Engine noise cont...
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Trailering
Joined: Oct 2023
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Engine noise cont...
Hi all
Posted a while back about a peculiar engine noise coming from my 1975 Ford F250 360.
To recap the engine was making an odd knocking sound which does not seem to be a bearing, lifter or exhaust gasket leak.
Oil pressure is good, and the valve train feels tight.
One thing I did notice was some of the valve push rods are very slightly bent, very slightly.
The motor was gone through, (perhaps in auto shop?) and I am thinking that maybe the push rods were not returned to the engine in the same position as they came out.
After an exhaustive visual search around and up in the engine I have still not found the source of the noise.
I am now considering replacing the push rods because some are bent and because perhaps slight play on multiple rods could be making this noise, maybe.
So now I need advice as to how to proceed. I understand rods come in different lengths, and I also have an impression that removing and replacing the rocker train needs to be done in a careful manner or damage can result. Any advice would be appreciated.
Thank you!
Posted a while back about a peculiar engine noise coming from my 1975 Ford F250 360.
To recap the engine was making an odd knocking sound which does not seem to be a bearing, lifter or exhaust gasket leak.
Oil pressure is good, and the valve train feels tight.
One thing I did notice was some of the valve push rods are very slightly bent, very slightly.
The motor was gone through, (perhaps in auto shop?) and I am thinking that maybe the push rods were not returned to the engine in the same position as they came out.
After an exhaustive visual search around and up in the engine I have still not found the source of the noise.
I am now considering replacing the push rods because some are bent and because perhaps slight play on multiple rods could be making this noise, maybe.
So now I need advice as to how to proceed. I understand rods come in different lengths, and I also have an impression that removing and replacing the rocker train needs to be done in a careful manner or damage can result. Any advice would be appreciated.
Thank you!
Lead Driver
Joined: Oct 2018
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Impossible to guess what the noise might be without hearing it.
Getting the pushrods in the wrong order wouldn't cause any noise. other than changing the wear pattern it wouldn't do anything, I never worry about it.
If it can roll a pushrod on glass and get a tick it needs replaced, if you can see a bend it's bent bad. and yes that could cause a ticking sound.
To do it correctly you need to check the preload with the cam on the base circle. this is normally done with a length checker and a custom length is ordered to get it right if needed.. if you want to shortcut it you could bring a piston to TDC compression stroke and check the preload on that cylinder. you should feel some resistance when you twist the pushrod, and you should be able to push it down and collapse it farther. this won't mean your preload is fine, it just means it should work. if you want to do it right we could go into that .
Changing the pushrods is a simple task . just back the bolts of a half turn at a time until they are loose then carefully pull the rocker shaft off keeping everything together. replace the pushrods and put the rocker shaft back on tightening the bolts 1/2 turn at a time then torque it down. you're done.
Getting the pushrods in the wrong order wouldn't cause any noise. other than changing the wear pattern it wouldn't do anything, I never worry about it.
If it can roll a pushrod on glass and get a tick it needs replaced, if you can see a bend it's bent bad. and yes that could cause a ticking sound.
To do it correctly you need to check the preload with the cam on the base circle. this is normally done with a length checker and a custom length is ordered to get it right if needed.. if you want to shortcut it you could bring a piston to TDC compression stroke and check the preload on that cylinder. you should feel some resistance when you twist the pushrod, and you should be able to push it down and collapse it farther. this won't mean your preload is fine, it just means it should work. if you want to do it right we could go into that .
Changing the pushrods is a simple task . just back the bolts of a half turn at a time until they are loose then carefully pull the rocker shaft off keeping everything together. replace the pushrods and put the rocker shaft back on tightening the bolts 1/2 turn at a time then torque it down. you're done.
Hotshot
Joined: Feb 2004
Posts: 10,837
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From: The Shenandoah Valley
If returning lifters on a cam from which they were removed, I use a "organizing block" (I made it) to keep them in order Lobes don't move on a cam, so I just clean and inspect them.. I will only reuse a cam in the same block it came out of. If I pull pushrods with intention of reusing them, I inspect, check for length, straightness, etc, and just store them in a place where they will not get bent. Rocker arms, *****, nuts, etc ... get inspected for cracks, wear, and put in a box. I will keep each ball or fulcrum with it's rocker.
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Trailering
Joined: Oct 2023
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440 sixpack,
Sorry for the late reply,
When I was checking the pushrods I spun them unloaded in place they twisted easily but some rotated with a slight ellipsis so I assumed they were bent.
In my original post I uploaded a video with sound to demonstrate the noise, some of the responses led to me dropping the pan to look for metal shavings, found none.
How many variations of pushrod legnth are there for a stock 360 that has been rebuilt at least once, if that is a reasonable question.
Thanks!
Sorry for the late reply,
When I was checking the pushrods I spun them unloaded in place they twisted easily but some rotated with a slight ellipsis so I assumed they were bent.
In my original post I uploaded a video with sound to demonstrate the noise, some of the responses led to me dropping the pan to look for metal shavings, found none.
How many variations of pushrod legnth are there for a stock 360 that has been rebuilt at least once, if that is a reasonable question.
Thanks!
Last edited by manni59; Jun 11, 2024 at 08:17 AM. Reason: this reply was to '440 sixpack'
Lead Driver
Joined: Oct 2018
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Anytime you're concerned about metal in the oil just pull the filter and check. if it's clean you have nothing to worry about.
There is a standard length pushrod that should work for most engines. but decking the block , shaving the heads, improper stem height or a cam with a different base circle height can all change the preload on the lifter. wear on components can also. checking the length with a checker is the proper way to see what length you need, then have a custom set made that length. it's a common practice.
If you want to keep it simple just bring a piston TDC on compression and twist the rods, if you don't feel some resistance then it's too loose, if it has any slop you have to do something. you need some preload, but you can't have too much. that's why a checker is really best.
If your video posted I don't see it.
There is a standard length pushrod that should work for most engines. but decking the block , shaving the heads, improper stem height or a cam with a different base circle height can all change the preload on the lifter. wear on components can also. checking the length with a checker is the proper way to see what length you need, then have a custom set made that length. it's a common practice.
If you want to keep it simple just bring a piston TDC on compression and twist the rods, if you don't feel some resistance then it's too loose, if it has any slop you have to do something. you need some preload, but you can't have too much. that's why a checker is really best.
If your video posted I don't see it.
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Trailering
Joined: Oct 2023
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I found the video of the 360 running, the noise is most evident when accelerating, so I was briefly hitting the gas to make the sound more obvious to record. I had to "go advanced" to upload the video.
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Trailering
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When I check the pushrod length, do I remove all of the pushrods on the bank I am checking?
I was going to buy two Howards Cams pushrod checkers and install them on the intake and exhaust valves in the compression position, set the length on both so there is a slight drag when twisted in position, then pull and measure. Is this good practice?
I was going to buy two Howards Cams pushrod checkers and install them on the intake and exhaust valves in the compression position, set the length on both so there is a slight drag when twisted in position, then pull and measure. Is this good practice?
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Lead Driver
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that will work. but you only need one checker, typically if you check a few for length that's good enough because if you have uneven stem height's or anything like that you'll just be chasing a rabbit down a hole. in that case just pick a length that works and run with it. you can get it right when you rebuild it someday. no need to remove any pushrods other than the one you're checking, but you can if you want it's easier sometimes with a rocker shaft set up.
Hard to tell from your video, there are so many things it could be. what you say about louder on acceleration is indicative of an exhaust leak. on deceleration do you ever hear muffled popping?
Hard to tell from your video, there are so many things it could be. what you say about louder on acceleration is indicative of an exhaust leak. on deceleration do you ever hear muffled popping?
Laughing Gas
Joined: Aug 2020
Posts: 821
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From: Pelham Alabama
Well,,, just like 440 said too hard to tell from a recording
But from the speed of the noise, it seems too fast to be a rod or lifter.
I have not read all the posts BUT has anyone mentioned removing all the belts to see how it sounds.
Almost sounds like an alternator bearing????
But from the speed of the noise, it seems too fast to be a rod or lifter.
I have not read all the posts BUT has anyone mentioned removing all the belts to see how it sounds.
Almost sounds like an alternator bearing????
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Trailering
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I am not sure about the popping on deceleration, i will have to check that next drive.
I removed all of the belts at one time and ran the engine and the noise remained.
Many have said that it may be an exhaust leak, I can see no carbon buildup around any of the ports and it does not seem to be coming from that area.
i did have to replace the RT bank exhaust gasket when I acquired the truck. it was blown out next to the heat stove for the thermo choke lines.
the noise was loud enough it covered this one I am dealing with now.
the manifold did not look damaged, nor did the head surface it was attached to.
i looked all over for cracks, recently and did not see any.
the sound has the same rhythm as a lifter noise, so if it was a leak I would doubt it would be the doughnut.
now that i think, one thing i have not done is to check around the manifolds with a fuel hose in my ear for gas escaping.
i will try that.
so with the push rods, if i do not need to check all of them for proper length, should I just check the exhaust?
I understand referencing the rods on the ends of the heads are a good sample for length, if that makes sense.
I removed all of the belts at one time and ran the engine and the noise remained.
Many have said that it may be an exhaust leak, I can see no carbon buildup around any of the ports and it does not seem to be coming from that area.
i did have to replace the RT bank exhaust gasket when I acquired the truck. it was blown out next to the heat stove for the thermo choke lines.
the noise was loud enough it covered this one I am dealing with now.
the manifold did not look damaged, nor did the head surface it was attached to.
i looked all over for cracks, recently and did not see any.
the sound has the same rhythm as a lifter noise, so if it was a leak I would doubt it would be the doughnut.
now that i think, one thing i have not done is to check around the manifolds with a fuel hose in my ear for gas escaping.
i will try that.
so with the push rods, if i do not need to check all of them for proper length, should I just check the exhaust?
I understand referencing the rods on the ends of the heads are a good sample for length, if that makes sense.
Last edited by manni59; Jun 16, 2024 at 10:57 AM. Reason: need to add question
Lead Driver
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It doesn't matter which pushrods you check the length on the entire set will be the same. but that doesn't mean you don't have a lifter, rocker worn or something like that making one or two need a longer pushrod. if you want to check them all and see if you can find the noise you can, but that's not going to be the pushrod you determine the proper length for the set by.
A cracked manifold will give you a tick and it doesn't always appear obvious. might even be where you can't see it. generally its worse on acceleration and often gets better after warming up.
Sometimes the best thing to do is just run it on an older engine. the problem will make itself obvious, and if it doesn't then it's not a problem.
A cracked manifold will give you a tick and it doesn't always appear obvious. might even be where you can't see it. generally its worse on acceleration and often gets better after warming up.
Sometimes the best thing to do is just run it on an older engine. the problem will make itself obvious, and if it doesn't then it's not a problem.