#1: 1.4i TU3JP cylinder head temperature sender - copper washer? Author: Bordonbert, Posted: Fri Oct 06, 2023 11:30 am ---- Hi. I'm finishing off a head gasket repair on my wife's 2002 1.4i. It's a stunning engine! We've had it since 65,000miles and it is now at 145,000miles and it still has the honing in the bores right up to the top with no perceptible wear ridges or piston rock. When Peugeot get it right they certainly get it right. The valve seals and camshaft seal looked new too. With my many years of experience with BLMC A-Series engines that's an eye opener!
Has anyone any experience with the coolant temperature sensor that sits low down on the gearbox end of the cylinder head? Not the one that sits on top of the thermostat housing, this one is direct into the head itself pointing straight out in the direction of the gearbox. It's actually a b***h to unhook the plug from as it sits tucked under the housing and almost surrounded by it.
It is blue with 1 pin and is a M14x1.25 thread to a thick stubby brass base. Here is a pic from an online supplier catalogue.
I'm well into the rebuild and have to refit this sensor now but it has no copper washer on it and that niggled at me. It seems to come without one anyway and looking at it you can see it has an angled profile behind the threaded portion which I reckon sits directly into a cup shaped base on the head.
Am I correct in assuming this does not need a copper washer at all? I still think I'm going to put on a smear of gasket sealant on the last few threads to help. I'm sure it can't hurt.
#2: Re: 1.4i TU3JP cylinder head temperature sender - copper was Author: Sim, Location: West CountryPosted: Fri Oct 06, 2023 7:37 pm ---- No washer in the exploded diagram, so it's the taper to the rescue.
If there are traces of some sealing compound, certainly good to cleanup and apply anew.
Also found this nugget of information for whomever opens this thread in the future and wants a bit of background info on these sensors:) www.206info.co.uk/Foru...tml#486380
#3: Re: 1.4i TU3JP cylinder head temperature sender - copper was Author: Bordonbert, Posted: Fri Oct 06, 2023 11:22 pm ---- Thanks Sim, that Service Box page is eventually exactly what I found. Bit odd that it only shows up there. I looked everywhere else in Service Box without finding a sign of it. If you aren't using it as part of your daily routine it can take a bit of getting around.
I got a small mirror and had a look at the mounting position on my own head - with great difficulty! That clearly shows that the only contact between sensor and head has been made on the angled surface just beyond the threads and not the flat flange face itself. So it appears that, while it may be a slim surface for sealing, there is no washer needed. Like you said, taper to the rescue.
It hasn't even had any gasket sealant applied in the past, I think it must have been there since new in 2002. I still think it won't hurt to apply a little to the final few threads at least.
For the benefit of anyone else needing to work on this here are some details. Assuming you are removing/fitting the sensor with the head on the block in the car, you will need to remove a few things for access. (Note I didn't say "easy access"!) Start with the filter air hose between the filter box at the front and the inlet manifold at the rear. It's a couple of large worm screw hose clips. As a tip, it is much easier if you then remove the support bracket which carries the power steering pipes and electrical connectors and which screws to that end of the thermostat housing. That is what is arrowed in the first picture. You can see it's fitment more clearly in the second pic. It does restrict access to the sensor which is just below it and makes the job more awkward. It's only a T30 torx screw for the pipe carrier and two small screws (10mm) for the bracket itself.
The pics aren't of my own head. My bracket is the same as the first pic and not the same as the second. However, it does fit in exactly the same place in the same way. The temperature sensor we are talking about is NOT the one you can see on top of the thermostat housing just below the arrow in the first pic and the green one in the second. It shows as the blue one in the second pic, clearly buried below the pipes and wiring connector blocks that are to the right of the head. Even getting the connector off it is a pig. It is the type with a spring loaded wire locking clip which has to be pushed towards the sensor body to release. Don't be too aggressive with that, use something to push in the clip and gently tease it off.
Then, assuming the coolant pipes are still in place, it's absolutely 100% impossible to address the sensor with a spanner of any sort. It may look like you can from the Service Box pic but, believe me, you MUST have a deep 19mm socket, and a slim one is easier. It must be a deep type to fit far enough over the plastic connector part to engage with the metal seating. Even an old school tubular spanner does not work and will only engage on the plastic though it may feel like it has slid fully home. (Ask me how I found that out and why I'm waiting for a new sensor and a deep socket!!!) Getting a ratchet socket drive or a torque wrench in there to drive it is still a bit tight but can then be done. Service Box says torque setting for the sensor is 8Nm (0.8 daNm).
Hope this helps others and good luck to anyone trying to change this.
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