The Diesel Stop banner
1 - 20 of 24 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter · #1 ·
I apologize if this has been answered already, I have been searching all weekend and can't find any posts about this.
I am having a problem with my truck not starting. When I turn the key the battery gauge on the dash is in its normal spot on the n on normal, as soon as the glow plug relay clicks the battery gauge on the dash drops to the red line and the truck only clicks when you try to start it. I put a new starter on about 3 months ago and changed the starter solenoid at the same time, changed out the valve cover gaskets 6 months ago. I have replaced the glow plug relay this weekend and still having the same problem. I had the batteries load tested yesterday and they tested good. both are sitting at 12.5 and 12.6 volts. I have tested the glow plugs with a test light and they all showed fine. I have checked all the fuses and they are all good. I have been checking connections and wires all day today and haven't found anything loose, burned or worn through. If anyone has any suggestions or ideas I would be grateful. I can't afford to take it to a shop and I can't get it started so I couldn't take it in anyway. Thanks in advance.
 

·
Premium Member
Joined
·
9,669 Posts
It's normal.

The glow plugs draw upwards of 200 amps when the key is first turned on. That is what is drawing the batteries down and that is why there are 2 batteries. Then the starter draws another bunch of amps.

Even with the batteries being load tested and testing good I would wager that you have one or both of the batteries just won't handle the amperage draw that happens when you start these trucks.

What size are your batteries? Stock I believe that they were 750 cca, but most of us run 850 cca batteries.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #3 ·
Mine are both motorcraft max 850cca. They are less than a year old, I know that doesn't mean they are still good but hopefully I can get them prorated. Thank you for the help. I really appreciate it. Will post when I get the new ones to let you know if that fixed it.
 

·
Premium Member
Joined
·
9,669 Posts
What happens if you disconnect the glow plug relay and try to start?

Depending on where you are located at and the temperature it could take a bit of cranking to do it.

Also when you had the batteries tested were they tested by themselves or were they still connected together?
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #5 ·
When we unhooked the glow plug relay the the drop at the gauge didn't happen but it still just clicked. I live in Texas south of Fort Worth, so its hot enough here it should just start. LOL Its my daily driver and everything was fine before last Tuesday. I took them out to take them in and he tested them one at a time.
 

·
Premium Member
Joined
·
9,669 Posts
If everything was fine then check the voltages on the cables themselves. You may have a bad cable that looks fine but has gotten water inside the insulation and you may not be making good enough contact for the amp draw.

Also look at the grounds, you will have two main ones on each side of the front of the block coming from each battery.

I just replaced my battery cables this last spring and only did it because of the clamps being worn and I figured that they would start to cause problems. I was surprised at the corrosion that I found once I got the old ones off where I could do a real good inspection on them.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #7 ·
Ok I will go do that right now . I've been thinking about replacing my cables for that same reason. After buying new tires all the way around on the truck I was trying to wait till I saved up enough to do it. LOL Everytime I am working on something and unhook the battery I am amazed at the amount of corrosion thats hiding under the clamps. Thank you for all your help. I am going to go check all the cables and grounds so I will let ya know what I find.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #8 ·
Battery cables are showing 12 volts at the ends. Both grounds are clean and tight. I had cleaned them last week after this all started but I figured it couldn't hurt to check them again.
 

·
Premium Member
Joined
·
9,669 Posts
You should have the same voltage on the cables as you get when you go across the battery terminals.

Also, you can have someone try and start the truck with your volt meter on the batteries and see what happens and just how far down the voltage drops.

I was wondering, when you are getting the clicking when you are trying to start is it the fender mounted relay clicking or the starter just isn't able to turn the engine over? If it is the starter then the voltage should be drawn down quite a bit.
 

·
Premium Member
Joined
·
9,669 Posts
To give you a baseline here is what my voltages read:

Batteries alone................12.99

Key on with glow plugs...........11.75

Key on start with glow plugs........10.8
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #11 ·
Yes Sir it was the same. I will get my friend to help me check that here in a minute.
When I try to start it it sounds like the fender mounted relay is clicking. I put a different one on that I knew worked and it didn't change anything. Thank you for the baseline. I will go get some help and check the voltage with the key on and let you know. Thank you so much for your help and taking the time to try and help me.
 

·
Premium Member
Joined
·
9,669 Posts
The test that I did was with fully charged batteries, I keep a battery maintainer on them when it is parked.

If your batteries are not fully charged then the voltages will vary but at least you can see about where the voltages should be.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #14 ·
I think once I get this sorted out I will get a battery maintainer to keep on mine. Just to be on the safe side.
 

·
Premium Member
Joined
·
9,669 Posts
I'm 99% sure that it is your batteries.

Even if it did turn the engine over it would not start the truck since you need a minimum of around 10 volts to activate the computer.
 
  • Like
Reactions: Craig Alberts

·
Registered
Joined
·
13 Posts
Discussion Starter · #16 ·
Ok, so I will go as soon as I can get a ride and get new batteries. I will update after I get them in and let you know how it goes. Thank you so much for all your help. I was pulling my hair out trying to figure out what was going on after they bench tested good. You have been a life saver today. I hope you have an awesome day and Thank you again.
 

·
Registered
Joined
·
4,981 Posts
Check the alternator output at idle should be around 14 volts. DENNY
 

·
Registered
Joined
·
20 Posts
I apologize if this has been answered already, I have been searching all weekend and can't find any posts about this.
I am having a problem with my truck not starting. When I turn the key the battery gauge on the dash is in its normal spot on the n on normal, as soon as the glow plug relay clicks the battery gauge on the dash drops to the red line and the truck only clicks when you try to start it. I put a new starter on about 3 months ago and changed the starter solenoid at the same time, changed out the valve cover gaskets 6 months ago. I have replaced the glow plug relay this weekend and still having the same problem. I had the batteries load tested yesterday and they tested good. both are sitting at 12.5 and 12.6 volts. I have tested the glow plugs with a test light and they all showed fine. I have checked all the fuses and they are all good. I have been checking connections and wires all day today and haven't found anything loose, burned or worn through. If anyone has any suggestions or ideas I would be grateful. I can't afford to take it to a shop and I can't get it started so I couldn't take it in anyway. Thanks in advance.
The little hand-held battery testers are great for saying failed batteries are OK. To test what a battery will do under load -- and believe me glow plugs plus cranking a large V8 with very high compression ratio IS a load -- you need a load tester. That you will not find at O'Reilly's, Autozone etc. I own an automotive shop. We regularly condemn batteries that will not crank a vehicle or pass a load test. When the customer tries to return the battery to O'Reilly, Autozone etc. they are told the battery is good. But the vehicle won't start without a jump until the bad battery is replaced.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #19 ·
The little hand-held battery testers are great for saying failed batteries are OK. To test what a battery will do under load -- and believe me glow plugs plus cranking a large V8 with very high compression ratio IS a load -- you need a load tester. That you will not find at O'Reilly's, Autozone etc. I own an automotive shop. We regularly condemn batteries that will not crank a vehicle or pass a load test. When the customer tries to return the battery to O'Reilly, Autozone etc. they are told the battery is good. But the vehicle won't start without a jump until the bad battery is replaced.
Thank you for the information. I took them to the nearest shop to me to get them tested. Wasn't there when he load tested them so not sure what he used to test them. Just got the new batteries in and it cranked right up after sitting for 2 weeks.
 
1 - 20 of 24 Posts
Top