In the process of retiring my rusty old e99 and passing it along to someone else. This has entailed pulling some stuff off and putting it on my new to me 2002 7.3.

I had installed the Prestolite alternator last year on the 99 and didn't have any probs. At the same time I installed a larger crossover, larger positive lines, and 2 extra grounds. Well I pulled all this out from my old truck and in the interest of time, I just swapped the alternators so the next owner at least has something to work with (I also pulled my still in great condition SS exhaust and a few other things). In the interest of time, I installed the Presto into the 2002 and just used the existing harness (I will upgrade the wiring later).

I took it for a quick spin and then popped the hood to check things and noticed the Presto was quite warm, almost too hot. Never noticed the temp of an alternator before so I was a bit surprised. The batteries were fully charged prior to the swap (or I assume so since I didn't have any probs). The serp belt doesn't seem any tighter than with the stock type alternator. Aside from removing the negative connections at the batteries, I didn't do anything else electrically.

Any thoughts on what might be happening? Like I said, the casing was pretty dang warm, it didnt seem right.

 

Upon reflection and a couple of voltage measurements, it appears the stock charging/grounding wiring is too wimpy for the Presto. I reinstalled the stock type alt and everything returned to normal.

 

You don't call yourself "pvdiag" for nothing!

Prestolite Voltage Diagnostician.

Thanks for reporting back on what you found the issue to be.

I don't know if Prestolite (or the ever increasing knock-offs) of that Leece-Neville AVi160 series alternator include instructions or not, but the instructions from Ford for that alternator's installation into the LCF required technicians to upgrade the charge wire, stating that the factory wiring was not adequate to handle the output. Your finding of increased resistance of smaller wire creating heat appears to affirm Ford's finding. Ford even sold a wiring kit upgrade for the LCF. No such kit was made available for the Super Duty... not even the 6.0L Super Duty that use glow plugs designed to withstand higher voltage input.

 

Good one!

I think I still have the paperwork on the Leece-Neville Idle-Pro. I'll pull it out and see what it says. Since on the original install I did a wholesale wiring upgrade, whatever it may have said on that specific matter didn't register.

I am glad I took it for a quick burn and checked. If I waited until this morning (where I just drove it for 90 min), there could have been some big problems, given after only 5 mins last evening the casing was almost too hot to touch.

 

Further to this, after 5 min of runtime, not only was alt casing hot, but I had steam coming up from underneath the engine. I had also swapped out the T-stat housing and wound up with a pretty good leak, sending coolant to the part of the engine where the main grounding block is located. I have convinced myself that the alternator overheating was due in large part to the grounding system being overwhelmed.