Cylinder head pits in head gasket mating surface

I took the head off to r/r the head gasket due to it pressurizing the coolant system. I've found small pits in the head gasket mating surface around the cylinder bore on section of one cylinder. They are not large enough to catch a finger nail on. Are these a problem?

I also did something that is potentially stupid. I took a fine wire wheel on a drill to clean up the carbon and gasket on cylinder head. I only thought about it after the deed was done.

I used a razor on the block. I still see stains, but no gasket material is left. How clean does it have to be? (I think I've read a thread where rotarykid just lifts the head and slips in the gasket to save on disassembly work.)

Avoiding the longer down time and expense of getting a the head decked and rebuilt is the goal. I have ARP head studs, so if I need to do this again, I'm ok with that. Unless it is really stupid to put this back together and see if it'll run, that is what I would like to do. So is it really stupid?

To clean the cylinder head (gasket surface) I use a (lye free) oven-clean and a tooth brush.
Remove the glow plugs and the fuel injectors.
Spray the head gasket surface with the oven-cleaner and let sit for approx. 5 mimutes and then use the tooth brush to work the cleaner. Wipe the head surface with a rag and then re-apply the oven-cleaner and repete the cleaning process untill your satisified. Then flush / rince the cylinder head in pleanty of water.
I've had good results with this cleaning method.

Here's where your going to get a number of opinions.

As you have already guessed, the wire wheel is less than ideal - would not use on on aluminum. For gaskets, a little staining is fine (at least it has been in my experience), for the pitting, depends on where and how big the pits are - can you get a picture?

I generally clean heads and blocks with a safety razor blade, angled square and near perpendicular to the surface being cleaned. never had a problem with gouging that way, and I have never had a HG come back for leaking afterward.

I have made MacGuyver repairs on pitted surfaces before using JBweld, and as long as the surface was prepped and flush with the surrounding metal, it has not leaked. I have not had to do this in the fire-ring sealing area though.

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I use G12 (now g13) but the junkyard engine I put in looks to be rusting in the coolant passages from previous mistreatment. I'll have to flush it I suppose.

We use these plastic discs at work that aren't too abrasive but work well. i'm trying to find them on the internet now.
Use this: http://www.oreillyauto.com/site/c/d..._MMM_-1_-1&mn=3M(R)&mc=MMM&pt=N2022&ppt=C1954
or this...
http://www.oreillyauto.com/site/c/d..._MMM_-1_-1&mn=3M(R)&mc=MMM&pt=N2022&ppt=C1954
Just use your head and don't remove too much metal while cleaning.

$200G's said:

We use these plastic discs at work that aren't too abrasive but work well. i'm trying to find them on the internet now.
Use this: http://www.oreillyauto.com/site/c/detail/MMM0/07527/N2022.oap?ck=Search_N2022_MMM_-1_-1&mn=3M%28R%29&mc=MMM&pt=N2022&ppt=C1954
or this...
http://www.oreillyauto.com/site/c/d..._MMM_-1_-1&mn=3M(R)&mc=MMM&pt=N2022&ppt=C1954
Just use your head and don't remove too much metal while cleaning.

Click to expand...

I have concerns with my judgement. This is my first head gasket install. In my block photos, do I need to remove the stains, or is what I have pretty close to good? (It needs a wiped down with acetone yet at a minimum.) On the cylinder head, the place where the old gasket sealed has little pits or nicks. Is that ok? Does the judgement of "if it doesn't catch the fingernail, it is clean enough," still apply to these head gaskets? That is the rule I follow for prepping for installing other types of gasket installs.

I have read that GM released a TSB stating that they would not warranty bottom end bearing failures if an abrasive product like a roloc or scotch brite was used to prepare the gasket areas in a head gasket replacement. So I'm a little skiddish to use them. I suppose if I block the passages and cylinder bores, try to clean up real well and change the oil before running, I should hopefully be ok.

I'm trying to learn good judgement before having a bad experience, for a change.

Thanks!

Scotchbrite pads (I have a steady supply on hand) are a mixed blessing.

New, they can clean quite well, but can also gouge aluminum - I tend to do aluminum heads by hand. If the gasket material on the iron block is caked, I sometimes use a scothbrite disc carefully to remove the debris, being careful not to aim the rotation of the disc so that any grindings go off the edge, and not into the cylinder bore.

Again, as above, I use a safety blade, and carefully scrape with the blade perpendicular to the surface - like shaving.

If that were my engine, I would get the head decked - every cylinder has that pitted ring, and you are just looking to have it leak and pressurize again if you leave it.

I would clean the block a little better as well.

That doesn't appear to be pitting, that looks like carbon buildup.

Windex-Thanks for the advice. The method you describe of using a safety blade is how I have been cleaning the block surface. I guess I have more razor dragging to do.

2many diesels- Yes, there is carbon buildup around the valves on the cylinder head. If you look closely you'll also see a ring where the head gasket sealed the cylinder bore. That ring appears to be small pits/nicks to me. That is the area I'm unsure about.

MLS head gaskets need a super smooth finish. I would have that head rebuilt and resurfaced myself. The very first part of a VAG engine that wears out is the valve guides anyways... and you already have the head off....

I use a wet vac to help keep carbon and particles out of the engine parts. Those pits look like they are in the carbon build up. It still looks like there is plenty of sealing surface though. I would check the head with a machined straight edge and feeler gauge. It's in the Bently manual.

Good point Yakko. I haven't checked to see if it is warped yet. That would settle the debate in my mind to put it back on or not. Where does one source a decent machined straight edge that is good enough to do the check? I'm guessing a carpenter's square isn't going to cut it.

I have one from Snap on. I have found little dips on the head. Most of the time they are not in a critical sealing area. No a carpenters square isn't it. I bought mine back in the 80's. I just stopped by a snap on truck and asked if he had one. I just lucked out. A local machine shop should have one.

I took the gamble and cleaned up the block a bit more with a brass brush and put it back together with the head as is. So far things are ok. I took it for a few heavy boosting test drives and so far the hoses don't get hard like they did before. After I finally got the air purged out of the system, it doesn't appear to be drinking coolant anymore either.

I suppose I should strip down my spare head and get it rebuilt so when this head gasket fails I'll be ready to do the job right next time.

Please post back in a few months if everything is OK, or if the unfortunate happens and it starts leaking again.

Will do.

It is going to get a good stress test within a month. A 2500 mile road trip in 4 days with about 700 lbs. in the car and a 2000 lb trailer load.

The TDI heads seem more robust when it comes to warping. The older IDI turbo
engines had head gasket leaks after 150,000 miles or so. i think it was due to the higher compression ratio. I replaced plenty of bad IDI head gaskets. I don't think many of the dealers were re-torquing the heads at 750 mile break in. My brother marked the valve cover nuts on his IDI diesel and they never did his. So we did it. Oh well, I don't have any faith in U.S. dealers. They have to be monitored.