Engine rebuild decision making time..... Need help.

Ok, some of you may remember me with the dark blue 1991 B2200 that I was more or less restoring. Some of you should also remember the horrible smoking problems that it was having. Ever since the smoke got really bad and to the point where the truck could not move I have been toying with what to do. I needed to figure out whether it was the piston rings or seals.... Or both. I did the compression test and determined it was the piston rings.

Today I finally got the head off and now can directly see the pistons and cylinders. Before I go on and replace the piston rings I want to know if there are any tests or things I should look at to see whether the cylinders are even in workable shape or are completely scratched and wrecked. The cylinders have ALOT of burnt grease and all everywhere but I don't see any major scratches in the 2nd / 3rd cylinders (the 1st and 4th are too high up to see the walls)

So in other words, before replacing the piston rings is there anything I should check. Also, is there any special advice you have for putting new piston rings in?

I don't know much about motors and have basically been teaching myself thus far with help from my brother.... Who is also teaching himself lol.

Here are some topics to refreash your memory of my project:


My Mazda B2200 Log
[url=71728:efm476ml]Compression Testing

Thanks,
Zac

Heres some pictures....





Zac

the crosshatch is still pretty clearly defined.
if you cant feel any major scratches in the cylinder walls with your thumb nail, you should be fine for a rebuild.
i would definately want to check all 4 cylinders to make sure one is not screwed.

and the carbon buildup on the pistons is rather minimal; when i rebuilt mine, i could chisel it off!!

Really, I thought there was a lot of carbon build up my truck was burning A LOT of oil... I was wodnering about the crosshatch, I cannot feel it, it feels like glass. I am going to probably go ahead with the rebuild, any other opinions?

Also, anything about the piston ring swapping I should know? I have my Hanes manual and thats all I was really going to go by.

Thanks for the help Nikc

Zac

Since you are replacing piston rings- and you have the engine down to the short block- go ahead and pull it out of the truck.

Once it's out- tear it apart- labeling and being very careful with everything. Inspect the bearings and rods and crank- check the cylinder walls for a scratch that you can feel with your fingernail. If all looks ok- that it down to your local machine shop- bring them the block and the crank and the rods and pistons. Have them acid dip/ clean everything and have them check all parts- measure all parts- and if all is ok tell them to lightly rehone the cylinder walls- All of this work at a machine shop should be about 100 bucks- well worth it. Also bring in your oil pan and other greasey oil covered parts and have them throw them into the acid dip as well.

When you get a freshly honed and cleaned block back- go ahead and clean the outside of it again and tape it off and paint it so it's won't rust- just the outside! Acid dip will eat all over your paint. Same for the oil pan and other parts.

After the paint dries, and you have all of your new rings and bearings and seals- take the block out in your driveway- get a hose and a bucket of saopy water and some rags and spray that sucker out- wash all the microscopic metal off the cylinder walls- out of the oil and coolant passages. Then dry it off real good- and use some compressed air and blow the water out of all the nooks and crannys. Then reoil all bare surfaces with motor oil- just use a rag and oil- or a squirt bottle with oil- now you are ready to assemble a fresh bottom end that will last you another 200,000 miles.

Make sure also to get your head checked out- cleaned, and have it plained lightly to ensure a good headgasket seal. Replace the valve stem seals as well!

Hmm... Well now I am really on the fence. I would LOVE to rebuild the bottom end but for one, know nothing about it, for two, don't really have the time to do it and for three, I am already in the hole (money wise) on this truck that its killing me. It should have been on the road back in November of last year... I ended up buying another car for the mean time.

I am not sure what I want to do. I will likely call around and find out some prices for a block acid dip / hone and valve seal replacement.

How hard is it to pull apart the block and all? Would I have to do it anyways to get the pistons out if I were only going to replace the rings?

And of course if I am pulling the block then my truck is going for paint early and I will paint the engine bay and body then bring it home and install a nice and fresh motor.

Thanks for your input.

Zac

you don't have to pull the motor to replace the rings, but it wouldn't be fun to try to pull it apart still in the truck. major pain... you'll need to pull the oil pan off and then remove the rod caps and push the pistons out the top. there might be a little tiny lip at the top of the cylinder walls that needs to be taken care of before you remove the pistons, or it might break a ring. good luck to you and your rebuild.

If the firewall in those pictures was white I could say that's my truck! That's exactly where I'm at with mine. I'm getting the block cleaned and honed in a couple weeks. We did a compression test last week and all cylinders were in the low 170 range. Which is like 26 lbs less than stock but not horrible. Well I took off the exhaust mani and did the compression again and all were in the 115-120 range. So somehow I had about 60 lbs of backpressure running through the motor. Header is definatly getting purchased to remedy!

did all that on my last mazda. lol. was a beast. in 1 day i redid the head, the next day i dropped the pistons, gave it new bearings and rings, the 3rd day i bolted her back up, and went for a drive.