Finally pulled the head...m30 pr0n

[marshallnoise]

Cross posting this from my build thread:

As you can see, I got the head pulled apart. First off, there was a lot of oil/coolant mixture in cylinders 3, 4 & 5. I couldn't tell if it is was from me pulling head or not, but it looked well mixed. However, I drained the oil just before and other than looking dirty, it had no coolant in it.

There was a lot of corrosion though and general nastiness as you can see. This is only the second time I pulled a head off an engine and the first time was my wife's MKIV Jetta to do a head gasket. It did not look as bad as this one.

Anyone have any insights and what I am looking at? The compression test numbers were in the 90s on the middle 4 and 150 on the outer ones. The leak-down test had similar results, but the air sounded like it was rushing out the exhaust valves. Raul's friend chatted with me and he said it is common for the middle of the head's exhaust valves to get hot and stop sealing. I will eventually test the sealing of the valves physically by pouring gas in each of the closed combustion chambers. I will also attempt to see how warped the head is with a straight edge and a feeler gauge.

Thoughts? Comments?

Edit: Oh, the cross hatching on the cylinder walls are in great shape. Pistons are in good shape too from what I can tell. I will probably pull the pan and take a look at the underside of the motor. But first, I will have to change one position of the mounting points on my stand. Cause I am a retard.

[lobster rodeo]

What's the mileage on it?

[ttrousdell]

Sounds like it overheated.

[marshallnoise]

Mileage was 177k. I am sure it over heated as the previous owners of the 735iL were a retarded teenage couple. It had a hole in the radiator.

Next step is to test how well the valves are sealing in the chambers. If they do, then check the straightness of the head. The gasket looked ok to me. No obvious blow outs.

If I am lucky, then it was just an overheat that disrupted the head gasket seal enough to lose compression.

[bastianshaw]

Mileage was 177k. I am sure it over heated as the previous owners of the 735iL were a retarded teenage couple. It had a hole in the radiator.

Next step is to test how well the valves are sealing in the chambers. If they do, then check the straightness of the head. The gasket looked ok to me. No obvious blow outs.

If I am lucky, then it was just an overheat that disrupted the head gasket seal enough to lose compression.

[marshallnoise]

Haha for sure.

I forgot to update this thread. I filled the chambers individually and 1 and 6 are tight as a drum. The other 4 are leaking from the exhaust port. Raul's friend Frank is right. Exhaust ports got hot first. I am going to try and pull another head from the junk yard for $35 bucks complete and make one good one out of two. The head is stripped down though and there is definite warpage going on too.

[Jaxx_]

This might help you with regard to flatness:

http://www.mye28.com/viewtopic.php?t=122593

I pulled a head from a junkyard that was like .012 out, had overheated for sure. I wouldn't want to do more than .005" personally.

Inspect the cam for wear as well, it was an issue for two of the heads I pulled. Then again, an m30 is harder to kill than Detective John McClane.

[marshallnoise]

Great thread there. Thanks for that.

Here is a pic of the head with the cam and rockers out. The journals look good to me. And getting the rocker shafts out was easy.

[marshallnoise]

Went to the junkyard and bought another m30 head. To me this one looks much better. The motor I pulled it from had nice green antifreeze and less corrosion everywhere. Didn't get to do a compression test on it or check it for level. But I have a good feeling. Will take better pics later.

[marshallnoise]

The junkyard proved to be fruitful! I have a good head for $45 bucks!!! 91% Isopropyl Alcohol in the combustion chambers never leaked a drop.

Now the chambers are filled with Dawn detergent. Should clean right up. Yayzorz!!!