qmikep

I'm currently replacing the head gasket on my truck. It's my first time doing a head gasket so I wanted to seek the advice of those who have experience on a couple of things; as I definitely want to make sure its done right and I don't damage anything.

After I got the head off I took it to a a machine shop to have it cleaned and checked for cracks ,flatness etc.

Upon inspecting the deck of the block I noticed a few things that caused me concern.

The first is what appears to be light scoring in cylinder # 3. I've had the truck for 6 years and do oil analysis regularly and everything is always good also have very little blow by. I can't feel it with my finger nail. What do you guys think?

The next thing is I have what appears to be a pretty heavy carbon or soot build up on the ridge of the cylinders and on the pistons(I'll attach pictures). Does this look abnormal or bad? What is the best way to clean this build up?

Could anybody give me advice on cleaning the deck of the block up? I searched and found most folks use razors to scrape and brake clean and green scrub pads. Bu then I saw a few posts that said never use the scotch bite type pads as the fibers are hard to get rid off and can cause bearing issues.

Any insight is appreciated.

qmikep

Another picture

qmikep

Cylinder scoring

Angry Johnny

Personally I wouldn't worry about it. I use the scotchbrite pads (by hand only) if I'm taking the entire engine apart and it will be thoroughly cleaned, otherwise just razor blades. Never, ever use a roloc disc on a die grinder. The fibers go everywhere and you can actually remove some metal from the deck creating a surface that will never seal without machining.

nascar mark

For the blocks deck in frame, the correct way to clean is to pull dowels & with a flat stone (type you would sharpen a chisel with) work the block in long strokes with the course side 1st for approx 20 mins, then with fine side of stone for another 20 mins or so. If you can’t find a new stone, then you can use a perfectly flat piece of hardwood block (chunk of steel works too) & some 120 grit, then move on to some 400 to finish up. Chase all threads, vacuum out all area’s after & clean with brake cleaner. Re-install new dowels & your good to go.

NJTman

according to this guy, you need to contact the manufacturer of the engine to find out what the spec is for the block surface conditioning.

Resurfacing Cylinder Heads & Blocks? Mistakes to Avoid

Granted, that is for way out crazy super heavy duty engines, but I figured I'd throw it out there.

I've replaced a few heads, rebuilt a few engines in the past. Never went crazy as that guy, and they still ran for as long as I owned them.

edwinsmith

I always clean off the old gasket and sealer and check the block and head for flatness. The headbolt torque is most important IMHO. I've done several small V-8s and a 6 cylinder Binder but never done a Cummins. The V-8s were a steel shim type and the IH was a fiber-metal gasket. Come to think of it I've done a couple of Ford V-8s and a 6-banger also. Never had one leak.

Sanding the block sounds risky as you might get abrasive dust in the rings but like Mark said you clean that out well with brake cleaner.

Edwin

Angry Johnny

That method that Mark mentioned is great if the engine is coming apart. I too would not risk getting any of the left over abrasive left in the cylinder. It's really tight between the piston and cylinder wall and very difficult to get it all cleaned out for sure. Left over abrasive is going to do more damage than any benefit you would get as long as the deck and head surfaces are flat and clean.

NJTman

Wow, I guess I'm the only one one who stuffs the cylinders and open passages with old towels, then blue duct tape,the inner walls so that the debris doesn't get in The cylinders. I use a shop vac while cleaning to collect debris.

Oh well, I guess I'm just a wack-a-doodle.

Angry Johnny

If I had to do something like that then yeah, I would tape it up too. I've done that on cylinder heads before because I didn't want to take them back off. Being a flat rate tech all my life I'm all about not making more work for myself, so most times I'm not doing that.

nascar mark

No, that’s why I mentioned vacuuming everything out good. Can also hit it with shop air but only after vacuuming things out good. Yes, rags are your friend....figured that part would be a no brainer. No risk at all if you use your head. We did well over 100 head gasket jobs over the years when I was at PDR.

Ever wonder why the spec for a cyl head surfacing is almost mirror smooth....well anyone going to tell me a razor blade & scotch brite by hand is going to do anything on a cyl block? No wonder I see guys saying why did my head gasket blow again.
Come on guys, give your heads a shake & do it right the 1st time.

Angry Johnny

No problems here mark. I've been a tech for over 44 years and have done literally hundreds of engines with never a problem.

When I was in Vo-Tech school for auto mechanics I would only get B grades in auto class. One day I asked the teacher why I only got B's when all my class work was A's, all my tests and homework were A's and all my shop work was perfect.

He said, that's the problem. I said huh? He says all your work is perfect and when you go out in the field as a flat rate tech you will never make any money, you have to draw a line at what is a good job that will last and not worry about perfection.

I learned that lesson well. So although a beautiful shiny finish on the deck surface sure is nice, it's not a necessity that it be that way. If you can't feel it with your finger nail the gasket isn't going to either.

Now if the surface isn't flat it should be machined. Trying to do that by hand in my opinion is not a good method.

YMMV, so in the end do what works for you.

edwinsmith

Yes. I agree. The rags and tape to keep the dirt out are a good idea. The surface should be smooth but I think a slightly rough surface is better than a mirror finish. A rough surface has more area for sticktion than a mirror surface.

Edwin

NJTman

I believe that the surface finish is also based upon the type of material that is being mated.

Aluminum heads on a cast iron block, for example. I believe I read, some many moons ago, that the aluminum head will physically expand and contract significantly more than a cast head. This requires that the gasket be made accordingly, and allow for this microscopic "sliding back and forth" of the aluminum surface against the gasket, otherwise problems arise.

Don't build engines for a living, but I'm sure there is some criteria regarding.

I'll again, revert back to the website that discusses this here:

Head Gaskets and Fasteners - Engine Builder Magazine

edwinsmith

Anytime you have dissimilar metals, and Aluminum and Iron are good examples, mating under conditions of fluctuating temperatures you're going to have problems. Because aluminum expands to a greater extent than iron the aluminum can get distorted to a much greater degree and the design of these components should take this into account.

The Mazda with the Wankel Rotary engine suffered because the rotor shells were aluminum while the other pieces were iron. The 2 rotor shells were sandwiched between the iron end plates and when the engine was over heated the aluminum got crushed and then leaked badly when the engine cooled down.

I had one for a while and I had to take out the spark plugs every morning and crank out the water and dry the plugs off before I could start the engine. It ran great but it leaked water all of the time.

Edwin