engine noise 4.0L 1990

[wannabeMJ]

I was about to go for a test drive but when I started the truck today it was making a weird noise

like I have a valve problem

here is a video of it

 

that tic tic tic

the sound is going faster as I rev up the engine and also at low idle it kinda fade away for a couple seconds and then comes back

any idea?

[JeffN]

is your oil pressure ok?

If it is then it sounds like you have a lifter failing by not pumping up.

Try and throw a can of seafoam engine treatment in the crankcase and see if it goes away.

[wannabeMJ]

just did the seafoam Ill let it run for about 10 min to see what it does

[wannabeMJ]

still there

anymore ideas???

[knever3]

It sounds like it could be a lifter because it doesn't exactly follow rpms. You may have a collapsed one. How long did the motor sit? If it sat for a long time the oil might have run out of the lifter and it may take some time to get the oil back in it compared to removing them and letting them sit in a jar of oil and depressing them from time to time to get the air out. I don't know what seafoam is but I would drain the oil and put some cheap oil in it along with a bottle of Lucus Oil Stabilizer run it for a while until the noise suppresses and then change the oil with fresh good oil.

 

It sounds like you have good oil pressure because it's only one lifter making noise. The only other scenario it could be is if a rocker arm was loose under the valve cover. This could be making noise against the pushrod or the valve tip. It wouldn't be a bad idea to pull the cover and see if they are all tight. You could also have a sticky valve but this would cause the engine to have a miss most likely and this does not sound like a miss to me. It's too loud to be a spark related issue also.

 

I hope this helps and thank you for the video it's much more easy to diagnose these kind of problems.

 

Good Luck!!

[wannabeMJ]

ok if I take the valve cover off I'm pretty sure I won't be able to save the gasket

1 what will I be looking for : loose parts, loose rockers

 

2 can I put RTV gasket maker instead of a real gasket ?

 

by the way thanks for the answer

[knever3]

Loose rocker nuts mainly. You could run the engine without the valve cover on and find out what lifter is sticking by placing a stick near the valve. The other end of the stick will be placed near your ear. DO NOT PUT THE STICK IN YOUR EAR! Kind of like a stethescope, by the way they sell automotive stethescopes at the auto stores cheap, a much safer way. Anyway back on topic if you take off the valve cover place some rags on the edges to soak up any oil so it doesn't run over your exhaust manifold since this could cause a fire if too hot. You may just be able to place your finger on the rocker stud nut and determine the one at fault. When the engine runs the tension will change if the valve is seated or closed. You can also take the time to remove the spark plugs and rotate the engine manually until each valve is seated, but that is way to much work in my opinion.

 

On the cover gasket don't use RTV, it will leak and cause a huge mess. Get a felpro gasket to replace it when you have found the problem. The old one is probably cork and rock hard. Make sure the surface is very clean and all gasket material is removed before re-installing.

[Kenbob]

If you have any rubber vacuum hose and small copper tubing or wire that fits the inside diameter of the hose, it makes a swell scope for checking out all kinds of sounds. Make sure you put the metal end to the noise and the soft end to your ear and not the other way around. Actually, I have used a coat hanger for mechanical noises. Straighten it out. Keep the loop end resting on the ear lobe and the other end near the noise.