Valve stem wear

[PaulProe]

I've run across something beyond my paygrade.

A set of Edelbrock FE heads, the standard Edelbrock valves, have approximately 30,000 miles on them without issue and all of a sudden, the thing starts burning oil bad. As we got into it, determined the valve guides were shot. Got the thing apart and the valve guides weren't all that bad but the valve stems themselves were worn enough to cause the issues. The machinist says he's seen this before and is blaming ethanol gas. Says you should add Stabil every other tank to keep ahead of the issues. Says the ethanol gums up the valve and they get 'sticky' and fail.

Has anyone else run into this? I would have thought the brass valve guides would have gone first, not the steel stems? Is this legit or a wive's tale?

[Falcon67]

Got lots of motors here - big and small - that have been running on 10% for years and have no valve issues at all.  The bronze guides in the iron 351C heads in the door car haven't seen a machine shop in 20 years.

[67xr7cat]

If the car sits alot yes can cause sticking valves.  Can mess up carbs and fuel systems too.  Main issue is if water gets into the gas.  Stabil is a good idea regardless, but can still have problems. Some buy gasoline without the alcohol in it.

As to the chewed up valve heads not so sure it is the gas fault. I'd be looking at your rockers and valve train geometry. Also what oil is used and that everything's getting oiled correctly.

[pbf777]

Has anyone else run into this? I would have thought the brass valve guides would have gone first, not the steel stems?

     Not so uncommon, normally attributed to 'fuel-wash' causing a reduction in the lubricants ability to function; and many of the more recently introduced ( that is in the last few decades) "bronze" materials have proven quite resilient in comparison to the valve stems, this to the point of perhaps proving what might be less than a truly compatible wear surface.     

     But, you won't be calling up the guide manufacturer complaining that your valve guides are all worn out!     

     Scott.

   

[70tp]

Any chance the fuel tank is a little rusty inside?   Fine rust will pass through some filters and likes to eat intake valves and seats, rings also

[Jim Kramer]

Perhaps another possibility would be some sort of dirt or debris imbedded in the guide metal, or maybe if your guides were honed to size on set-up and not cleaned properly afterward.......Jim Kramer

[shady]

GM had an issue in the mid 80s with bad chrome on the valve stems leading to oil burning. they didn't use seals just a cup over the top of the springs. I put Ford FE umbrellas on the stems and problem solved.

[Diogenes]

GM had an issue in the mid 80s with bad chrome on the valve stems leading to oil burning. they didn't use seals just a cup over the top of the springs. I put Ford FE umbrellas on the stems and problem solved.

I'm with Shady here, I've seen what happens when the surface finish on valves have been compromised or are "not correct".

[PaulProe]

The confusing part of this is the motor performed excellently for 30,000 miles then severely oil burning occurred in less than 500 more miles? No minor valve seal leakage or minor oil burning. It went from good to bad in less than 200 miles.

Could it be an oil additive issue? Could a change in driving habits cause any of this? The vehicle had a change in ownership and drivers in this timespan. Just seems very confusing there were no symptoms.

[shady]

I think your problem lies elsewhere.

[PaulProe]

I think your problem lies elsewhere.

? ? ?

I am open to any comments or ideas to try to get to the bottom of this

Paul

[Diogenes]

Unfortunately, without engaging in some likely costly material analysis, establishing a definitive cause of your failure is not likely. It is my opinion the issue revolves around the valve, but this is only speculation. It seems to me that an oil additive issue would have caused other issues in the engine long before the valve problem. Valve material issues seem most likely, but again, without material analysis this will remain speculation.

[shady]

PCV issue or an intake gasket failure. If the the valve guide or valve stems were the fault of heavy oil consumption, the problem would have come on very gradually.

[GerryP]

I think your problem lies elsewhere.

? ? ?

I am open to any comments or ideas to try to get to the bottom of this

Paul

I would gather up your heads and take them to another machinist for a second opinion.  I agree with Shady.  I think there is another explanation for your rapid transition from no oil use to massive oil use.  The valve guide/stem relationship didn't fail suddenly.  It doesn't happen that way.  A PCV, or a gasket failure, or maybe ring or piston failure would be on my interest list.  I don't know what it is, but I think this valve stem thing may be going down a rabbit hole.  I wrote this on the other forum, but E10 fuel does not do that so that makes me suspicious of the machinist's diagnosis.

[dcm0123]

As 67xr7cat suggested, look at the valve train geometry.

Check the witness mark the rocker makes on the valve stem tip as shown in the attachment. Sorry but I do not remember where I found the process which shows how to do this. It will help you determine if you have a problem with the geometry.