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PostPosted: Sun Aug 25, 2019 9:02 pm 
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My 351C started making this loud tapping sound. It's tied to RPM. Can't hear it when cranking, but while idling and faster, it's very audible. Would like ideas on what to check. Here's a link to a Youtube video with the sound:
https://youtu.be/1T9GYjVhbpc

It's got hydraulic lifters. I have adjusted them to zero lash, then went half turn more before locking the rocker arms. These lifters and cam have only 1,000 miles on them.
With a stethoscope, the sound is most pronounced when touching the intake manifold. I removed the intake, rockers, rods, and lifters. No noticeable damage to my untrained eye. When I try to compress the lifters, all are firm, except 1 lifter depresses about 1mm. Is that my culprit?

Has anyone disassembled Comp Cams lifters before? I see a lot of videos with foreign makes, (volvo, BMW, etc) cleaning out lifters and re-assembling. I'm guessing there's dirt in mine, perhaps?

Appreciate any suggestions.


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PostPosted: Mon Aug 26, 2019 6:37 am 
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Joined: Tue Nov 06, 2012 10:23 am
Posts: 1018
Location: Texas
Well that is not a nice sound. Is it a hydo flat cam? If so, did you use good break in oil and brake the cam in correctly? Did it just start to make this sound or was it after cam brake in? It Could just be a bad lifter, i had that happen before with some cheap Autozone lifters.
-Matt


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PostPosted: Mon Aug 26, 2019 7:19 am 
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Hydraulic lifters will bleed down over time, just because the spring pressure forces the oil out of them. However, if you check them immediately after shut down and they are all firm except for one, I'd say that's a clue.

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PostPosted: Mon Aug 26, 2019 7:40 pm 
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Thanks for the feedback!
They are hydraulic flat tappet lifters. (not rollers)
This is a link to them: https://www.compcams.com/hi-tech-hydraulic-flat-lifter-for-ford-289-351w-c-400m-429-460.html
884-16 for the set. Had a machine shop do the cam, lifter, valve spring install for me. I did see that they had some special grease/oil they used on the cam/etc. I also gave them the special lube that Comp Cams included.

I did what I believe to be a proper break-in. Ran it for about 20 minutes around 2,000 RPM as soon as I got it started. (would have gone 30 minutes but thermals prohibited that) This noise just started out of the blue, about 1,000 miles in, after break-in.

I checked all the lifters on this bank of cylinders, about 30 minutes after I took the video, and all were firm except the one that gave away about 1 mm.

I thought about checking with my machine shop that did the build, and also calling Comp Cams tech support.


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PostPosted: Mon Aug 26, 2019 10:41 pm 
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Joined: Thu Jul 25, 2019 9:05 pm
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If you do not already, you need to learn to adjust you own valve train. One of the benefits and the problems with a hydraulic setup is the oil pressure adjusts the lash for you, and if you are not accurate in the adjustment you can run the lash deep. By this I mean the lash plus XX# of turns from the correct starting point will usually net the correct adjustment, but as things become routine the whole process becomes thoughtless. If you adjust too far off of the opening and add the preload you can run it deep and instead of the lifter pumping up it will bottom out at full lift and essentially kill the lifter. There is no recourse here as there are other reasons you can kill the lifter like over-reving the engine or getting on it before operating temperature occurs. I would pull the intake and check the lifters my guess is the one with the play is damaged. Hopefully no harm done if it was a solid lifter ran deep one or more of the pushrods would be bent at the very least.

Did you change the oil after break-in? I would drain the oil and look for metal hopefully you didn't wipe a lobe. Check the play of that lifter and check the pushrod and make sure it is straight.

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PostPosted: Tue Aug 27, 2019 10:01 pm 
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Thanks. Good advice about doing it myself. Just some follow-up:

After inspecting the rockers more closely, I think I might have potentially found the issue. One pivot ball has some damage.
Image
This results in a slight catch you can feel with your finger when you articulate the pivot ball in the rocker. Could this cause such a noise?

These heads (valves, springs, guides, rockers, push rods, studs) have all seen rough duty already on the track. I inherited them and don't know the history, but can tell that the valve this damaged pivot ball came off, had some serious issues at some point. The guide finger has been welded back on
Image
and the black spring cap at the valve stem shows signs of a serious problem.
Image

The bottom of the rocker arm also shows damage, as does the roller (but roller damage not shown in pic).
Image
I'm guessing all that damage happened previously, and possibly even that pivot ball damage. Maybe to save money, the rocker was just put back in the engine after the guide finger was repaired. Doesn't matter, I'm going to replace this rocker. Just don't understand why it was quiet for 1,000 miles then the noise appeared, unless that pivot ball damage somehow just happened.

I also talked to Comp Cams about this issue and had them view the video. (This was before I found the rocker issue) They told me that I should make one full turn on the rocker, after zero lash, not a half turn. The guy said they are getting ready to officially revise their guidance on their hydraulic flat tappet lifters to reflect this. He attributed the sound on the video, to insufficient tightening after zero lash. He said the lifters I have could tolerate up to 1.5 turns, but they don't recommend that. He said at 1 turn they should operate much more quietly. I have always thought this engine has a faint diesel sound, or faint pinging at the valve covers that wasn't natural.


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PostPosted: Tue Aug 27, 2019 10:40 pm 
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mcbain wrote:
Thanks. Good advice about doing it myself. Just some follow-up:

After inspecting the rockers more closely, I think I might have potentially found the issue. One pivot ball has some damage.
Image
This results in a slight catch you can feel with your finger when you articulate the pivot ball in the rocker. Could this cause such a noise?

These heads (valves, springs, guides, rockers, push rods, studs) have all seen rough duty already on the track. I inherited them and don't know the history, but can tell that the valve this damaged pivot ball came off, had some serious issues at some point. The guide finger has been welded back on
Image
and the black spring cap at the valve stem shows signs of a serious problem.
Image

The bottom of the rocker arm also shows damage, as does the roller (but roller damage not shown in pic).
Image
I'm guessing all that damage happened previously, and possibly even that pivot ball damage. Maybe to save money, the rocker was just put back in the engine after the guide finger was repaired. Doesn't matter, I'm going to replace this rocker. Just don't understand why it was quiet for 1,000 miles then the noise appeared, unless that pivot ball damage somehow just happened.

I also talked to Comp Cams about this issue and had them view the video. (This was before I found the rocker issue) They told me that I should make one full turn on the rocker, after zero lash, not a half turn. The guy said they are getting ready to officially revise their guidance on their hydraulic flat tappet lifters to reflect this. He attributed the sound on the video, to insufficient tightening after zero lash. He said the lifters I have could tolerate up to 1.5 turns, but they don't recommend that. He said at 1 turn they should operate much more quietly. I have always thought this engine has a faint diesel sound, or faint pinging at the valve covers that wasn't natural.


Looking at the pictures I am of the opinion that the rocker / pivot ball and retainer are the result of a different problem likely in the rocker geometry/clearance not the cause of the issue. The valve tip looks mushroomed also. The neighboring rocker arm to retainer clearance looks real close check that lifter and pushrod I would guess they are done.
If the lifter bottomed the minimal clearance between the rocker and the retainer was eliminated and the roller tip was forced into the valve stem until the roller stopped spinning under load and caused the valve stem to mushroom.

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If some doesn't try it how will we know if it works...a stupid question is meant to p-off the questioned, all others are for focus and higher learning.


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PostPosted: Fri Aug 30, 2019 10:57 am 
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Joined: Mon Nov 05, 2012 3:54 pm
Posts: 62
mcbain wrote:
Thanks. Good advice about doing it myself. Just some follow-up:

After inspecting the rockers more closely, I think I might have potentially found the issue. One pivot ball has some damage.
Image
This results in a slight catch you can feel with your finger when you articulate the pivot ball in the rocker. Could this cause such a noise?

These heads (valves, springs, guides, rockers, push rods, studs) have all seen rough duty already on the track. I inherited them and don't know the history, but can tell that the valve this damaged pivot ball came off, had some serious issues at some point. The guide finger has been welded back on
Image
and the black spring cap at the valve stem shows signs of a serious problem.
Image

The bottom of the rocker arm also shows damage, as does the roller (but roller damage not shown in pic).
Image
I'm guessing all that damage happened previously, and possibly even that pivot ball damage. Maybe to save money, the rocker was just put back in the engine after the guide finger was repaired. Doesn't matter, I'm going to replace this rocker. Just don't understand why it was quiet for 1,000 miles then the noise appeared, unless that pivot ball damage somehow just happened.

I also talked to Comp Cams about this issue and had them view the video. (This was before I found the rocker issue) They told me that I should make one full turn on the rocker, after zero lash, not a half turn. The guy said they are getting ready to officially revise their guidance on their hydraulic flat tappet lifters to reflect this. He attributed the sound on the video, to insufficient tightening after zero lash. He said the lifters I have could tolerate up to 1.5 turns, but they don't recommend that. He said at 1 turn they should operate much more quietly. I have always thought this engine has a faint diesel sound, or faint pinging at the valve covers that wasn't natural.


2X to what Brent said. Also, look at the edge of the retainer closest to the valve keepers. It's heavily gouged and that too is most unusual.

If it were mine, I'd pop the heads, check every valve/guide, replace all the retainers (and be sure the right keepers are used) check spring tension, dump the ball rockers and purchase a good set of roller rockers. Then check for clearance to the retainer/pushrod/p-rod guide and check the sweep (p-rod length). Good luck.


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PostPosted: Wed Sep 04, 2019 7:45 pm 
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Joined: Thu Jul 25, 2019 9:05 pm
Posts: 35
^^^^^^ Agreed, the guide plate should not have enough side load to break with the proper geometry, check the pushrod length, and the rocker to retainer clearance something is amiss. Looking at that retainer it is lucky the keeper didn't release and drop the valve.

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If some doesn't try it how will we know if it works...a stupid question is meant to p-off the questioned, all others are for focus and higher learning.


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PostPosted: Tue Sep 10, 2019 10:00 pm 
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Joined: Sun Apr 21, 2019 9:09 pm
Posts: 16
Just a update: No root cause yet. Started off with easier stuff first. Pulled off the intake and removed all the lifters. The lifter associated with the pictures in this post, was a little difficult coming out of it's bore. I replaced that lifter with a new one, and replaced that rocker too. I also adjusted the lash + 1 turn on each rocker arm, per Comp Cams advice. None of this affected the sound.

To rule out a header gasket leak, I pulled each spark plug wire, one at a time, on that bank. No change in sound.

I think I may be at the point others have already suggested I follow - pulling the heads and inspecting the valves, guides, p-rod, spring tension, etc.


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