Starter clicks but doesn't turn when hot - how do I find the root cause? (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
May 13, 2013
Threads
37
Messages
148
Hello everyone,

Looks like my New Year's resolution is going to be to finally sort out all of my LJ70's big issues. I'm using it as my first responder truck now that the farm has taken our Ford pickups full-time and I need a bit more dependability than I've experienced the last few years. What I think I need to fix the hot start issue is some guidance on the tools I should have on hand and the procedures I should follow so that I can get to the bottom of this the next time it happens. To date I have replaced the starter relay/solenoid on the inside fender/engine compartment, replaced the battery, and I've had the starter professionally rebuilt. The flywheel ring gear was examined when the clutch was replaced at the same time and it is in good shape. I've also replaced all of my ground cables and cleaned all of the ground contacts for the big cables on the engine and in the engine compartment. The issue I'm having is the classic truck starts fine when cold, starter spins fast, etc. When the motor is hot and its been sitting a few minutes, all I get is a loud click when I turn the key to start. It used to be that with repeated attempts it would sometimes start working but now I really just need to let it sit for a while and then it starts right up. Something is getting too hot and too resistant it seems. I've tried the rocking the truck in gear procedure and it doesn't help and I've also hit the starter with a hammer (without having the key turned at the same time however) but it makes no difference. I have a multimeter and lots of wire for bypassing various components. If someone could tell me how I should systematically go through the system the next time it happens to single out the faulty part, I'd really appreciate it. Best, Rich
 
You may require someone to assist you....
Remove the wires that come from your keyed ignition switch that go to the starter solenoid and check voltage on the terminals going to the solenoid when the ignition is switched to start.
Have you noticed other electrical problems that could be symptoms of oxidized ignition switch contacts or electrical connections to the ignition switch ?
 
You may require someone to assist you....
Remove the wires that come from your keyed ignition switch that go to the starter solenoid and check voltage on the terminals going to the solenoid when the ignition is switched to start.
Have you noticed other electrical problems that could be symptoms of oxidized ignition switch contacts or electrical connections to the ignition switch ?
I have no other electrical issues. I will check the voltage as suggested the next time I either get it good and hot or actually have the problem. Any thoughts on what would be too low/marginal for each or all of the wires at the solenoid under starting conditions? Thanks!
 
Ages ago I had a Diehard battery and could not start my car after running for awhile.

Started fine when cold, didn't when warm.

Turned out to be an internal short in the battery. New battery and all was fine.

Never experienced it since. Of course, never bought a Diehard again either.
 
When the motor is hot and its been sitting a few minutes, all I get is a loud click when I turn the key to start.

My guess is that it will either be a voltage drop at the starter or a fault within the starter/solenoid. Heat tends to make problems worse with starters.
 
So I did some baseline voltage measurements at the starter relay. Battery was at 12.7v. Continuous hot wire was the same with the key off and then dropped to 11.5 when the key was on to first click, even after glow plugs kicked off. At start the reading on that wire was the same. On the other side, voltage was nothing until the key went to start at which point I had 11.4. Went for a drive and got everything hot, though not hot enough to cause the fault, and voltage was 12.9 at battery, 12.1 on hot side at rest. 11.7 on hot side at start position and 11.6 on other side at start. Should I have 12 volts or more on both sides of the relay in the start setting? If so, does this indicate a corroded switch or some other problem?
 
Just to clarify above, this is of course with the starter relay removed as I can’t access the connections with it in place.
 
What is the voltage at the battery and the alternator charging stud with the engine running ?
With the engine running the alternator should be putting out 13.5V at a minimum; preferably >14V.
When the engine is off and cooled down for a couple hours; the battery voltage should be >12.3V.
The voltage on the wires that energize the starter relay should be almost the same at the battery.
If there is more than .5 V drop there is something running (ie. electric fan, glow plugs, stereo) or you have some seriously dirty electrical connections in the circuit.
 
Voltage at battery with engine running 13.3. Voltage at alternator stud 14.4/14.5.
 
The voltage at the battery terminal should be within a couple tenths of what the alternator stud is. With those numbers.... there is a serious voltage drop that could either be caused by a heavy drain on the system or some really dirty electrical connections....
You can troubleshoot to see if there is a electrical system drain by removing fuses one at a time from the fuse block checking the battery voltage to see when the voltage goes up dramatically. Just make sure the fuses you remove to do not affect engine operation.
 
Last edited:
I once had very bad connection where one of the main battery cables was soldered to its battery clamp terminal. Fault was not readily apparent. Exterior of clamp and battery post were clean and bright. De-soldering, cleaning and re-solder fixed it.
 
Yep. I'm starting to suspect some of the grounds that I didn't replace in first go around. I've ordered some new clamps that I should be able to install over the weekend.
 
Yep. I'm starting to suspect some of the grounds that I didn't replace in first go around. I've ordered some new clamps that I should be able to install over the weekend.

When you install the new clamps and clean the ground connections; apply some oxidizing inhibitor to those connections to decrease the chances of this reoccurring in the future.
 
That inhibitor was a good suggestion. Used some today. Seems like good stuff. Wish I’d bought the electrical cleaner that goes with it. File did the trick however. Didn’t get to the bad clamp yet. Just reinstalled my second battery and the dual battery monitor system.
 
During my last visit to the PI the battery terminals and clamps needed the connection surfaces cleaned. In the PI electrical connections develop oxidation and corrosion quickly due to the heat and salt air. Prior to reconnecting the clamps I installed a set of battery terminal corrosion protectors.

Corrosion Protectors
66192900.jpg
 
So my truck lived in Liberia in a beach front compound for several years before I brought it to the US. This was after life as a snowplow in Switzerland. You can imagine the corrosion issues :).
 
So now that I’ve been paying much closer attention to my electrics I’ve noticed something happening I don’t understand. When I turn the key to the first click, I hear the glow plugs kick on and see the voltage drop below halfway on the gauge. There is another click and a slight rise in voltage after about 10 seconds, which I always assumed was the glow plug relay kicking off. However, the high-level voltage drain stays on for about another 30 seconds until something clicks off and the high drain load stops with the Voltage gauge kicki jug back up to halfway between 16 and the half mark. I can confirm this with my battery monitoring system and other voltage meters. Do these trucks have a two-stage glow circuit or is the first 10 second click something else? Thanks if anyone knows the answer.
 
I should clarify that this is also how the truck behaves after I’ve started it and it is running. The large voltage drain stays on for about half a minute idling or moving with the gauge at halfway before it clicks up to normal.
 
Hot start problem fixed. Had local starter and alternator place in Roxboro NC - City lake Automotive - rebuild it. First rebuild done 7 years or so ago apparently wasn't comprehensive enough.
 
It is good to support those shops.
 

Users who are viewing this thread

Back
Top Bottom