Weird truck problem...
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Freshman User
Joined: Dec 2010
Posts: 44
Likes: 0
From: Archdale, NC
Weird truck problem...
1987 Ford F-150 4x4 5.0L
I've heard of older trucks having issues starting when its cold...but mine fires right up with no problem. However, after I've driven it on the highway for 20 miles or more and stop off at the store, it acts like it doesn't want to crank....it DOES crank since I changed out the Starter Solenoid...but just barely. But...if I just let it sit and cool off more, she cranks just fine. Its as if the old truck needs to catch its breath before going again. Any clue as to what might be causing this?
I've heard of older trucks having issues starting when its cold...but mine fires right up with no problem. However, after I've driven it on the highway for 20 miles or more and stop off at the store, it acts like it doesn't want to crank....it DOES crank since I changed out the Starter Solenoid...but just barely. But...if I just let it sit and cool off more, she cranks just fine. Its as if the old truck needs to catch its breath before going again. Any clue as to what might be causing this?
Lead Driver
Joined: Dec 2000
Posts: 6,298
Likes: 47
From: South central, Minnesota
I had a 87 Bronco 5.0L that was the same way it ended up being a bad starter. Don't know if that's your problem for sure but it was on mine. Cold it started no problem. Once it was warmed up I would have to jump it to start it. For some reason the starter was pulling way too many amps when it was warm. I replaced the starter and didn't have the problem anymore.
Postmaster
Joined: Oct 2008
Posts: 3,026
Likes: 0
From: Renton, WA
It's very common for less then great starters even new ones to be very weak when hot. This is because the wiring has higher resistance when hot. There are 2 ways to solve this, which is most effective will depend on your truck and the condition of components.
1. Better starter, solenoid, battery and/or cables, mostly starter and cables, many overlook worn or corroded cables. A way to check is with a couple simple voltage tests, voltage at the battery and starter while cranking, and voltage drop between the starter and battery during cranking.
2. Keep the starter cool, the block is of course hot and heating the starter, but often the very high heat that overheats it comes from it's proximity to the exhaust. If you have headers or possibly the pipe just comes very close it is a very good idea to put a heat sheild in between the starter and exhaust, or wrap around the exhaust to keep the heat in. These are common and inexpensive on sites like summit.
1. Better starter, solenoid, battery and/or cables, mostly starter and cables, many overlook worn or corroded cables. A way to check is with a couple simple voltage tests, voltage at the battery and starter while cranking, and voltage drop between the starter and battery during cranking.
2. Keep the starter cool, the block is of course hot and heating the starter, but often the very high heat that overheats it comes from it's proximity to the exhaust. If you have headers or possibly the pipe just comes very close it is a very good idea to put a heat sheild in between the starter and exhaust, or wrap around the exhaust to keep the heat in. These are common and inexpensive on sites like summit.
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Elder User
Joined: Mar 2010
Posts: 571
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Whatever you do, please don't replace your starter with an expensive, brand new one until you've bench tested it and actually KNOW it's the starter. I hate to see people diagnose by random replacement. Unless you're using cheap-o junkyard parts, try to diagnose your problems first. It WILL save you money.
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