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Discussion Starter · #1 · (Edited)
I recently bought a 2002 f350 7.3L, ive heard that a high pitch crank is a sign of low compression but before i do get a compression test i wanted to see if there was any insight. Truck has 176,000 miles

if I leave the truck sitting for a couple of days it wont start up unless I charge the batteries, so I got a battery and starter test done at AutoZone and they said it had good voltage and passed the so called test. I do have a oil leak, I'm guessing the HPOP, which I've heard can affect the crank. its not a terrible leak but its noticeable and I do plan on getting it done. I took a video but I'm not sure how to post it. I also took a couple of pictures of where I see the oil. i do plan on getting a compression test done to it before i dump any money into it. I'm just curious as to what some of you think it could be. the truck runs pretty good, I've only driven it for a little bit since I've got it. it does seem like its lacking a little in power but it does have an exhaust manifold leak and like I said I've only driven it a little bit so might not be used to it yet. Any questions please ask, I don't know much about diesels but I will try my best to answer. Thanks!
 

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Discussion Starter · #3 ·
when it won't start what does it do ? I suspect your battery tester was flawed
I haven't let it sit so if I remember correctly it'll crank for like a second then it'll slowly die out. Then ill try and crank it again and ill get nothing at all, it'll just show the lights on the dash. once I put it on a charger for maybe a minute it'll start up. I cant remember what the crank sounds like when I charge it up. I drove it around today and turned the truck on and off after doing errands and it had a fast high pitch crank but the truck was warmed up still.
 

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So first, because we need Big High Capacity batteries (to support both the Glow Plugs and the need for a powerful starter to rotate a large high compression engine) the Only way to properly test their capacity is on a Load Tester and this tester needs to be able to put a very high draw on them (not one of those 100A load testers the Parts Stores use on 4cly gas engines, we need a 250/300A load to see of they can hold-up). This might become very important in the coming months as Cold weather arrives for you depending on where you live.

Good Vid on what you describe happening ->
 

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You need over 100 RPM to start the engine reliably -- so first thing is get a monitor -- search this forum for ForScan

Sounds like your batteries are shot -- also need to monitor the alternator voltage to see if the batteries are being properly charged
 

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Discussion Starter · #6 ·
So first, because we need Big High Capacity batteries (to support both the Glow Plugs and the need for a powerful starter to rotate a large high compression engine) the Only way to properly test their capacity is on a Load Tester and this tester needs to be able to put a very high draw on them (not one of those 100A load testers the Parts Stores use on 4cly gas engines, we need a 250/300A load to see of they can hold-up). This might become very important in the coming months as Cold weather arrives for you depending on where you live.

Good Vid on what you describe happening ->
His Crank sounds normal to me, mine starts normal then goes high pitch but starts up. Won’t start up if I leave it sitting a couple days. Once it’s on the charger it’ll start up again. It’ll increase in pitch until it’s started, it doesn’t take too long to start up it just doesn’t sound normal. Truck doesn’t shake or anything when it starts up. I’m hoping batteries and not low compression. It runs fine when I’m driving it. Is there a way I can post a video?
 

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Discussion Starter · #7 ·
You need over 100 RPM to start the engine reliably -- so first thing is get a monitor -- search this forum for ForScan

Sounds like your batteries are shot -- also need to monitor the alternator voltage to see if the batteries are being properly charged
I’m hoping bad batteries, the guy I bought it from replaced the alternator two years ago. I’ll take a look at the ForScan
 

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Make sure the Starter Bolts are tight (not uncommon to find them loose).

"High Pitch"? Might be the fact that the starter is unloading just before it starts maybe?

Again, the right Load Test will give you a good evaluation of their condition, but you'll have to find the right place to do it (or, as I did, go to Harbor Freight and get a 500A tester for yourself...)
 
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