The top alternator is a 4G Ford, bottom is a 3G Ford. If you have a 4G alternator in your Mountaineer, you most likely cant run the 3G because it is deeper and will hit the coolant crossover pipe that is behind the alternator. There are some exceptions though in certain year 4.6L Mountaineers.
The 4G is probably one of, if not the worst alternators Ford ever used. 3G's are not far behind, but the 3Gs can at least be replaced with 6G's which are actually fairly decent units..
When it comes to HO use, 3G's and 4G's are a 4 letter word for me, and we just wont build them for HO use. We had castings made to run the much better GM type AD244 alternator in all the Fords with 3G or 6G alternators, and there is no Ford alternator even close to being anywhere near as capable in output, nor as reliable as the AD series alternators so we designed something better. Just for reference here's a pic of one of our alternators next to a 3G. I hope this helps, if you have any other questions, let me know.. Rob
These are the alternators that are on autozone website. I have a choice between these models. The reason I was looking at them is to see what style of alternators there were for factory replacement.
This is what the Alternator looks like on my Mercury Mountaineer
Here is the other one they have for my Vehicle
Now the question if both these alternators are made for my vehicle.. what is the difference between the two types?
Would I have to replace it with the one that matches what I have or can you use the other one.
Now as far as after market High Output alternators do you just use the housing from the factory design or do you just use a larger casing that will fit my vehicle?
I called a local shop around me that has been in business for 30 years now. It is called P&G electric to ask them what is the most output they could get out of the factory Alternator. What they told me was that the most you could get was 150amp at 1200rpm and half of that at Idle. I told them about High Output alternators that would put out 260+ amps and he did not believe me. He said I would have to see that, that is was not possible. So with that said what is the difference from what he is doing and what people like Iraggi , DC Power and Mechman are doing?
I mean you are all working with the factory casing right?
Edited by Noobtastic14, 08 February 2010 - 11:43 PM.
No need to quote pix again rob :)