Broken Valve Spring

[redwitch]

I was getting water in my oil last June, The motor ran bad, bad noise, water in oil. traced to broken valve springs on #4, I replaced all the valve springs, a few valves, new head gasket, ran perfect untill now, last weekend the motor sounded bad, running on 3 cylinders. I checked tune parts good, I removed the valve cover plate and found #4 exhust spring broken again and #2 cylinder spring damaged, I dont know what can cause my valve springs to break, I warm the motor up and do not over rev it. Im going to replace all the valve springs again. I just dont know what the cause, any Ideas, Thanks Ed

[Don Moyer]

Ed,

The only experience we have ever had with valve springs breaking has been that which resulted from water damage to the springs (slight rustiness) and/or water damage to the valve stems and guides which caused the valves to stick a bit. The combination of those two situations would cause the springs to break in multiple places along the length of the spring.

I'm not sure what springs you've been using, but the OEM springs from the 1980's and 1990's were particularly bad in this regard. We began using springs from another manufacturer around 2000, which helped considerably, but we still had a few reported failures in the aftermath of water intrusion episodes that resulted in sea water backing into the combustion chambers. About a year ago, we began using stainless valve springs and to this point have no reported failures.

Regards,

Don Moyer

[redwitch]

thanks Don, I installed your valve springs last July, I suspect stainless (shiny) I may have a prolbem with my exhust. I replaced made a new exhust from the manifold out, I may not may not have made it tall enough??? I did use the old one for a template, but as I said I may not have made it tall enough I dont want to replace the valve springs every 9 months. thanks Ed

[Don Moyer]

Ed,

We don't want you to be replacing your valve springs every 9 months either. Would you please send all of your old springs (especially the broken ones) to our Moyer Marine Warehouse, 242 N. Spring Street, Middletown PA 17057? Yours may be the first reported failure that we've had, and I'm very anxious to have the springs analyzed to determine all we can about their failure mode.


Thanks,

Don

[redwitch]

no prolbem I will send the springs next week. I plan to have them out saturday. Thanks Ed

[dplidr@gmail.com]

Valve springs - Stainless?

Ed,

The only experience we have ever had with valve springs breaking has been that which resulted from water damage to the springs (slight rustiness) and/or water damage to the valve stems and guides which caused the valves to stick a bit. The combination of those two situations would cause the springs to break in multiple places along the length of the spring.

I'm not sure what springs you've been using, but the OEM springs from the 1980's and 1990's were particularly bad in this regard. We began using springs from another manufacturer around 2000, which helped considerably, but we still had a few reported failures in the aftermath of water intrusion episodes that resulted in sea water backing into the combustion chambers. About a year ago, we began using stainless valve springs and to this point have no reported failures.

Regards,

Don Moyer

Hi Don,
I just received the new springs for my rebuild and I've noticed that the pencil magnet I have is attracted to these new springs (not as strongly as the old ones, but clearly magnetic). Is that what you'd expect?



thanks,
-DaveL

[Don Moyer]

Valve spring material

Dave,

We questioned the manufacturer many years ago on this point, and they told us that it's normal for their stainless valve springs to have a bit of magnetic attraction. In all the years we've been using these springs (25+ years), I don't recall ever seeing one of their springs fail from rust. Don

[Mo]

FWIW

I worked on a troublesome engine a few times and the culprit was he changed the exhaust layout. The right conditions would allow water back into the top end resulting in sticking valves, broken spring and a broken valve at one point. Fixed the engine (twice), and figured water had to be causing it...I looked at the riser and it seemed low but he said he'd replaced it the year before exactly as it was and had run for years. On my advice he put in a higher riser up from the exhaust manifold and the engine has been fine since. Something to ponder and check out.

[ndutton]

Magnetic properties of stainless steel vary by the grade (typical for marine purposes are 304, 316 and 18-8).

[dplidr@gmail.com]

Thank you Don for your very quick response. Reassuring to know you don't find that slight magnetism indicates bad spring material.

Appears from reading that the cold forming and other methods can impart magnetic properties and in some cases a bit more ferrite content can help avoid cracking.

A couple links for those who want to know more about the different magnetic properties of different SS grades and different SS manufacturing.

https://www.kimballphysics.com/magnetic-response-of-stainless-steels

https://clevelandmixer.com/why-are-stainless-steel-castings-magnetic/

https://www.greenwoodmagnetics.com/resource/what-is-the-difference-between-304-and-316-stainless-steel/

Thanks again,
-DaveL