I have a '92 efi engine that was rebuilt by a shade tree about 5000 miles back. Recently the motor started to knock and I found that the rod and main bearing were bad. It appears that bearings were poorly matched and the clearances were to tight. So I pulled the motor and crankshaft but before I reinstall I would like to clean the oil galleries and block before reassembly. I have read alot of threads about cleaning the block but most of them are about complete rebuilds. So what is the best route I can take given the limited work I am performing?

 

Compressed air should clean out any dirt in oil passages assuming you can access them all, machine shops will dunk the block if you strip it down. To avoid a repeat of this failure the rods and crank will have to be measured not only for size but trueness and then ground true if necessary. It's likely the PO skipped this step and now you have to repeat the work.

 

How much work are you performing? It sounds like this block and crank need to be at least measured properly and at a minimum the crank polished. There are a couple questions that need answering before you put this thing together. The main one being is the crank undersized? If the PO installed undersize bearings with original size journals this needs to be fiqured out.

Back to the cleaning, have you taken the engine all the way apart or are the heads still on. If the heads and pistons are still on/in the block cleaning can be tricky. Get yourself some big/long pipe cleaners or a rifle cleaning kit you don't use anymore and pull the oil galley plugs at both ends and brush them out spray with brake clean and blow with air. Also some hard line taped to a vacuum can do alot of good getting to all the passages and corners. Hope this gives you some ideas.

 

I agree with you opinion on the PO and the bearing size. I have the motor out and heads off. I am having the crank polished and I will have the shop properly size the bearings. Thanks for the tips with the vacumn and cleaning the galleries. The oil galley plugs are the allen head plugs on either end of the motor? When it comes to removing the carbon deposits from the tops of the pistons any suggestions? Also what would you suggest for someone working in their garage as to how to clean the crankcase section of the block. The good news is that the PO must have tanked the blocks and heads because they still look like new but I want to make sure when I am done I don't leave anything behind.

 

Sence it's apart you can go to town cleaning it. I would pull the galley plugs and maybe pop the cap out the back of the cam bore. Grab some pipe cleaners a couple cans of brakeclean and a can of wd-40 and a roll of towels. Then throw it all in the back of a truck and head to one of those coin-op presure wash car washes. Empty a can of brakeclean, brush it out, pressure wash it, another can of brakeclean, rinse, dry, then coat everything in wd-40. This isn't much differant then what I have done with hundreds of engines at the machine shop, just be carefull not to damage the cam bearings, and use lots of wd-40. Oh ya and bring a big garbage bag to cover it after.

If you are unaware this is the intended use of wd-40, wd stands for water dispersant formula 40 NASA engineerd it to stop corrosion caused by condinsation in the spacecraft.

For the tops of the pistons, It's not rocket science a wire wheel or scotch pad would work fine. The top is hard to damage but be carefull of the ring grooves a dent there could cause problems.

Sence you have it apart are you having your guy check the rods to? Rods need machine work to and if they haven't been adressed in a while the big end can be elongated. I also asume you have a way to rescuff the bore and are using new rings.

 

$50 at my machine shop gets me a 'prep for assembly' cleaning, which is just what it says, if I supply freeze plugs, etc. They scrub it, install plugs, etc., and I get it back ready to assemble. For a few dollars more ($30-50) they'll mic the crank, and use a dial-bore gauge to make sure the bores are within tolerance, and let me know if I need to adjust my bearing sizes by mixing and matching accordingly. By all means, do the mains and rods both. No Tolerances are accurate unless the caps on all are torqued to spec with bearings installed, period. Call me ****, but my motors last, and they're run HARD.
JMHO

Pete

 

I had my crank mains and connecting rod journals ground. I planned on spot checking with plastic gauge as I assembled the crank and rods. I assumed that if I had the crank ground and bearings sized per the shops spec I would be good to go. Do I need to use plastic gauge on every journal in this case?

 

Sounds like a good deal and a great machine shop.

djmac I suggest at least having the rods measured to make sure they are to spec.

Plastigage can never be used to much but is notorius for false readings if not done right, be carefull, take your time, and double check any readings before making changes.

 

Thanks for the warning. BTW I will be able to hone the cylinders out myself and I will drop my rods off at the shop to be checked out.

Thanks guys, I am sure I will be checking back in soon.