[Urbana1750]

After 27 years (so I can't blame the previous owner for much of anything) I am rebuilding my 69 1750's engine. After taking the engine apart, with the exception of worn out rod and main bearings everything inside looks pretty good. There is no real sludge to speak of however, the interior of the motor is coated with a thin brown deposit from years of hot oil. Nothing that I've yet tried seems to remove this deposit. So far I've tried, heavy duty engine degreaser (kerosine?), spray carburator cleaner, isopropanol, and acetone.
I have a couple of questions for you more experienced Alfitsi:
1) Is there a practical way to remove these deposits?
2) For rebuilding my weekend fun car in stock form is it even worth worrying about?

 

[Gordon Raymond]

Aluminum Cleaning

Often "Easy Off" Oven cleaner, the strong one, will do the job. It can leave a black discoloration on some injection molded castings. There is also available, from industrial supply houses, an aluminum oxidation prep spray, for use prior to welding aluminum parts. The one I use is "Arcair Protex alclean" by Thermadyne. Nasty stuff. Use gloves, eye & skin protection. Use OUTDOORS! Do not breathe fumes! This does make aluminum blocks look like new. It also may discolor front covers and other injection cast parts, I don't use it on those. First I use foamy engine brite, then soap & hot water. Then the Arcair. Follow with more hot water.
Years ago (40) when it was available for use, we used Hydro Floric Acid on aluminum race engines. REALLY DEADLY STUFF! It eats GLASS! It made the castings beatiful, but probably shortened our life spans. I can no longer suggest this option. Gordon Raymond

 

[1166]

If I feel like cleaning that stuff off the inside of an engine block, I use Castrol Super Clean. It comes in a purple container. I wet the block and spray on ONLY where I am going to clean. Do not let it dry or it will etch the aluminium (discolor it). Work it with a small toothbrush for a few minutes, rinse and repeat.

If I don't feel like breathing in nasty fumes and getting dirty, bring it to a machine shop and let them put it through their washer (WAY easier).

 

[John M]

Eagle One aluminum wheel cleaner. Not the clear coat type. The full strength type. Following degreasing with one of those gunk type degreasers and pressure washing.....coat the inside and outside with the wheel cleaner. Let set for a few minutes then pressure wash. Repeat as necessary. Will make the block look new inside and out. For rods, main journal caps, bolts, pulleys, etc....get a can of the gunk cleaner that has the dipping tray inside. Its about the size of a quart of paint. Soak and pressure wash. Don't forget to blow out the ports in the block. You have a couple of plugs to remove so you can go wild pressure washing the galleries.

Best Regards,
John M

 

[elite38868]

What about a pressure washer? They have to be somewhat as cheap as some of these brain destroying chemicals...

 

[Urbana1750]

Thanks guys for all the suggestions. After reading your suggestions and considering the chemistry involved (saponification). I decided to try the oven cleaner first. A pressure washer only got the loose oil but didn't touch the cooked on brown residues. I used the fumeless oven cleaner which has a somewhat different chemistry than the straight lye stuff. This got alot of the baked on stuff. I left it on initially for only 15 minutes and then did a second run today with a two hour soak with spritzes of water to keep it damp. Still wasn't real satisfied, and had found some "etching" alloy wheel cleaner made for rough cast wheels. The ingredients include hydrofloric and sulfuric acid. Considering the suggestions this seemed worth a try and it worked amazingly well. Still have a few hard to reach areas to finish, but my block is now gorgeously clean. Thanks again for all the suggestions.

 

[au-yt]

Molasus and water

An old school method that works a treat and is very user frendly is 50 50 Molasus and water a big tub and soak it. you can stick your hands in it and its biodegradable.

 

[Urbana1750]

au-yut, Do you mean molasses-as in the syrup from sugar refining? That sounds like a great solution although kind of hard to imagine it working. All the other treatments involve very harsh chemicals this seems so gentle. Even if it takes days soaking it would be a much better way to go. I will try it on some small parts I have yet to clean.

 

[1750GT]

I just finished cleaning my engine of 30 year old oil deposits and started with varsol first to get the heavy grease and dirt off first. I then sprayed on a mag wheel cleaner product on small 4in x 4in areas while using a stiff tooth brush to agitate and help the product work faster....I then washed off the resulting foamy residue with water using a spray bottle. I found I needed to do about 4 applications of this all over...but man was I amazed at how well this stuff worked...the outside of the engine block almost sparkled it was so clean. Granted the inside of the block took a lot more time to do, but I did not need to brush hard at all....just continuously and repeatedly....it was kind of fun seeing the block looking new again little pieces at a time.