Cleaned my cooling system: the full scoop...

e9999

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OK, just finished doing a thorough cleaning of my cooling system (my ’97).
Did more than the basics primarily cuz I wanted to see if I had any gray sludge in my system and also see if I could get rid of it if I saw any.
Here are a few observations that might perhaps be useful to the less experienced among us. Of course, I did read first a bunch of posts on the forum that were most helpful. Thanks to Doug, Rich and others for all that good info.

First removed the skidplate of sorts right behind the rad so I could access the rad petcock.

Drained the rad through the petcock. Note that a piece of old 5/8" hose will fit just right through the hole in the crossmember but be large enough that it will hold by itself around the petcock drain plug so it does not splash all over the place and you can collect the coolant in a container. I never full removed the petcock. (That thing feels weird, like there is a big O-ring in there that's sticking.) Flow rate out is limited so it takes a while to empty the rad this way. Also drained through the block drain.

Note that if you drain the rad first and then later the block drain you will still get a lot of water out of the block. There are obviously 2 separate low points, as an inspection will also reveal. To find the block drain plug: separate a bit the middle and rear skirts in the wheelwell on the US DS. You will get a narrow slit. On the left is a vertical bracket supporting the shock. On the right is the rear most skirt. On top is a horizontal bracket. On the lower side are 2 hoses. All these frame a narrow vertical rectangular opening. If you look straight at the block through this opening you will see a lonesome bolt head on the vertical face of the block. That's it.

Started out by backflushing my heaters. Connected a hose thread-to-5/8” adapter into the outlet hose of the heaters before the Tee. This is the hose end that connects with the metal tube going into the water pump. Disconnected that hose from the metal tube before connecting the adapter to the hose end, and left the metal tube open for the time being. Note, the metric hoses are not exactly 5/8” but it’s close enough that 5/8” adapter and hoses fit OK and don’t leak with a tight hose clamp. Any garden hose thread to 5/8” barbed insert will do (see garden hose menders at your local hardware store). I also put in a similar adapter into the inlet hose between the heater valve and the inlet Tee to collect the water coming through the heaters via another garden hose. Note with this arrangement you are backflushing both heaters at the same time. The purpose was to see if I would get any sludge out of there at all. Put in a hose full blast (mine is 120 psi water pressure at the wall, less at the end, saw no evidence of pressure build up with my gauge). Result: nothing to be seen. No sludge. See photo 1 below to show the arrangement for heater backflushing. Note I used quick disconnect hose adapters to lessen the stress on the heater hoses due to screwing a big hose in. You also want to support the hoses (not on the fender). Also added a pressure gauge. With this arrangement, there is no water flowing through the rest of the system which I wanted so I could see better if there was any sludge in the heaters. I ended up changing the lower straight little piece of hose below the heater valve, right after the 180o metal turn with a new 5/8”. Should have changed both and made them a tad longer for convenience. I also changed most of the original hose clamps (the sardine can opener type) with worm gear ones. Much easier to remove and reclamp that way although not as neat looking. (Note all the flushing below done with heater valve open by setting the temp to highest on the dash (you need to turn the ignition on for the heater valve to move, btw.))

Next I did backflush my radiator. For this, I removed the big radiator hose that is vertical right before going into the thermostat housing, the second one from the bottom of the radiator on the PS side (US). Turns out that the diameter of this hose is very close to the OD of a 1” PVC straight external coupling. So I built a little manifold with PVC pipe. It has a pressure gauge so I can be sure that I don’t overpressure the rad. (Did the same precaution with the heaters). The straight coupling is put in the upper end of the vertical hose and secured with a hose clamp. On the other side of the manifold I connected a garden hose again. See photos 2 and 3 below. This way I could backflush the rad with serious flow and I collected the water coming out of the normal inlet (top DS of the rad) from which I had disconnected the hose. I used a flex hose from a shop vacuum to collect all the water off the rad top. I collected it in 5 gals bucket to see if I got any sludge out. None to be seen. (Note that there was also none seen through the rad cap on top so maybe my rad was already very clean.) I should say that there was a smidgen of gray sludge in my overflow tank which I collected for posterity and possible tests. This was odd cuz the rest of the system looked so clean. Perhaps the PO did a professional flushing and rad cleaner job and forgot to clean the overflow tank?
(afterthought: should have also checked if I could see/feel any sludge in the rad inlet (top DS) while I had the hose off - forgot...)

Then I backflushed my block by connecting a hose to the same heater outlet hose I used before but this time I reconnected the inlet hose in the normal arrangement. Opened the block drain plug (worked just fine with 16” of extensions and a ratchet wrench through the wheelwell – put it in between the middle and rear curtains) and the rad drain petcoc&. Did the same again with the manifold in the big hose next to the water pump inlet, but hose on DS top of the rad reconnected. And various other setups to push water in various directions. All the above done with a cold engine.

When I thought I had flushed all the gunk –if any at all- from the innards of the thing, I ran some radiator cleaner (NAPA, cheaper than Prestone and looked like better chemicals). I did it at this late point in the process cuz I wanted to see as an experiment if it would resuspend more gunk, but if you are not interested in such an experiment it is much better to do this earlier, before all the serious flushing. Ran the cleaner for 30 mins with engine idling then flushed again. This was a pain cuz that stuff has some surfactant in and you need to really flush and flush to get rid of it. Again, would be better to do that right after dumping the old coolant so all subsequent flushes help get rid of it. Anyway, no gunk came out after this cleaning either. To get rid of the cleaner I had to reconnect a hose to the heater outlet because just adding water to the radiator would not help cleaning the cleaner out of the block, I thought. You really got to push a lot of water through. Just filling the rad and emptying it with the petcock will not be enough as that water may not mix much with the water/cleaner in the block.

Important note (I think): remember -IIRC- that the thermostat essentially isolates the block from the radiator. So if the engine is cold, the thermostat will be closed and whatever you do as far as flushing the rad will not help much with the block and vice-versa, I guess. Well, actually, there is the tiny hole in the thermostat with the jiggle valve but that is small indeed. More importantly and dangerously perhaps, if you empty the system through the block drain plug and refill through the rad, keep in mind the possibility that there may not be enough water in the block passages which could create some overheating problem if you start the engine and the thermostat is closed. I imagine the jiggle valve is there partly to avoid that problem but it worried me, so I added water through the heater hose instead to be sure the block would be always filled first. Work out a routine so that you don't chance starting the engine with the block drain plug out, put the plug next to the key or something...

I replaced my thermostat and the gasket while I had the thing opened up. Cheap and easy PM. Old one looked just fine though. Had to loosen the exhaust manifold heat shield to get to the housing nuts, though. Housing nuts go back with 15 ftlb IIRC. Put the jiggle valve (little hole) on the thermostat on top aligned with a metal ridge on the housing.

Also changed all the big rad hoses since they were likely the original ones. There are a bunch of small ones too but I did not change those as the risk of rupture seems much smaller with the smaller hoses. If you want to change the little guys, buy some length of heater hose in 5/8” and ½” (and less) and also get the shaped ones from CDan. Changed most of the hose clamps for the big hoses to worm gear type. Much easier to deal with. Big hoses took some efforts to take off. Helped to insert a small screwdriver under the rubber from the end and wiggle it. Thought about putting some lube on when putting them back on to make it easier to remove them next time, but was not sure what to use so I abstained.

I did some more flushing with water trickling in from either the rad cap or the heaters outlet hose with engine running and rad petcoc& opened to mix and flush even more. Also trickled some water in the heater hose and let it come out the rad cap with engine running. Did not try to flush by running the engine with the block drain open. Too risky, I think.

Finally, I added the 5/8” Tee from a Prestone Flush kit into the S-shaped hose at the heaters outlet. See photo. Much more convenient and perhaps cheaper ($4) than to try and find the adapters separately (edit: saw the Tees sold separately at Autozone). This is to make it easier to backflush the system later on. I had a straight coupling ready in case the Prestone Tee would leak but it looked fine and did not leak. The Prestone adapter is a tad long. You might want to cut a ½” off the hose to keep it standard length. I didn't cuz I did not want to kink the bends too much. Seems OK. See photo 4 below for the final arrangement. You might want instead to install this adapter first thing as it is indeed much more convenient to flush the block but as I said earlier I wanted to see if sludge would come out of my heaters. Note that it is easy to catch all the water from the rad petcoc& but not so from the block drain (although it slows to a trickle if you keep the rad cap on). You might not want to push a lot of cold water through the heater hose into the block with a hot engine, btw. I only trickled some in slowly while the engine was running. Btw, never got the water above 80C/180F in the radiator with engine idling. Thermostat housing never got above 180F either. Note that some folks think it is better not to leave this Tee in as a potential weak point. Indeed, a serious leak could prove disastrous if one were to lose coolant quickly. On the other hand, removing and replacing the hose each time you want to backflush may eventually weaken the hose ends as well. Your call!

Then after all this, it was time to flush with distilled water. This is time consuming if you want to let the engine cool down before draining (a good idea I think) so plan for a 1/2 day or so, maybe more if you want to let the engine really cool down and do several changes. (Afterthought: one could remove the thermostat to do this part so the water mixes readily without the engine needing to be hot? That would make it much faster. Better still, go someplace where they have deionizing columns and put a hose into your Tee and flush away with DI water...) Remember that you need to get it very hot for the thermostat to open and the water to circulate around (keep your heaters on too). I opened up the block drain and rad petcoc& and let it all come out. Then refilled with distilled water. Only was able to put in 2 and ¾ gallons, rather than the nominal 4 for the system per the FSM. This means that you don’t get all the tap water out by far, which is annoying. So I filled the rad with distilled water and then ran the engine again to hot so it would all get remixed (got to get it to go above 82C for the thermostat to open, of course). Then let cool, drained again, refilled with distilled water. Etc. You decide how many times you want to do this, but keep in mind that if you only drain once, you may end up -if like my system- with over a gal of tap water still in there. More drains and refills will reduce the amount of tap water in there. After all that, drain last time. Don’t forget to empty and clean the overflow tank. Add the 2 gals of Toy red in the rad, top off with distilled water, check for leaks with a hot engine over a dry pavement spot (if any left), check that there is some coolant in the overflow tank, and that’s it – finally…

I assume my cooling system is now clean as can readily be made by a DYIer. FWIW I am satisfied that it is very unlikely I have any serious amount of gray sludge in there. Of course, it could be that there is some that refused to budge, but I doubt it. That was a lot of work and probably much overkill, but what I read convinced me that a clean cooling system is good PM to reduce the chance of the dreaded HG failure. So I think it’s worth taking the trouble. Took me most of a weekend, but that included waiting a lot for flushing and going on errants to buy parts, installing new parts as PM, and also futzing around with hoses and such. Now that I think it’s clean, got it out of my system, and with the new hardware on, I could do a basic coolant replace in half a day perhaps, including waiting for flushing and draining.


Here is what I would suggest one should buy before cleaning the innards of the cooling system to be prepared for most eventualities:
-Thermostat and gasket (not essential but good to have if you plan on opening up the thermostat housing in case the old gasket gets damaged.)
-Shaped radiator hoses as needed. At least the big ones. I think replacing them is good PM and you can keep the old ones as spares for an emergency.
-A length of 5/8” heater hose for unexpected repairs, especially with the heater hoses. Perhaps some ½” also. Good to have around anyway. NAPA etc have those.
-Block drain plug, maybe, in case you misthread it and it gets ruined (start it by hand, not with the wrench, of course). Unlikely this will happen (esp. given it has a guide stem) but if it does you’re stuck until you get one. Goes back in with 22 ftlb.
-I might get a spare rad petcoc& and its gasket/O-ring -if any there- to be safe. That thing looks fragile and I ended up opening and closing it well over a dozen times.
-Prestone flush kit for the 5/8” heater hose Tee. Note, you'll need to decide if it's smart to leave it in when you're done. I probably will.
-A hose thread to 5/8” adapter -or better 2- for more serious work on the heaters if you wish.
-Several worm gear hose clamps that will fit a 5/8” hose. Some for the big rad hoses as well.
-Toyota red coolant (2 gals, ungodly expensive stuff...)
-Distilled water (at least 5 gals I would say, I used more like 10)

The tools that come to mind as most helpful were:
-14mm (IIRC) socket and 16” of extension for the block drain plug
-ratchet wrench and torque wrench for same
-socket for thermostat housing (12mm? forgot)
-pliers, screwdriver and socket for hose clamps
-cutting pliers for sardine can hose clamps (annoying little buggers...)
-little screwdriver to pry off hoses
-Needle nose pliers for rad petcoc& opening and closing.
-Shears to cut heater hose if you want to do that.
-Garden hose with good pressure (and pressure gauge if pressure is high)
-A second hose to collect water
-Buckets and gallon containers to catch coolant and water
-Something to cover the fender so you don’t scratch the paint –as I did, grrrr….- when you lean over to reach in.
- Gloves so you don't scrape your knuckles on the wheelwell when you try to unscrew the block drain plug... don't ask....

Well, hope this may help, long as it is...

Eric

Addendum:
-draining first the rad, I got about 1.5 gals, and then 1.25 from block
-draining first the block, I got out about 1.75 gals and then 1 gal out of the rad
-refilled and drained 4 times with distilled water, 2.75 gals each time. Note that if you do that, even if about a third of the water is left in the system each time, after 4 drains you only have about 1% of the original flushing tap water left. Ain't that amazing? Good enough for me!
 
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e9999

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dang, can't add the photos using the Modify function. Will try again below.
 

e9999

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here they are....

photo1
This shows the arrangement for heaters backflushing. Used garden hose thread to 5/8" hose insert adapters.
The feeding hose goes into the heaters outlet (it's the hose with the orange quick-disconnect and the pressure gauge). The collection hose goes into the heaters inlet (the plain gray hose).
Note the water does not get to any other place in the system so this arrangement is best if you want to maximize flow through the heaters and check to see if any sludge comes out.
Heater backflush2.jpg
 
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e9999

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photo2
This shows the manifold in place for rad backflushing. It's put in the rad hose right next to the thermostat housing.
rad backflush2 .jpg
 
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e9999

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photo 3
this is the manifold I made for rad backflushing. The part connecting to the hose is the straight part on the left of the 1" PVC Tee. It fits just fine in the big rad hose. I connected a garden hose on the other end of the manifold with a quick-disconnect.
rad rig2.jpg
 
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e9999

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photo4
this is the final arrangement with the Prestone Tee to hose adapter in the heaters outlet hose. Easy for flushing the block. Note for those of you up North, this will obstruct the flow a tad so may reduce the flow through the heaters. But I'm still cranking out air at 150F through the dash, so that'd be enough for California I think...
Also: Warning! if that thing ever leaks seriously, you may be out an engine, so caution is suggested.
heater adapter2.jpg
 
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e9999

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darn, glad that's over...
now next changing the belts... :p
getting closer to serious wheelin', folks... :D
Eric
 
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Thanks for posting the details and pics.

Glad to hear you didnt find any sludge. Good peace of mind there.
 

LandCruiserPhil

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Well done job and write up. FAQ material.

The one thing I did not see was the amount of time you have invested. Could you add it to your post?

Thanks Phil
 
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Good write up.

If one is not inclined to leave the flushing tee installed permanently there is an alternative approach.

Instead of cutting the dogleg heater hose just remove the dogleg hose from the metal tube that runs to the water pump. Using a few inches of straight 5/8 heater hose connect one leg of the flushing tee to the metal tube. Connect the factory heater hose to the other leg of the tee.

Only use this alternative installation if you will remove the tee after flushing, as the extra length of the tee and additional hose puts an awkward bend in the heater hose that is not desirable for a permanent installation.

I don't know that there is any issue to leaving the Prestone tee installed, but since it is made of unreinforced plastic and located above the exhaust manifold I opted for the temporary approach.
 

e9999

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Hi Phil, I'm embarrassed to say how much time it took, but added something above.

Rich, yes you could do that indeed. I'm vaguely uneasy about leaving the Tee in. Would be bad if it broke, so I may perhaps remove it later on. This kit has been very popular for years. I would think they would have removed it from sale if it gave problems because of poor durability. We'll see.

E
 
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E: Thanks for the write-up :beer:

One general question - I believe that coolant is quite toxic, so I'm assuming you drain the rad/block, etc into a bucket (5 gal is enough?) and then take to some facility? Then, when you are flushing, do you just let it drain onto the driveway because it's so diluted?

Cheers, Hugh
 

e9999

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I did collect the coolant from the first drain. Still have it. Will call the sewer guys and see what they say about disposal.
Yes, after the first drain, everything is pretty diluted. And it is biodegradable, I was told.
E

edit: did some reading on disposal of EG. Seems like it is indeed biodegradable but can also be recycled. Small amounts (?) are said to be OK to sewer. Will call anyway.
 
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[quote author=Rich link=board=2;threadid=15351;start=msg145272#msg145272 date=1082963392]
I don't know that there is any issue to leaving the Prestone tee installed, but since it is made of unreinforced plastic and located above the exhaust manifold I opted for the temporary approach.
[/quote]

FWIW,
I did mine a few months ago and as I recall, the preference was not to leave the Prestone T in line. I also recall C'dan recommending not to cut the factory heater hose, as it is a preformed hose and not available at your run of the mill auto shop.

BTW, not trying to steal your thunder Eric, you've done a nice job.

Seemed like the right-up I followed had me working from the other side of the heater valve. Don't know if that matters. I just unhooked the hose that attaches to the heater valve and connected the T to it, then looped about a three foot peice of hose (to avoid the congestion and kinks) back into the heater valve.

Unless you take special procautions, the fluid pretty much gets everywhere when you open up the petc@ck. Put the pets up and hose it down good.

:beer:
Rookie2
 

e9999

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Hi R2:
I don't think cutting the heater hose is a biggie. You can always put a small metal straight coupling in there with hose clamps to sew it back up if you so wish. Would be stronger than any number of other places in the system and would only cut down a bit on flow.

If you worked from the heater valve (i.e. inlet to the heaters), you probably did not backflush the heaters but rather the opposite I would think.

If you put the piece of hose on the petcoc& stub and don't remove the petcoc& completely, it won't splash at all but instead gently drip into your container.

Eric
 
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[quote author=e9999 link=board=2;threadid=15351;start=msg145442#msg145442 date=1083000821]
Hi R2:
I don't think cutting the heater hose is a biggie. You can always put a small metal straight coupling in there with hose clamps to sew it back up if you so wish. Would be stronger than any number of other places in the system and would only cut down a bit on flow.

If you worked from the heater valve (i.e. inlet to the heaters), you probably did not backflush the heaters but rather the opposite I would think.

If you put the piece of hose on the petcoc& stub and don't remove the petcoc& completely, it won't splash at all but instead gently drip into your container.

Eric
[/quote]

I'll definitely keep this in mind next time around.

:beer:
Thanks,
R2
 
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I found some gunk in the oil cooler passages during my engine rebuild. You might pull that off next time if you feel like digging it out from under the exhaust manifold and motor mount.

No big deal on the prestone T. It seems like standard equipment on used cars :).
 
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This is a good write up-- but I have a couple of questions.

I may have misunderstood, but why did you do a two step process on backwashing the heater cores and engine block. If you used the same input in both steps, couldn't you just back flush it all out through the engine block?

Or were afraid that gunk from the heater core would get stuck in the block?

And one more question--why didn't you just replace the heater hose you had to cut (for the t-fitting) when you were done?

Jared
 

e9999

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Jared:

Yes, I could have backflushed the heaters into the block but thought that I might end up with more gunk in the block that way. By doing only the heaters, I got more flow / pressure and was able to collect the water/gunk right out of the heaters. I wanted to see what if anything would come out as a warning sign that I was into gray sludge territory.

I didn't replace the heater hose cuz I wanted to leave the Prestone Tee in. Besides, it's a shaped S piece that could not be easily replaced by a by-the-foot 5/8" chunk unless it'd be pretty long. Also, remember that I started out by not cutting it and simply tying a hose into it. So the cutting was strictly to put the Prestone Tee in. I may or may not change that.

E
 

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