OM642 Coolant Temp sensor stuck and sheared off…!

[MrGreedy]

Some more thoughts having slept on it.

Get a much fatter screw into that thing. If it can go in at an angle and clear over the fuel rail, you might be able to get a crow bar on it to use in similar way to a slide hammer. If not, be prepared to have a think about getting that fuel rail off. How hard can it be!?

Depending on angles on the crow bar head, you could try two different approaches. Do not use this in the levering way you would normally with a crow bar, this is for precision tapping of the new, fat screw that is in the sensor!
If you are trying this route, make sure the screw actually fits and engages with the crow bar notch and isn't too fat. If it is too fat, you could gently grind some material off the shaft of the screw and under head to allow the crow bar to engage positively.

You need a crow bar with a notch in the head for nail removal (of course I have a wide selection that have been used as part of my small, 6 year house renovation project).

1.
Crow bar with an obtuse head angle, like this.

Roughneck Heavy Duty Gorilla Wrecking Bar

Hardened and tempered, drop forged alloy steel. Bar to claw angle permits use near flat surfaces. Extra wide chisel blades and oval shank.

www.toolstation.com

You might be able to get this on to the head of the screw, depending on the height of all the crap on the top of the engine/turbo pipe. You might need to remove some of that stuff to get the crow bar closer to the engine. Lay the crow bar horizontally across the top of engine, left to right, with the crow bar head on the passenger side pointing down to the screw, and the tail of the bar pointing towards the driver side. Engage the screw head with the notching of the crow bar used for nail removal. Gently tap the sharp tail/point of the crow bar with a heavy hammer. This might then act as a 24" rod that you are tapping to try and get the sensor popped out or loosened.

2. If the angles are all wrong for 1, you could try a crow bar with an acute angled head, like this.

Roughneck Traditional Wrecking Bar

Forged and ground with hexagonal shank.

www.toolstation.com

Here the crow bar would again be horizontal left to right, but this time the crow bar is flipped 180 degrees and the tail of the crow bar is not across the engine, but heading out towards the passenger wing. You will probably need to raise the tail of the crow bar a bit to get best use of angles for the 'pull' when you give it a tap. Get you largest, most rubbish set of mole grips, and very firmly clamp them on to the shaft of the crow bar towards the tail end. You can then try tapping the mole grips (connected to the crow bar, connected to the screw) to act in the manner of a make shift slide hammer (just without the slide bit).


Both jobs might require a glamorous assistant to either firmly hold the crow bar in place, or GENTLY tap the long pointy end or mole grips attached to the crow bar (depending on their mechanical sympathy and awareness and how much you trust them to not just smack it with a hammer) to try and get this moving and make sure the notch stays engaged on the screw head.

Alternatively, if you can't get the head of either of those bars in there, you might be able to robustly wire the crow bar (other implements are avaiable) to the head of the screw using some heavy gauge galvanised gardening wire or similar (I'm thinking 1-2mm strong stuff, not thin stretchy green stuff). The principle here is to leave a gap between the heavy implement and the screw head (e.g. 6-12 inches) to distance what you need to gently tap with a heavy hammer from the sensor. This wire needs to be very secure, and wihtout any kinks in, as any kicks or bends in the wire will act to reduce the pulling force, because all the pulling force will be trying to do is straighten the bent wire. The idea is again to get something on the end of it heavy that you can gently tap, which will transfer the tapping (pulling out) motion and importantly the peak loading of the tapping to hopefully start this thing moving. If you have a slide hammer with a head that won't securely engage with the screw head, you could also wire it on via this method and maybe forego the crow bars. The reason I mention them first is they are cheap and you might have them laying around, and will be excellent at transferring that shock to the screw in a controlled manner with very gentle taps with a small lump hammer.

If all this achieves is pulling out the plastic resin from inside, maybe you can then very very carefully try to fold down the now exposed brass rim of the sensor, that would break the corrosion/scale bond and free the beggar.

 

[Petrol Pete]

Drill and fit a thread insert 'Helicoil' , the bigger the better, then screw in threaded bar and make yourself a slide hammer. Best of luck

 

[TeddyRuxpin]

Left a screw hook with a bigger thread in the resin with glue on the threads for 24 hours, felt pretty confident I’d be able to use zip ties and a big bar and my massive muscles to shock it out… Unfortunately 24h later you could pull the hook out with your pinky… the Plastic/resin/blancmange had nothing left in it. The idea might have worked if I'd tried it right away when the plastic had some integrity.

Had to go for the chiselling round the edges with a tiny screwdriver to fold in metal and then grabbing with a pair of needle nose pliers.

As you can see, I did go through the end of it, and there is probably a combination of rubber/plastic/copper/‘rust loser’ in the coolant system…? I hope I haven’t damaged the area that the sensor has to sit into too much with my screwdriver and my bad language. Neighbours think I’m insane, out in the dark with a head torch (don’t have any other time to try it!).

It’s dark, and I’m not even going to attempt a cleanup and replacement tonight, that’s enough for now…

 

[TeddyRuxpin]

Some more thoughts having slept on it.

Get a much fatter screw into that thing. If it can go in at an angle and clear over the fuel rail, you might be able to get a crow bar on it to use in similar way to a slide hammer. If not, be prepared to have a think about getting that fuel rail off. How hard can it be!?

Depending on angles on the crow bar head, you could try two different approaches. Do not use this in the levering way you would normally with a crow bar, this is for precision tapping of the new, fat screw that is in the sensor!
If you are trying this route, make sure the screw actually fits and engages with the crow bar notch and isn't too fat. If it is too fat, you could gently grind some material off the shaft of the screw and under head to allow the crow bar to engage positively.

You need a crow bar with a notch in the head for nail removal (of course I have a wide selection that have been used as part of my small, 6 year house renovation project).

1.
Crow bar with an obtuse head angle, like this.

Roughneck Heavy Duty Gorilla Wrecking Bar

Hardened and tempered, drop forged alloy steel. Bar to claw angle permits use near flat surfaces. Extra wide chisel blades and oval shank.

www.toolstation.com

You might be able to get this on to the head of the screw, depending on the height of all the crap on the top of the engine/turbo pipe. You might need to remove some of that stuff to get the crow bar closer to the engine. Lay the crow bar horizontally across the top of engine, left to right, with the crow bar head on the passenger side pointing down to the screw, and the tail of the bar pointing towards the driver side. Engage the screw head with the notching of the crow bar used for nail removal. Gently tap the sharp tail/point of the crow bar with a heavy hammer. This might then act as a 24" rod that you are tapping to try and get the sensor popped out or loosened.

2. If the angles are all wrong for 1, you could try a crow bar with an acute angled head, like this.

Roughneck Traditional Wrecking Bar

Forged and ground with hexagonal shank.

www.toolstation.com

Here the crow bar would again be horizontal left to right, but this time the crow bar is flipped 180 degrees and the tail of the crow bar is not across the engine, but heading out towards the passenger wing. You will probably need to raise the tail of the crow bar a bit to get best use of angles for the 'pull' when you give it a tap. Get you largest, most rubbish set of mole grips, and very firmly clamp them on to the shaft of the crow bar towards the tail end. You can then try tapping the mole grips (connected to the crow bar, connected to the screw) to act in the manner of a make shift slide hammer (just without the slide bit).


Both jobs might require a glamorous assistant to either firmly hold the crow bar in place, or GENTLY tap the long pointy end or mole grips attached to the crow bar (depending on their mechanical sympathy and awareness and how much you trust them to not just smack it with a hammer) to try and get this moving and make sure the notch stays engaged on the screw head.

Alternatively, if you can't get the head of either of those bars in there, you might be able to robustly wire the crow bar (other implements are avaiable) to the head of the screw using some heavy gauge galvanised gardening wire or similar (I'm thinking 1-2mm strong stuff, not thin stretchy green stuff). The principle here is to leave a gap between the heavy implement and the screw head (e.g. 6-12 inches) to distance what you need to gently tap with a heavy hammer from the sensor. This wire needs to be very secure, and wihtout any kinks in, as any kicks or bends in the wire will act to reduce the pulling force, because all the pulling force will be trying to do is straighten the bent wire. The idea is again to get something on the end of it heavy that you can gently tap, which will transfer the tapping (pulling out) motion and importantly the peak loading of the tapping to hopefully start this thing moving. If you have a slide hammer with a head that won't securely engage with the screw head, you could also wire it on via this method and maybe forego the crow bars. The reason I mention them first is they are cheap and you might have them laying around, and will be excellent at transferring that shock to the screw in a controlled manner with very gentle taps with a small lump hammer.

If all this achieves is pulling out the plastic resin from inside, maybe you can then very very carefully try to fold down the now exposed brass rim of the sensor, that would break the corrosion/scale bond and free the beggar.

Thanks so much for this lengthy reply, your last paragraph was what gave me the confidence to attempt this, once all of the plastic/resin core was out, there wasn’t much else to try/lose. Thanks again, you’re always a super helpful and generous member of the forum.

 

[W1ghty]

I’m never going to change that sensor myself .
Good job buddy .

 

[colinallcars]

Left a screw hook with a bigger thread in the resin with glue on the threads for 24 hours, felt pretty confident I’d be able to use zip ties and a big bar and my massive muscles to shock it out… Unfortunately 24h later you could pull the hook out with your pinky… the Plastic/resin/blancmange had nothing left in it. The idea might have worked if I'd tried it right away when the plastic had some integrity.

Had to go for the chiselling round the edges with a tiny screwdriver to fold in metal and then grabbing with a pair of needle nose pliers.

As you can see, I did go through the end of it, and there is probably a combination of rubber/plastic/copper/‘rust loser’ in the coolant system…? I hope I haven’t damaged the area that the sensor has to sit into too much with my screwdriver and my bad language. Neighbours think I’m insane, out in the dark with a head torch (don’t have any other time to try it!).

It’s dark, and I’m not even going to attempt a cleanup and replacement tonight, that’s enough for now…

Regarding the debris, once you’ve got the sensor out don’t immediately drain the system. Use a hose in the filler hole to ‘blast’ the bulk of the debris back out the sensor hole. What’s left should settle somewhere out the way, it may even come out when you drain the system after doing the above.

 

[E55BOF]

You've done the hard bit...

 

[Bellow]

Regarding the debris, once you’ve got the sensor out don’t immediately drain the system. Use a hose in the filler hole to ‘blast’ the bulk of the debris back out the sensor hole. What’s left should settle somewhere out the way, it may even come out when you drain the system after doing the above.

The above - but gently to begin with at least and see if you can't 'float' the debris out. Blast to finish!

 

[TeddyRuxpin]

Thanks all - I have an oil suction pump with various sized hoses - I was thinking of washing out the hoses or even getting a new one (as to not further contaminate) and going that route to extract some fluid? I also have a couple of plastic syringes that have a relatively wide hole for extracting small amounts.

Perhaps I could try that and see how I get on, then go for the hose in the coolant tank option if it seems like it might be required?

 

[E55BOF]

If you have a 'wet and dry' vacuum cleaner, rig up something with a piece of smallbore hose into the thin nozzle (Black Nasty is good for this). You'll get better suction that way than with anything else, I would think.

 

[Bellow]

If you have a 'wet and dry' vacuum cleaner, rig up something with a piece of smallbore hose into the thin nozzle (Black Nasty is good for this). You'll get better suction that way than with anything else, I would think.

Sticky tape will work too.
If no small pipe is at hand - break open a Biro and use its outer. You're not necessarily aiming to 'Hoover up' the debris. Getting it to stick to the end of the pipe where you can manually remove it will do.

 

[MrGreedy]

I use this trick when vacuuming out debris from deep holes in masonry. But the trick is not to suck up the straw, but to use the straw to allow air deep into where your trying to suck the debris from. Just making the loosest of seals with your hand, whilst poking a straw in creates enough of a pressure differential that all debris flies out of the hole. Whereas trying to use the small pipe to suck up the debris isn't as effective.