603 Head is Off...hone the cylinders? - PeachParts Mercedes-Benz Forum

zooklm · #1 04-04-2014, 10:35 PM

I have the engine out (87 300D) and head off (blown head gasket and cracked head). I see a little surface rust in a couple spots in 2 different cylinders. I think I can clean it up with scotchbrite pads and then superfine (1200-1500 grit) aluminum oxide paper. It ran well except the head problem so I don't suspect any bottom end problems. I am considering pulling the pistons to hone the cylinders as an alternate to the local spot cleanup. I was wanting to get peoples experiences with both approaches. I did search the forum and got several hits, but was not able to discern views on these approaches.

Thanks,
Lee

t walgamuth · #2 04-04-2014, 11:14 PM

If you pull cylinders you gonna put in rings?

ah-kay · #3 04-04-2014, 11:23 PM

How competent are you with engine work? I did it on 2 OM603 engines. Removed the oil pan and pushed the pistons out. You need to lift the engine a bit to remove the pan. Honed the cylinders and put everything back together. I reused the compression rings but not the oil rings. The oil rings will break when you push then out. I bought the oils individually on eBay. Soaked the pistons to get rid of all the carbon. It is a lot of work but I rehabitated 2 engines.

zooklm · #4 04-05-2014, 09:57 AM

I have the engine out on a stand with the oil pan off so removal of the pistons is not a big deal. I figured on replacing all the rings. I would evaluate journal wear and see if there is any wear. I have been working on cars for many years and have done almost everything mechanically on a car. Just wanting to learn from other's experience before I make a $250 additional cost ($50 rings, $200 rod bearings) decision/commitment.
Thanks for the inputs.

t walgamuth · #5 04-05-2014, 01:04 PM

The bottom ends on these engines are pretty rugged. I would not be surprised if you could re-use the bearings. if you are pulling the pistons, then yes, I'd hone the cylinders if they have acceptable taper and put in new rings.

zooklm · #6 04-05-2014, 06:59 PM

Thanks for the encouragement. I'll probably clean up the bearings and journals, measure and plasti-gage them to check the clearances and go from there on the decision on buying new bearings.

rscurtis · #7 04-05-2014, 08:26 PM

If you had no symptoms of bad bearings and you don't see any copper, put it back together and don't worry about it.

Diesel911 · #8 04-06-2014, 01:03 AM

Quote:

Originally Posted by ah-kay

How competent are you with engine work? I did it on 2 OM603 engines. Removed the oil pan and pushed the pistons out. You need to lift the engine a bit to remove the pan. Honed the cylinders and put everything back together. I reused the compression rings but not the oil rings. The oil rings will break when you push then out. I bought the oils individually on eBay. Soaked the pistons to get rid of all the carbon. It is a lot of work but I rehabitated 2 engines.

Breaking Piston Rings pushing them out generally happens if you don't ream off the ridge at the Top of the Cylinder. The Ridge is formed by the unworn part of the Liner and Carbon Buildup.

I think you can find instructions on how to use a Ridge Reamer in a General Automotive Book you find in the Library or of course there should be pics on the Internet somewhere.

Back in the 1960s-1970s they used to rent Tools like a Ridge Reamer. I have owned one so long I don't know if they still do that or not.
Somplace that rents Torque Wrenches might also rent other Engine overhaul Tools.

Diesel911 · #9 04-06-2014, 01:18 AM

I think you can also rent Cylinder Hones. One for deglazing Cylinders and putting on the Cross Hatch Pattern are nick named "Dingle Berry Hones" as the look a lot like a big Bottle Brus with abrasive Balls on the end of the Bristles.

There is various grits but 220 grit seems to work on Gasoline and Diesel Engine. However, consult your Mercedes Manual on what it recommends.
I also suppose some people have their preferences as to what grit to use.

The above type of Hone is best turned with a slow and strong Drill Motor. A 1 inch Drill Motor works better than a 3/8" Drill Motor for the Job. Either one needs to be variable Speed.
You also need to decied what lube you want to use.

You can also use the regular Stone Type of Hones with 3 or 4 Stones and 3 or 4 spring loaded arms on them to deglaze the Cylinder. They are easier to turn with the Drill Motor than the other type of Hone because the Stones don't contact as much surface area and therfore do not drag as much.
If you let the Stones pop out of the Cylinder while you are doing the job and the Drill Motor is at some speed it can sometime dammage the Hone and you if something flys off.

No matter what you use for a lubricant Soap and Water gets the grit and metal particles off better than Solovent or even Brake Cleaner. Oil the Cylinders so they don't rust up as soon as you have wiped them dry.
I did not believe that Soap and Water did a better job till I worked at a place where I was told that.
I tested it. I tried Solovent and wiped the Cylinders down till I believed they were clean and then did the Soap and Water and wiped it down. Sure enough I had grit and Metal residue after following up the Solovent with Soap and Water.

Diesel911 · #10 04-06-2014, 01:20 AM

I think you can also rent Cylinder Hones. One for deglazing Cylinders and putting on the Cross Hatch Pattern are nick named "Dingle Berry Hones" as the look a lot like a big Bottle Brus with abrasive Balls on the end of the Bristles.

There is various grits but 220 grit seems to work on Gasoline and Diesel Engine. However, consult your Mercedes Manual on what it recommends.
I also suppose some people have their preferences as to what grit to use.

The above type of Hone is best turned with a slow and strong Drill Motor. A 1 inch Drill Motor works better than a 3/8" Drill Motor for the Job. Either one needs to be variable Speed.
You also need to decied what lube you want to use.

You can also use the regular Stone Type of Hones with 3 or 4 Stones and 3 or 4 spring loaded arms on them to deglaze the Cylinder. They are easier to turn with the Drill Motor than the other type of Hone because the Stones don't contact as much surface area and therfore do not drag as much.
If you let the Stones pop out of the Cylinder while you are doing the job and the Drill Motor is at some speed it can sometime dammage the Hone and you if something flys off.

No matter what you use for a lubricant Soap and Water gets the grit and metal particles off better than Solovent or even Brake Cleaner. Oil the Cylinders so they don't rust up as soon as you have wiped them dry.
I did not believe that Soap and Water did a better job till I worked at a place where I was told that.
I tested it. I tried Solovent and wiped the Cylinders down till I believed they were clean and then did the Soap and Water and wiped it down. Sure enough I had grit and Metal residue after following up the Solovent with Soap and Water.

I will let someone else explain how to get the Hone and Drill Motor to produce the crossed hatch pattern. It is much easier to show someone then to write about it. Perhaps there is a Youtube on that.

zooklm · #11 04-14-2014, 06:46 AM

I was able to pull the pistons this weekend. All bearings looked ok except #3. This is a picture of the cap side. The rod side had the same bright, slight groove. You can catch a fingernail in the groove and it does not seem to have much depth. I have not had time to evaluat the crank for #3, yet.