M816 Wrecker Won't Start

[Lawrence of Arabia]

I have had the truck for 3 years. I put batteries in it from the get go. It started on it's own a few times, but mostly I have always had to hook slave cables up and jump start it. Now it just clunks when I try to start it. I pulled starter and starter shop said it needed a solenoid. I had them put one on and put starter back in. Still just a clunk, clunk, clunk when I try to start it. Batteries all charged up. Getting proper voltage to big studs on starter. Anyone have any suggestions on where I go from there?

 

[swbradley1]

Control box?

 

[M35A2-AZ]

Control box?

 

[Tow4]

Jump the solenoid at the starter and see if the engine cranks. If not, you have a starter or connection problem assuming the batteries are good. If the engine cranks, check the control box and starter control circuit.

Good luck.

 

[swbradley1]

Upon further reflection I would also like to suggest checking the connections. In a no load scenario voltages will read good. As soon as you put a load onto a faulty connection resistance can increase to the point where you are just generating heat at the resistance point and the starter won't crank.

 

[Wile E. Coyote]

Connections first, then Protective Control Box. I've had a couple of them fail on the 800s at work, and seem to recall another one where the box didn't seem to be grounding - but that was a long time ago.

 

[Coffey1]

Just throwing this out.
I had a Ford E350 the head gasket started leaking. At first it was just slow to turn over like weak batt.
Then it got worse and when you tried to start it also was just clunk.
Hope this is not your problem.

 

[Floridianson]

Put the transfer case in netrual and the trans in 5th bar over the jackshaft and see if motor spins free.

 

[Floridianson]

What is the difference between a click and a clunk. Little problem big problem.

 

[Lawrence of Arabia]

I got it jump started with my 923 yesterday and it runs strong still. I spoke with Memphis Equipment and the service guy said they have put batteries and a starter in trucks before and had the same scenario. He said the old battery cables would not carry the amperage needed to start the truck. He said once they changed out the cables it solved the problem. Today I will be trying this. Control box clicks when I turn dash switch on and it started with a jump so I can only assume the control box is good.

 

[doghead]

You can test your battery cables with an ohm meter.

 

[Jeepsinker]

Some careful visual inspection will go a long way too. 95% of the time battery cable problems are within 3 inches of one of the connection points. Look for broken conductor strands and inner- insulation corrosion.

 

[Gamagoat1]

Sounds real simple but, Check the Battery grounding connection at the frame.

 

[Lawrence of Arabia]

Replaced battery cable to starter as it was smashed and had a questionable spot in it. Replaced one other cable as it had a thin spot in it from arcing with batter charger. Still won't start. Thinking since I can jump start it, maybe the generator is not charging the batteries, but the batteries are still fresh enough and have enough in them to keep it running. Going to jump it tomorrow and see what the generator is putting out.

 

[5tonman1971]

but the batteries are still fresh enough and have enough in them to keep it running.

Once the truck starts the batteries don't keep it runing. On the 809s the batteries are mainly for starting and lighting. I see no one has asked you but what are the type of batteries you put in? How many CCA do they have? You may just have put to small of batteries in it. My 816 and 813a1 I have 4 750 CCA batteries in them.

 

[sandcobra164]

I agree with the above as the slave receptacle on these trucks hook to the battery cables at the source. If you can slave it off, that rules out the battery cables but does not rule out the battery connections themselves. They should be clean and tight. I've got a 5 ton in my front yard with some group 31's in it. Guess how long it can spin the starter when it gets cold out? Anything over 45 seconds of intermittent cranking and they are in need of a charge and we get a clunk.

 

[Lawrence of Arabia]

Not sure the specifics on the batteries, but I did buy the Military direct replacements from the battery warehouse that supplies my repair shop with batteries and they were familiar with the Military batteries.

 

[Hoefler]

Check your ground wires
pete

 

[5tonman1971]

If you put the correct military battery in then the only other thing that I can think of is that your battery cables at the battery could be bad and not allowing full amperage being delivered to the starter. It may be the starter it self and or a bad ground like others are saying that would also cause it to not supply full amperage.

 

[autoshopteacher]

I just read this post so if it is OBE'd (overcome by events) please excuse me. I have an M817 and never had any crank or electrical start problems. One day after working it several hours, I shut it down to refuel and upon restart attempt I got only a solenoid engage clunk. I shorted the solenoid terminals with the same result. Got a jump from a tow service but they had bad jumpers; frayed and bad clamps. Pulled it 2 feet and it started. Drove it to my shop and checked cables, terminals, ground. I did a voltage check on each battery seperately. All registered above 12.4 VDC showing fully charged but one totally failed a load test. Replaced it with a NAPA MIL equivalent and no more problems.