Cleaning the deck on a block...

[inthedirt]

Just wondering what you boys use or do to clean the block when you pull a cylinder head? How clean is clean as far as sanding the deck? Do you use a scraper only or is it kosher to use a "cookie" and a die grinder (3M Roloc disc). I recently had to have a head gasket changed on a freshly built DT466 ('95 model) that had the gasket wrinkled and leaked coolant. After changing head gasket under warranty, the IH dealer sent it out without an oil change. Personaly I always change the oil and filter after running for a bit. Our shop seems divide on what we use to clean the deck. Also does your answer change if it is liner-ed or parent-bore?

 

[Randy88]

The die grinder and disc is quick and easy but it takes more than gasket material off, a mechanist friend of mine has always complained about the grinder method, he claims that most damage is from grinding off more than the gasket material and then the part needs to be remachined to spec. On cylinder heads I prefer to not use the grinder and disc method but a good scraper and knife blade instead but thats just me. I used to use the grinder quite often until I took in one of my parts to have plained back down so the gasket held, he showed me what damage had been done over the years from repeated use and I quit using a disc and grinder right then and there. I invested in an air gasket scraper a few years back along with a razor blade knife and those do the job now. Anything aluminum is really bad to use the quick method even a touch can sand off too much. Now if I have a thick and stubborn gasket I might still use it thin off the gasket but when I get close to the metal I quit and use the scraper and knife method again. Its a good question and I'd like to hear from others on the subject.

 

[ScottAR]

Head gasket or other machined surfaces I only use a scraper and brass wool. It's not as fast, but like Randy said, you can remove more than the gasket without really trying. Aluminum is especially prone to damage. Stamped steel pieces I don't worry so much but a light touch with the discs is the rule. Always get your gasket surfaces white towel clean too. It really helps.

 

[GOINGBROKE]

Grinder with a wire wheel has always worked good for me. Agree roloc disks take too much off.

 

[John C.]

Haven't had to do one in awhile but I used the rubber finger disks put out by 3M. Local machinists put out the word years ago about the brillo pads so when these disks that were made or rubber came out I jumped on them.

I'll take a photo when I get the chance if I have any left.

 

[inthedirt]

I'm pretty sure I know what "fingered" discs you are talking about, but post a pic anyhow. The consensus so far pretty well lines up with what I have always been led to believe. The rolocs eat more metal than people realize, but I've also been warned about the flying abrasive debris that can get in coolant passages, and lifter bores. I was also led to believe that the discs with fingers have abrasive in them too, so on the abrasive side of things I wasn't sure if they are any better? See what you guys believe, but I was told that when you peel off a head gasket and sand it down, there comes a point where you can still see a "stain" where the gasket was but it doesn't even catch fingernail and is smooth. I was told its okay to leave this, but one guy in our shop isn't happy until he has sanded the deck with rolocs and the surface looks almost like a mirror (only with swirl marks). I have always felt this was too far and that it isn't necessary to eliminate the stains from the gasket left on the metal surface. What do you fellers say?

 

[inthedirt]

Taken from 3m's website (I'm not promoting or demoting them, they just make 'em)
"Disc is a molded, abrasive filled bristle disc instead of wire brushes for automotive use on aluminum and metal. Use for deburring, blending, finishing, polishing, cleaning and for coating, defect, scratch and rust removal."

 

[3rdGenDslWrench]

What I'll usually do is take rags and plug the lifter holes and the coolant jackets. Most of the time you can get the deck fairly clean with a razor scraper and a screwdriver for the heavy stuff. Any spots that are left I'll touch them up with 400 grit emory paper. I watched a mechanic I worked with take a roloc disc to the oil cooler base of a 320B ( Cat 3056 engine ). After the 3rd gasket in two weeks he wondered why it kept blowing the gaskets out of the cooler. Ray Charles could have seen where he got a little to trigger happy with the roloc. :Banghead

 

[fast_st]

3GDW has it right, plug all the passages with rags, a razor scraper or just a hand held razor blade on iron parts. A little easy-off oven cleaner will loosen gasket material in a big hurry, it'll also take paint off a block if you use too much (maybe not a great idea if you don't want to wash your top deck down with a wet rag or two when you're done) Taking time and being meticulous counts big time here, you want zero debris/gasket/cement left behind, just smooth clean steel. It takes very little to give you a leak. Sometimes a razor sharp wood chisel can be used for heavier stuff but make sure its free of any burrs

 

[RobVG]

I've used Loctite Chisel with mixed results. I've got to try the oven clean next time.

 

[Abscraperguy]

Spray bomb gasket stripper and razor scraper or if you want to be like the engine rebuilders build a varsol cooker. After a night in the cooker they are whistling clean. Everything's gone including the paint. My Dad's shop they also do a pass with a 320-400 grit DA sander to get the final polish and remove the minute burrs that might be there.

 

[Randy88]

Inthedirt, if you can't feel the gasket with your fingernail or a good razor blade knife, I'd ignore the visable look of a gasket there and don't do anything else with it and just move on, the stain left should not hinder the new gasket at all, remember the new gasket can't see the old stain but can feel if you'd cut some uneven excess metal out and leave a depression where it'll be prone to leak. I know of a lot of guys that can't accept the look of the stain and get carried away and when you cut and can see the swirl marks left by the disc or sanding pads its apparent they took off way too much, if you'd lay a straight edge on the flat surface and shine a light to see the spots that are cut too deep and let light under the straight edge you'd know its not level and a machined flat surface any longer. I've machined parts myself and know how to run the straight edge and also feeler guages and how to calculate how much material has been taken off and how much more needs to be machined off to get another flat service back on it.

Use the simple fingernail or razor blade test, its usually bullet proof unless you have a warped surface your dealing with to start with. I almost always lay a machinest straight edge over pieces to see how true and flat they are before reassembly, expecially if it'll take more than a few minutes to replace the gasket the second time around if it leaks but thats just me. Almost all machined surfaces have tollerances allowed before needing machining again, it depends on what and where they are and how used in the engine or component, the problem arises from die grinding with the discs is you never take the same amount off in any given area and in a few minutes you can take a perfectly acceptable surface within tollerance and turned it into one no gasket will keep sealed but it'll look nice and shiney with swirl marks and a excellant pollished mirror finish, just like it comes back from the machine shop with except, now its out of tollerance and the new gasket will never seal it up again.

The very best advice I was ever given was from a macinest one time and he told me this, "remember an engine can't see and gasket surfaces can't think, they only do one thing and thats seal, think of it like a making love to a woman with the lights out and use your fingers to determine the surface at hand not your eyes." I got quite a chuckle out it at the time but in the general gest of things maybe he was right. Before leaving he handed me a straight edge and told me to throw away my grinding discs and said if its smooth and level leave it alone, if not bring it in and I'll grind it so its right and ignore the look of it completely.

 

[John C.]

I'm with Randy88 about the straight edge. I've seen quite a few heads replaced where the liner protrusions and the flatness of the deck was never checked.

Basically the head should have never been reinstalled on a few motors I had to redo for other people. The gaskets were leaking not because the previous work cleaned to deep, it was because the liners had sunk or the head bolt holes were not cleaned out or they reused the old head bolts or the deck was no longer flat anyway and so on so forth. I usually sanded the dark spots on the deck down to make sure there were no steps to hold up a straight edge. That was usually good enough.

It basically comes down to the mechanic being able to make all the necessary checks before reassembling the engine. He also has to communicate to the machine owner what has to be done and give the owner options of how far to take the repair. It's really not rocket science, it just seems like it at times.

 

[Greatwestcam]

I have been to both Cat and Cummins failure analysis coarses and they both say to NOT use power tools to clean block deck or heads. Use the razor scraper and if futher cleaning is required use the maroon coloured scotch brite pads and clean by hand. Cat showed some pics of block decks "over done" by roloc disc that damaged the area where the liner flange sits that required counter bore cutting/shims to repair. said that no matter how careful you are, it will deform the edge and cause liner flange breakage. Cummins goes on saying that the particle that come off the roloc disc are very harmful in that they are not always cleaned from every passage, and these bits are hard and damaging. Have seen several engines come in that were "just rebuilt" and shortly after have major failure, usualy spun #4 or #5 main bearing from being first one getting oil supply. Sounds like several of you guys have seen issues from power cleaning and the damage that can be done. Good old manual labour gets it done, and doesn't take that much longer. good thread and great input here!

 

[Justin]

To me the problem lies in that to many people get in to big of a hurry to get to the next job and the reloc discs help them get to the next job faster. I know in an automotive shop that pays on flat rate does not help with cleaning gaskett surfaces correctly. So if you can cut a corner and put more money in your pockett most people will. I did until it bit me in the a*#, and had to replace a aluminum intake becase I got to grind happy with a reloc disc. They do have a place and it is for non tolerance fit surfaces. I agree with Greatwestcam good old manual labor will get it done.

 

[sh0rtlife]

once your done getting it all off wipe it down with brake clean or laqure thinner till the rag comes off clean...most carb cleans leave behind a bit of oil residue

 

[fd30]

i agree with the manual way the 3m maroon pads and a razor scraper i see a power grinder near an engine block or head i"fire it out the door

 

[bobb]

i like to use good ol elbow grease and my favorite scrapers. add a vacum cleaner while doing it and its all good. liquid gasket removers and a small paintbrush work well on delicate aluminum that a sharp scraper can damage. i feel that any kind of method that creates dust will get the dust where i dont want it. sure, scraping creates dust too but i feel its minimal and the vacum will catch most of it. doing it by hand also gives you a feel for the tiny bumps that a grinder will miss. a machinist staight edge as mentioned is always a good idea, especialy on something that has been apart before. i like grinders and have at least a dozen of them so i dont have to change tooling on them so often, i just dont use them on gasketed surfaces.

 

[wsw]

I agree with the guys above saying scraper, wire wheels and steel wool. even fine sandpaper. You can use a rolox disc but it can remove metal and usually does when cleaning between cylinders when the liners are out cause it gets real narrow there