Engine 03 4.6l In A 98 Gt

PonyboyAdmire

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Feb 8, 2018
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Hey all, I hope some one could help me in this problem that has acured. I have a 98gt and the motor went out. I also have a 4.6l out of a 2003. Will this bolt right into what I have? I would be using everything from the 98 that I can including transmission, wiring harness, everything. I have heard that the flywheel won’t match and I have also heard everything would bolt right up plug and play. Let me know what any of you have come across if you can, and I appreciate your help.
 
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wmburns

SN Certified Technician
Aug 14, 2009
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Will this bolt right into what I have? I would be using everything from the 98 that I can including transmission, wiring harness, everything.
Yes it will bolt up with some "minor" changes.

I have heard that the flywheel won’t match
Both motors mentioned came with 6 bolt flywheels. So they WILL interchange. But you do need to decide which clutch you prefer to use. If 10.5" use a flywheel from a 1996-1998. If 11" use a flywheel from a 2001-2004.

Again there are minor differences to be over come. As with many things in life there is more than way to "skin a cat".

The post does not state which application the 2003 came from. Obviously if the donor motor was mated to an automatic then the flex plate will need to be changed for a flywheel.

If changing from a flex plate to a flywheel it will also be necessary to add a pilot bearing.

Bottom line. Put both motors on an engine stand and make the new motor look like the old.

Reuse:
  • fuel injectors and fuel rail.
  • ignition
  • front belt acc
  • wiring harness
  • EGR
Adapt:
  • PVC
  • Heater hose return
 
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PonyboyAdmire

New Member
Feb 8, 2018
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Yes it will bolt up with some "minor" changes.


Both motors mentioned came with 6 bolt flywheels. So they WILL interchange. But you do need to decide which clutch you prefer to use. If 10.5" use a flywheel from a 1996-1998. If 11" use a flywheel from a 2001-2004.

Again there are minor differences to be over come. As with many things in life there is more than way to "skin a cat".

The post does not state which application the 2003 came from. Obviously if the donor motor was mated to an automatic then the flex plate will need to be changed or a flywheel.

If changing from a flex plate to a flywheel it will also be necessary to add a pilot bearing.

Bottom line. Put both motors on an engine stand and make the new motor look like the old.

Reuse:
  • fuel injectors and fuel rail.
  • ignition
  • front belt acc
  • wiring harness
  • EGR
Adapt:
  • PVC
  • Heater hose return
Thank you much! The donor is a 2003 mustang GT manual. I'd like to keep as much of the 98 as possible as it as a stage 2 clutch and 4-10 gears and the trans is fairly new. Both are manual and I thank you for putting it that way. I guess my biggest worry was that the 2003 4.6 has pi heads and was worried I would need the wire harness from that. The flywheel in the 98 is fairly new as well so I was wanting to use that as well. Once again thank you.