|Vehicle details:||Ford Focus|
I had a 2003 Ford Focus 1800 TDCI Duratorq come in with a hard start issue from cold. Once it was warm it would start great every time. No DTCs stored and live data showing good pressure generation. Checking amps on the injector harness confirmed commencement of injection too.
Even though glow plugs are not generally associated with cold start issues on modern common rail systems, the fault gave the exact same symptoms of a failed glow plug that you would encounter on a direct injection setup. So I decided to confirm that they were OK anyway. Sure enough they were all good, and I was running short of ideas!
After exploring all reasonable diagnostic approaches I could think of, I decided to go back to basics. One vital ingredient for a good cold start is cranking speed. This particular car didn’t sound too lazy when cranking, but with the list of possibilities running out, I decided to scope the starter motor current.
This capture with the original starter is taken with the cam sensor disconnected…
Here it is again, only a little closer and with some measurements taken…
Now with the new starter…
Again seen closer…
The captures display very nicely the benefit of the new starter motor. Not only has the crank speed increased from 194 rpm to 291 rpm, but the current required (211 amps against 165 amps “average”) to achieve this increase means that more energy is available for other vehicle systems. The signal on the new starter capture is a lot cleaner too.
With good frosts over the next few days for repeated testing, the car now starts quickly at the first attempt.
Imagine how hard it is to convince a customer that his starter motor is the cause of his cold start issue, especially when it sounds like a healthy unit!
Waveforms provide great evidence to back up your diagnosis and repair!
January 17 2016
Probably one of the best posts ever, thanks.
February 14 2015
Does the glow plug light now stay on longer as it should after replacing the starter and seemingly resolving the cold start issue by any chance? mine fires and stops many times before finally starting while I hold the throttle to the boards. Perfect when hot. Many thanks
November 17 2013
perfect got focus yesterday with this problem top information. cheers sam
March 10 2013
I am glad I found this , I had the same problem with cold starting , changed my starter motor last week and it now starts first time
February 22 2013
Hi, I was just wondering if its possible to diagnose this as a cause without spending Â£60 on ford diag, or access to scopes etc? I’m good with spanners, but not so with elastic-trickery, and don’t have anything other than a multimeter. Would a particular voltage drop during cranking indicate an issue? Would jump starting, help it to start properly when cold? either option indicating either a starter/battery issue at least.
January 15 2013
Spot on, had same problem with my tdci, and i was scratching my head a bit until i read your posible cause, i fitted a new starter this evening and it now starts first time every time.
Thankyou for your help.
September 13 2011
Having recently been affected by the dreaded ‘click’ on my 2001 TDCI when turning the ignition key, as an emergency measure I discovered shoving the car in 3rd gear got the starter to engage. You need to be fairly muscular to do this! After some procrastination & the problem worsening i.e. happening more often, I decided to dismantle the starter. Apart from the brushes end needing a good clean along with the commutator and a sticking brush needing freeing all looked good. In fact the brushes were sufficient to drive the engine to the moon on them. The dreaded ‘click’ still remained. It occurred to me the starter was struggling and turning very slowly. This can only be caused by lack of current. The only thing in the circuit between the battery and the motor being the operating solenoid which is activated by turning the ignition key and supplying 12volts to the solenoid coil.
Having completely dismantled the failing solenoid, the problem is as I expected. Contacts are the weakest link in any electrical system. They get eroded; make increasingly poor mechanical and electrical contact and circuit which in this case means even with a good battery the starter turns slower; that is if it turns at all. Having ‘dissected’ the solenoid I can categorically say the problem is erosion / build up. The ‘contacts’ are in fact the terminals on the solenoid to which the cables are connected; one which goes to the battery and the other to the motor. The ‘terminals’ are actually bolts made of copper and tinned. The heads of the bolts are used as the contacts to pass the battery current across a copper strip on the end of the solenoid when it is activated (by turning the ignition key). The heads of these bolts are flat and square with a diagonal grooving or slotting across their surface to give better contact and resist arcing when they meet the copper strip on the solenoid. Over many thousands of applications of the solenoid the heads of the bolts / contacts erode in the same way a welder works; metal is taken from one surface and deposited on the other. Direction of build up / erosion is dependent on direction of current flow.Due to operating tolerances of the solenoid as the bolt heads / contacts erode they make less and less contact with the solenoid copper strip. This ultimately results in the dreaded ‘click’ syndrome. So if the headlights, horn etc work O K its NOT the battery. To repeat in my 50 years of experience of electronics, electrics and in particular contacts and relays the latter are BY FAR the weakest element in ANY system. Motors and brushes will outlast ANY relay / set of contacts.
The moral of this story is: when someone says its your starter motor mate and that’ll be Â£120+VAT plus fitting it is infinitely more likely to be the solenoid contacts, so try and find an auto electrical supplier who will replace the solenoid. An emergency ‘get-U-home trick is to give the starter motor / solenoid a sharp tap,(don’t savage it!) this will usually jar the solenoid contacts and get you started. I have done this many times in the past. Getting at starters is not easy these days—either from under the bonnet or grovelling under the car.If you buy a ‘new’ starter and it starts clicking you have been sold an old one with worn solenoid contacts. Insist it is replaced with a REAL new one. Happy motoring!
December 14 2010
I was a bit slow to get this done, but the new starter has really helped - car was almost impossible to start on old starter now it’s so cold - new starter made all the difference
December 05 2010
I have repaired several starter motors on Ford Mondeo and Transits after DMF failure. I would recomend starter recondition along with any DMF failure.
October 29 2010
Thank goodness for people like you Dave, same problem just swapped starter this morning myself, fired up first click. I also had a new DMF about 18 month ago, certainly must be a factor. FOCUS 18 TDCI. Keep up the good work mate.
October 12 2010
I have exactly this issue - thanks for a new line of investigation. I also had a failed DMF so I’m wondering if debris from this has compromised the motor. Poor starting & failed DMF seem very common on this model.
September 06 2010
Yes it’s an interesting question & I am not sure that my answer will satisfy.
The starter when it left the factory would have been lets say for the sake of discussion 100% efficient. Over its life in service, there is bound to be some degradation in all of the mechanical components that go into its construction. Losses in bush or bearing lubrication will cause a degree of tightness maybe. The brushes & commutator would most likely lose some of their ability to pass current so efficiently. The contacts in the solenoid would deteriorate over time too.
It should be considered also, that the replacement unit may have been subject to modification & possibly up rated for the task. We are seeing this more & more often, as vehicles exhibit problems whilst in service. The manufacturers respond, by changing specifications on components.
In summary, the starter motor had not failed as such, but had deteriorated to the point where its performance had compromised the engines ability to combust the diesel on cold mornings.
I hope this explains my thoughts
April 28 2010
In many of your other articles you explain the nature of the device malfunction. But for defective starter motor current to increase by 46 amps gives about an extra 460 watts to be dissipated in for example stiff brass journals or shorted armature segments without contributing to starter speed and torque. How did the starter motor fail?
February 21 2010
Dave where did you find the specs for the starter, ie peak, amp draw for each make of vehicle. This kind of info is what every good tech wants keep up the good work and again thanks
July 02 2009
Sorry for the weak english!
I had the same problem too, a year ago. Focus 1.8 TDCI very hard to start. The starter motor’s sleeve was dilapidated. Becouse the motor was full of metal dust. And the dust came from the dual mass fly-wheel…
May 25 2009
Had the same problem cost Â£60 for a Ford dealer to tell me it was the starter motor, which confirms your info above. I wish I had found your website first. Changed the motor myself on my Focus 1.8TDCI, took me 1.5 hours. Now no Issue with starting.
March 06 2009
hi dave im a lexus technician, thanks for nice technical information. more power.
February 28 2009
Nice.. I kind of like my brute force method. I just use 3 full sized batteries to start my 6.5 Makes sure it cranks nice and fast compared with just two on the 6.5. With just two if even one of the batteries starts to go bad it wont crank fast enough to start on a cold morning. The only downside that I can see is it seems to be a bit hard on glow plugs.
January 29 2009
Though it may sound funny, but I do know that many customers will look into your eyes trying to figure out the truth with an interset in carrying away the old one immidiately even after the problem is sorted.
January 26 2009
The “Peak voltage” comment is an error on the part of the guy who put the final edit together. That section of text belongs in another article altogether. Funnily enough it was removed at my request, but it has sneaked back in. Good to see you questioning though!
“The signal on the new starter capture is a lot cleaner too.” Is that the same?
Thanks for the interest guys
January 25 2009
Sorry for my ignorance, but how did you get the RPM?
You also mentioned ‘a much healthier peak voltage’.
Did you measure that separately?
January 25 2009
I think its also worth noting the amount of “noise ” present in the original waveform.
January 23 2009
Interesting case. I have a Volvo XC70 D5 common rail coming in next week with exact same fault, no codes flagged, etc. At my wits end I’ll certainly check S/motor.
January 19 2009
how did you come up the rpm?
January 18 2009
Thanks gentlemen for the kind remarks.
Are you asking that I explain the whole of my diagnostic path, throughout this repair? Or are you attempting to pin me down on a specific test that you would have performed & therefore assume that I should do the same?
January 17 2009
Good diagnosing, I find your technical tutorials and troubleshooting very interesting. Keep them coming! I myself find them very helpfull to keep a broader mind in the learning curve of diagnosis.
January 17 2009
Interesting diagnoses, but where is your basic test result / e.g. voltage drop, what was the difference?
December 22 2008
Well done dave, keep them coming, can’t wait for the next installment