Engine 2004 V6 to V8 swap starter problem.

[SnowB]

Well this one really has me stumped. Just got the 4.6 bolted in, hooked up the bare essentials to get the motor started, (open long tube headers ) But when I go to start the car, nothing happens, no click, nothing. Fuel pump primes in accessories, (and yes I have EVERYTHING from PATs hooked up from the donor car) So I decided to jump the starter relay, and I get a horrible grinding sound, no crank. I check all the grounds and the power cables, everything is hooked up and secure, I thought maybe the battery isn't strong enough to throw them bendex so I put a jump pack on, still grinds.At 16 I don't really have enough experience to diagnose a serious eletrical problem like this, so any help would be very appreciated. Also new here so take it easy on me maybe?

 

[SnowB]

Donor car is a 2004 GT Manual
Receiving car is a 2004 V6 Manual

 

[wmburns]

Just wondering. Did you check the negative ground between the motor and the battery?

Did you re-attach the grounding strap between the left hand motor mount and the frame rail? This grounding strap is frequently over looked during a motor swap.

Note, I think you have two problems. A problem in the neutral safety switches (NSS) and with the starter itself. IMO you should focus first on the starter. The starter should work normally IF the starter solenoid is jumped.

Here's some information on how to test the quality of the ability of the circuit to carry high current. Don't focus on the specific parts being tested but try to understand the CONCEPT behind the test.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

 

[SnowB]

Hey, sorry for the late reply, lots of work recently. I looked down and noticed the strap from the motor mount the the frame rail was missing, so I got that in, still grinds. I'm not sure about what you mean with the concept, the starter is getting 12 volts and all of the grounds are connected, and terminals look good. Are there any more engine grounds besides the 3 on the core suppprt and the one motor mount one? Thank you.

 

[wmburns]

I'm not sure about what you mean with the concept

Did you actually review and watch all of the information provided in the "howto perform a charging system voltage drop test"?

The example provided gave an example of how to do a voltage drop test on the alternator. However a voltage drop test can be done on any circuit the MEASURE the quality of that circuit to carry high amps (such as a starter circuit). This is the CONCEPT behind a voltage drop test.

As for additional grounds, there is another that is attached to the lower front left of the motor. It's a very heavy black wire.

If you are unable to understand the concept behind a voltage drop test another way is to measure the voltage at the starter and starter case. Note this reading. Now engage the starter. What does this voltage change/drop to? If there's a poor electrical connection the voltage will drop very low. This method will not pin point where the problem is only that you have a problem.

Note, if the voltage does not drop at all, then likely the starter is not actually engaging and drawing any real current.

 

[SnowB]

So I finally got time to work on the project, had one of my fathers mechanics diagnose the issue and he deemed the starter had went bad. I replaced the starter and now when I jump the relay it cranks!! I then had to figure out the turn key no crank issue and you were dead on about the Neutral safety switch, I forgot to plug it in.. After plugging it in I went to crank it and she started! Time to start piecing the interior together and fill the fluids up. Thank you so much for the help.