Stuck and broken coolant temp sensor (OM642) nightmare

[TeddyRuxpin]

HI all,

Tried to remove my coolant temp sensor on a W212 E350 and the plastic was so brittle it just disintegrated in my hand as soon as I touched it. Just two metal prongs were left so I used pliers and gave it a tug and the two prongs just came out... all that’s left is some plastic, with the sensor stuck in the hole. Nothing to tug on.

Today I managed to get a screw in there and tried pulling on it with everything I could - I simply couldn’t get it out. Ended up using a screw longer than the sensor itself (see last pic of screw and how deep it is in relation to a new sensor) and it’s just pulled the screw through. I’ll need a thicker screw/bolt.

This screw went in easy just with a screwdriver, no drills. Hardly any effort, the plastic is so soft.

I’ve applied so much 'pulling pressure' with needle nose pliers, vice grips, and the 'nail pulling' end of various hammers to try and get it out. This thing must be completely rusted in and seized. So little room to move due to fuel rail. You can’t pull straight out for a start, and you can’t really use the intercooler pipe or fuel rail as leverage. I doubt you’d get any kind of average slide puller in there. Yes, the retaining clip is out.

I can see blue coolant through the hole now... I’m worried the old coolant temp sensor is rusted to bits and I’ve gone completely through it (from the inside). If I have I'm then worried about brass bits now being in the coolant lines in the head... nightmare no. 2

I wonder if I should call a mobile mechanic at this point, although I’m guess they won’t like that I’ve been meddling.

Any suggestions? It's a pull out sensor, not a threaded/screwed in sensor, in case that wasn't clear.

Cheers!

 

[onefortheroad]

Possibly try drilling through it and use one of those snapped bolt remover threaded bar kits. It may turn and pull out ??

A thin wood working chisel would probably get it going and pick the bits out, looking at the sensor I'm thinking the water way also narrows quite a bit ,the deeper it goes, so if you can get the edges of the brass to maybe fold in , might get it moving.

 

[peterws1957]

I'd be tempted to use a Dremel with a pointed grinding stone and to grind away the plastic, not going too deep (you've got the new one as a guide). I've done this in similar situations and found that by removing material it loosens the bond and you can gradual take out the remains. with a screwdriver or similar. An awkward job that's for sure.

 

[Ivanhoo]

Is there not a cerclip on there there seams to be a Grove around the outer sleeve bit

 

[tode]

^^^^ I would think that there must be something holding the sensor in - I can't imagine that it was just shoved in the hole when first mounted . . .

 

[Wighty]

Can you enlarge the drilled hole by adding another 2 holes in line , then using a screwdriver or chisel to try and turn the sensor to break any seal/corrosion that has got it stuck .

 

[onefortheroad]

It looks like there is a clip holding it in position , from 3.10.

K

You can see on Ted's photo the slot is there for the clip . Maybe he's took it off ??

 

[malcolm E53 AMG]

OP says retaining clip is out. It really needs another hole drilling so he can use two screws and a screwdriver between so he can break the seal by rotating it

 

[KennyN]

OP says retaining clip is out.

Missed that part of the post

K

 

[KennyN]

FWIW i would remove the fuel rail , three pipe connectors and a couple of bolts , to get better access.

Look like you used a wood screw , try a 6mm self tapper and possibly heat it up to melt the plastic around it as it is going in to get a better grip. It will either pull out the whole sensor or just the plastic , if just the plastic is removed i may let you bend in the outer part of the sensor to get a decent grip of it.

If you have went too far through with the screw then the metal will be punctured and pushed through so nothing should have came adrift and into the coolant.

K