Clean out piston oil ring drain back holes. Both sides.

On this engine all pistons had these holes on either side fully blocked. I hand drilled them out which was a little bit tedious getting the caked on black oil deposits out.
Not 100% sure but I think the hole allows oil to travel from the oil rings to the gudgeon pin area under the crown of the piston. Maybe it stopped the oil in the oil rings from draining away. Do the holes allow cooling and lubrcation to the gudeon pin. Any thoughts ??

 

Nice thread Phil!

Yeah.....I thoroughly clean the pistons if I am going to reuse them. I have rebuilt a couple of dozen of these Mazda 4-cyl engines over the years, from the 2.0L FE, the 2.2L F2, and the 2.6L G6 engines. If there is not a noticeable ridge at the top of the cylinders, and the piston are not worn, scuffed, or grooved, I will reuse the the Mazda pistons (I don't think you can buy better ones unless you special order them) and lightly hone the cylinders.

Some people frown on this......but it clearly shows in the Mazda Factory Workshop Manuals that if the engine wear items fall within certain specifications, you can rebuild the engine without boring it out and buying larger pistons......and I follow the Mazda manual throughout the rebuild process.

The combination of good quality metals in the Mazda engine blocks, and the low tension, thin piston rings, adds up to a engine that you can put 200,000+ miles on, rebuild it to the factory spec tolerances, and have a standard bore rebuilt engine that will go another 200,000+ miles again!

What my stock pistons look like when I clean them up.....

 

Totally agree with you Axel Breaker Earl. It seems the G 6 engine is a prime candidate to refresh even at high klm’s. The pistons and big end bearings in this engine are in as new condition and no lip or scores in the bores. I changed oil and filter once a year.
I have just purchased a three stone hone to deglaze the bores.
Love how clean you got your pistons. I will have to soak mine again and hit them with the toothbrush.😃
Do you happen to know the tension for the conrod nuts. ?

 

I have cleaned the pistons & rods by hand with a degreaser mixture of water and Purple Power, and used old tooth brushes and such to scrub them.......don't use any tools/brushes that will scratch the piston skirts.....even light scratches are less than ideal!
I have used my Ultrasonic Cleaner with the same 50/50 mixture in it to clean them as well.

Here are the torque values for the rod nuts.....

 

Thanks Axel Breaker Earl. You are a champion. This forum has been so helpful. I am a bit fortunate that I can take my time with this job.

 

That is a good thing. I have about 5-6 of these trucks and 3 of them I drive regularly.......it's always nice to not have to hurry through a repair, or engine build.......I can always drive a different truck!

 

I am a bit fortunate that I can take my time with this job.

That is a good thing. I have about 5-6 of these trucks and 3 of them I drive regularly.......it's always nice to not have to hurry through a repair, or engine build.......I can always drive a different truck!

Same here; I have '98 and 2004 Frontiers, and 1971 and 1970 VWs (and Mrs. Cusser has a 2014 Yukon) so I never have to rush through.....

And Axel is a champion !

 

Agreed . Axle is the best resource you can ask for.
I just finished my rebuild. Took me close to 3 years… I’m very slow… but I bought the OG shop manual, followed it to the letter, and took as much advice as I could get from Axle and all the other amazing contributors on this forum.
Love my truck. It’s officially a driver now. I reused pistons and rods. New rings and rebuilt head. Mine was a blown head gasket rebuild from FB marketplace with 279k miles. So much fun to rebuild. Stout little engines…

 

Thanks Josh, that’s encouraging. I’ll keep you all up to date.
Hey also “Love my truck”
I have had to be driven and drive our new Subaru station wagon during this process.

Well does it nag!!
Keep your hands on the wheel
Keep your eyes on the road
Slow down
Washer bottle is low
The only respect I get is when I get in.
it says Hello Phil and then adjusts my seat and mirror to my spot.
Then I get a repeat from Mrs Bravo Phil 😩
I can’t wait to get my rebuild done.
“Love my truck”