Author Topic: Engine block and gearbox cleaning?  (Read 353 times)

Offline Lone Star Mini

Engine block and gearbox cleaning?
« on: April 22, 2021, 08:35:47 AM »
All,   Iím in process of disassembling my engine and gearbox.  Through the grapevine, I have found/contacted a guy named Jim Davidson down in the Austin TX area who in turn referred me to a machine shop that he has used for his minis over the past 20 years.  Outside of general engine modifications, they no longer offer acid baths to thoroughly clean inside/outside of engine block and gearbox housing.  Apparently the acid baths are now environmentally taboo.  Therefore Iím wondering if this could be a DIY project and whether or not any of you knowledgeable folk have either created a solution to soak your blocks in and/or is it acceptable to blast the block.  Blasting, however, will not be able to reach the inside so what is recommended?   What about the head, can it be blasted or soaked as well?   
 
Thanks for any tips!!
Lone Star Mini
1982 Morris Mini 1000HL (heck of a lot of work ahead of me)
1992(?) Mini Cooper
1964 Austin Cooper
1980 Mini 95 (Pickup)

Offline MPlayle

Re: Engine block and gearbox cleaning?
« Reply #1 on: April 22, 2021, 08:46:04 AM »
When I cleaned up the replacement 998 for the Moke I was restoring a few years ago, I only did the outside.  I used spray on engine degreaser from the auto parts store to reduce the oil/grime buildup.  Then I used a home-made soda blaster arrangement to "deep clean" and remove most of the old paint.  I followed that by a thorough wash and blow dried out the nooks then let it air dry a couple days before painting it.

The soda I used was from Harbor Freight and is biodegradable.


Offline Lone Star Mini

Re: Engine block and gearbox cleaning?
« Reply #2 on: April 22, 2021, 09:10:23 AM »
Thanks Michael,    I currently have glass beads in the borrowed blaster I have.   Perhaps I can cover the inner cylinder walls thoroughly.  I more curious about the inner cavities because right now there is apparently loads of orange colored rust or gunk in the coolant cavities.   
Lone Star Mini
1982 Morris Mini 1000HL (heck of a lot of work ahead of me)
1992(?) Mini Cooper
1964 Austin Cooper
1980 Mini 95 (Pickup)

Offline cstudep

Re: Engine block and gearbox cleaning?
« Reply #3 on: April 22, 2021, 10:01:21 AM »
The water based rust soakers like evaporust or WD40 specialist (there are others as well) actually do a decent job of cleaning up rust, that is what Dave soaked that really nasty looking block and head in I think, and I have used it on things with decent results in the past.

A DIY electrolysis tank is fairly easy to make and will remove just about everything paint, grease, etc... It's more of a hassle and if there are any soft metals (especially aluminum) intermixed you have to be real careful as they can be pretty easily damaged in the process. If you have everything stripped down to just iron it works great.

I would be real careful using any sort of blast media that could clog up oil galleries and such, soda is water dissolvable so no problem there, but it's also not all that aggressive so you have to remove most of the rust and heavy grease another way first.

A combo of a good degreasing, followed up by a soaking in the water based rust removers, followed up by a soda blast of the exterior would probably net the best overall result without resorting to an electrolysis setup.

Offline MiniDave

Re: Engine block and gearbox cleaning?
« Reply #4 on: April 22, 2021, 11:33:42 AM »
Do not use glass bead on the inside of the engine or head, that stuff embeds itself in the cast iron and you'll play hell cleaning it out - and if you don't get absolutely all of it, you risk having tiny bits of it get into your oil later.

Soda blast is fine, as it's water soluble as Paul says.

I use a knotted twisted wire brush on my angle grinder on the outside after I've pressure washed it if I need to get loose paint off.

Cleaning the inside to bare metal isn't necessary or even a good idea as the block is seasoned in now. When the machine shop cleans it they put it in a jet washer - which is a pressure washer with a bunch of nozzles and a rotating platen - it actually does a pretty good job of getting it clean - but if you're doing the assembly you'll need to clean the bores and bearing surfaces afterwards as it leaves a little soap residue on those surfaces.
« Last Edit: April 22, 2021, 11:37:46 AM by MiniDave »
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline MPlayle

Re: Engine block and gearbox cleaning?
« Reply #5 on: April 22, 2021, 11:39:53 AM »
I was cleaning up only the outside.  I taped off/closed all of the ports/openings before doing the cleaning.  I was also putting on a fresh head, so did the cleaning with the old head still in place.

If you want to borrow my soda blaster setup, I still have it and lots of extra soda.  Will you be coming to any of the drives next week?  If so, I can try to fit it in to pass along.


Offline Lone Star Mini

Re: Engine block and gearbox cleaning?
« Reply #6 on: April 22, 2021, 01:02:56 PM »
Good info....   thanks guys.  I will use soda and see how well it works along with evaporator for down inside the holes...   

@Michael...   I will not be coming down this month as our Texas Freeze forced me to use a week of vacation. I was trying to come down on Friday, but ?
Lone Star Mini
1982 Morris Mini 1000HL (heck of a lot of work ahead of me)
1992(?) Mini Cooper
1964 Austin Cooper
1980 Mini 95 (Pickup)

Offline MPlayle

Re: Engine block and gearbox cleaning?
« Reply #7 on: April 22, 2021, 02:09:09 PM »
I will be returning to San Antonio sometime Friday - after leading the "optional" drive that day if it happens.  If you will be down for the Friday drive, you can follow me back to San Antonio and pick it up.  Otherwise, we can make other arrangements to meet somewhere and hand it off.

Let me know.


Offline Lone Star Mini

Re: Engine block and gearbox cleaning?
« Reply #8 on: April 24, 2021, 10:52:40 PM »
Michael...  in borrowing a friends blast booth, I assume that soda would work in any blast booth system.  Would this be correct?  If so, I can easily empty the glass bead and pour in soda.  This way I would not have to borrow (at a distance) yours.  I greatly appreciate your generosity!!
Lone Star Mini
1982 Morris Mini 1000HL (heck of a lot of work ahead of me)
1992(?) Mini Cooper
1964 Austin Cooper
1980 Mini 95 (Pickup)

Offline MPlayle

Re: Engine block and gearbox cleaning?
« Reply #9 on: April 25, 2021, 09:16:46 AM »
I do not know for certain whether you would be able to use soda in your friend's booth.  I would think so.  Mine is a simple diy arrangement for use out doors - not a booth.

I have a small bucket set up as the siphon bucket for the soda and a siphon nozzle for on an air hose.  I load the small bucket with soda from a larger bucket as needed.

Offline MiniDave

Re: Engine block and gearbox cleaning?
« Reply #10 on: April 25, 2021, 09:40:08 AM »
One of the benefits - and negatives - of soda blasting is that it's not nearly as aggressive as other media - so it works great taking paint off of sheet metal without damaging it, not so much on rust.

I'm not sure how effective it is on an engine block for getting the paint off as that stuff the factory puts on is really stuck on there! But the good news there is that you can paint over it with proper prep and it will stick.....

As for the inside of the engine, what ever method the machine shop uses to clean it is usually plenty good - normally a jet washer -  but before you assemble the engine you need to clean the bores and journals thoroughly. After a soap and water rinse, I wash them again with WD40 - then lastly with a white rag and more WD, if the rag comes out with any black on it, it's not clean enough yet.
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline Lone Star Mini

Re: Engine block and gearbox cleaning?
« Reply #11 on: May 09, 2021, 10:04:52 PM »
I now have my engine block 98% disassembled and I'm basically read to begin cleaning the block.   In reading and doing some research, I find loads of opinions on how to "properly" clean the block.  I'm to the point that I may merely take a wire or nylon brush to the outside.  A friend in the UK keeps telling me that acid dipping is the only way, but he can't get it in his head that acid dipping is illegal here even though I've told him a 100 times.   Many of you have been this route with experience, but being my first rodeo I am merely wanting the best option possible.  Does anyone have a DIY acid bath solution for the inside?  I will of course take Dave's advise and talk with my machinist as soon as I can..       
Lone Star Mini
1982 Morris Mini 1000HL (heck of a lot of work ahead of me)
1992(?) Mini Cooper
1964 Austin Cooper
1980 Mini 95 (Pickup)

Offline MiniDave

Re: Engine block and gearbox cleaning?
« Reply #12 on: May 10, 2021, 09:42:55 AM »
Don't get fixated on getting it clean like fresh out of the foundry - the cast iron is "seasoned" internally, it has absorbed a certain amount of oil and it doesn't hurt a thing that it's still there....you just want to make sure there's no sludge or acidic stuff left in there - the jet washer will clean that easily. My machine shop guy washes mine twice - once before he bores it and again after. As far as the outside goes, use anything you want to get it ready to paint, sand blast, soda blast, wire wheel on an angle grinder - whatever you like. Just be sure to prime it with a good etch or 2 pack primer.

Also, be sure to remove not only the water jacket core plugs but also the four small ones for the oil galleries - I use a small wire brush in those to make sure any crud is gone, then blow them clear again - you can get those wire brushes from Harbor Freight

https://www.harborfreight.com/airbrush-cleaning-brushes-5-pc-68155.html

On the 998 I'm building the head and block were both thoroughly encrusted with rust in the water jacket - I had to use screwdrivers and scrapers to clean it out - that's where an acid bath would help.

The only ones I've seen (home use) is where you make up a solution of molasses and let is soak in it for a week or so.....
Complete failure at retirement

1989 Cooper Racing Green
2009 Clubman S
2014 Audi Allroad

Offline bob01b

Re: Engine block and gearbox cleaning?
« Reply #13 on: May 10, 2021, 08:05:13 PM »
I've read in multiple forums about using phosphoric acid, which you can purchase on amazon and I am sure locally.  And from my google search phosphoric acid should be neutralized with calcium hydroxide or carbonate before disposal. Also easily available.  It does not pose a threat for the environment when neutalized, so it can be disposed almost everywhere.  This link points to a Triumph TR6 restoration page.  The guy does beautiful work overall and swears by the phosphoric acid treatment on coolant passages.  Worth a look. 
http://bullfire.net/TR6/TR6-4/TR6-4.html