serious problem......

[98-5.0]

so my 5.0 was re-ringed.........put her back together after the wreck and shes been runnin like a new soul for about 2 weeks now..........drivin to work one mornin and it started knockin.........but it goes away with rpm...............so not a rod........its in the valve train......so i pull the plenum to find a wet area around the gasket from upper to lower around #8......so i pulled plugs...........all are good except #8 is not......(huh go figure)....its completly black and soaked in fuel..........so i take the valve covers and lower intake off...........and all the lifters wont push in like they should..........but everything looks in tackt.....i got brand new lifters and pushrods here but i dont know what my problem is..................its basically a stock gt engine.......not really but prety much.......but somemore to think about.........when it started knockin.......the car would mis and fall on its face when you would accerlerate.......so im lost as of diagnosis now.......i guess bein a tech......we always get the bad problems.......and diagnosing our own cars become a bitch.......so please help me out.

 

[stang4u2nv]

Hey man sorry about your ride. i don't know but it sounds to me as if that cylinder wasn't firing, the soaked in fuel plug indicates that a the spark plug hasn't been firing much, and if a plug is not burning then the car would fall on it's face and hesitate and all kinds of shit, to me sounds like an ignition problem. I would check (all ignition parts) from plug to everything else. The knocking sound i don't know but it could be a roller rocker, if you have adjustable units, or if you have stockers the one could be loose or something god knows... recheck ignition and lifters or rockers.

 

[98-5.0]

well there was deffinatly a knocking.......nothin in the bottom end loose.......but i didnt drive it after it started it........its obviously a problem with #8 cylinder but the motor idles and ran like a beauty........so i doubt that cylinder never fired.........but.......all the other plugs are awsome.........but that one.........all the valve train looks in good shape and nothin out of the ordinary..........without the head off........i dont know what the bottom looks like but im goin to do a compression test tomarra morning.........and that will solve some ?'s .......i hope........its got to be something stupid..........a few people have told me that i could have been detonating or spark knocking in that cylinder......but good news is it just started doin as i can tell.................so maybe i caught it before any serious damage.......ill look into it but im still kinda down on my diagnosing......i dont know why......i can diagnos other cars without a problem but mine give me trouble......its the technition curse i guess.........so any other tips will really help me out........

 

[95Grandtouring5.0]

Have you had the codes checked? Thats the first thing you should do. And it could be a bad fuel injector that isn't spraying properly. Did you change spark plug 8? You also might want to change the wire as it might not be sparking. Check the easiest things first before you go spending money on more expensive stuff.

 

[Anrev]

After you check ignition. You need to make sure the valves are moving. With the valve cover off, rotate the engine by hand and see if the intake and exhaust valves are actually moving. If they arnt then you need a new cam. If they are, make sure they are the same as the other valves. A compression test is also a good idea.

 

[95-stang]

If the valve adjustment on a cylinder is too tight, valves will stay open, and that cylinder will have little or no compression, result is a wet plug and a dead cylinder. Worth checking anyway, as well as the obvious electrics.

 

[Addermk2]

you mentioned a wet gasket. what was it wet with? oil, fuel.. etc

It is possible that your PCV system is malfunctioning and you could be sucking alot of oil into that cylinder.

 

[Mr. OAM]

You won't be able to compress a lifter easily in an engine that's been running. That's because the hydraulic aspect is doing it's job, automatically adjusting valve lash.

As mentioned, seems like an ignition issue in that cylinder. Check that sparkplug wire for excessive resistance. Take a look under the distributor cap. When is the last time the cap and rotor were replaced? Do you have original wires? If so lose them.

Let us know how the compression test went.


Steve

 

[95-stang]

Keep forgetting the hydraulics. < Duh.

 

[98-5.0]

well all this info is good.......i like it.........but what would be causing the noise/knocking........thats what i dont understand...........its deffinatly sounds like a rod but it goes away with rpm............a rod would stay a knockin away.......and also the fallin on its face when your tryin to drive it..........i pulled the lower intake......all the valve train, lifters and pushrods and cam look great.........and it just started to do it at a stop light..........and it was really freakin weird.......no codes at all.........

 

[mcaligiuri]

a spun rod bearing could do this, i had a problem like this on my v6, it knocked when it was under a load, as time went on it got louder and louder till i heard it all the time.

 

[Willautoy]

How about a stuck open injector? Wet plug,running like crap and could make a knocking noise(hydrolock type of deal.)

 

[95Grandtouring5.0]

How about a stuck open injector? Wet plug,running like crap and could make a knocking noise(hydrolock type of deal.)

Thats what i said, to check the injector/replace it. I just get ignored lol.

 

[Willautoy]

Ha ...OOOppps sorry I'll shut up now :angel:

 

[98-5.0]

ok sry the post is late...........but for all that was curious............the number 8 intake valve guide was shot and the valve wouldnt seat right............the leakdown test showed 95% on that cylinder and blew my hand off the lower intake port when i put 125psi to the plug hole........so both heads went out for machining and they was all fine but that one valve guide but put new springs valve job....all the wrorks..........so i get em back wednesday and well see what happens ............i guess the knocking was actually spark knock or detonation.........so i should be all fixed up