Problems with worn valves. Need good advice

[nonickatall]

Hi guys,

In search for my too high oil consumption, i figured out that my valve stem seals are not good anymore so I decided to swap them.

Today i started the work which is like Holliday on this engine, if you ever did this on a BMW from the same year of production.

But when I did the first cylinder I found valve stem seals, I never saw before and I don't think that this is their normal status. See first pic

I started at the right bank, so I now on cylinders nder four and all the valve stem seals look like that.

But now it comes to real problem.

On the intake valve of cylinder four it looks like, that the valve is to short and the retainer or what you call that, these two wedges that hold the spring to the valve were worn in, by the rocker arm.

At first I thought they weren't sitting properly, but they actually only have one position in which they fit.

The valve obviously seems to be too short, or worn off at the top.

Actually it doesn't look like it, because the edge of the valve at the top is actually straight and smooth. I don't know if they installed the wrong valve, back then, which I can't imagine. Has anyone ever seen this or has an idea what could be there?

 

[nonickatall]

Im measured the valve and the intake valve is approximate 3 Millimeters shorter....

When I look at this, I think that the rocker arm had wear out the valve. How could that be?

 

[Doubeleive]

I don't know about those valve stems, but all that snot in there doesn't look good at all, are you loosing coolant?

 

[nonickatall]

Yes I do, but I also lose oil between the oil changes, but the oil does not look bad. I made a co test and there was no co in the cooling liquid..

 

[nonickatall]

I put the old valve stem seals together and here you see a comparison to the new and correct ones. I guess the garage choose wrong valve stem seals.

The former owner told me that they did something on the cylinder heads to make the heads lpg resistant.

But that dont explain the worn out valve...

 

[nonickatall]

I have more worn out valves. Is that common at these engines? Never heard about that. What can cause that? And obviously only intake valves are affected.

I am suspicious if the used a rebuild head and someone put in wrong valve stem seals and cheap valves which are not hardent enough?

 

[Doubeleive]

@iamdub @swathdiver

 

[swathdiver]

Might be because of the LPG. It's been a long time since I read up on them but do remember something about using different valve seals.

 

[rockola1971]

Overtightened rocker arms will wear a valve stem tip down. That rocker arm pic says it all.

 

[nonickatall]

@swathdiver what they sometimes do is change the valve seats, but not the valve stem seals. And the ones they used were too short, which caused the disintegration of the valve stem seal housing, so to speak, from the seal itself.

@rockola1971 how should over tighten rocker arms, wear the valve stem tip cover? The rocker arm assembly sits on the cylinder head. If you use too much torque, then you may damage the threads, but you will not get movement or too much pressure on the valve stem tip. The pressure on the valve stem tip comes from the spring and the camshaft. And there is a supplement from GM that the rocker arms of the aluminum heads should not overtighten 24nm which can cause the threads to fail.

But thank you both for trying to think about that with me. That makes a forum good, to exchange with people with the same afficination.

For me at the moment, I can only see two reasons for that wear. Too much friction, because of a lack of lubrication, or less quality of the valves.

Too much friction I would denie, because oil pressure was all the time good. I used good quality oil and changed it regularly. As well. Why only the intake valves are affected? I mean, if the intake and exhaust valves have the same quality, the exhaust valves must wear more, because of the higher temperature.

So I think, when they did the cylinder head, and the former owner told me, that they did the valve seats, they probably used cheap intake valves, which are not hardened enough.

Fact is: I cannot drive that engine anymore, until I do the cylinder heads, because if this small rest of the tip breakes, the valve spring releases and the valve falls into the combustion chamber….

Then the engine is for sure ready for the junk yard.