The story so far...

Bought a lovely looking 2006 Fiesta 1.6 16v with FSH & full MOT from a guy I'd bought from before for £800 after trade in for scrap on my Pug Partner Combi on which the diesel pump failed. After two days the Fiesta developed symptoms of HG failure including coolant loss when something gave way on the way to work. Confirmed with an exhaust gas leak test so replaced the head gasket and confirmed a small coolant leak into cylinder 4 on the battery side. Replaced: water pump, belts, valve stem oil/intake/throttle body seals, exhaust/temp sensor housing gaskets, themostat & housing, etc. Still dealing with an air-lock and coolant loss (a small amount suspected from the thermostat housing). The driver side rear door warning came on occasionally, reclosing the door fixes it usually.

Currently developing...

• After redex for a short while the slight stumble at idle which isn't like a misfire, disappears when up to operating temp.
• The passenger door and bonnet have now developed the same issue as the rear drivers door.
• Started driving this morning and the battery warning light was on, the voltage meter on the adapter in the cigarette socket was 13.4v which I suspect triggered the warning light so the battery could be in poor condition without proper long trips since I got it, only short ones with a lot of reconnections, etc.
• A small oil leak at the back which appears to be coming from the drivers side at the valve cover, so need to investigate.

Parts ordered...

• Used, good alternator 90A with warranty (not the 70A because it's a Ghia with all the extras)
• New expansion tank and cap - probably aftermarket, so going to be cautious
• 10l ready-mix coolant

My hypotheses...

I have some poor ground points relating to the central locking and the ignition which are contributing to poor idle at cold, the door/bonnet close switches (which set the alarm off once) and potentially the smart charging from the alternator.

My plans...

• The battery is on charge now, but the smart charger did some funny stuff, going up to 14.6v indicating near full and back down to 13.5v indicating half full; this could be voltage stablising accross cells, so will leave it going for another couple of hours and again tomorrow. It seems to have stabilised at 13.5v charge at half full for the moment.
• Check battery warning after a full battery recharge
• Replace alternator if required
• Reattach thermostat housing with liquid gasket
• Remove valve cover and find the source of the oil leak
• Investigate earthing points for corrosion and restore where needed
• Replace expansion tank and cap to cover off potential coolant loss from the HG leak there
• Attempt a better coolant refill using ramps to help dislodge air locks

It's a lot of work I know, but I'm not confident driving it at the moment

What are your thoughts?

Does anyone have a list of earth points for the locking and poor idling issues I've mentioned?

P.S. The Pug has been spotted around town by my son and a few people I know, so kicking myself for not diving in to that project again after four years of keeping it on the road - I replaced the HG on that too. Just didn't have a spare pump to hand or the patience for the rebuild kit. BTW it's the last mk1 pre-facelift Pug Partner Combi on UK roads and it started life in Glasgow - the welding did wonders!

Intermittent door open alarm is probably due to a failing microswitch in the door lock assembly.

Battery fully charged today, going to start removing parts this evening to get to the thermostat housing again and refit with the new old alternator at the weekend.

I had thought the microswitch when it was only the rear drivers door, but for the bonnet and passenger door to start doing it shortly after made me think about earth points as after a period in Spain, it had been sitting in a Cumbrian yard for five months through winter before the MOT. Possibly what started the old HG failure too. It'll teach me to ask more questions when buying an old car from trade in future.

5 minutes ago, MAH310583 said:

... the microswitch when it was only the rear drivers door, but for the bonnet and passenger door to start doing it shortly

Water ingress to the GEM is the most probable cause.

On 5/13/2025 at 3:58 PM, MAH310583 said:

The story so far...

Bought a lovely looking 2006 Fiesta 1.6 16v with FSH & full MOT from a guy I'd bought from before for £800 after trade in for scrap on my Pug Partner Combi on which the diesel pump failed. After two days the Fiesta developed symptoms of HG failure including coolant loss when something gave way on the way to work. Confirmed with an exhaust gas leak test so replaced the head gasket and confirmed a small coolant leak into cylinder 4 on the battery side. Replaced: water pump, belts, valve stem oil/intake/throttle body seals, exhaust/temp sensor housing gaskets, themostat & housing, etc. Still dealing with an air-lock and coolant loss (a small amount suspected from the thermostat housing). The driver side rear door warning came on occasionally, reclosing the door fixes it usually.

Currently developing...

• After redex for a short while the slight stumble at idle which isn't like a misfire, disappears when up to operating temp.
• The passenger door and bonnet have now developed the same issue as the rear drivers door.
• Started driving this morning and the battery warning light was on, the voltage meter on the adapter in the cigarette socket was 13.4v which I suspect triggered the warning light so the battery could be in poor condition without proper long trips since I got it, only short ones with a lot of reconnections, etc.
• A small oil leak at the back which appears to be coming from the drivers side at the valve cover, so need to investigate.

Parts ordered...

• Used, good alternator 90A with warranty (not the 70A because it's a Ghia with all the extras)
• New expansion tank and cap - probably aftermarket, so going to be cautious
• 10l ready-mix coolant

My hypotheses...

I have some poor ground points relating to the central locking and the ignition which are contributing to poor idle at cold, the door/bonnet close switches (which set the alarm off once) and potentially the smart charging from the alternator.

My plans...

• The battery is on charge now, but the smart charger did some funny stuff, going up to 14.6v indicating near full and back down to 13.5v indicating half full; this could be voltage stablising accross cells, so will leave it going for another couple of hours and again tomorrow. It seems to have stabilised at 13.5v charge at half full for the moment.
• Check battery warning after a full battery recharge
• Replace alternator if required
• Reattach thermostat housing with liquid gasket
• Remove valve cover and find the source of the oil leak
• Investigate earthing points for corrosion and restore where needed
• Replace expansion tank and cap to cover off potential coolant loss from the HG leak there
• Attempt a better coolant refill using ramps to help dislodge air locks

It's a lot of work I know, but I'm not confident driving it at the moment

What are your thoughts?

Does anyone have a list of earth points for the locking and poor idling issues I've mentioned?

P.S. The Pug has been spotted around town by my son and a few people I know, so kicking myself for not diving in to that project again after four years of keeping it on the road - I replaced the HG on that too. Just didn't have a spare pump to hand or the patience for the rebuild kit. BTW it's the last mk1 pre-facelift Pug Partner Combi on UK roads and it started life in Glasgow - the welding did wonders!

I would be going on a ground connection cleaning tour! The grounding issues are so common that I have assembled my own kit of tools and equipment to deal with that exact problem. Once our Fords have been on road for five years the ground connection problems become more common and I have found that the glitchyness of many features is rooted in either a poor ground connection or a weak battery. The modern car is not tolerant of unstable voltage regardless of the power requirements for the various components. In fact, clean and stable voltage is even more important on components that require a low voltage signal to operate or communicate with the processors. I am applying a nice coating of petroleum jelly to the cleaned grounds once I have finished cleaning and fastening them back into place.

23 hours ago, Scottman said:

I would be going on a ground connection cleaning tour! The grounding issues are so common that I have assembled my own kit of tools and equipment to deal with that exact problem. Once our Fords have been on road for five years the ground connection problems become more common and I have found that the glitchyness of many features is rooted in either a poor ground connection or a weak battery. The modern car is not tolerant of unstable voltage regardless of the power requirements for the various components. In fact, clean and stable voltage is even more important on components that require a low voltage signal to operate or communicate with the processors. I am applying a nice coating of petroleum jelly to the cleaned grounds once I have finished cleaning and fastening them back into place.

Love the ground point refurb kit!

I think I've already got what I need it but it's not organised.

When delving into the rest of the jobs I should get good access to the points around the engine and will start with those. Got a good stack of assorted W&D paper and read up on the ultimate point on the battery terminal which is caked in blackened grease, so that needs some attention.

Later I'll remove some of the interior trim on the A&B pillars and front sills, check those points against a battery reference voltage and condition as required.

The locking issue is intermittent and may not even involve driving the car or disturbing the switches which is why I suspect poor grounds but, if it continues after some TLC with the connections, I'll probably have to source new latches.

On 5/14/2025 at 6:08 PM, unofix said:

Water ingress to the GEM is the most probable cause.

I'll take a look and reattach the plugs to see if that makes a difference but I'm relcutant to go down the route of removing it just yet.

After attaching the new, used alternator the battery issue was initially solved. The battery is old and the strap nuts are rusted - looks like it's been like that for a while since the battery strap at the side is twisted and the cradle broken from someone trying to get it off. I'll try a solder gun on it to see if I can get it off with a bit of heat.

The battery light started to come on again the first time it's driven each day, the voltage fluctuating between 12.5v and 15.8v before steadying after about 5 minutes to around 14.4v and the light will go out. I've put the old battery on charge again this evening to see if that eliminates the issue, but suspect dodgy connection to the smart voltage regulator. My wife will be using it tomorrow and I'll use the bus because her car failed the MOT last week, it's fixed and due for a retest on Tuesday which it will pass so, when I get mine back I'll try to get the code read with Forscan.

I've come to the conclusion the door sensor switches are the problem not the ground points. Is it worth sparying liberally with WD40? Or simply replacing the latches? The bonnet latch was just down to not closing properly - not a problem now.

Also got water leaks in the boot to sort - got new sealing foam sheets to make some replacement gaskets for the lights and the trim above the numberplate. I think I've got some clear sealant I can use on the slightly cracked welds at the top too. Wish me luck!

My wife's car passed, so before driving to work today in my car I wiggled the alternator regulator plug before starting it; the voltage rose steadily from 12v to 14.1v and stayed there without the battery light coming on. This was for all three trips today so I suspect connection issues only at the moment. I think a good clean and adjustment of the connections with some electrical grease will be enough to resolve this little problem for a while longer. This gives me some time to use plenty of penetrating fluid on the battery strap nut in the hope it will eventually come free without further damage to the battery tray.

Got some copper pipes at the front corners of the brake lines I want to replace with kunipfer (there are a few spellings, but it's the same stuff), copper is only a very short term solution to a car with ABS. I've done stainless steel flaring and couplers to the kunifer for a Focus in the past, a bit a pest but sure I can do a better job than the mixed metal join with copper there at the moment. Spotted a video on youtube about using Forscan to bleed the brakes, I think he's ThatFrozenFez with his ST150. It's convinced me to do the same with mine to get the bleeding done right. I think it might be time for another thread though, I will continue to post here about the doors if/when I get round to those.

The occasional blip with idle which is more prominent when warming up I think, is due to the oil separator (PCV built in) so will check out the gas escape at the oil filler cap and oil level tube to help diagnose. I think these Duratec/Zetec engines are rather sensitive to this - comments welcome. I want to take it off for a deep clean and gasket replacement but it will have to wait until I get some time off work.