Recommendations for M20 blocking clean prior to assembly

[Lugnuts]

Apologies if this has been posted elsewhere.

Curious to know what people recommended for cleaning/prep of an M20 block prior to assembly.

The first (and only) M20 I assembled, I went at it with a pressure washer and a couple cans of WD40 to prevent flash rust. That engine's still running but, no idea if I got lucky...

Machine shop advised against using water and instead go for brake cleaner and lots of shop towel - wipe/spray until it's spotless. This would almost certainly be easier than the whack-a-mole rust-prevention when using water...less risk of missing a wet corner/surface also.

I read elsewhere that lacquer thinner is pretty common.

[zaq123]

Hmm my previous post has been flagged as a spam? Once you edit the post, the system flags it ...WTF? Weird....here is my post....again:

is the block out of the car? are you painting it?
Rule #1 in my book: KEEP THE SCOTHBRIGHT (aluminum oxide pads) aka "engine killer pads" AWAY from the engine. if they were used at some point: soap/ lotsof pressured water is the only way to clean the mess.

gallon can of Kerosine (any Homedepot sells it), a few cans of degreaser (basically kerosine in the can), compressed air, lots of rags and variety of bottle cleaning brushes (Harborfreight or Amazon).
If painting, I would still clean it with degreaser and Simple green/ warm water (externally) after bores/ crank seating machined surfaces and the deck were slightly greased to avoid flush rust. Air dry, wiper the grease to make sure no water is trapped under it and paint. After paint dries, pop the gallery plugs (drill/tap/screw/pull), use kerosine socked brushes/WD40 etc to clean the oil gallery nd all oil passages. Run some compressed air through the oil gallery to get rid of everything and plug the gallery
(oil resistant High tack sealant on plugs). Blow all the dust out of everything, use clean lint free a rag and some Marvel Mystery Oil to wipe the deck/bores/inside the engine/crank sitting surfaces etc etc. Wipe it wet so everything listed above remains oily. Bag it.
Rule #2. Keep everything clean. Before the engine assembly: Triple clean the room/garage: vacuum, mop the floor or at least wet broom it (to keep the dust down), keep the door closed as not to introduce any dust into the assembly room and during the assembly, use clean tools and wear clean cloth. I use thin film of Marvel Mystery oil on fresh bores/rings/pistons for assembly/keeping the rust away/first start/break-in purposes. Good quality assembly grease on rods/cam/crank/rockers.

[Lugnuts]

Thanks zaq123. I'm aware of the aluminium-oxide impregnated scotch pads being bad for engines on account of the abrasive dust they give off. Only made that mistake once.

Block is out of the car - already been machined for new pistons and painted. Freeze plugs were replaced in the process. Gallery plugs weren't removed. I asked the owner of the shop (builds E30 race engines) and he said unless the engine failed, he generally doesn't remove them. The block was tanked twice - before and after having work done on it. I'm on the fence about removing them. I have a pack of new plugs, it's just the removal I'm not 100% sure (confident) about. Found a post somewhere of someone tapping the oil gallery holes, replacing the plugs with a nice threaded SS allen-head plus + sealant.

Garage is getting a good clean this weekend!

[zaq123]

I'm aware of the aluminium-oxide impregnated scotch pads being bad for engines on account of the abrasive dust they give off. Only made that mistake once.

Block is out of the car - already been machined for new pistons and painted. Freeze plugs were replaced in the process. Gallery plugs weren't removed. I asked the owner of the shop (builds E30 race engines) and he said unless the engine failed, he generally doesn't remove them. The block was tanked twice - before and after having work done on it. I'm on the fence about removing them. I have a pack of new plugs, it's just the removal I'm not 100% sure (confident) about. Found a post somewhere of someone tapping the oil gallery holes, replacing the plugs with a nice threaded allen-head plus + sealant.

Garage is getting a good clean this weekend!

I would get the gallery clean well even if there were no engine failures. If the block has been tanked, definitely remove them and glean the gallery well out of all possible gunk. No need to thread the hole for some threaded plug since you got new plugs on hand.

Drill a hole in both old plugs for the tap, tap them for a bolt, screw the bolt, pull the bolt with a slide hammer, clean the gallery, apply a little bit Curil or High tack to the hole, apply some more to the plug, drive those new plugs in. 15 min task...very simple.

[digger]

you've come this far, just remove one of the plugs intially unless you see a whole bunch of goop remaining in there

[Lugnuts]

Thanks guys. My slide hammer is a $30 eBay PoS, so I improvised. Killed a few washers but she's out.

Think I'll just do the front one, should be good enough for some rigorous gallery cleaning.



Going to see if my crappy USB camera on a stick will fit in the hole. Can't really see much atm.

[dvallis]

See my Das Beast thread for complete engine tear down and block prep. We used brake cleaner fluid and a power drill with wire brush. Was the only way to really get it clean. I used a small crowbar and long ass pipe as a lever to pull the drilled freeze plugs. Slide hammer would have been more elegant but I didn't know how to spell slide hammer back then. :-)