The theory on hydraulic lifters and cams

[JHZR2]

I know I have a few threads on my projects, but this is a more universal question.

What is the theory with repurposing used good hydraulic lifters?

I think I’ve seen some discussion that they wear in together and there can be damage. But I think I’ve also read that this is more so when used lifters are used with a used cam, and that new lifters that don’t have a funny wear pattern then just wear in with the cam.

I’ve also heard where folks pull lifters, dump them in a bucket of oil, then just reinstall.

I have ten lifters that are good.

The wear pattern on the top, which I don’t have a good photo of, seems radial on all but one that had a small semicircle in the top center. I’ll need to knock that.

But fundamentally, if these are good, are they ok to use in the future in a different ~200k mile engine. Lifters are only $13 each for German made OE, but x10 or x12 when I now have ten otherwise good ones is an unnecessary expense. It isn’t a hard job to swap at all.

So, what’s the theory of hydraulic lifter reuse?

 

[spasm3]

I've always been told that you can use new lifters with a used cam, but not worn lifters with a new cam. I was always advised to keep the lifters to the corresponding camshaft lobe when reinstalling after removal.

 

[supton]

Cam buckets for Toyota engines get reused, right? the ones that come in a range of sizes as they aren’t adjustable.

Its a matter of hardness, no? If little to no wear pattern exists, then why not reuse? No pattern, no issue.

 

[ARCOgraphite]

I am familiar with pushrod designs in general I have not pursued OHC. Likely some online references on this subject. Pushrod engine cam lobes are tapered, the tappet face is not flat, but convex. I do not recall the radius - though it is large vs. the tappet DIA. Tappets should rotate in operation.

Is this engine a shim under inverted bucket design? I would not reuse tappets unless absolutely necessary - which means no re-machining/refacing option or no NOS or replacement parts are available.

Pushrod engine tappets general design (profile greatly exaggerated for clarity)

 

[Trav]

On those bucket under cam lobe style lash adjusters it doesnt make much difference as long as the face is not marred. There is only actual valve spring pressure which is low acting on these unlike a system that uses lifter, rocker arms, slippers, lobes that actuate multiple valves etc, these all multiply spring pressure being exerted on the cam lobe and lifter. I have used new lifters on old camshafts but not used ones unless they were previously run on that lobe, a new cam requires new lifters on these valve trains, roller lifters if not showing wear or loose bearings can be used.

 

[JHZR2]

On those bucket under cam lobe style lash adjusters it doesnt make much difference as long as the face is not marred. There is only actual valve spring pressure which is low acting on these unlike a system that uses lifter, rocker arms, slippers, lobes that actuate multiple valves etc, these all multiply spring pressure being exerted on the cam lobe and lifter. I have used new lifters on old camshafts but not used ones unless they were previously run on that lobe, a new cam requires new lifters on these valve trains, roller lifters if not showing wear or loose bearings can be used.

Thanks. I think I’ll soak them in oil and store them in a clean Chinese food container or something. No reason to dispose of them if it doesn’t much matter to reuse in this engine design.

If I’m ever in the future doing a rigorous rebuild I’d buy new, but if I ever get a leaky/noisy one, I’ll just keep these. I guess why not reuse if it’s just one noisy one in another old engine…

Thanks!

 

[JHZR2]

I am familiar with pushrod designs in general I have not pursued OHC. Likely some online references on this subject. Pushrod engine cam lobes are tapered, the tappet face is not flat, but convex. I do not recall the radius - though it is large vs. the tappet DIA. Tappets should rotate in operation.

Is this engine a shim under inverted bucket design? I would not reuse tappets unless absolutely necessary - which means no re-machining/refacing option or no NOS or replacement parts are available.

Pushrod engine tappets general design (profile greatly exaggerated for clarity)

View attachment 222731

No these are perfectly flat it seems from the factory.

 

[dguzzi]

an egg container works well for keeping them in order, if you need to.