Flat camshaft follower issues

[Bisbee]

So, I’ve been following this back and forth about the flat vs roller tappet problems with the 4 valve motors. Thankfully, my 2017 Stelvio is clear of this issue. And yet in thinking about it, and studying the diagrams/ photos, maybe the basic engineering wasn’t so bad. After all, since the twenties, at least a couple hundred million engines have been produced with flat tappet valvetrains. My 69 Alfa went 100K miles with no wear on its flat cups. BMW K bikes easily go several hundred thousand miles with no one ever complaining about flat tappet deterioration. So what happened?         
1) Reduced amount of ZDDP in modern oils. Flat tappet motors need it but it will mess with the cat converters so it has been almost eliminated.

2) Inferior metallurgy with the tappet. Did Guzzi make them or an outside supplier?  Were the tappet faces chrome plated? A definite road to ruin.
3) incorrect heat treatment of the tappet after grinding and polishing. This has been a recurrent problem for even the best manufacturers costing endless millions in recalls.
I remember reading years ago that the area of most extreme pressure in an engine was the interface of cam lobe and tappet face. The oil film is gone and the protective film on the molecular level is the antiwear additive. This was the function of ZDDP.  Go buy some if you’re running flat tappets.
Always willing to read other opinions.

[Kiwi_Roy]

Its obvious to me that 4 valves per cylinder must be double the weight on the cams, no wonder they give out.

[beetle]

Ooh. This will be fun.

 

[oldbike54]

Ooh. This will be fun.

 

 30 pages easy 

 Dusty

[randy yocum]

I've been curious about this whole flat tappet failure debacle for years.I bought a Honda CB-750 F new when they came out in 1979 it was the first year of the double over head cams.I remember having to switch out those quarter sized hardened shims from time to time for valve adjustments.My question is why didn't Guzzi use tappets that were ground and hardened like are used in so many engines today.They worked fine in those old Jap Bikes way back when,I never noticed any wear on those hardened shims.And they run directly in contact with the cam lobe just like the Guzzi Tappet runs in contact with the cam lobe on these 4 valve heads.Seems like the Guzzi tappets used in the early heads should have used the same type of hardened metal instead of relying on some black coating that eventually wore off exposing the softer tappet metal underneath.I'm glad I finally got that off my chest ,now I'll just wait to find out how wrong my theories are.

[pete roper]

1) Reduced amount of ZDDP in modern oils. Flat tappet motors need it but it will mess with the cat converters so it has been almost eliminated.

Nothing to do with it.

2) Inferior metallurgy with the tappet. Did Guzzi make them or an outside supplier?  Were the tappet faces chrome plated? A definite road to ruin.

With the initial chilled cast iron tappets? Yes. Partly. Subsequent DLC coated, forged steel tappets? No.

3) incorrect heat treatment of the tappet after grinding and polishing.

Nope.

Go buy some if you’re running flat tappets.[/quote.]


Don't waste your money.

Pete

[Rebochi]

   The 4 valve Guzzi motor lubricates the cam and lifters with oil that was used to cool the head and exhaust valves. My scientific wild ass guess is that the oil going to the lifters loses viscosity due to high temps at high engine that it is not an effective lubricant.
   Requiring 10W60 indicates that there is a potential heat problem in the engine.

[SIR REAL ED]

30 pages easy 

 Dusty

   Me thinks both of you understand human nature very well.......

[bodine99]

So, I’ve been following this back and forth about the flat vs roller tappet problems with the 4 valve motors. Thankfully, my 2017 Stelvio is clear of this issue. And yet in thinking about it, and studying the diagrams/ photos, maybe the basic engineering wasn’t so bad. After all, since the twenties, at least a couple hundred million engines have been produced with flat tappet valvetrains. My 69 Alfa went 100K miles with no wear on its flat cups. BMW K bikes easily go several hundred thousand miles with no one ever complaining about flat tappet deterioration. So what happened?         
1) Reduced amount of ZDDP in modern oils. Flat tappet motors need it but it will mess with the cat converters so it has been almost eliminated.

2) Inferior metallurgy with the tappet. Did Guzzi make them or an outside supplier?  Were the tappet faces chrome plated? A definite road to ruin.
3) incorrect heat treatment of the tappet after grinding and polishing. This has been a recurrent problem for even the best manufacturers costing endless millions in recalls.
I remember reading years ago that the area of most extreme pressure in an engine was the interface of cam lobe and tappet face. The oil film is gone and the protective film on the molecular level is the antiwear additive. This was the function of ZDDP.  Go buy some if you’re running flat tappets.
Always willing to read other opinions.

   Valvoline VR-1 easy to get

[Two Checks]

Those Japanese engines don't have what you guys are calling tappets, aka lifters.
They have rocker arms that actuate the valves directly off the cam. I had a rocker arm break in a 350-4 while it was idling. The cam follower had no wear. Those things are smooth as a baby's hiney and appear to have a chrome surface.
If your lifters are tapping on the cam you have a real problem!


The old Kaw C10 Concours engines used forked rocker arms that operated two valves per lobe. Many of them had problems due to porous castings. Had nothing to do with ZDDP or spring pressure. The cams were crap. Mama Maw replaced a bunch of em but they never fixed the problem to my knowledge. Some failed, some didn't. Some failed quickly, others took time. Thats where that nice warranty came in handy.
Some cams pitted but didn't wear the rockers. Some self destructed. Guzzi isn't the only company using established engineering that fails.

[Markcarovilli]

this thread needs links to the old threads where this has been hashed and re-hashed - oh and did I mention re-hashed....

Mark

[rocker59]

   Valvoline VR-1 easy to get

Valvoline VR1:  1300-1400 PPM  ZDDP


Mobil-1 is also easily available at any parts store:

Mobil-1 V-Twin 20w50:  1600-1750 PPM ZDDP

Mobil-1 Racing 4T 10w40:  1200-1300 PPM ZDDP

Mobil-1 15w50 "grey cap":  1200-1300 PPM ZDDP

Mobil-1 5w40 Diesel Truck:  1100-1300 PPM ZDDP


https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide.pdf

[guzzisteve]

Really, I was putting in the new improved ones in 09/10 so, it's HASHED for 10 freaking years. Let the one's NOT fixed die a rattley death. ALL JUNK

[Wayne Orwig]

I remember reading years ago that the area of most extreme pressure in an engine was the interface of cam lobe and tappet face. The oil film is gone and the protective film on the molecular level is the antiwear additive. This was the function of ZDDP.  Go buy some if you’re running flat tappets.

I did. Did not help a bit. Made me feel good, but it still failed.

IMHO, the simply had too much load on the flat tappets. Or maybe the cam profile was a bit too extreme.

[Dilliw]

This was the function of ZDDP.  Go buy some if you’re running flat tappets.

A failure as common and as significant as the 8V flat tappets is not going to be prevented by varying the amount of ZDDP.  Could additional ZDDP extend the mean time between failures?  Maybe. But you are still left with the fact that the motor is going to fail. 

Switching to the rollers is the only real solution.

[guzzisteve]

If it was an oiling issue wouldn't those little wheels that ride in a groove or the tiny needle bearings on the rollers be trashed? Solid fix for issue.
Off sourcing tappets, 1st batch in new bikes were too flat, didn't spin. 2nd batch the coating came off, bad process in coating.
ALL computer generated good, not tested substandard CRAP. JUNK, and they knew it all the time. That's what's bad about it.

[Kiwi_Roy]

I may be completely wrong in my thinking that if you have two valves to close instead of one you must have greater pressure on the cam but I do know there's something going on and I don't want any part of it. I know my thought process is flawed but it saves me having to save up and buy a 4 valve flat tappet bike, even though they are a great idea.
 

[pete roper]

Just leaving this here.

How many failed flat tappets have you seen? Affecting how many engines?

What resources, other than Google, have you based your theories on?

That's it.

Have at it.

[Huzo]

I may be completely wrong in my thinking that if you have two valves to close instead of one you must have greater pressure on the cam but I do know there's something going on and I don't want any part of it. I know my thought process is flawed but it saves me having to save up and buy a 4 valve flat tappet bike, even though they are a great idea.

The pressure would likely be greater opening the valve..?
The springs would do most of the closing.

[Bisbee]

Not looking to make anyone get testy about this , but after reading all the above , I can only conclude that the metallurgy and or heat treatment of the flat tappets were in error. Since the problems took awhile to show up they simply kept carrying on until it all came crashing down. Since the EPA mandated that certain additives in the oil had to be virtually eliminated, engine design had to evolve. Just guessing but I doubt that many new flat tappet engines are being produced today. My error in thinking that new oils that seem to have new and better API classifications almost yearly must be great for these old designed engines. I now think that is wrong. Therefore, I ordered several bottles of ZDDP yesterday and will juice up my old BMWs and the EV. May not make a bit of difference since they never had problems anyway but ignorance is bliss. On the subject of why didn’t I research old threads on this, with new members joining the group (me), it’s not a bad idea to bring up old subjects for discussion. It’s educational for people that would be oblivious to the subject. I truly enjoy reading discussions on topics that have no bearing on what I will ever do. My days of rebuilding engines are hopefully over but I love to read these stories and counter opinions. Much of it is arcane knowledge but that is what makes this discussion board so great.

[Wayne Orwig]

Not looking to make anyone get testy about this , but after reading all the above , I can only conclude that the metallurgy and or heat treatment of the flat tappets were in error. Since the problems took awhile to show up they simply kept carrying on until it all came crashing down.

The early year motors quickly started to show issues. (2009?) So they had a recall and put in DLC coated followers. A zero mile bike got the new followers. With miles, it got a new cam and followers.
But it turns out that the DLC coating just delayed the problem.

 

[Wayne Orwig]

If there is an oil film between the cam lobe and follower it will not wear out prematurely but you still need to start the engine where there can be scuffing.
#
The follower can get a hard time from cams with aggressive ramps... a round, crowned follower that rotates is already on the path to a roller follower.

Follower and cam problems are nothing new in the automotive world and going to a roller follower was the remedy in a lot of cases and it was oil based.

The 'clamp' that holds the cam in place, is also an oil bucket. So even after sitting, the cam lobes SHOULD be well oiled.

Or so it appears.

I know that when you pull a cam box and turn it over to look for wear, you get oil everywhere.     Ooops.

[guzzisteve]

Just so you know, I talked to TechRep yesterday and was told the roller campaign is still going on. Get your rollers now. They supply parts, you pay labor at dealer.
This is the latest thread on this subject I could find.

[Kitze]

Maybe they used FRAM filters? I mean everyone know they’re a ticking bomb?

[Zoom Zoom]

Thanks Steve. I passed this onto a friend with a Griso that ought to consider it.

John Henry

[Griso8V]

OMG.  Not going to touch this topic after the last flame job I got on this topic;I know nothing about this; I just ride mine, rode it 150 miles just this week.  It still running...I am just some poor soul waiting for it to blow up...