hard to turn over when hot

Could be a sign of seriously neglected scheduled maintenance....I don't think it's a battery problem. but it's not that expensive to have them check for dead cells.

Most parts expand during cool down, try letting the truck idle 5 min before shutting down...never turn off a truck when it's been running uder a load until the temp guages return to normal.

Oil breaksdown, depending on how much contamination...sample the oil.
worn seals and bearing due to corrsion....( bad oil )
Upper cylinder wear....( bad oil )
voltage regulator needs checking ( would not properly charge batteries)

Check the service manual and confirm proper maintence has been done in the past related to mfg specifications. When all else fails read the manual and consult your nearest dealer.

Good luck!

 

It looks to be centered around the batteries and/or connections between the batteries, but without seeing any maintenance history of the truck, it could be something else. Before replacing the batteries, you should disconnect all of them and check each connection for corrosion, leaking battery fluid, temperature or broken wires. You or a shop can test each battery for a bad cell. It could be just one battery causing the problem or multiple. If none of these batteries have been replaced since the truck was new, it is no surprise they would need to be replaced now. I have seen this on a few Peterbilt trucks, but this is not really a Peterbilt issue, but more of a electrical problem that could occur on other model trucks just the same. Is the alternator putting out at about 13-14 volts currently? If it was not, then it would be known by now as the batteries would all be dead, especially if you have been driving at night with your lights on and/or using the AC.

Looks battery centered, but check the alternator function as well.

 

starter is where i would have gone first too
i dont know of batteries that would rejuvenate themselves
after sitting an hour
but it is never a bad idea to check clean connections and test batteries
especially before winter season

 

Has it been this way since you bought it? Has any engine work been done prior to you buying it? It could be a timing problem if it had engine work done before you got it. What I'm getting at is they just don't get out of time they have to be put there.

 

I would look at the batteries. That's what it sounds like to me. The batteries can be checked and all the terminals can be cleaned as well as the cables. batteries are about $100 each. I would also have the cylonid checked as well

 

Can a bad battery start a cold truck better that a hot truck? Seem the amps would be lower on a bad battery and it wouldn't matter if the engine was hot or cold...just my 2 cents.

 

Starter, that's what it most likely is. The second thing to look for is a bad ground or bad cable to the starter.

The starter can had an issue with heat expanding within the case and cause issues where it will turn slow.

The cable issue can be a bad connection which expands when it gets hot.

 

check charge, should be 14 volts with all accessories running.

test batteries, individually. all cables disconnected.

check tighteness of ALL battery and starter terminals. (could be the most likely problem)

voltage drop at the starter cables. don't know the spec on trucks but with cars. it's .5 on positive. .3 on negative. to measure, use a simple voltmeter. one terminal at each end of same stater cable. measure while cranking. so your going to need 2 people. if voltage drop exceeds threshold. the cable is corroded and causing more resistance to voltage and amperage draw.

cranking amperage. what does the starter pull when it's hot, what does it pull when it's cold.

solenoid. probably not likely, but who knows.

i just did a week tour with one battery COOKING. smelling up the truck with sulphor. had no problems starting up truck. so even if one battery is bad. the other 3 still did the job.

 

Had an old FORD T800 ( and no not a KW T800 it was a FORD ) years back that acted up like the OP posted , turned out that I had a damaged battery ( had only 1 ) , get hot the battery would slightly expanded and the plates would short out not enough juice to crank over the engine , let it cool down touch the key and start right up