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1999 Mustang GT Knock Noise and Rebuild Advice

2942 Views 3 Replies 3 Participants Last post by  heavy metal
Hello everybody. I have mainly just been a reader here to find out problems but recently I've come across what I believe to be a spun rod bearing and I decided to make my first post and get some help and advice on how to proceed.
I have a 1999 mustang gt automatic 115000 miles with the real 35th anniversary package (not just the badge). Recently I've been hearing a knocking sound coming from the core of the engine. With some advice from my mechanic friend I decided to replace the timing chain in hopes that this would resolve the noise but to my demise its still there and now im assuming that its a bearing whether it be a rod bearing or something else.
When I cold start it is noticeable at idle but when it warms up I only seem to hear it when it shift from 1st to second around 2000 rpms. When I gently let it shift before 2000 it is either noticeably dampened or I don't hear it at all. It sounds like someone is tapping a hammer inside of the engine trying to get out.
I've looked around and read up about some things and at this point I think rebuilding is the way to go assuming its as bad as I think. The question is I would like to improve the power along with removing the noise and adding some life back into the motor. What are some cheapish ways to do so that won't break my wallet but will also be worth the money. I'm hoping to stay in the $2000-2500 range. Would some aftermarket cylinder heads do me any good? I've also read that stroker kits aren't ideal for the 4.6s in terms of keeping its lifespan. Should I look into buying a used one off eBay? What do I do!?
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Hey! you're in the same boat as I am, except I have a donor engine to run my car on while I rebuild it.

first things first, pull out your oil dipstick, see if it looks sparkly, if it does, rebuild your engine. If it doesn't, drop your oil pan. In the bottom of my oil pan there were literally inch and a half long metal shavings (make sure you empty all the oil out of the bottom it can hide it, best way is to run it through a strainer, in fact you can just do an oil change but leak the oil out through a strainer, before you actually pull the pan)

Basically metal shavings/dust = rebuild. Clean oil (well not clean but no metal in it) = the knock might be an easy fix that doesn't involve pulling your engine.

If you do end up pulling the engine and are looking for power adders, look into cylinder heads and camshafts first. There are tons of options out there for our cars, do a search.

Heads- you're already PI (performance improved, 99-04) and so what you can do is port your current heads (send them to the machine shop so they can make them flow even better), or you can look at something like trick-flow heads. Some members here make major power running through trick-flow heads, but personally I have no experience with them. (not 100 percent sure I'm even saying that right tbh).

Cams- don't get comp cams. They're cookie cutter generic cams, and for me personally it makes no sense to use a cam that is "universal" because being universal means power is left on the table. For the same price you could get your own cams custom ground, then you'd make more power AND you can have them set up for whatever you wanna do. Or you could look into buying totally new (not getting your current cams machined) aftermarket cams.

Personally what I am going to do is invest in a rebuild kit that comes with forged internals. This way I'll have a 0 mileage motor that can handle whatever power I wanna throw at it in the future, and I'll never have to pull the engine again (not to say I won't, I just won't need to). Then if i get rich enough for forced induction I'll be ready to go (tranny is also being rebuilt). Technically heads can be pulled with the engine in the car if you ever want to ugrade heads or cams, it's just harder, but it isn't like internals where you NEED to pull the engine to replace. Because of this I will spend MY money on internals not on cams/heads until later in life. (albeit it did not take me long to pull my engine and so I may go the route of pulling it again anyways if I wanted to do head work, but I wouldn't HAVE to.)

More power through internals/heads? raise your compression ratio! If you never plan on going forced induction (you'd want low compression in this case) go for a high compression build. I don't know enough to offer any suggestions on this, just remember higher compression=more power along with a tune capable of keeping your engine safe. Just remember though, you'll never get super high HP (350+ rwhp) out of a naturally aspirated 2v 4.6. (don't nitpick the NEVER, I just meant it wouldn't be economical) But if you do want to stay 300-350 compression is the way to go.

For me, until I have coilovers and insane suspension I'm not going to try and go for big power (anything over 300). Suspension work will get me not only faster than more power, but it'll handle better to. There was a member on here that had stock horsepower on a 2V 4.6 and was running mid 12's I believe with drag slicks suspension work subframe connectors gears etc and a good driver. Hard acceleration is fun, but wasting power by spinning tires isn't, and besides corners are more fun. (I autocross :))

If you want, I could upload a video of what my car sounded like and when I get around to pulling the engine apart I'll let you know exactly what was wrong in case you have the same issue I did.
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Thank you for your response. I had it diagnosed as a rod bearing with a compression test. I'm gong the route of a reman engine... hopefully I'll have good luck
Welcome to the site!!
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