Cylinder surface corrosion/head gasket surface preperation

I have been in the process of replacing the head on my ALH after a broken timing belt and life has of course gotten in the way of completing it quickly. I have had the head off for about 3 or 4 weeks and after a discussion with a customer at Oriellys I have become worried about the surfaces becoming corroded after being exposed to the air. Is this a valid possibility? If so how should I prep the cylinder walls before putting the new head on?

I am also in the process of figuring out how to clean the carbon deposits of the piston heads and the surface of the block for the head gasket. The block surface does not have carbon deposits but there is a bit of build up. Both are minimal but there. I have used seafoam to clean the intake manifold, is this a valid product to use for this? Is there something else better that I should order?

Any and all suggestions are appreciated.

Morning cofee bump. Any Ideas/suggestions? I have searched for several different combos of keywords and came up short. Closest I got was to use a wire brush.

Green Scotchbright pads work well for the head gasket surfaces.

Is there corrosion on the cylinder walls? It sounds like you haven't checked yet.

As for the cylinders, wipe out the ones with the most exposure to the air with a paper towel dampened with WD-40 or similar. Then rotate the engine so all pistons are at about the same level in the block (half way up/down). Then clean the other two cylinders the same way. Your cylinder walls will be just fine!

Block top surface: place rags, paper towels, etc., in each cylinder. Put anything that you can retrieve easy in the water jacket holes, bolt holes, etc. Now, scrape off the cylinder block top using a putty knife, pocket knife, etc., and maybe even use some 600 sand paper to finish off. You can use a shop vacuum to sort of clean up as you go........compressed air to blow off debris.

Top of pistons: I'd rotate the crankshaft for two pistons on top.......use a brush on a drill to knock off the deposits. You need to use the shop vacuum to suck out anything that falls around the edges of the piston (between cylinder and piston). Then, with compressed air blow out the rest............ I would not shoot for nice shiny pistons on top .......waste of time!

I've never used seafoam. I dump in el-cheapo Awesome full strenght and let soak for a couple of days! You should follow-up with a pressure wash if possible.

Hope this helps!

I had gotten some ultrafine steel wool pads from the autoparts store. Thats all the green ones are right is steel wool? Or is there a solvent/soap on them like the pink ones. My plan was to put a little seafoam on the steel wool pad, scrub-a-dub and see how things look afterwards.
[edit] I found this website with some pictures. http://www.google.com/url?q=http://...RiXAPg&usg=AFQjCNFA9wISDPSajtCr0j_6cXter-Lkhg Are you talking about the No. 96 pads? I tend to way over-think things, engineering habbit. I was someone worried about messing up any surface coatings they may use on the pistons/cylinder walls[/edit]
I havent looked in the past few days. The cylinder walls seemed okay a week ago when I was looking at the piston heads. My main problem is beyond tangible 'rust' I wouldnt know what to look for even if they were coroded. Could you describe to me what surface corosion on the cylinder walls would look like? Or even better, know where there might be some images of a corroded wall on the net?
My instinct would tell me that it weould just feel rough. If its rough and not smooth, its corroded. And if it is coroded , scrub it with steel wool, wipe it out with a rag with some seafoam on it. BOOM done. That said, my instincts are also responsible for alot of bad decisions.
I finally found someone to let me use their parts washer to clean the intake manifold so I should be able to get some work done on it tonight if I can get some answers.

You are overthinking the cylinder wall thing. If the car sits for a month with the engine assembled, there will be cylinders that are exposed to air. Do as Andy mentioned and get it back together and be happy.

Just for when anyone else comes looking I found more detailed information on the scouring pads by 3M. As usual Mcmastercarr goes above and beyond for those worrysome/curious types (like me). It looks like the No. 96 pads are made exactly for cleaning corrosion off metallic surfaces, cylinder walls and piston heads for example. However I have read that the 7447 pads are used to finishes on Titanium bike frames. I guess I will try both. Thous it seems like they may be slightly too abrasive.
Mcmaster site: http://www.mcmaster.com/#3m-scotchbrite-abrasive-pads/=gcg497
grangier site: http://www.grainger.com/Grainger/sp...rZ1z13b3xZ1z0r597?Pid=search&fromViewAll=true
a pdf describing the different products from 3M: http://www.google.com/url?q=http://...TQcB7Q&usg=AFQjCNHrcPc3A52BTobDI9OnKE_4u_wdTA
site citing the 7447 pads use for Ti frames:http://www.bikeforums.net/archive/index.php/t-685309.html
I couldnt find a good description of the diferences between the No.96 and the No. 86 pads in the pdf. I was looking for "grit" description or "hardness" but I guess thats too picky.

Just use the green pads.

@Andybees
Thats exactly what I was looking for, thanks for the advice. I dont have compressed air, but I do have a shopvac. Its amazing how hard the simplest things are the first time.

@whitedog
It has sat for a month with the head off while I have been procrastiniating, that why I was asking. I figured it's been long enough to worry about but I think Andybees suggestions will take care of everything.

And wheres the fun in just taking someones word for it? In all seriousness they have alot of "green pads" it didnt take long to figure out which ones you were talking about but I thought I wouldd document my internet adventure anyway.

Along those lines, for those in need all the 3M products are available at lowes or home depot in the paint isle apparently.

Steel wool

There should be steel wool on the shelves in paint stores, automotive stores without soap in it. It is used for doing fine work with bondo, etc., prior to painting (not just washing dishes). Les Stroud (Survivorman) surely hasn't bought them all up for starting fires .........LOL.

My guess, if you never done anything to the cylinders or the pistons, they will be just fine.

Cleaning the block surface for the head gasket is #1. Number #2, being careful to not get any debris in the water jacket, oil drain-back holes, bolt holes and .......very important, the one oil hole from the oil gallery of the block.........look on the old head gasket to find that hole. It will have a rubber type material around it just for the purpose of sealing extra good! That oil hole provides lubrication for the head ....lifters, cam journals, etc.

Finally got around to taking pictures. Whitedog, do you see anything I should be worried about?
Block surface

Cylinder 4

Cylinder 3

Cylinder 2

Cylinder 1

Cylinder wall

Bonus shot of cylinder 4

This concludes my first photo post... please hold your applause.

Pistons and bores look fine via the interwebs. Now it's time to go after that gasket surface.

The deck needs to be cleaned. Green pads and razor blades should do it.

Looks like the cylinders could benefit from a light honing. " ball of grapes" style hone with lots of wd-40.

Just my quick 2cents


Also you were leaking coolant and used water. In rust we trust. Clean up as best you can

Be careful using green pads. They are impregnated with silicon carbide, on heck of a strong abrasive. You don't want that between pistons and bores.

andybees had mentioned using something easy to retrive from the jacket holes to prevent gunk getting in, I cant think of anything. Any suggestions? Maybe cotton balls?

I also appear to have knocked some stuff into the holes getting the head off, I can see some debris if I use a flashlight. I was going to try and suck it out using a shop vac unless someone has a better idea.

The fluid in the jackets looks cloudy, is that normal?

@btcost
Could you expand on your "ball of grapes" method? Ad what makes you say that about the coolant and water?

@ski
So just be careful not the leave any behind is what you are getting at?

Check out the other thread I made here if you want to help me figure out how this all happened.

http://forums.tdiclub.com/showthread.php?p=3711985#post3711985

I'm trying to keep separate threads for related questions/topics.

There are two popular tools used to hone out cylinder walls, one of which is refered to as a "ball/bunch of grapes" because that is what it looks like. You attach it to a drill and run it up and down the cylinder wall to attain a nice "cross hatch" pattern. Said pattern helps the piston rings do their job better.

In your case that extra work may not be needed.

I mentioned the water because I saw what looked like rust in your water jacket.

These motors are very sensitive to the type of coolant used, if the motor always had the proper VW G-12 coolant, even after 300+ thousand miles. . . no rust. . .not a spec.

But run water or auto part store green coolant in there, and bam!!! rust city, almost right away. What is MORE sensitive is the head (because its made of aluminum) look into the "goose neck" below the vacuum pump. I bet yours is brown or mis colored. another sign of the "wrong" coolant.

I know it may seem like a PITA to buy the right coolant, but do it. your engine will thank you.

I have had the car since new and had the car serviced at the dealer for the first 100k and always used G12 myself after the warranty expired. Is there anything else that could be causing the discoloration? I noticed that the fluid in the jackets seemed cloudy, however all of the fluid that I drained out is clear as a bell. Perhaps its from sitting for a few week exposed?

Must just be the exposure from the past few weeks.

Enjoy putting it back together. It's very satisfying.

Keep oil on the mating surfaces until you are ready to put the HG on and head. You will need to get all the black flaky residue off around the cylinder seal area, thats either carbon or leftover gasket seal from the old HG. True on the green pads, and the razor blades, be very careful with razor blades as they can easily scar the surface.
I would just use some elbow grease and some pb blaster or similar detergent/degreaser/cleaner type of liquid with a rag that won't fray or fall apart.

When all is clean and ready for instal, grab a few cans of brake clean, clean the pistons/walls etc and both mating surfaces and let it dry quick, stab the head on and torque it.

You should use two of the old head studs for guide pins, as the ALH is not easily put on with aftermarket HG's. The HG hole isn't big enough for the sleeves still inside the block, pull them out and use the studs for a guide, slot them at the top to extract with a magnet/screwdriver when you get other studs back in.

TDI_bubble said:

Keep oil on the mating surfaces until you are ready to put the HG on and head. You will need to get all the black flaky residue off around the cylinder seal area, thats either carbon or leftover gasket seal from the old HG. True on the green pads, and the razor blades, be very careful with razor blades as they can easily scar the surface.
I would just use some elbow grease and some pb blaster or similar detergent/degreaser/cleaner type of liquid with a rag that won't fray or fall apart.

When all is clean and ready for instal, grab a few cans of brake clean, clean the pistons/walls etc and both mating surfaces and let it dry quick, stab the head on and torque it.

You should use two of the old head studs for guide pins, as the ALH is not easily put on with aftermarket HG's. The HG hole isn't big enough for the sleeves still inside the block, pull them out and use the studs for a guide, slot them at the top to extract with a magnet/screwdriver when you get other studs back in.

Click to expand...

Since I got the ARP studs which are threaded on either side I was going to put two of them into the block to use as guides, I dont have anything to grind the old ones down with. I'm a little unclear as to why you need guides, and how to use them If I do.

What is this about the sleeves? You mean the two silver things on the firewall side of the block? I was wondering why I need the guides at all as the sleeves line everything up, but if I have to take those out... how do I do it?

Nevermind... you just pull them out.

Ski in NC said:

Be careful using green pads. They are impregnated with silicon carbide, on heck of a strong abrasive. You don't want that between pistons and bores.

Click to expand...

I was thinking the same thing. I wouldn't use green pads unless the block was disassembled. Gasket remover and a flat edge tool softer than the surface you're trying to clean should be all you need.

Im not cleaning the head, and the block is iron right? is it really that prone to scarring? I was going to lower the piston to BDC, clean the walls with wd40 and the pads, bring the piston to TDC, clean it. use brake clenaer to dry it all out and then put the gasket on.

Guys I am not a mechanic by trade, but I have done and helped do, a good number of head removal/replacements.

It's all about using common sense. Simple tools, elbow grease, precautions about dropping debris into holes (oil drain holes, stud holes, water jack holes, etc.).

I've used my pocket knife, putty knife, etc., to scrap the block. The cast iron block will not be damaged by using them .....just don't pound them with a hammer.

I use bits of paper towels to plug holes. Walmart el-cheapo Carb cleaner works good to loosen up stubborn spots. Blowing out the bolt holes with compressed air is really important.

I cannot imagine why you would hone the cylinders? You didn't install new rings......so, there is no need to hone the cylinders. Where is all that crap going to go?......right down between the pistons and cylinder walls.

Clean up the top of the block.........that's straight forward.

Wipe out the cylinders with a cotton rag soaked/coated with WD-40 (paper towels will work). That's all they need!

You should clean the head surface. Water, Dawn, 1500 sand paper, and Carb cleaner. Use the sand paper with the Dawn and water very lightly........... I've done numerous 1.5 and 1.6 heads with no blown gaskets later. It's pretty obvious you should remove the Cam and lifters to clean the head. Just make sure the lifters go back in the same holes. Admittedly, I have only done three ALH TDI heads. Cleaned all three of them using this method. All of them are out on the road putting miles on the odometer with no problems.

You probably need to flush out the cloudy fluid in the water jackets. Just remove the Coolant flange where the T-stat is located. That should allow enough drainage to do the flushing. Assuming the cloudy stuff is a rusty water/coolant mixture, I suppose the other lines as well as the rad need flushed too. You probably will not get it all ..........but, 100k miles from now, you will not know the difference. When finished, fill it up with the correct coolant.

I do agree with one poster's comment/statement/question. Why did the head gasket blow? That needs to be determined and address the problem. My apology if I over looked that explanation.

Head gasket didn't blow, timing belt broke. Were most of the way done now, I will update later but thanks for all the help!

I use 3M roloc in my air drill to clean block surface. Very effective.

I thought I would wrap this up with some pictures. I ended up using the green 3M scouring pads (see previous disussion) and seafoam to prep the block surface, it worked really well. DO NOT use it on the cylinder walls, it removes the crosshatching that helps the rings seal. I ended up leaving the cylinder walls as-is since mine were pretty clean. The part that I scrubbed off of cylinders 1 and 4 luckily is above the max height of the rings as far as i can tell so i dont think I will have any issues.

Before I started, I plugged up all the oil channels and cylinder jacket holes with shop towels. When removing them I used a shop vac to suck up any debris that had collected, just place the vacuum close to the hole and use tweezers to pull it out and into the suction. (There are before pictures earlier in the thread...)

Thanks for all the help ya'll!