Hot Tank Cleaning

[TurboWeenie]

I've read quite a few times that you are supposed to replace freeze plugs and oil drive shaft bearings when you hot tank a block, because the chemicals will eat them away. When I asked my machinist about this, he'd never heard of this or had any problem with it. He did recommend, however, that the freeze plugs be be removed prior to hot tanking to clean everything out better. I did some huntin around and it looks like different chemicals can be used in the hot tanking process. Is there a standard solution used or does it vary? If so, what ones do I need to worry about eating up my bearings and freeze plugs? If my machinist tells me I don't need to worry about it do I believe him?

Basically, what I am trying to accomplish is to get any crap cleaned out of the block caused by honing and having it decked. Is hot tanking the best solution or are there any alternatives to accomplish this?

Thanks for any help

 

[jetjock]

Freeze plugs are usually removed prior to hot tanking. At least that's how I remember it. Hot tanking is becoming rare in many places these days due to environmental concerns, often being replaced by aqueous cleaning. Think big dishwasher.

 

[AF1JZ]

Freeze plugs are cheap. Just remove them and install some new ones after it is cleaned.

/thread

 

[Doward]

If it's a caustic hot tank (which the EPA really frowns upon) then yes, any 'soft metal' will be destroyed (bearings/expansion plugs)

JJ mentioned it, but to REALLY clean everything, you want those removed PRIOR to the cleaning - which most machine shops won't do (even though it is the same freaking amount of work)

 

[TurboWeenie]

Freeze plugs I'm not so worried about, because like you said, they're cheap and not real hard to replace as long as the block is out of the car. I'm more worried about bearings and getting them installed. Also, hot tanking will take the paint off the block and I'd have to repaint it. Regardless, I'd like to know about alternatives, and if if they are common. Most of the machine shops around here are run by 60 year old guys who haven't done anything different since they started the shop.

 

[jdub]

Use Toyota freeze plugs when you replace them...the plugs are metric. If you use aftermarket (like Dorman), the plugs are 5 thou smaller in diameter. I had one blow for this exact reason and they are a real pain to replace with the motor in the car.

Also, make sure the plugs are fully seated on the hole machined surface...the front one behind the water pump is recessed slightly more than the others.

 

[TurboWeenie]

Yeah I've read about our freeze plugs through threads on this site. Lots of good info. I plan to use toyota plugs.

JJ can you elaborate on aqueous cleaning? Is it just plain water under high pressure?

I've talked to a guy here in my area that does mainly cylinder head work, I think this it what he uses for cleaning. I may take the block to him to have it cleaned after it's decked. Anybody think having a block cleaned this way is a bad idea?

 

[jetjock]

Yes, it's mostly water but other stuff can be in there. Surfactants (soap), rust inhibiters, stuff like that. The water is heated and depending on the system can even be ultrasonically conditioned.

The machines use all sorts of movable manifolds and spray heads to get stuff clean. Think of several high pressure power washers but enclosed and with better control. I ran an intake manifold through one not long ago and it came out spiffy. Better than my wife's dishwasher and with less bruises

Not that you'd be hot tanking aluminum parts but you get my drift. Google around for more info on the process. These guys seems to be big in the biz:

http://tinyurl.com/yp8kkr

Frankly, I doubt they'd be all that effective at cleaning the interior cooling passages of a block though. I typically run oxalic acid through them when in the car. Few other things will clean up a cooling system better.

 

[TurboWeenie]

Yeah, the main thing I want to accomplish is just to clean out any metal shavings from milling the block. This should be more than adequate shouldn't it?

 

[Doward]

JJ, where are you buying oxalic acid at?

IIRC, isn't oxalic acid a really strong acid, that forms precipitates with many metals?

Assuming you want the acid to literally eat the rust from the iron block? Could be wrong here, clear me up if so!

 

[IJ.]

LOL @ Wiki.....

 

[Doward]

LOL @ Wiki.....

LOL @ having just looked it up.

We were discussing acid/metal (redox) reactions in 2045 lab 2-3 weeks ago I remember Sweiter talking about some O-acid that tears into metals pretty harshly.

*edit* Yep, that's the one - wiki lists it as being used in rust removal in automotive apps.

http://en.wikipedia.org/wiki/Oxalic_acid

 

[IJ.]

NOT good for skin

 

[jetjock]

Well, you're not supposed use a lot. Just a touch under the eyes and a bit on the cheeks for color

Doward: Prestone Heavy Duty Cleaner is oxalic acid but it can be hard to find. Comes in a yellow two part cardboard can with the cleaner on top and the neutralizer on the bottom. The neutralizer is sodium carbonate. You can buy oxalic acid from any chem supply house. I get it on Ebay (yes, Ebay) and keep a pound around for the abused cars I occasionally get asked to work on. It's handy for other things too. Better living through chemistry

 

[supraguru05]

im using aftermarket freeze plugs they are metric though and they worked fine

 

[jdub]

^^^ At least so far they are
(mine lasted almost a year before the front one blew)

 

[supraguy@aol]

The front one has to be dimpled- aka pounded in the center, as it's made convex. That drives the outer edge into the block seat.

I got a brass set on Ebay, packaged specifically for the 7M (all metric).