I am preparing to pull my engine, L24, and when I removed the thermostat housing it looked like someone had packed it and the head full of Stove Top Stuffing.  It was a crazy amount of corrosion.  I dug as much as I could out, but I'm sure there is more of this crap in the water jacket.  The water pump area did not look too bad.  This engine was sitting up for 15 years.  Any suggestions on how to proceed cleaning? 

Pressure washer

Here’s a couple of screenshots from when I was looking into this. Haven’t tried it. Guess the engine would have to be in a running state also






Sent from my iPhone using Tapatalk

If the engine is still running or even if it is not I've used full strength CLR and leave it over night then flush it out with a garden hose, if the freeze plugs have already been knocked out then as Patcon says a power washer does a good job.

That stove top stuffing is probably remnants of someone using one of those products that is supposed to stop leaks.

I didn't have a pressure washer, so I made a little garden hose blaster instead. Of course, a real pressure washer would have been more powerful and presumably more effective, but it's what I had access to at the time. With "standard" household garden hose pressure, my contraption will shoot about thirty feet, so it's not bad.

Cobbled together from stuff I had laying around. Looks like this:

Here's the business end. I just crimped down the sides in a bench vice. Very scientific like:

Soldered a piece on the end to adapt to a hose:

And put on an in-line hose valve:

It's small enough that (with the freeze plugs removed) I could reach up inside the block and around the piston jackets into the dark recesses.

 

 

When you pull the motor you can take it to a spray type car wash if you don't have a pressure washer. A couple of cans of cheap walmart oven cleaner will clean the block and transmission of the oily sludge stuff before you work on it. You can set the motor on an old tire to keep from denting the oil pan.

Separating the transmission will be easier too. Those rubber plugs at a hardware store work good on the transmission. I think it's a 2"?

I do have a pressure washer, and the engine will be on a stand.  The freeze plugs all look in good condition though.  Should I remove them to aid in cleaning?

The back of the block builds up worse than the front from what I've seen, calcium mostly. I had to pick and chisel that stuff out. Never thought about @grannyknot idea of using CLR soak. 

I would remove the plugs knowing how easy it is, the side ones not the ones on the front and rear. They are cheap too, $15.00 for a set of brass plugs from amazon.com if I remember right. I had the the two on the ends done when I had my block vatted at a machine shop. They are too close to the cylinder wall for me to mess with.

8 hours ago, adivin said:

The freeze plugs all look in good condition though.  Should I remove them to aid in cleaning?

No you don't have to but if you have no information on how the engine was taken care of then it's always a safe bet to start clean, years of tap water and antifreeze can add up to a lot of crud. Removing the plugs are easy, just whack one side of it with a punch or old screw driver so the plug pivots and grab the side sticking out with a pair of vise grips.