on changing the thermostat and water pump on my Z3 (M44) tonight but unfortunately one of the bolts was sized for the thermostat and has snapped. The attached pic shows it's the bottom right one which appears to have a locating peg and the bolt goes into that.

Has this happened to anyone else and does that peg come out or is it part of the casting? Any ideas on how to fix this?!

 

[BMBabe]

@Lee @t-tony @Nodzed

 

[t-tony]

From what I read it's a common problem. Will require drilling out and re tapping the thread.

Tony.

 

[Lee]

Or if your feeling lucky, try an easy out.

 

[mwpe]

An eazy-out might work but I would give it a good soak in Plus Gas or something similar first. If an easy out shears you are in deep ****.

 

[Nodzed]

Easy out may work but lots of WD40 (lots of other penetrating fluids available on the market ) and soak for hours
Not much help now but an old trick my Dad told me (heavy plant fitter for 60 odd years) if you think any bolt will be a problem or wont easily start to undo try to slightly tighten it before you start to loosen it, dont know why but it works.

 

[5harp3y]

I wouldn't bother with an easy out, in my experience they snap causing more trouble

That needs to be drilled out and re tapped

 

[hard top]

dont know why but if works.

We always do that with drilling equipment, increase make up torque before break out, it stretches the threads slightly but do not over torque or you can bell (deform) the female connection.

 

[Dickymint]

If it was me I'd start it off with a hard drill bit like a boron drill bit the reason is because they cut better and wont wonder off centre then after its gone a little way in use a left handed drill bit and you will probably find the heat and the left handed twisting action will unscrew it

 

[t-tony]

If it was me I'd start it off with a hard drill bit like a boron drill bit the reason is because they cut better and wont wonder off centre then after its gone a little way in use a left handed drill bit and you will probably find the heat and the left handed twisting action will unscrew it

Well worth a try with the same warning don't snap it off in the stud. Good luck with it.

Tony.

 

[Mm2004]

I finished work early today so I cracked on with the job whilst there was still daylight!

After soaking it with WD40 the other day, I centre punched the stud and started drilling with a small drill bit, gradually get larger to a 4mm bit. While I was doing this I realised the 'locating peg' turned out to be the steel sleeve from the thermostat plastic housing that had corroded onto the bolt. I was able to remove this which left a stud big enough to get some mole grips on it and turn it out thankfully!

So I've fitted the new water pump and thermostat, the temperature gauge now comes up to midway whereas before it wouldn't move away from cold. Unfortunately the heater only blows cold so,I'm assuming I have air still in the system so I'll try and bleed it again over the weekend.

Thanks for everyone's advice

 

[t-tony]

Great news mate, hope you get the air out easily. Can be a bit tricky but it will bleed out eventually.

Tony.

 

[Mm2004]

Cheers Tony, I've just been reading other threads about it so i'll jack the car up and bleed it again tomorrow

 

[Grandparipper]

This is a good reason to use anti-seize on any bolts that could corrode and cause problems. I am glad you got it out without having to drill! Good luck is sometimes better than being smart!

 

[gookah]

leave the filler cap off overnight It helps to get rid of air in the system