Stuck Valve or Bad Cam?

[bacelaw]

Hi all:  while adjusting valves I noticed intake on #5, the tappet doesn't travel as much as the others, if at all.  Am I looking at a bad cam lobe, or could the valve stem just be stuck?  

 

Thanks!

[Plymouthy Adams]

cam to lifter is direct contact and X lift as ground into the cam all relates to the components with no wear....failure to attain the lift is either cupping of the lifter due to wear or eroded metal on the toe of the cam lobe and could/often be a combination of both.  You will need to ensure the lift is correct in order to proceed in your troubleshooting.  

[bacelaw]

Just now, Plymouthy Adams said:

cam to lifter is direct contact and X lift as ground into the cam all relates to the components with no wear....failure to attain the lift is either cupping of the lifter due to wear or eroded metal on the toe of the cam lobe and could/often be a combination of both.  You will need to ensure the lift is correct in order to proceed in your troubleshooting.  

 

The lift isn't nearly correct via eyeball instrument test.  It moves about half of what it should.  I was hoping it could be something else other than a bad cam.  Can a lifter be cupped that badly?

[Plymouthy Adams]

once the surface hardening has been compromised the wear to the remaining metal is rather rapid....

[bacelaw]

Just now, Plymouthy Adams said:

once the surface hardening has been compromised the wear to the remaining metal is rather rapid....

 

That makes sense.  The same valve has leaky guides too and that condition is worsening quickly too.  I did a long run at 55mph on a hot day, probably about 90minutes and I could tell something wasn't quite right.  I bet the hardening was compromised and the long run wore it down.  Thanks for confirming. I'll do compression test before I commit to rebuild. 

[Los_Control]

Sad to hear, sounds legit though.

Not really something we hear about on our flatheads.

 

I remember it used to be a common thing on early SBC, especially the lobe that ran the fuel pump.

I had a 68 chevelle with a worn out 327 .... cam was flat and could not pump enough gas at high speeds .... install a electric pump and it got enough gas at high speeds to tell you the rest of the cam was flat also.

 

Just saying it happens, sad it happened here  

[keithb7]

Remove oil filter. Cut it open. Press out oil from paper in a vise. Inspect for shiny material. That will confirm if tappet and cam lobe are failing. I published a video its on YT. Detailed instructions how to do this. 
 

 

[keithb7]

https://youtu.be/rI5-MPzZtwM?si=adwXe-f4zZUL2pU_

[bacelaw]

35 minutes ago, keithb7 said:

Remove oil filter. Cut it open. Press out oil from paper in a vise. Inspect for shiny material. That will confirm if tappet and cam lobe are failing. I published a video its on YT. Detailed instructions how to do this. 
 

 

 

Great idea!

 

[bacelaw]

44 minutes ago, Los_Control said:

Sad to hear, sounds legit though.

Not really something we hear about on our flatheads.

 

I remember it used to be a common thing on early SBC, especially the lobe that ran the fuel pump.

I had a 68 chevelle with a worn out 327 .... cam was flat and could not pump enough gas at high speeds .... install a electric pump and it got enough gas at high speeds to tell you the rest of the cam was flat also.

 

Just saying it happens, sad it happened here  

 

Motor mostly sat for 50 years.  I've been driving for two summers and for the first time looked at the valves. Maybe some sludge caused the wear.  58k original miles.

 

I bet she'll still cruise around town for another 80 years, but 55mph is no longer happening.  

[Los_Control]

21 minutes ago, bacelaw said:

I bet she'll still cruise around town for another 80 years, but 55mph is no longer happening.  

That Chevelle had a million miles on it already but did run ok. I ended up giving the car to my sister. It was her only car and she drove it to work for a couple years yet.

It was very dependable and just needed normal maintenance to keep it going. .... Brakes, alternator .... the motor hung in there.

 

Still ran but was getting pretty tired and sis was in a better position and bought her dream car 72 Nova.

 

I'm sure you are correct it will hang in there the way it is. .... If only we had push rod extensions   🤔

[soth122003]

4 hours ago, bacelaw said:

while adjusting valves I noticed intake on #5, the tappet doesn't travel as much as the others, if at all.  Am I looking at a bad cam lobe, or could the valve stem just be stuck?  

Pull the head and check the valve travel. It might be stuck partway up and not seating all the way down. If true, you're not using all the cylinders and the loss of power in one, will run ok, but not a full power at higher speed.

 

1 hour ago, bacelaw said:

Motor mostly sat for 50 years.  I've been driving for two summers and for the first time looked at the valves. Maybe some sludge caused the wear.  58k original miles.

 

So about 60-62k total miles. 2 summers worth of driving should not cause that much wear or even the 58K before then unless no one changed the oil or ran it low all the time. Sludge build up is highly probable. Maybe the sludge is causing a sticky situation. As Los said it is not something we really hear about on the flatheads. I would look for a stuck tappet, gummed up spring or valve. That IMO is the more likely factor. You might try an engine oil flush for about 50 miles and look at what comes out of the pan. 

 

Joe Lee

 

 

Edited July 19 by soth122003

[bacelaw]

3 minutes ago, soth122003 said:

Pull the head and check the valve travel. It might be stuck partway up and not seating all the way down. If true, you're not using all the cylinders and the loss of power in one, will run ok, but not a full power at higher speed.

 

 

So about 60-62k total miles. 2 summers worth of driving should not cause that much wear or even the 58K before then unless no one changed the oil or ran it low all the time. Sludge build up is highly probable. Maybe the sludge is causing a sticky situation. As Los said it is not something we really hear about on the flatheads. I would look for a stuck tappet, gummed up spring or valve. That IMO is the more likely factor. You might try an engine oil flush for about 50 miles and look at what comes out of the pan. 

 

Joe Lee

 

 

 

 

I love your optimism.  With the valve covers off, and the engine running, to my eye it looked like the #5 exhaust tappet was moving half the distance it should.  To me it was not moving "up" far enough - I thought the only explanation could be the cam lobe is gone, or else the tappet would move.  If the cam were good, wouldn't it move the tappet?  I could see if a tappet was stuck up, bit mine is down and not traveling...

 

 

 

[Sniper]

If the valve was not seating fully and that was your problem a compression check would show no compression in that cylinder. A valve that is not opening enough because of a worn low would show less compression than the other five cylinders but it would still show some sort of compression.

[Los_Control]

Agree with @soth122003 a engine flush is good .... I actually like to do a oil change and add 1 quart ATF then fill with normal oil .... ATF is a good cleaner and will clean sludge.

 

You had your valve covers off and you would see there how much sludge your engine has.

Here is a engine that has been properly sludged up .... I would expect issues if your engine looked 1/2 this bad ....

 

 

I just installed a used engine had 135K miles on it in a modern OT car .... it had a little sludge in it .... basically evidence of it, tiny amount in the corner on top of a rocker arm.

I just feel it is common to see some sludge inside a engine, the older the engine the more sludge you will see .... is just common.

 

The engine above most likely used non detergent oil ..... even later oils like Quaker state and Pennzoil had a additive I believe was paraffin ...

Had a buddy at work that had a new crate engine in his 67 Ranchero, ran nothing but Pennzoil in it ... pull a valve cover and looked like this.

 

Long story short, if your seeing some serious sludge inside your valve covers, you should pull the pan also .... if not bad, never hurts to run a flush.

[soth122003]

I just finished a quick read on the valve adjustment and checks of the 35-53 Plym's in the Motors Manual. Here's another thought for you The valve spring is weak and compressed and as such the tappet adjustment will be higher to make up the difference of a short spring. With out the engine running, rotate the engine to TDC on each cylinder and look at the spring lengths. Compare the other cylinders intake springs with the #5. Does #5 look shorter than the others?

 

Or it might be the valve itself being worn down.  Thinking about it, these might not be your problems, but jumping straight to the cam or tappet is a bit like jumping the gun. It might be the tappet or cam, but to pull that whole thing apart when you don't need to can be frustrating and leaving you feeling a little foolish for a simple fix.

 

I'm just listing the easy things before pulling the front engine components to pull the cam to check it. Basically rule out the easy stuff before jumping to the hard or maintenance intensive stuff.

 

On the old Plm's and Dodges the tappets rarely wear out, the cams even less so. Since the Springs, valves and guides are list in a maintenance manual to check during routine maintenance and the tappets and cams aren't, check those first. Might just be a weak/broke spring or a valve.

 

Joe Lee

Edited July 19 by soth122003

[keithb7]

@Los_Control that’s one heck of a great example to be smearing around the internet.  Wow. A ton of sludge in there! I cannot imagine running an engine as long as it would take to accomplish that, and never take the valve covers off. Lol. 
 

“Engine developed a miss. It got worse so I parked it. Ran when parked”. Lol. 

[Los_Control]

6 minutes ago, soth122003 said:

The valve spring is weak

Thats a good point .... I noticed that on my first project I never could finish. There was only 1 cylinder that had compression and low.

When I pulled the head, the valves were stuck open ... I was shocked at how easy it was to push the valves down by hand.

Literally took zero effort, the springs just were weak and would not pull them down because of the gum on the valve stems going through the valve guides.

While I could use my little finger and easily push them down.

 

Since I was using a bar on the stomp starter to roll the engine over, I just used a small rubber hammer and roll the engine over then tap them down .

I really felt like I was playing the kids game whack a mole .... Within 1/2 hour all valves were functioning correctly.

 

A compression check on all cylinders would give a good idea on whats going on.

[Los_Control]

43 minutes ago, keithb7 said:

“Engine developed a miss. It got worse so I parked it. Ran when parked”. Lol.

As funny as it sounds, I was maybe 17 years old and working at a Union 76 gas station at night .... think we closed 10 or 11 pm ....

I had full use of the garage during the evenings, I could bring my cars in and play with them while working ... while keeping the gasoline customers happy.

I had a full garage with lift and tools at my hands .... The owner actually encouraged this activity, there were 2 bays and if customers needed help like a new fan belt or such he wanted people there that could handle the job .... I think he considered it on the job training.

 

Just showing a photo because we all like pics.

So I bought a car, not this one for $50. It was baby blue with a white vinyl top, hub caps and a 6 cylinder. Grandma's version.

Everything was perfect on that car, interior, body ... car was 10 years old .... They ran Quakerstate oil in it, when I pulled the valve cover it looked almost like the photo above.

Since I worked at a gas station, we had a barrel out front .... We would take the cardboard containers and insert the spout and pour oil in customers cars.

When finished we would take the can and insert the spout in the barrel and let it finish dripping there .... We could use this oil anytime we wanted, it cost $$ to get rid of it.

 

Just saying I mechanically removed all the sludge  I could .... Then kept running fresh oil and ATF through it .... I would remove the valve cover and monitor it.

Think it was 2 months and sold that $50 car for $500 .... It really ran well and cleaned up nice .... nobody complained.

 

[bacelaw]

5 hours ago, soth122003 said:

I just finished a quick read on the valve adjustment and checks of the 35-53 Plym's in the Motors Manual. Here's another thought for you The valve spring is weak and compressed and as such the tappet adjustment will be higher to make up the difference of a short spring. With out the engine running, rotate the engine to TDC on each cylinder and look at the spring lengths. Compare the other cylinders intake springs with the #5. Does #5 look shorter than the others?

 

Or it might be the valve itself being worn down.  Thinking about it, these might not be your problems, but jumping straight to the cam or tappet is a bit like jumping the gun. It might be the tappet or cam, but to pull that whole thing apart when you don't need to can be frustrating and leaving you feeling a little foolish for a simple fix.

 

I'm just listing the easy things before pulling the front engine components to pull the cam to check it. Basically rule out the easy stuff before jumping to the hard or maintenance intensive stuff.

 

On the old Plm's and Dodges the tappets rarely wear out, the cams even less so. Since the Springs, valves and guides are list in a maintenance manual to check during routine maintenance and the tappets and cams aren't, check those first. Might just be a weak/broke spring or a valve.

 

Joe Lee

 

This makes sense, thank you.   I'll check compression, and maybe pull the head off to inspect.   I really hope you're correct...

 

I'll report back. This group, as always, is really a wealth of knowledge 

 

[bacelaw]

Update: compression check, okay.  Leakdown test, okay.  I spun engine by hand and carefully watched each lifter.   They are all travelling fully.  I did find one valve way out of adjustment - thanks to Keith's videos.

 

So, false alarm all around, but thanks to the wisdom of this group I learned alot.  I think the engine is pretty tired, but there's no damage.  

 

[keithb7]

Excellent news. Love it! Glad to hear another flathead Mopar will live on. 

[soth122003]

On 7/19/2024 at 11:02 AM, bacelaw said:

The lift isn't nearly correct via eyeball instrument test.

I use the Mk 1 eyeball as well. Most times on still or objects that aren't moving fast, it works well enough. The lifters at 500-600 rpm move pretty quick. The Mk 1 eyeball also has a drift factor that looks at other moving objects, because it just can't help itself and can cause a little confusion. When you rolled the engine by hand and slowed everything down, it was easier to focus on the suspected fault and compare it to the others.

 

I'm glad it worked out for you and you were able to verify the condition of the engine. The best method of working on these old cars is the K.I.S.S approach. Keep it Simple Stup**.  In other words Start with the easy stuff first. 

 

Next time I'll use the Grinch approach. "Yep sonny boy it's the cam for sure. Why back in my day these cams just wore out on one lobe after 30K." LOL

 

Joe Lee

[Plymouthy Adams]

as I stated in my first response...ensure the lift is correct before proceeding....glad you took the time to measure this.

Edited July 25 by Plymouthy Adams