How (and why) I flushed my cooling system

[miner]

I have both success and failure to report.

I went to replace my shut-off valve today. I got the valve unscrewed from the IP but couldn't get it all the way out becase I didn't unscrew the top plate of the IP and swing the ALDA out of the way. Well, I thought, I'll just remove this coolant hose coming out of the block here that is standing in the way of things. The postive: With the coolant hose out of the way the valve comes out easily. The negative: with the coolant hose out of the way lots and lots of coolant pours out of the engine.

So I am reasonably sure that at least a little coolant got into the IP where I had the valve hanging out. Actually, I guess it got into the crankcase, not the IP itself, because there was oil all over the valve when I took it out, not diesel fuel.

So this adds two more jobs to the work list: change the oil and flush the coolant. I had been planning on flushing the coolant at some point anyway since my coolant was green. Just not right at that moment.

So ... the reason why I am posting: here is what I did to flush my coolant. It seems pretty easy. At least easier than removing the engine block drain plug that I only just caught a glimpse of when I crawled under the car.

1. First I removed the radiator drain plug as usual. That got some coolant out.

2. Then I removed the hose that goes from the thermostat housing to the heater line pump on the front of the pass. wheel well (at least I think it is a pump. It has wires going to it and it connects to the mono valve also via a hard line). Tons of coolant came out of this. All of it can be directed down into a bucket too.

3. Then I removed the very topmost heater line coming out of the mono valve. This is the highest point in the system I think. I flushed water through the radiator from top to bottom, then I flushed from the monovalve. All the water and A LOT of coolant came out the hose at the heater pump. I did all this until I saw no more green stuff.

4. Then I put the hose back on the heater pump and flushed some more from the monovalve. The water cam out of the radiator drain. There is a bypass in the thermostat housing that allows this to happen I think.

5. I put the rad. drain plug back in. I filled up the whole system with water from the hose at the monovalve until I saw it fill the expansion tank. This gets the entire system filled with water, right?

The rest is standard: Started up and ran for a while with the heater on as is usually done to let the water circulate. It was getting late so I drove around for a bit and left it there. There was no green tint to the water in the expansion tank that I saw.

Tomorrow I will put in some chemical flush and run it for a while. Then drain everything and fill it up with zerex coolant from the monovalve just like I filled it up with water.

As far as I can tell, this procedure allows you to flush the entire coolant system (heater core and lines, engine block, and radiator) and you don't need to remove the rusty drain bolt.

I ceratinly could be missing something, though. If you think I am let me know so I can fix it tomorrow.

[dieseldiehard]

The only way to get the heavy stuff (rusty scale) out of the engine block is to remove the drain plug, but if you don't see rusty water coming out of the radiator when you drain it it probably isn't worth a block flush. And with that plug being stuck in most cases and very hard to remove without a long extension on a a 1/2 in breaker bar, and using heat, its not worth the effort - just use the chemical flush. Drain out thru radiator and fill thru the S shaped heater hose at the L side where it leaves the block and passes by the oil filter cannister. I've never thought of filling from the mono valve. You want to fill the head to prevent an air bubble, I don't know if the mono valve will pass fluid back to head without going thru the heter core or maybe it OK, I don't know, I just always fill as I was taught - thru the head.
I also stick a hose nozzle (the kind that has a tapered brass end, set to "stream", and run the water full blast into the head and let it come out the radiator, you can remove the lower radiator hose too to get it out faster.
After the chemical treatment flush the system with water at least two times until the discharge doesn't feel "slippery". I usually flush 3 or 4 times before I feel the discharge is clear.
Be sure to drive the car a mile or so to warm up the engine to operating temp and open the heater each time before each flush. Let the engine cool about a half hour before draining the system so you don't hit it with cold water while its hot. Properly done, this entire process will take around two to three hours.

[Brian Carlton]

Originally Posted by miner

As far as I can tell, this procedure allows you to flush the entire coolant system (heater core and lines, engine block, and radiator) and you don't need to remove the rusty drain bolt.

I ceratinly could be missing something, though. If you think I am let me know so I can fix it tomorrow.

DD is correct.

You can add flush water from the top all you wish and the lowest point in the system where it can exit is the thermostat housing. All the coolant in the block remains below this point. It's not a very good design and it requires you to remove the block plug if you wish to get the last three quarts of coolant out of the system.

[rrgrassi]

What about using a "reverse" flush kit from Prestone?

[Brian Carlton]

Originally Posted by rrgrassi

What about using a "reverse" flush kit from Prestone?

The kit connects at the top of the engine. It does a decent job......similar to what was accomplished above.

However, all the coolant in the block remains relatively untouched.

[dieseldiehard]

Originally Posted by rrgrassi

What about using a "reverse" flush kit from Prestone?

If you remove the little Tee that they give you to install for the flushing process, OK.
If you leave the Tee in there, you are on your way to disaster!
My brother lost the engine in his Lexus over that stupid thing. What happened was the center of the cap blew out, after about a year and a half. By the time he saw his temp warning light ON it was all over with! scored cylinder walls and warped head.
I did a search on the internet and found someone else also had the same exact experience! I'll bet there are more than just a few cases like this, as few people are inclined to go and put the info on the Internet, for every one that does there are probably 20 that don't.
So I have to say my opinion of that thing is that it uses cheap parts that are likely to fail and when that happens and the result is most likely your engine will be toast.
Do you want to risk yours???

[Brian Carlton]

Originally Posted by dieseldiehard

If you remove the little Tee that they give you to install for the flushing process, OK.

Naturally, you put the T in place for flushing only.

Who would leave the T in there permanently??

[rrgrassi]

They actually made the tee to be left in. I have left the tee's in my current gassers with out any issues. But, if the coolant does not get touched in the block, then what is the point. The truck has had it's tee in since 20k miles. 169k with out Prestone tee issues.

Only thing I do not get is, why would the block not be affected by a reverse, or even a foward flush for that matter, engine running, hose disconnected, but with a water source feeding the system. It would seem that if the block does not get flushed, then coolant is actually not circulating either. I do see how that happens with a drain the radiator, and drain the head only scenario.

[Brian Carlton]

Originally Posted by rrgrassi

They actually made the tee to be left in.

Actually, they didn't. The durability of that crappy plastic should be clear evidence that it's "one time use".

I'd never leave one of those POS in place.........additionally because they reduce the flow volume by nearly 50%.

[Diesel Giant]

Originally Posted by Brian Carlton

Naturally, you put the T in place for flushing only.

Who would leave the T in there permanently??

Ahhh I left it in my '73 Camaro for over 15 years. Never a problem. Would not do it again after hearing the Lexus story.

[miner]

Originally Posted by rrgrassi

Only thing I do not get is, why would the block not be affected by a reverse, or even a foward flush for that matter, engine running, hose disconnected, but with a water source feeding the system. It would seem that if the block does not get flushed, then coolant is actually not circulating either. I do see how that happens with a drain the radiator, and drain the head only scenario.

This is my thought too. Heavy rusty stuff might not come out, but fluid ought to. I flushed with a garden hose and nozzle. If the coolant in the bottom of the block doesn't move with that, then I don't see how it would ever move. I am convinced that all of the green coolant was removed. The water was perfectly clear after running it for 20 minutes. I'll do a few more flush and runs, though, just to be safe.

I am not currently up to taking out that block drain. The heavy rusty stuff is going to have to stay in there I'm afraid. Actually, though, I am not too worried about loose chunks of rust. I didn't notice any particles or other contaninants in the coolant. I just needed to get it all out so I could put in the pink stuff that is recomended. But, then again, I do have to fix a busted aircleaner assembly at some point. The plug ought to be easier to get to with that off.

Thanks.

[dieseldiehard]

Originally Posted by Brian Carlton

Naturally, you put the T in place for flushing only.

Who would leave the T in there permanently??

AFAIK they don't tell you to remove the tee, so people have a tendency to be in a hurry and don't have a splice or want to buy a new hose to replace the one they just cut to install the tee ~~~~~

[dieseldiehard]

I did a search, now READ THIS

http://www.peachparts.com/shopforum/showpost.php?p=787499&postcount=13

or just see the link! http://www.lunghd.com/Tech_Articles/Cooling/BurpAirMod.htm

[deerefanatic]

This is how I did my flush last fall.

First, be sure you have 2-3 5 gallon buckets!

1. Put empty bucket under radiator. Make sure engine is cold or very close to it. Remove radiator drain plug.

2. Insert garden hose with adjustable nozzle of some sort into coolant resevior. The idea is to leave the drain plug out and have water running in at just the right speed such that it flows in and out at same rate of speed and keeps radiator full of coolant (water in this case).

3. Start engine and run at fast idle with heater on MAX. As engine warms and thermostat slowly opens, you will see a light green tint (or whatever color old coolant is) come into your water stream. Run engine like this being sure to keep water level in radiator up until water runs from radiator clear for some time. Please note, this is not dangerous to your engine as the thermostat opens slowly enough to keep a "rush" of cold water from hitting your engine and doing bad things!

4. Stop engine, plug drain, and fill system with water and radiator flush. (I used prestone citrus flush). I drove car on errends for 3 days with just flush water (NO AC! ) and kept an eye on the temp.

Repeat steps 1-3.

5. Fill with coolant.

-Matt

[Jeremy5848]

I own one of those Prestone kits, had it in a gasser for years with no problem. It didn't obstruct cooling water flow since it was in the heater line. I don't recall problems with the heater, either. I did keep an eye on the plastic cap, however. Nonetheless, I probably wouldn't install it permanently in my M-B.

I would think that hooking a hose to the radiator line on the left side as DD says and allowing water to flow through the system and out the overflow tank would work, especially if you idle the engine so that the water circulates in the block. Water won't leak out of the mono valve because of its check valve (well, that's the theory, anyway) and you can turn on the a/c so that the mono valve is de-energized.