hi everyone seicento 2001 1.1 mpi. The problem is that when I've been driving a long time and the car gets hot in traffic it will cut out and not restart until it cools.
So far replaced coolant sensor ( green one top of engine looking right hand side as looking in engine bay). This has not helped. I have worked out that if I disconnect it and reconnect it the car will start. It will start and run with out this connected,but I guess this is not too good to do.
History .I replaced Head gasket, thermostat etc about a year ago with help from members of this forum.
I remember this problem appearing when I first got the car and pre head gasket failure.
Any help would be much appreciated
Thanks
sean

Any management light?

I migth be saying something wrong but I read somewhere that the lambda sensor only comes into play when the coolant is above 80 degres (they call it the closed looped engine).

Could it be a faulty lambda?

Faulty lambda should trigger the ECU light.

But this is a wierd issue.

Hi Thanks for responses .I think fingers you helped me with cylinder head about a year ago. I 've re joined forum as forgot password etc. No, no engine management light. This only comes on it I have to disconect coolant sensor to get it started.This then clears itself after about half hour of driving.

What is missing when it stops?

Dry or wet plugs?

Overheating crank sensor?

Cheers

D

MISSING ? good question. When it happens I've not been in a position to check. I'd previously let car cool down and then it would start later. when I searched the problem I picked up on a thread to do with coolant temperature sensor. so when it happened again I disconected this and the car fired up immediately and continued ( continues ) to run when connected. As it gets to the point where the car is getting hot it feels like the revs drop slightly at idle before it eventually stalls.
So next time it happens are you suggesting I take a plug out ? I can do that . How to I check if the crank sensor is overheating?
When I MOT'd the car in April after it hat not been driven for six months it had trouble getting through emmissions test. Whilst I was watching the MOT man ran the car for ages . The fan cut in but the car eventually over heated. I mean properly with water bursting out of coolant bottle. Stopped engine immediately. After a good run the car passed emmisions. But this makes me think something is causing the engine to run hot in traffic. Problem is I live in sticks and so this is never a problem unless I go into town and the car gets a chance to get hot in town traffic. Hope this extra info helps
Thanks

Water pump, clogged (etc.) radiator, water leak, white box thermostat.

Certainly needs further investigation.

thanks what is "white box thermostat. Also I am losing a little coolant somewhere top it up every couple of weeks

White box thermostat is one that's unbranded, comes in a plain white box. I've known them fail within 1000 miles. Halfords ones are usually OK, ones from Fluffy or FIAT are a safe bet.

You shouldn't loose any water -- the danger is that a small leak becomes a big one. Likely places for small leaks are the water pump itself, the water rail to water pump O ring, and the water rail itself (eventually they rot out).

Thanks i'll double check water pump. it was replaced when I did head and head gasket job. Please forgive me if I'm being stupid here but I replaced the thermostst when I did the head gasket. Is this white box thermostat the same thing ? Are you suggesting I replace the thermostat with a white box thermostat or is this something different. All this does make me think that whatever the problem is maybe it was the cause of the original head gasket failure ? Thanks again

I'd replace with one from FIAT or Fluffy (eurocarcare).

Ok so I'll order a new thermostat. I went for a long drive this evening and when I stopped I checked all hoses and all were hot ,top bottom, etc. Car ran ok but left heater on. It didn't cut out but I just sense it could .I'm very conscious of letting it cool down when I can.
In my reading around the net I found this on wikepedia " The first sign of crankshaft sensor failure, usually, is the refusal of the engine to start when hot but will start again once the engine has cooled." Is it worth changing this as I guess the one on the car has been there since new and eurocarcare have them for about £25 I think

You could always keep the old one as a spare. They're not uber reliable, hence a few folk putting 16v engines in with aftermarket management have swapped them for the Hall type/.

Thats why I was asking what is missing. If the spark has gone, it could well be crank sensor.

Cheers

D

Update 1
I'll keep posting until it's resolved so that this may help someone else.
Drove round for the last few weeks with heater on. This seemed to help with no reoccurrence. However daughter drove car yesterday only short distance and same thing. Car would not start. She left it for a while came back and it started!

Parts arrived today . So I removed inner off side wing to gain access to crank sensor. Surprised to find coolant on and around sensor? I wiped clean the area .I replaced the crank sensor with new one. Started car first click. I ran the car for ten/fifteen minutes to get it up to temperature and also to look for source of coolant leak. NO sign of leak. AS the sensor is below coolant bottle I guess some must have been spilt whilst topping up? Or could bottle be leaking?NO evidence of this in short test , but I am losing a small amount of coolant each week.

This brings me to Thermostat. I have a new one ready to fit but want to wait and see if crank sensor solves problem first. The thermostat appears to be working any way. If someone can confirm . This is what happened. From start car gradually got hotter. Top and Bottom hose felt cold. After about ten minutes I felt the hose gradually get hotter from the Thermostat down towards the radiator. It did not get hotter in a rush the heat just gradually crept along the hose towards the radiator. Bottom hose got hotter too. After another 5 mins the fan cut in, ran for a bit stopped then after a few more minutes cut in again. This must mean thermostat and fan are working normally ? Or could it still be a faulty thermostat?
Thanks

Thermostat sounds OK, fan switch circuit seems OK.

I think you have two seperate problems. The first is the coolant leak, the second the non start issue.

A water leak in the area of the crank sensor is most likely either water pump, water pump to coolant rail O ring or the water rail itself.

The leak needs sorting as it will get worse.

The non start issue may be:

Coil pack(s) breaking down
Crank sensor
Faulty water temp sensor (blue coded on the inlet manifold for SPI, green coded for MPI).

Next time it conks, test for fuel past the injector(s) and spark.

Thanks fingers
non start issue: already replaced green coolant sensor (green on my mpi) Today replaced crank sensor. So if this does not improve things then I need to look at coil pack. That makes it clear what to do next.
The Leak. I'll take the car for a good run this afternoon and see if I can find the leak. I replaced the water pump when I did the head gasket.
thanks I'll update when I see how things progress

LEAK- I let car cool down looked underneath and saw a small dribble of water running down sump under bottom pulley. I've removed belt covers and then replaced bottom pulley kept all cables out the way and run engine to see if I can see where leak is coming from. It is not obvious .It seems that more water appears as vehicle cools down. As I look at the water pump straight on it appears to be at worst weeping a minute amount of moisture from left of water pump where it is closest to big roung circle thing pressed into crank case. It certainly isn't an obvious leak. However as engine cools there is more moisture below this point around lumps bumps and bolts going into crankcase .I guess evaporation makes it difficult to spot small leak.
Where is the O ring you mention .Is this behind the water pump? sealing it to the crank case. sorry if I sound stupid Also is the water rail the metal pipe the is behind the water pump?
MY QUESTION- If I remove the water pump (new when head gasket done) can I clean it up and replace it using just blue gasket compound ? or do I need to wait and order a paper gasket? Thanks

Y'know, it could even be the

big roung circle thing pressed into crank case

Click to expand...

-- core plug.

Try rubbing the area very dry with a J Cloth or something, then rubbing in a little talk. The leak should then show clear witness lines.

The OE water pumps don't use a paper gasket anyway -- just sealant: a fairly thick silicone (I've used polyurethane -- Sikaflex -- in extremis). But before disturbing, I'd be very sure where the leak comes from.

O ring and water rail: