6 replies to this topic

[zorgster]

Hi

I have braved the idea of changing the Coolant Temperature Sensor from under the inlet manifold... luckily the only issues i have had have been missing a 15mm and 16mm spanner in my set .. otherwise all gaskets etc look clean and re-usable ...

so i finally pulled out the holy grail... the inlet manifold .. (and found it has two cups to drink from - so the grail is meant to be shared? )

The sensor on the bottom appears to be two parts .. the threaded part slides around on the sensor stem... the new sensor I have bought is a solid piece... neither sensor screws down all the way into the manifold body ...

Could anyone tell me if this is correct? I bought the new sensor from Stockwell Motors who looked up the part on their system based on my registration - so type of Mini and that it's an SPI .. it's made by Commercial Ignition, England (CI) - part number is XTT41 ...

The Mini is an N-reg Mini Sidewalk 1275 SPI..

It would be a shame to have to put the old one back in or put everything back in with the wrong part ... after all the trouble of removing everything...

Oliver

[andatche]

The CTS should be a single solid piece like this., so that sounds correct. Replacing it should simply be a case of unscrewing the old one and screwing the new one in. IIRC, when changing mine recently, the sensor didn't screw all the way down. This shouldn't be a problem, just torque it up to the correct setting and make sure it isn't leaking.

[Sprocket]

The CTS should be a single solid piece like this.., so that sounds correct. Replacing it should simply be a case of unscrewing the old one and screwing the new one in. IIRC, when changing mine recently, the sensor didn't screw all the way down. This shouldn't be a problem, just torque it up to the correct setting and make sure it isn't leaking.

Thats just it! its not a single solid piece, it is two pieces. The 'nut' is seperate fromt he sensor and is allowed to rotate on the sensor body.

I have never seen an SPi sensor that its one piece. The sensor itself is the same shape and threads to fill the standard temp sensor hole in any A series engine. It is a one off sensor.

[andatche]

The CTS should be a single solid piece like this..., so that sounds correct. Replacing it should simply be a case of unscrewing the old one and screwing the new one in. IIRC, when changing mine recently, the sensor didn't screw all the way down. This shouldn't be a problem, just torque it up to the correct setting and make sure it isn't leaking.

Thats just it! its not a single solid piece, it is two pieces. The 'nut' is seperate fromt he sensor and is allowed to rotate on the sensor body.

I have never seen an SPi sensor that its one piece. The sensor itself is the same shape and threads to fill the standard temp sensor hole in any A series engine. It is a one off sensor.

I didn't notice this when recently changing mine, though I'm not disputing it. When tightning the sensor in the hole, the nut itself did not rotate about the threads on the sensor, should it? Is there any reason for this? Should the nut be adjusted to sit flush with the surface of the inlet manifold where it screws in after tightening?

[zorgster]

I didn't notice this when recently changing mine, though I'm not disputing it. When tightning the sensor in the hole, the nut itself did not rotate about the threads on the sensor, should it? Is there any reason for this? Should the nut be adjusted to sit flush with the surface of the inlet manifold where it screws in after tightening?

does it have to be two pieces?

the CTS keeps on showing faults on diagnostics ... replacing the sensor is one step in diagnosing why my Mini almost made me stop dead on the slow lane of the M1 at the junction with the M25 (2-3 fast lanes on either side of me) after nearly 150 miles of incident free driving ...

other faults on diagnostics were the MAP sensor and the throttle potentiometer...

i found splits in the vacuum pipes.. and replaced them all... i drove around fine for two days .. and on the third day i drove round the block and every time i got into second gear, touching the gas pedal slowed down the engine... quickly releasing the pedal preventing the engine from dying as it had previously .. so i drove round the block in first gear without stalling .. which previously i could not do because i was trying to press the accelerator too hard to force petrol .. which worked but didn't help with knowing what was happening...

i think i might have knocked the connector of the CTS on the third day with a long screwdriver just to feel around ...

i perhaps did not need to replace the sensor .. but i wanted to pull the injector housing to pieces and clean it .. check gaskets and spacer etc ... i wanted to know the state of things... it could even be the wiring to the CTS .. i wanted to check that it wasn't melted or trapped..

there appeared to be a bit of oil around the inlet heater (PTC heater?) ...

so anyway... once the CTS is tightened in the hole it'll hold together like it's one piece no? there's no insulation between the two pieces ...

i put the part in and have put the manifold, injector housing and throttle body back together .. perhaps the most satisfying thing was turning the ignition and having her start first time ... took 3 days to take apart and 3 hours to put back together ... as i had to deliberate and weigh up the pros and cons of removing each part ... what happens if this breaks whilst i am undoing it .. etc.. i got to the fuel pipes and i had a 17mm but the 16mm and 15mm (for the union nut) were missing from my set of spanners.. so had to go and get a new set (from Lidl for £8)...

(note.. i turned the ignition - could hear a whirring from the fuel tank.. click from the engine.. switch off .. click click click from the engine... - if i immediately switched the ignition back on, nothing from the fuel pump - but if i waited a bit then i heard the whirring again... )

i ran the engine for about 10 minutes .. to run the coolant through the engine... i left it on idle all through that ... idle sounded a little high... - question: in the throttle body there's a flap which flips when the accelerator pedal is pressed .. should that be fully closed in idle? or should there be a slight (one or two mm) gap?

after about 10 mins of idling ... the engine wavered very slightly a couple of times... the frequency between waverings appeared to be increasing .. i had the feeling that if i was driving that would be the point where it would stop... i stopped the engine...

now the engine will have cooled down i need to check the coolant level .. and top that up .. and then i'll test the driving ...

if it fails then I guess i'm back at the drawing board ...

Sprocket ... what are the signs of throttle potentiometer failure ? how can it fail? most of the parts around this area on my Mini are the original parts - not been changed .. (only about 35k on the clock)

then i'll have to suspect the fuel pump or relay failing when they get hot... what else ? the ECU ... the loom ... cylinder leak at high temp?

[zorgster]

I checked the coolant level and appears to be ok... i filled it slowly last night squeezing the pipes every now and again... so I took her for a drive up the road and had no problems at all.. sounded clean... the high revs had calmed down a bit... got to the local shop and back with no problems at all...

i'll go for a slightly longer trip tonight to take a friend home ...

trouble is i did this after replacing the vacuum pipes and three journeys later i had problems again ... just because i can drive without a problem now, does not mean i've fixed it ... which is a little frustrating...

i'm currently in London and once fixed i've got to drive back home to the Peak District .. so finding the fault is important...

another thing i noticed when getting to the inlet manifold was that the bolts attaching the manifold to the cylinder head were a bit loose... the bolt furthest left was almost so loose that i could undo it by hand... the other bolts only need a light tap to undo... the Haynes manual says the torque should be 22nm... so could this be a cause of intermittent loss of power at random points in time?

[zorgster]

Well .. i think i've solved the puzzle ... as I've driven her around for about a week now and not a flinch in the system...

whilst undoing everything to get to the inlet manifold i took care on each part to look at their state etc ...

1) the accelerator cable is sticking .. to be replaced...
2) coolant pipes screw up metal ties are rusty and need replacing ...
3) and perhaps the most important ... the manifold retainer nuts were hand loose.. i could unscrew all the bolts on the back of the cylinder head by hand... but the torque in the book reads 22nm...

So the smoke from behind the cylinder when the engine was hot was coming from there... the complete loss of power was due to a shift in the engine releasing fuel through the gap between the manifold and the engine? ... Could this be a cause of suddenly stopping dead from 60mph on a motorway?

Now I can drive at over 70... all the way .. and stop at a service station .. and then drive all the way home ... usually she would have died completely... but even two days later she is still driving as well...

now to replace the coolant pipes ... any suggestions?
accelerator cable?

anyone know a good body garage that could do a new door/doorskin with tartan decals for a Sidewalk? in or near the Peak District?