351m tapping on start up.
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Senior User
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351m tapping on start up.
Just recently when starting up my 81 Bronco with a 351m there is a definate tappin noise in the engine. The noise stops if i rev up the engine and I never hear it agian. My friend thinks it may be the lifters. I changed the oil before this started occuring. Maybe i need to put some thicker oil back in? Do i have to buy new lifters? The oil pressure has always been low, could this be a problem i need to fix?
Posting Guru
Joined: Aug 2000
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From: (near) Denver USA
351m tapping on start up.
Low oil pressure, and specifically worn main bearings, are the cause. New lifters won't help.
Check out my explanation on this other thread:
https://www.ford-trucks.com/forums/s...848#post770848
Check out my explanation on this other thread:
https://www.ford-trucks.com/forums/s...848#post770848
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Senior User
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351m tapping on start up.
The thing is that before it started making noise i was running 15w-40. I just switched to straight 30, i am not sure weither or not to change the oil back agian. I just changed it a couple of days ago. I am curious weither or not switching back to 40 weight would eliminate the problem. It never made the noise with 15w-40.
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Senior User
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351m tapping on start up.
I hear Risolone works, also I hear and old school trick is to take the valve covers off and pour ATF down the lifters when she's cold and tapping.
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New User
Joined: Jun 2003
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From: kentucky
351m tapping on start up.
Yeah, but you can't leave it in there. It'll desrtroy your motor. The idea is to clean the inside of the lifters. I don't advise using ATF becuse it's only a bandaid, and could damage your bearings. There's a lot of products out that will help with lifters but eventually you'll need to diagnose the problem completly and solve it!
Posting Guru
Joined: Aug 2000
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From: (near) Denver USA
351m tapping on start up.
In general, with worn bearings, the only cures are more viscous oil (temporary) or new bearings (less temporary).
At cold startup, straight 30W is more viscous than 15W40. It is possible that the higher viscosity is slowing the oil down at start-up and aggravating the problem.
The "lifter" noise is actually the pushrods banging around between the top of the lifters and the cup on the rocker arms. Inadequate oil supply to the hydraulic lifters causes excessive lash (clearance) in the valve train, which allows the pushrods to bang around and make the noises you hear.
If you don't fix it, eventually the push rods will bend and allow more and more lash until the ticking won't go away.
At cold startup, straight 30W is more viscous than 15W40. It is possible that the higher viscosity is slowing the oil down at start-up and aggravating the problem.
The "lifter" noise is actually the pushrods banging around between the top of the lifters and the cup on the rocker arms. Inadequate oil supply to the hydraulic lifters causes excessive lash (clearance) in the valve train, which allows the pushrods to bang around and make the noises you hear.
If you don't fix it, eventually the push rods will bend and allow more and more lash until the ticking won't go away.
New User
Joined: Jun 2003
Posts: 24
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From: kentucky
351m tapping on start up.
I can see I've got alot to learn. Up untill now I just did a short visual inspec of the internals and recomended oem parts to complete the overhaul. This is a lot of tech. I'll try to keep up.
