Gents,


I have been searching the threads to find an answer to my issue and I am not sure that I am able to pinpoint what it is. So...


Have had a hard starting issue for several months now. I initially thought it was the batteries so I had them tested. Auto Zone said yep, need new batteries. Made sense to me, first thing I thought of. Old batteries were 4 years old and I live in the dessert which kills batteries. Anyhow, put new batts in roughly Oct/Nov. 2104 time. Seemed to start fine. Fast fwd to present time, still have hard starting issue. It is progressively getting worse. In the morning, I let the glow plugs do their thing, then fire her up. It seems like it takes forever to start, almost to the point where it seems like the batteries are going to die. It's not a consistent occurrence either. If I have been running the truck for a while and I shut it off to go to the store or let it sit for a while, it may or may not start right up. It seems to be more prominent in the colder temps of the morning but, again, it is not always the case.
I have had the new batteries checked and they check out good. Also had the starter system checked and supposedly checked good. Auto Zone guy said alternator was not putting out correct voltage, could this be the cause?
I'm at a loss at this point and I don't really want to take it to the mechanic; 1: the cost, 2: not really any good diesel mechanics in my town.


Thanks in advance fellas.

 

How does it run when it finally does start? Rough idle that gets better as it warms up? Any smoke or strong odors from it when it first starts?

 

F350-6, I have not noticed any smoke or strong odors other than the normal diesel smell. I haven't noticed a rough idle either so I am puzzled by this. I read some of the posts on the forum that say injectors could be the problem but I only have 113K on the engine so would my injectors really go bad after that few of miles? I have noticed an oil leak which looks like it is coming from the front main seal but I didn't attribute the leak to my starting problems. The leak is not consistent either. Some days it will leak more than others but the leak is not a big leak. So...here I am.
Side note, temp this morning was roughly 37 and it started but it only started after it sounded like the batts were going to die, then at the last sec, it turned over.

 

Oil leak in the front could be something to check out. If the HPOP reservoir is draining down due to the leak, it could cause a slow or hard to get started condition.

 

I have the same issue on a 7.3 2000. New Motorcraft batterys were put in cables cleaned. It starts hot no issue. Cold over night it's not a firing issue but speed of crank. I crank once and it is clearly slower than normal. I stop wait crank again it's slow then if lucky it will speed up just a tad and fire. If cranking is too slow the PCM won't trigger the injectors.


Today I pulled the ground end of the cables on the front of the engine one on both sides. On the DS there was corrosion under the cable and on the engine boss. I wire brushed, cleaned and reinstalled. Then I did the pass side. Some corrosion but not as much. If either of these have corrosion and high resistance they will cause one battery to not supply enough power to crank.


I haven't tested mine yet on a cold night but I suspect I have another problem also. So my issue isn't not starting but slow cranking with new batteries and clean cables. I think we both may be dealing with the same issue.

 

Update: Today I checked the batteries just for ****s and grins. DS battery was 12.9V and the PS battery was 12.85. Also checked the alternator and starting system based on a troubleshooting guide that I saw somewhere on the forum. So here is what I found:
KOEO:
voltage between Battery + on alternator and mounting bolt:11.6V
voltage between battery + and alternator mounting bolt:11.79V
KOER:
voltage between Battery + on alternator and mounting bolt:14.3V
voltage between battery + and alternator mounting bolt:14.1V
KOEO: Starter test
Battery + and starter case bolt:11.7V
KOER (Cranking):
Starter connection + and starter mounting bolt -: 9.5V


So, based on the results of my troubleshooting, it looks like I have a bad starter. I was thinking about pulling the starter and see if I can have it bench tested tomorrow. Anyone have anything to chime in about that maybe I am missing? I know the starter is original and not been replaced before so I suppose it's likely the fault. Any help is greatly appreciated.

 

What was the Battery Voltage while cranking. That number and the Starter should be within .50v

 

Your numbers are very close to mine, When cranking my starter voltage drops to 10.0 volts and this is with two different sets of batteries both new. I have also concluded the starter needs replacement and started shopping for a new starter. It may be two weeks before I can give you results of the new starter. Mine gives the biggest problem first start of the day. After that it cranks slow but does start.


My battery voltage was 12.9 on both new batteries when I did the test.


I suggest you also start shopping for a new starter. My truck has 180,000 miles , 14 yrs old and the original starter.

 

I did not measure that. I didn't even think to check that voltage. I will test that next before going after the starter replacement. I didn't get a chance to pull it and have it bench tested this weekend either, so I will have to get that done as well before throwing $200 at it.

 

Your issue sounds exactly like the problem I am having. Weird...
My truck is an '03 and I only have 113K on mine but it is the original starter, so who knows. Going to do some more checks when I get a chance before I toss $200 at a new part that may or may not fix the problem.

 

My brother in law has a 2003 7.3 and has gone through the same issue of slow cranking. His starter finally caught fire/burned and when he replaced it the cranking speed was a lot faster.


I also checked Youtube and there are videos of 7.3 slow cranking oem starter then after with new replacement and it is way noticeable difference.


My guess is the failure mode is brushes wear down causing high resistance low torque then finally the brushes arch over burn out and you are stick on the road somewhere.


Mine still cranks slow and starts, but when the rainy season is over I will put a new starter on. We are expecting rain for the next 7 days, and hopefully it keeps starting.


I called a friend retired military who was a diesel mechanic on the Delta. His comments are brushes wear down and there won't be enough current flow to the armature to make it spin fast enough and start. It was common practice in the military to pull starters and changes brushes and clean the commutator. For me I will just buy a new starter and hope it goes another 15 yrs.

 

Well, it looks like it is almost dead. I went to start my truck yesterday after not driving it for a few days and it barely turned over. I did not check what the cranking voltage was on the batts since I was in a hurry and didn't think about it. I can tell you this, I did not think she was going to turn over. It took me three times of turning the key off then back to start before she felt like turning over. Guess I will be looking for a starter tomorrow.

 

FYI the driver side ground lug on the front of the engine on mine had a lot of corrosion. After cleaning both DS and PS ground cables mine is starting a lot better. I might consider not changing the starter but living in hurricane evacuation zones I decided to replace it even though it is starting ok. Yours might just need only clean of the ground if you haven't already done it.

 

Ok, so today I checked the voltage on the batts while starting. Driver side battery was 10.4V when cranking and the passenger side was 10.5V while cranking. The starter voltage while cranking was 9.5V from the other day when I checked it. So, with that said, since the difference between the starter and the battery voltage while cranking is greater than .5V, does that mean I have a bad starter? Also, I did notice that the voltage on both batts was rising as the truck was running, meaning the alternator is doing what it is supposed to be doing, again, leading me to believe I have a bad starter. Any thoughts?


Oh on a side note, it seems as though the oil leak I had from the main seal has stopped...for now.

 

That is exactly what I saw almost the same numbers. Cleaning the battery cables did make a difference. Bad worn brushes in the starter can cause a similar issue. I decided to replace my starter.