hey guys just picked up an 05 mustang with the 4.0l yesterday and im getting ready to tear into it here in the next few weeks. somthing is definitely broken in the engine somewhere im just not sure what yet. I started it but only let it run for like 2 seconds. sounds like a chunk of metal banging around. so my question is if there is a way to determine what it is before I tear I apart ? if its a dropped valve it would be nice to know as I could just pop the heads off but I don't want to pull those off till the engine is out if its a connecting rod or something that requires me to pull the engine anyway. any ideas on diagnosing it would be appreciated. thanks

 

If you have a mechanic's stethoscope, try to localize the sound while the engine is running. You could also do a compression check on all cylinders. Once you have an idea what's the basic health of the engine, you can make a decision on what to do next.

 

thanks for the reply , ill definitely check compression , but as for the stethoscope I hate letting letting it run it sounded pretty bad when I started it the other day and I want to keep from damaging it any more than I need to. i was also thinking I might buy a camera and look down in each plug hole too see if I can find anything that way.

 

With how cheap the 4.0 engines are, and the expense of trying to fix the 4.0 (heads can be difficult to get the timing chains set up properly),it's better to simply pull and replace the bad engine.

 

replacing is for sure a lot simpler but used 4.0 on eBay with similar mileage is gonna cost me around $1200 I'm sure I could replace quite a bit on this one for a lot cheaper, but I haven't tore one of these apart so i cant relate to how difficult it would be. I have read on other forums that the 4.0 from explorers and f150s are not compatable with the mustangs. is this true ?

 

I think that compatibility depends upon the year. If it is 2005+ I think that they are compatible with the Mustang.

 

Have a look around www.Car-Part.com it will list salvage yards in your area and who has what you need.

 

ok mine is an 05 . Im assuming the donor vehicle needs to be 05+ as well ?
thanks I had a quick look there it seems prices are about the same unless I buy a high mileage one but theres a ton of them on there so mabey with a little digging ill find a deal.

 

pushed it into my garage last night and did a compression test and heres what I got :

cylinder 1- 166 psi
cylinder 2 - 156 psi
cylinder 3 - 185 psi
cylinder 4 - 129 psi
cylinder 5 - no compression
cylinder 6 - 128 psi

for anyone who doesn't know cylinder 4,5 and 6 are all on the same bank ( drivers side ) anything different happening on the drivers side vs. passenger on these engines ? anything like maybe egr is only recirculated to that bank or anything that would cause that side to be so much more worn than the other side ? idk what's causing no compression in #5 yet but there's some gouges I found with a camera on the cylinder wall and I think mabey a little pieces of metal wedged between the piston head and the wall . hard to say how deep the gouges are or if its a pieces of metal as the camera I got isn't super clear. let me know what your thoughts are. thanks

 

heres a pic of the #5 .what I thought was a piece of metal is the gouge you can see right about the piston head it looks like pretty deep from what I can tell. there must be peices of metal floating around to be causing that damage. sorry its such a bad pic.