S4 Starting problems

[Galwaylotus]

Be sure to check your earths under load. I had a similar problem and even removed the starter all to no avail. Then I disconnected the main earth in the boot. It looked fine - no sign of corrosion - but I cleaned it and reconnected it and the problem was solved. Just checking continuity with a meter is insufficient. You need to measure voltage drop under load (cranking or attempted cranking).

[collins_dan]

Where are the two power transfer contacts located in the starter? I took the old starter out, which was the original culprit, so can check that one first. Thanks. Dan

[prezoom]

I should have taken pictures at the time, but frustration got in the way. Start by removing the solenoid. If memory serves me, you can see the two large discs at that point and the lever that brings them together.

[billwill]

Somewhere on this forum, we reccommended that when fitting a starter with built-in solenoid it was easiest to merely use the existing bulkhead solenoid as a heavy duty relay and just connect the fat exit wire to the fat terminal of the motor AND ALSO connect the motor's solenoid wire to that same terminal on the motor.

That way you are sure that the feed to the built-in solenoid has very low resistance and you should have no problems with its pull-in current.

[mark030358]

Hi,
I had some chew with mine. Eventually turned out that the sandwich plate was ever so slightly kinked. This plate accurately aligns the starter and needs to be almost bob on.

If the starter is hitting the ring gear and then you have to rock the car to get it to engage and start, they were my exact symptoms.

By the way, refitted the Lucas, no more issues.

Cheers
Mark

[collins_dan]

Just a quick update. First off, no solenoid since I bought the car 13 years ago and this is the first starting problems, so I think the design is OK. Also, no signs of gear chewing. Problem is looking like the battery doesn't have the cold cranking power needed. I put it on a trickle charger to see if that helps. Question for Galway, or anyone that knows, how can I "measure voltage drop under load (cranking or attempted cranking)" and what are the numbers that I want to have? Thanks, Dan

[collins_dan]

I keep thinking I am going to post the final fix, but I am not there just yet. As mentioned before I replaced the starter initially thinking that was the problem. Not it. I did more checking of the voltage from the battery to the starter and concluded that the 7 year old battery was the problem. Not it. So I checked voltage at battery, then voltage at starter and it was the same. I checked voltage from ignition and it was much lower 11.7 vs 12.8. I replaced the white red wire coming out of the ignition and tested that and it was also 11.7. Checked the power coming into the switch via brown blue wire and it is 12.8. My conclusion is that I need a new ignition switch. Are there any other possibilities that should be checked before ordering a new ignition switch? Thanks, Dan

[Galwaylotus]

Did you check the voltage at the starter under load? If not it may be a bad earth. I had something similar and could measure 12V+ at the starter but not under load. It turned out to be a dodgy earth point in the boot.

[mbell]

Can you unplug the ignition switch and manually bridge contacts to simulate it?

Should allow you to confirm the switch before buying one.

[collins_dan]

I have no clue how to do that, nor do I completely understand how the switch works. I did check the voltage going into the ignition switch and it is 12.7. Dan

[prezoom]

My intermittent starter issue turned out to be something to be something I never thought of. Some times it would work and the next time is wouldn't. Finally took it to a local rebuilder, he tested it and it worked fine. Arghhhhhh. Told hime to rebuild it anyway. What he found was there there is a little rubber breather tube on the solenoid, and it was just loose enough to slip between the contacts, preventing the 12 volts from making contact to send the battery to the motor when the solenoid was engaged. I had told hime to replace everything, so he did as told, including removing the rubber breather tube, and replacing it with a rubber plug.

It worked just fine in the vise when I got it home, and when I installed it in the car. Tomorrow morning, will be the make or break test, as it will be the first time the Zetec will be started. Wish me luck.

[collins_dan]

Still suffering from occasional problems with this. Tested both the old and the new ignition switches by connecting the battery to the power in and multimeter to the switch spade. With the switch turned to on, 12.5 going in and 12.5 going out. Put either of them into service, connect everything up, 12.5 going in and 11.5 coming out?! What am I missing? Thanks, Dan

[nmauduit]

Still suffering from occasional problems with this. Tested both the old and the new ignition switches by connecting the battery to the power in and multimeter to the switch spade. With the switch turned to on, 12.5 going in and 12.5 going out. Put either of them into service, connect everything up, 12.5 going in and 11.5 coming out?! What am I missing? Thanks, Dan

that voltage drop reflects an operational resistance, which can come from a variety or combination of things : dirt or grease on operation contacts, oxidation or carbon deposits, wear (reducing the effective contact area), deformation or blockage preventing a strong contact force (making in effect the contact area smaller or less efficient, as there is a limit to the amount of current that can go through a given area) ...

That is why it makes sense to measure voltage under cranking load, since the contact behavior is not the same as without load.

[collins_dan]

Ok, so what do I do about it? Thanks, Dan

[nmauduit]

from what you posted (in summary with 12.7 coming to the switch wether the starter is on or off, 12.7V before launching the starter dropping to 11.7V when the starter is on) it seems that the switch is identified as defective : I'm not sure what type of switch you have, but you may be able to short it and see if the starter cranks faster then, which would confirm if need be that the switch has too high of an ON resistance (beware of the sparks, that is a lot of current) - or just change it for a new one...