[70 FJ40] Clogged cylinder coolant drain. (1 Viewer)

[Ramacher]

I've searched and found a couple other threads with the similar issue. Got some good ideas but while the majority of others that were clogged, they were clogged with the red rusty water. I drained the coolant from the radiator and then went to remove the cylinder drain plug and the freeze plug. It is clogged with hard black buildup. Read from another post that it maybe some of the radiator leak-stop stuff.

I've banged at it with screw drivers, chissels, put frame hanging wire and old speedo cable on the end of a drill and went to town on it. I'm pretty sure I've made it to the cylinder wall but it's still not draining fluid. It looks like I've got to the opening to the left of the drain hole but there's still more crud in their blocking the coolant from draining.

I've seen how others have used a pump to flush it with muriatic acid. Do i need to have the coolant flowing through the blockage to do that flush? Or will the acid eat up that build up if it just sits in there? I'm thinking of making a hose attachment/fitting to the drain hole and then filling the hose up with muriatic acid and letting it sit for a bit. Would this work?

I'm out of ideas and I've been going at it for 4 hours today. Any tips/tricks technique would really be appreciated!

Also the engine is still in the truck so space is limited, but I do have the flywheel, clutch, transmission and transfer case pulled.

Edit: Think I found my answer here: F engine block flush/ muriatic acid

If you want to try to attack the blockage at the Drain plug with muriatic acid, a way to do this and use a lot less acid is to insert a fitting where the drain plug goes, attach a hose to that, raise the other end of the hose and put a small amount of acid in the hose... give it a while to become exhausted, lower the hose to drain it out, and do it again... possibly several times.

If the acid is doing anything you will have some fumes appearing at the top of the hose most likely... and the acid will be heavily discolored yellow as it drains.


Mark...

Will try it out tomorrow.

 

[John McVicker]

Are you talking about...and is that picture the 'block drain', that is located on the US driver side and towards the rear of the block ?? Exactly where is the location of that picture ?

John

 

[Ramacher]

Are you talking about...and is that picture the 'block drain', that is located on the US driver side and towards the rear of the block ?? Exactly where is the location of that picture ?

John

Yes it's the cylinder block drain on the left rear of the block by the oil sensor.

Sent from my Nexus 4

 

[sggoat]

I'm thinking you might try the muriatic thing and add a good blast from an air compressor after soak-maybe 30 psi? That should bust it up enough to get the gunk out of a normal drain(lower rad hose)---t-stat would be out for this--
Whole system needs to be flushed after--
I would make sure all is drained, mix 1 cup Cascade dishwashing powder in 1 gallon hot water-add to system. Fill to top with distilled water(or RO water)--be sure to burp. Run engine up to op temp(may not get there since the t-stat is out)--run for ~ 20mins. Drain. Refill with RO or distilled. Run again. Drain reinstall t-stat, and refill(burp) with normal coolant--good to go.

 

[Ramacher]

I'm thinking you might try the muriatic thing and add a good blast from an air compressor after soak-maybe 30 psi? That should bust it up enough to get the gunk out of a normal drain(lower rad hose)---t-stat would be out for this--
Whole system needs to be flushed after--
I would make sure all is drained, mix 1 cup Cascade dishwashing powder in 1 gallon hot water-add to system. Fill to top with distilled water(or RO water)--be sure to burp. Run engine up to op temp(may not get there since the t-stat is out)--run for ~ 20mins. Drain. Refill with RO or distilled. Run again. Drain reinstall t-stat, and refill(burp) with normal coolant--good to go.

Thanks. I already have the thermostat out. I actually got the rubber tip of my air compressor blow gun stuck in the drain hole earlier today. Someone in another thread that was a few years old recommend Cummins Restore Plus. If I can't find that I'll try the Cascade dishwasher mixture.

 

[Ramacher]

Update. I've tried a lot of different things and it is still clogged. Well, I got to weep a little but it's not much.

I've decided to take the head off and attack the crud from the top of the block looking down into the coolant channels.

What's the minimal amount of stuff I've got to remove to take off the head? I don't want to take the valves out or anything that'll be a pain reinstalling.

 

[Ramacher]

Another update:

Head was easy to take off, and I got the cylinder block drain unclogged!

After I got the head off I poked around the rear coolant passages with a screwdriver and it wasn't going in more than 1-2"! I even got a screwdriver stuck by lightly hammering it into the gunk. I went it with my bore scope and could see it was badly caked up. So I used a brake bleeder bottle that connects to a compressor to suck up all the nasty coolant that was in the block passages. After that I stuck a funnel and poured in some muriatic acid (about 1/3 of a gallon). Let it sit for 5-10 minutes, started poking around with the screwdriver again and it was much easier to break up the gunk. It finally broke free and started draining out of the plug! I poured in more acid, let it sit, poked and scraped around and drained, and repeated that process one more times. Then I flushed with water a gallon at a time until the smell of the acid was gone and water was somewhat clear.

I made sure the acid wouldn't reach up to the water pump, but completely forgot about the freeze plugs. What are the chances the acid is going to damage those?

There's still build up in the rear right of the block that I'm going to go at tomorrow, should I use more acid or take it to a shop for a proper flush after I have it back together?

sucking out brown coolant

 

[Coolerman]

Another update:

Head was easy to take off, and I got the cylinder block drain unclogged!

After I got the head off I poked around the rear coolant passages with a screwdriver and it wasn't going in more than 1-2"! I even got a screwdriver stuck by lightly hammering it into the gunk. I went it with my bore scope and could see it was badly caked up. So I used a brake bleeder bottle that connects to a compressor to suck up all the nasty coolant that was in the block passages. After that I stuck a funnel and poured in some muriatic acid (about 1/3 of a gallon). Let it sit for 5-10 minutes, started poking around with the screwdriver again and it was much easier to break up the gunk. It finally broke free and started draining out of the plug! I poured in more acid, let it sit, poked and scraped around and drained, and repeated that process one more times. Then I flushed with water a gallon at a time until the smell of the acid was gone and water was somewhat clear.

I made sure the acid wouldn't reach up to the water pump, but completely forgot about the freeze plugs. What are the chances the acid is going to damage those?

There's still build up in the rear right of the block that I'm going to go at tomorrow, should I use more acid or take it to a shop for a proper flush after I have it back together?

sucking out brown coolant
View attachment 1211964

That is by far the strangest plumbing for the remote oil filter I have seen on a Cruiser to date!
Good job getting that mess cleaned out. The rear coolant passages are know to slowly plug up if not regularly flushed out.
For your freeze plugs, I would not worry. You didn't leave the acid in long enough to eat through the metal.

 

[Steamer]

With the pump and t-stat housing off I circulated straight muriatic for 20 minutes. That's when the neoprene pump impeller gave out probably from the heat generated. It really cleaned up a nasty a$$ coolant jacket. I had temporary freeze plugs in but didn't know about the rear one. All was good though.

Little help: flushing coolant / engine block...