95 5.0 valvetrain knock (video included)

[Christang95]

So I was up at school and developed a valve train knock. Brought it back home and found 2 slightly bent push rods. Was very short on cash so I replaced the 2 push rods 2 lifters and 2 rocker arms(took me forever btw, I don't know much about cars at all and did this almost all by myself by reading books and forums). Put it all back together and the same problem persists. Any ideas? im about to give up and start reading up on pulling an motor and maybe getting a 5.0 out of a wreck and swapping my intake onto the other motor.

95 Mustang Engine Valvetrain knock
just took this about 5 minutes ago, if you want another video I can upload immediately.

 

[FaykSaleen]

Are you sure it's valvetrain? Pop the belt off and start the car for like 2 seconds and see if it's still making the same noise.

My pickup was making an extremely similar noise and the water pump commited suicide, broke the belt and now there's no more noise. Then again theres no belt either :laughing5:

 

[Dysfunction]

Take a long screw driver and stick it around the engine with ur ear on the top of it and try to pin point the location. Thats how i figured out my smog put had chewed up it's innards.

 

[ThePope]

Sounds like a rod knock to me. Do anymore investigating?

 

[Christang95]

Well I popped off the belt and there was no difference. I would think its a rod knock but the noise isn't constant and it dies down occasionally.

 

[BlkoutGT]

Could be your rockers taping the VC. What all is done to your car? Intake? heads/aftermarket rockers etc? how did you tighten the rockers?

 

[Christang95]

valve train is stock, i have just some bolt on mods such as a upper and lower intake headers exhaust, MSD distributor.
I tightened the rocker to the proper torque 23-25 ft/lbs

 

[snakebit95]

Sounds like some bent valves to me. If the valves are not properly seated on the power stroke, the combustion will leak through the valves (along with the noise) which seems to be what I am hearing through the valve cover area. Depending on how badly the valves are bent, they may be making contact with the pistons and adding some additional tapping noises. Just a guess without being there to actually see / hear it. How many miles are on the engine? Still running the stock cam? If you swapped the cam, did you change the valve springs to match the cam? If the engine is a high-miler, the valve springs may have exhausted their life. Let us know what you find.

 

[Christang95]

there's alot of miles on the motor, i would say 140+, i think its a stock cam. I bought this last year from someone who didn't know much about the car. It drove good for a while until winter came along and it developed that sound. Im thinking about just swaping the motor...I have to figure out how to do that first though lol.

 

[FaykSaleen]

woow that sucks man! i was really hoping it would only be an accessory!

 

[98-5.0]

general rule of thumb for me is; if it makes the noise from cold start up, its probably not a rod. unless the bearings are litterally gone. if you start it up cold and it makes the noise, its usually valvetrain if its an internal motor noise. the screwdriver trick works but some people listen to the little noises that are already there. if you dont here a huge difference...then you got nothin. with that being said. i had a guy hit my old 96 car i swaped to 5.0, the strut tower came in and knocked off my tb and wide open she ran. i shut it off as soon as i could but motor was already blown. after the re-ring and all, i still had a noise...simular to yours but not as loud. leakdown results were messed up valve guides..its not common on a 302 but...its possible. might wanna break off the cover of the rockers and such your replaced and perform a leakdown test on them with piston at tdc and both rockers off....then 'with the handle of a hammer hit the tops of the valves and see if one is not seating right.

you say it kinda goes away after a while or fades in and out. that leads me to the lifters. id seen alot of 302's that people rebuild and or throw away from bad lifters. somtimes they will fool you to thinking its a bottom end problem. fact is over 80% of engine failure comes from valvetrain.

keep us updated on your diagnosis. its a pain but. the more you test the more you rule out...good luck

 

[d_punch]

i am far from an expert, but if you had 2 bent pushrods, wouldn't you also have 2 bent valves?

 

[98-5.0]

not necessarily

forgot to add. if its stock valve springs and you rev it alot, those stock springs are junk even brand new and you will valve float just like my motor did.. you may not hear it if your ears are untrained to hear it. that being said. if you are floating valves, sure you can bend one but, that guide is taking a beating at the same time to.. if the guide is worn out and have alot of play in it, then you are not sealing the combustion chamber.(like stated above in a previous post) which is leading to part of the noise.. my motor did this same thing...sound was very simular and i had zero (0) bent valves. i never had bent pushrods or rocker arms either.

 

[AaRoN]

It's definitely in your valve train. If it were a rod or piston, it would be making the noise twice as fast. Does it become louder at any point (cruising, when the engine is warm)? Can you get a compression test done? If you can get a compression test done, make sure they wet test any cylinder that is below spec.

 

[Christang95]

The Noise is so loud and sounds like it shouldn't be driven at all. The knock is usually more frequent a higher rpms. I though it was knocking more because the lifters had no oil at higher rpms but I guess thats not the case because I replaced the lifter. and how do I compression test? Sorry im a novice and before I replaced the lifter all I could do was change a tire lmao. Just kinda winged it

 

[snakebit95]

First, I would not run the engine any more. If it is a bent valve, you take the chance of it breaking and falling into the cylinder while running. When that happens, the engine will be fubar. I think Autozone has a tool lending program that offers a leak-down tester. They charge you the value of the tool upfront, but reimburse you 100% upon return. Hopefully you own a small air compressor. You will need to rotate the engine (by hand via the balancer bolt) until both valves are closed on the cylinder you are testing (TDC is best). Remove the spark plug and screw-in the leak-down adapter. Attach the air hose / gauge to the adapter. The gauge will read the percentage of leakage for that cylinder. Each cylinder should be under 15% or so. Less is always better. If you have a bent valve, the leakage rate will probably be over 25-30% if I had to guess. Hope this helps!!

 

[AaRoN]

CLT's are very time consuming. But it may help locate you're problem. If or when you do the leakage test, for each cylinder you test, the piston must be at TDC on the compression stroke. Leaks in the cylinder do not always point to a bent valve. It could be the valve seat that is bad as well.

I still say, do a compression test or maybe try to get your hands on a vacuum gauge. The vacuum gauge may not tell you a thing, but if you have a bad valve, it will show up as a steady drop or if the needle bounces around.

 

[98-5.0]

any results or diagnosis yet? let us know

 

[Win]

I keep listening and listening to it and it really sounds like a Rod Knock also. Any update ?

 

[Christang95]

I haven't got a chance to test anything on it yet. But I just bought a 95 5.o out of a wreck just a hour ago. Gonna pick it up and try to see if I cant swap it. I will probably figure out whats wrong when its out of the car.