cylinder head imperfection (pics). Would you use it?

[zaq123]

Ok I had some traces of coolant under the valve cover in the are of cylinder 6 and 5. So my first thought was cracked head so I took off the head for some testing. Head was never pressure tested by the shop who did the head work apparently. I'm about to test it myself with 60 psi, still building some adapters for the air fitting.
Obviously the pressure test should show what is happening. But based on the head imperfection location, I suspect that I could have had just coolant leak from HG into the nearest head bolt hole. Which sipped some coolant under the valve cover. I actually sort of reused HG twice: I swapped the cam mid build and had to loosen head bolts a little to get the cam out. Was thinking that it would be ok before HG was heat cycled, which was fine as far as the combustion sealing was.

Look at the location of the missing aluminium and corresponding area/print in HG. It's located where it's just touching black line on the gasket. Is there enough aluminium to seal? i didn't have any sign of leaks between the head and the block in that area. Also the system/ head/block assembly was holding vacuum just fine (when cold).
Let's say the head checks out for the pressure test (fingers crossed)....would you used this head with this imperfection?







Regarding the pressure test. Do you all think 60 psi room temp test is OK for the test or should I boil the water in the tub for that 212-210 F test? My test setup (still looking for 2 old head bolts haha)

[Northern]

I have seen people with the old Rover 4.0 engines have to warm the block up in order to find cracks at 60PSI, but that's a crack behind a cylinder sleeve.

I don't know much about the M20 head other than the usual crack 5-6 under the cam, and any valve-spark plug. I'd personally just visually inspect for those, but if you already have a setup, I'd probably go to 60 and see what happens.

[TobyB]

That's totally fine if it pressure tests ok.

I've used M10 heads with far more corrosion than that, and they sealed ok.
Even with Reinz gaskets...

t

[McGyver]

You still have roughly 75% of the face width to seal, and you're only sealing coolant pressure there, not combustion gasses. It's not ideal, and you may be able to clean it up by skimming more off the head, but I doubt it'll cause you any problems.

[zaq123]

You still have roughly 75% of the face width to seal, and you're only sealing coolant pressure there, not combustion gasses. It's not ideal, and you may be able to clean it up by skimming more off the head, but I doubt it'll cause you any problems.

I had leak down test done when the engine was assembled and also tested coolant for combustion gases... all good there. Since I saw traces of coolant under the valve cover I automatically assumed cracked head and took it off. Freshly rebuilt head, 1000 km on it. But after seeing the corosion, I suspected that it was the issue with a combination of me reusing (sort of reusing) HG when I swapped the cam. So I just want to test this head...just in case. Honestly I'm not even sure if it is a corosion or some casting imperfection and BMW was like "good enough, use it". It's the only spot with it and its sort of the same finish as not machined casting on the rest of the head

[digger]

Based on gasket pics it doesn’t appear to be leaking to the head bolt hole. You probably would have seen on the bolt when you removed it.

Was under the valve cover meaning signs of milkshake ? Sure it wasn’t just condensation?

you could add thin film of some goop to the cast area that didn’t clean up to get full seal coverage

[zaq123]

Based on gasket pics it doesn’t appear to be leaking to the head bolt hole. You probably would have seen on the bolt when you removed it.

Was under the valve cover meaning signs of milkshake ? Sure it wasn’t just condensation?

you could add thin film of some goop to the cast area that didn’t clean up to get full seal coverage

it wasn't never a milkshake. Just blue coolant sitting on top of the oil in cylinder 6 and cylinder 5 EX valve cavities (in the head, under the valve cover) It wasn't a lot but it was a consistent leak from somewhere.

[zaq123]

also just an update.. casting is bubbling soap in the area cyl 5 IN valve seat .. No visible cracks in that area but the air is leaking what appears to from the raised ridge leading to cam journal. Like 3 spots with pinhole leaks.

[zaq123]

won't let me edit the post. Meant not say not the valve seat but the valve spring seat