Starter Motor Rebuild?

[Benckj]

Anyone have any hints/tricks with rebuilding a starter motor on my 98GT?

Mine seems to be acting up with intermitant behaivour. Thought it could have been battery related but have discounted this theory. Sometimes when trying to start it won't engage and voltage drops from 12.8 to 11 volts. Appears to be a dead short and if I leave for an hour or so it sometimes kicks into gear with no issue & charging at 14.4vdc. Other times I'm not so lucky and it is DOA. Ignition circuit all works fine.

Thinking it may be a stuck brush or possible faulty selenoid. Planning to pull starter today and have a decent look at the motor internals. I see ebay has rebuild kits but not what available here. Not really keen on installing a second hand starter should I find a fault.

[GDII]

Starters do sometimes fail. Although curious that a low KMs late model SW would so. Mine is 8 years older and more KMs and never missed a beat. The solenoid might just needs cleaned up.

[Benckj]

I agree it’s very strange and I don’t have an answer just yet. Could be the selenoid or even the IGN switch. It is very strange how my voltage drops so low after trying to start with no response then 5 min later starts without an issue. Need to spend some time and diagnose problem.

[*84vvt]

Check the main feed wire from the battery to the starter motor has not corroded (read high resistance)
I had this fault on my AW stumped me for several hours before I found it.
And earths as well.

[Ben]

I would check the fused link off of the positive terminal on your battery. It should take only a minute to have a good look in there. My car would randomly start properly or not at all until I had found the issue there. Hopefully it's an easy fix

[Benckj]

I visually checked both of these and while looking ok I need to take some measurements. The part which confuses me and why I think it could be starter brushes is the sudden voltage drop on system after trying to start it. Acts more like a short than open circuit.

[Benckj]

Spent some time on the car yesterday and it seems to be starting each time now. Cracked the power leads off starter and re-installed with copper coat. Ran a spanner over all the earths and checked battery terminations up in frunk. Never really found anything wrong apart from plastic cover on starter lead had fallen off. Found it laying off on side so need to clean up and re-install

Managed to change oil and give everything a once over on top and underneath. Looking good for the most part but would like to detail out a few things as its not as clean as before. Mainly lack of use with a little surface rust on exhaust and oil leakage around CV's. Time to give the exterior a decent batch and knock some of the winter grime off. Would like to give exterior a ceramic coating treatment before the summer sun comes out to protect my new paintwork. Really need to take car for a decent run and blow some cobwebs off.

[GDII]

That's good it's sorted.

Got your boost control issues sorted?

[Benckj]

Yes, boost control sorted by installing the external wastegate couple years ago. Turbo was pushing too much air for internal gate to deal with. I've adjusted pressure down to a reasonable level as still running stock internals. Compressor really wants to sit at 21psi which is a tad too high for my liking.

Spoke to soon on starter fault After a dozen starts I went to crank over last night and it didn't go. Think I'd better pull starter to check selenoid and motor internals.

[GDII]

Good to hear the boost is under control. Just because it wants to sit at 21psi doesn't mean your controller and wastegate has to let it. What spring pressure are you running?

Might just pay to get another starter? Parts car still have one?

[Benckj]

I'd have to check but pretty sure the WG spring is 15psi. Really have to look at pressure vs flow to understand boost control. Response time can become a significant factor with high flow turbines.

As you mentioned before I sort of doubt the starter with the low km's would be the culprit unless water worked its way into windings. Do you know if the solenoid can easily be removed without pulling starter? Reason I ask is that it's fairly difficult getting onto the starter bolts unless I start removing coolant lines, etc. I don't have a spare starter or solenoid but figure it should easy enough to check/rebuild. With problems like this I like to diagnosis what's exactly wrong before I start part swapping.

[GDII]

I'd drop the wastegate spring down to 10psi if you are wanting to control it better. If your target boost is 18psi then the spring pressure is too high.

The starter is held in with 2 bolts. You shouldn't have to remove the coolant lines, just undo them. I think it's the heater hardline you are talking about.
You can take the solenoid off without removing the motor but it's a right pain to get back on. Best remove the whole unit.

If it works sometimes then it could be the starter relay? As a test I'd have the relay unplugged and jump the 2 power wires to set off the solenoid instead of using the key. Every time you go to start the car, if it fails to turn over then you know it is the starter itself.

[Benckj]

External gates work differently than the internals with sort of a push/pull arrangement on vacuum diaphragm (ref T method in diagram). They control better than internals but need to have higher spring tension to not open prematurely. I tapped directly into the turbine scroll case for bleed line into gate so it's very responsive now. I'll need to look at my docs to see what spring tension I ordered. Went down to 10psi with my internal and it was still impossible to control high pressure spikes.

On starter I have normal coolant/heater lines along with those to turbo and fuel lines to deal with on starter. I also installed a 3" intake duct from turbo to cold air intake so may need to pull completely off. Getting to starter bolts is a blindman's job with several extensions & swivel. I noticed last time I tried to start the solenoid clicked but starter didn't engage. I'll attack this weekend when I have some time.

[GDII]

Of course. External is different. How is the external installed? Does it have an adapter and the gate is 90° off that?
And how is the controller setup for gain?

[Benckj]

Got a bit excited today and pulled starter to have a looke. Figured if it is out I can inspect, lube up and reinstall with copper coat on the threads ensuring all grounds are ok.
After removal and pulling rotor from motor and then solenoid apart the only odd thing I notice is arcing on contractor off selenoid. Not entirely sure if this is the problem but will repair contact surfaces and re-install.
Thoughts?