valve covers

[Hans]

This is weird. One of my valve covers that I've used before (and have of course refinished) no longer sits properly in a 121 head. It seems to be rocking on something at the front. It does however sit properly on an E21 head that has the valve train loaded. Another valve cover from the collection fits properly - doesn't rock. WTF? The first one seems to have higher ridges inside. I assumed they were all the same. They have different casting numbers inside.

[Preyupy]

Are you using ARP head studs?

[Hans]

3 hours ago, Preyupy said:

Are you using ARP head studs?

No, everything stock.

['76mintgrün'02]

Do you have a camera?   

 

What are the dates on the covers?

[Conserv]

1 hour ago, '76mintgrün'02 said:

Do you have a camera?   

 

What are the dates on the covers?

 

+1

 

Valve covers fitting differently is something we don’t know...yet!

 

Regards,

 

Steve

 

Edited August 2, 2018 by Conserv

[Mike Self]

If you had the head surfaced recently and the shop didn't also surface the upper timing chain cover simultaneously, the cover is gonna sit a few thousands higher than the head, so the two mating surfaces with the valve cover won't align.  

 

If that wasn't the case, someone may have overtightened the valve cover at some previous time, causing it to warp.  You should tighten the valve cover nuts in a crisscross pattern, beginning with the two in the center, just like you would a cylinder head.  And the tightening torque is lower than you may think (check the shop manual for the figures).

 

To see if the valve cover itself is warped, place it on a sheet of plate glass; if it rocks there, then you'll need to have it surfaced at a machine shop to get it flat again. Otherwise it's gonna leak,..

 

mike 

Edited August 2, 2018 by mike

[Hans]

Closer examination on an E21 head with front cover removed shows an internal cross rib is hitting the oil sprayer bar at the front- with no gasket. That one is casting number 11802600069, no date stamp.

A spare valve cover stamped 1180260080.9 date 69 has lower ribs so it clears with no gasket. I'd never noticed this before  with the odd cover - ran it for years. On the 121 head on the motor now, with good even transition from head to front cover, I was getting oil mist coming out the front, with correct torque. So it wasn't sitting evenly on the gasket. Or maybe the newer gaskets are thinner? Very odd - I suspect the odd one is either the original (circa 66) or from a 1600. But aren't the valve train setups the same?

[Hans]

Has anybody run across this? Weird thing is that it worked for years with no leaking. This time the cover compresses the front of the sprayer bar and with fresh gasket, just sits evenly. But I'm not sure it will tighten enough to seal. I also wonder if everything else under there clears.

 

Another question: any reason why cover won't function of square plate is missing under "PVC" outlet?

[Conserv]

The smooth valve covers don’t generally have a casting date.  Their use peters out some time around ‘67.  Just about every ribbed valve cover, however, seems to have a casting date. I, too, would suspect a ribbed valve cover without a casting date of being a very early example, probably ‘67-ish, from the era that didn’t expect casting dates on valve covers.

 

I’m still surprised at what you discovered.  The E21 head was developed in 1975. If your valve cover dates to 1967 or so, it’s possible that subtle changes over time account for this odd mis-match.

 

I would guess that the square plate under the PCV valve is intended to prevent fresh oil — flying around under the valve cover — from being pumped out the PCV exhaust nipple. So are the small rivets that hold the plate simply missing?

 

Regards,

 

Steve

 

Edited August 5, 2018 by Conserv

[Hans]

2 hours ago, Conserv said:

The smooth valve covers don’t generally have a casting date.  Their use peters out some time around ‘67.  Just about every ribbed valve cover, however, seems to have a casting date. I, too, would suspect a ribbed valve cover without a casting date of being a very early example, probably ‘67-ish, from the era that didn’t expect casting dates on valve covers.

 

I’m still surprised at what you discovered.  The E21 head was developed in 1975. If your valve cover dates to 1967 or so, it’s possible that subtle changes over time account for this odd mis-match.

 

I would guess that the square plate under the PCV valve is intended to prevent fresh oil — flying around under the valve cover — from being pumped out the PCV exhaust nipple. So are the small rivets that hold the plate simply missing?

 

Regards,

 

Steve

 

To be clear , the odd valve cover with no date stamp is not happy on my latest 121 head. I used it for years on another 121 head without leaks. Maybe because the front cover was a titch high. Now it leaks because it is sitting on the sprayer bar at the front. With a fresh gasket it looks to be seated evenly but apparently not enough to prevent leaks at the front. I have several spare heads, but only E21 has all valve gear so I can see where it hits the tube at the front. The back seems to be OK. One of my spare valve covers is missing the square plate, so I'm wondering if I can use it temporarily until I can clean up and refinish a suitable replacement with the lower ribs. I'd be tempted to grind out some reliefs in the odd one but there is a big button of metal. I've been working on these motors for over 40 years and never ran across this before.

[Hans]

PS, it is a ribbed cover. Looks identical from outside, but inside cast ribs are higher.

[Conserv]

Oh. I misunderstood. The odd valve cover won’t even work on a 121 head!  I’m clue-less, unless there is possibly a subtle difference between 1.6 and 2.0-liter valve trains and the valve cover was intended only for a 118 head....

 

I’d guess temporarily using the cover missing the square plate under the PCV valve shouldn’t be too much of a problem.

 

Regards,

 

Steve

 

 

 

[jgerock]

Hans - are you sure the valve cover nuts are compressing the cover and gasket enough to seal?

 

I re-used old valve cover nuts (the dome type) on my 72tii engine and it leaked like crazy from the lower gasket areas.  The leakage went away when I substituted standard hex nuts (and recently I replaced the hex nuts with new BMW dome nuts with the integral washer).

[Hans]

3 hours ago, jgerock said:

Hans - are you sure the valve cover nuts are compressing the cover and gasket enough to seal?

 

I re-used old valve cover nuts (the dome type) on my 72tii engine and it leaked like crazy from the lower gasket areas.  The leakage went away when I substituted standard hex nuts (and recently I replaced the hex nuts with new BMW dome nuts with the integral washer).

When I put the odd cover on the top of the head without a gasket, it rocks back and forth on the oil sprayer bar at the front. Even pushing on it to compress the sprayer, there is a slight gap on each side of maybe 1/16th. Back seems to sit flat. Adding the gasket fills that gap, and the reason I'd never noticed this is because I always installed the gasket first. What caught my attention this time was oil film on the front cover, underside of hood and the fan blades when I got back from Ofest. So it had been getting out at the front. I had torqued to 6 ft lbs with regular nuts, but now I realize I was prob torquing down on the sprayer bar instead of fully compressing the gasket at the front. When I put the odd cover beside any of my spares, I can see the difference in rib height. What I find puzzling is how this cover would have functioned before - unless gaskets were thicker in the old days. What's frustrating is I had painted and polished the odd one. Do you suppose I could run two gaskets?

['76mintgrün'02]

Perhaps you could relieve the rib to gain clearance?

(just grind back the part that is touching)