just looking for thoughts....

[screamin gt]

just thought I'd take a video to see what you guys think the problem is before I start ripping this motor apart...

only thing I've done is disconnect each coil one at a time to see if I could pinpoint one cylinder, none of which had a different reaction than another.

bought the car this way, so I don't know what the circumstances were exactly when it started doing it.

I'll be taking it apart and checking compression, but just thought I'd get some opinions of possible causes first...

heres the vid

http://s78.photobucket.com/albums/j102/badaszx9r/?action=view&current=100_3798.flv

 

[blacksheep-1]

If the engine runs rough, then it's probably a dead hole, the compression check would show that. You might want to take the valve covers off and see if anything is floating around. To me, it sounds valve train related, usually the dull thuds are bottom end. The light raps are valve (pushrods, which you don't have) followers, etc. still, you can never go wrong with a compression check. I'm wondering, does this engine have the hypertectic (spelling) pistons? and did it detonate?

 

[screamin gt]

If the engine runs rough, then it's probably a dead hole, the compression check would show that. You might want to take the valve covers off and see if anything is floating around. To me, it sounds valve train related, usually the dull thuds are bottom end. The light raps are valve (pushrods, which you don't have) followers, etc. still, you can never go wrong with a compression check. I'm wondering, does this engine have the hypertectic (spelling) pistons? and did it detonate?

hmm.. engine is bone stock, its a 99.

the engine actually surprisingly runs/idles fine with the exeption of the noise. haven't driven down the street with it, just the driveway, but the power seems to be there still, not very sluggish or anything.

I'll be checking compression tommorrow hopefully

 

[modmonster]

I really hate to say it and i have been wrong before but it sounds like a bent valve. I have had one before and that sounds extremely simalar. The clearence in these motors is so little that if a valve is ever so slightly bent it will tap the piston aka PTVC. My case hapened to be I over reved the engine on accident pretty good and I bent it. Its a lot of work but luckily for me I just bent a valve and nothing else was messed up. It was a lot of work but I pulled the one left side head off (same side as you) and replaced 2 valves in the #8 and the valve seals. and all the gaskets that I obviously had to take off. A compression test will definately tell you if it is and which cylinder it is too so start with that. If money permits and you are doing the work I would suggest doing all the performance upgrades you have in mind(if thats what you want to do) while you have everything off. If not for gaskets,valves,lash adjsters,and rocker arms you will be looking at around $200 and a lot of work. Either way I wish the best of luck to you. Any q`s on the work part of it (if it is a bent valve) you can pm me and I will answer what I can.

 

[the98stang]

I agree with modmonster, since the noise does not go away after unplugging each cylinder. Take a stephascope (sp?) and see if you can pinpoint the noise.

 

[Performance Red]

Sounds like one of two things to me either a valve problem, or a spun bearing can sound similar to that, do a search on here for spun bearing and you will find a few with vids to compare to. I would do a compression check first before you start jumping to any conclusions it will tell you if its a valve related problem. Once you figure out what cylinder is the problem you can do a leak down test to see if its and intake or exhaust valve or both.

 

[screamin gt]

awesome guys, thanks for the info... I'll post up what I find out on the compression test.

not looking for any performance upgrades, just want to get it back to good running condition. keeping this one driveable.

I take care of my speed cravings on 2 wheels

 

[CobraRed_96_GT]

this doesnt sound like rod knock to anyone else, too high pitched? definitly not a spark problem, it's metal to metal

 

[CanadaStang]

From the vid, it doesn't sound like a rod, it seems to be in the top end. It's hard to tell just from the vid but I'm guessing once you pin point which side the noise is coming from, you will find the problem when you remove the valve cover.

 

[01Steeda]

doesnt sound like a rod to me, and I am a senoir at rod knocks lol


but different rods (location) can sound different because of the surrounding metals.. ie a rod at the front of the motor doesnt have as much density around it so it will make more noise.... from my experience...(3 motors all spun bearings)

I am the OVERREV KING!!!!

 

[blkhorse]

it is definitly hurt,trouble shooting at this time is a waste,time for teardown,you will find problem.only question is if you want to pull heads in car,then end up pulling motor,or just get it done and pull it now.

 

[screamin gt]

compression was 30# less on #8 cyl.

added some oil on that one and still got 30 # less consistantly. removed valve cover, nothing obvious there.

motors prepped to come out...

 

[screamin gt]

also talked to the guy I bought it from and he said it started as a very faint noise, thought it was an exhaust leak, but gradually got worse and worse.

it sounded to me like it was coming from the top end, but who knows, find out soon...

 

[CanadaStang]

Hope you give us an update when you find out what the problem was, I'm curious as to what was the cause.

 

[screamin gt]

Hope you give us an update when you find out what the problem was, I'm curious as to what was the cause.

I will do that, I just want to be positive first, and I still have a little bit of tear down to do, probly won't get there till monday/tues.

first nice weather week this year, so I'm taking a break to get some good riding in, the kawi needs some love too