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post #1 of 23 Old 02-27-2019, 02:59 AM Thread Starter
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Radiator drain/flush?

I've had a bit of a cooling issue for a while (fan stays on pretty much permanently after initial warm up) and I decided to try flushing the system. I removed the radiator cap and petcock and was able to drain almost exactly 1 gallon of antifreeze from the system. I will say that I thought it was running pretty slowly, but it came out in about ... well, I didn't time it, but I'd guess about 5 minutes. Anyway, this is the 1.8L manual, and should contain just shy of 2 gallons of coolant.

Poking around a little more, I read that there is a coolant drain on the engine too. But despite saying "see image", the Haynes manual has no such image. The factory workshop manual does roughly the same, saying "When draining all of engine coolant in the system, open water drain plug on cylinder block. Refer to EM-200." But EM-200 is "dismantling the engine" and doesn't seem to mention this at all.

This raises two questions. First, where is this thing? But second, if I open this and drain the coolant entirely, (how) will I ever fill it back up again? Presumably the reason it doesn't just come out the bottom of the radiator is that the lower thermostat it holding it in the engine, so will I be able to top it off, or will the thermostats also prevent filling as well as emptying?

I found one video on YouTube, but the guy never actually got more than the first gallon out of his radiator, and I don't think he even realized!

A third question is that I've already bought a new radiator (it's the engine coolant pathways I wanted to clean, prior to putting a new radiator on!) both thermostats, hoses, and temperature sender. Will I have a problem filing the engine with coolant after putting this lot on? Clearly if I pull the radiator, bottom hose, and bottom thermostat, I'll likely have drained the engine OK!

All explanations and guidance very welcome.
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post #2 of 23 Old 02-27-2019, 07:20 AM
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Often the drain plugs can rust in place and you never get them out.

Open the rad drain plug fully or even remove it if you can and then run a water hose into top of rad with just enough water coming out to balance what runs out of the drain. Start engine and idle it, once warmed the stats will be open to also flush the engine too. At that point (20 minutes warmed up or so) you have straight water in system and no antifreeze, you fill the rad back up with 100% antifreeze NOT premixed.
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post #3 of 23 Old 02-27-2019, 06:04 PM
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I thought it was important to use distilled water? or is that an old wives tale?
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post #4 of 23 Old 02-27-2019, 09:35 PM
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Depends on how hard the water is in your area. I never have in either the cooling systems or in batteries here in north Texas. No trouble ever.
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post #5 of 23 Old 03-01-2019, 05:07 PM Thread Starter
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Quote:
Originally Posted by amc49 View Post
Often the drain plugs can rust in place and you never get them out.

Open the rad drain plug fully or even remove it if you can and then run a water hose into top of rad with just enough water coming out to balance what runs out of the drain. Start engine and idle it, once warmed the stats will be open to also flush the engine too. At that point (20 minutes warmed up or so) you have straight water in system and no antifreeze, you fill the rad back up with 100% antifreeze NOT premixed.
This makes good sense for the flush. I've heard elsewhere about seized plugs, and I surely don't want to end up breaking something off in the engine.

I presume the idea of filling the radiator with 100% is because the engine has the water, and the mix will become 50/50 right?

My plan, however, hopefully after I've run flushing chemicals through the engine block, is to replace both thermostats, the hoses, the temperature sender, and the radiator. Given that the block will be "dry" at that point, how should I go about topping filling it? Can I fill the block, perhaps, with the bottom thermostat and hose connected, but the top thermostat missing and just pour fluid in the hole?

Any suggestions on what might work?

(and sorry for going silent for a bit there, work got in the way )
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post #6 of 23 Old 03-01-2019, 07:14 PM
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If the anti-freeze is clear without any suspended particles, I just drain and fill as I replace anti-freeze once every year.
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post #7 of 23 Old 03-01-2019, 09:23 PM Thread Starter
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If the anti-freeze is clear without any suspended particles, I just drain and fill as I replace anti-freeze once every year.
That seems fair in the general case, but it doesn't address my particular problem. The car is 140k miles, bought used, it's been crashed (yes, I made a terrible choice, but now I'm stuck with making the best of a bad job). It's not cooling properly, so I've already bought a new radiator and of other cooling system parts, so my particular problems are:

1) I would like to run a chemical flush though it, in case the pathways in the engine block are partially clogged. For that, I must be able to get the fluid out from "behind the thermostats". I don't think I can even use AMC49s suggestion for this, since the chemical is intended to be mixed with water, not with glycol.

2) whether or not I succeed with point 1 above, I will have to fill the cooling system from "empty and dry". And given that the thermostats seem to seal off the engine cooling pathways pretty tightly, I'm not remotely clear how to do this. The shop manual seems to talk about a specific tool for the job, vacuum system, and other complexities, so I don't think "pour it in and wait" is a particularly viable option.

So, hopefully I'm expressing my problem a bit more clearly / precisely now, apologies for failing previously and thanks for all the efforts you've all made to this point!
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post #8 of 23 Old 03-01-2019, 10:21 PM
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Are you concerned that you might have an over heating issue? or is it just that the fan run all the time?
In cold weather (20 degrees Fahrenheit) my engine temp data stream says it's around 190 once the car is warmed up. I haven't noticed what the fan is doing.

Does the fan run as soon as you start the car in the morning?
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post #9 of 23 Old 03-01-2019, 11:19 PM Thread Starter
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Originally Posted by scarecrowdjinn View Post
Are you concerned that you might have an over heating issue?
Yes. While it's been around 20F here she runs between 213F and 222F, the last couple of days, it's been up to maybe 50F and she's been peaking at 226F. Given that our summer temperatures spend days in the 90F region, and get close to 105~110F sometimes almost every year, I need to get this resolved.


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Originally Posted by scarecrowdjinn View Post
In cold weather (20 degrees Fahrenheit) my engine temp data stream says it's around 190 once the car is warmed up. I haven't noticed what the fan is doing.
Yeah, 190 would be OK, but over "boiling" is not. The fan kicks on at 101C / 213F and never shuts off again because the temperature never goes below that point again.

I suspect they might have put the wrong thermostat in the bottom of the engine, but given that the existing supporting crossmember was damaged in their little crash, I imagine the radiator is probably not in great shape (I have a feeling it's ineffective from being clogged up with leak-sealant, but I have no actual physical evidence of that!) As a result, I have already purchased the support crossmember, a new radiator, hoses, and both thermostats (and the temperature sender), so really all that's left is to install this stuff and keep my fingers crossed. Hence, my major concern is how to refill the cooling system.

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Originally Posted by scarecrowdjinn View Post
Does the fan run as soon as you start the car in the morning?
Nope, it kicks on as the coolant temperature (reported by the OBDII device I have connected) passes 101C/212F. It just never cools down again (well, not quite *never* but it hardly ever gets there, regardless of driving conditions.)
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post #10 of 23 Old 03-02-2019, 09:48 AM
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So many questions............here goes.

The engine may well run at 220 and higher, Fords run routinely at 220-230 (fans on and off temps) and all day long. You WANT to cross over 212 occasionally as it lets the PCV valve pull off water as it boils out of the oil. The water that stays in oil is what whoppingly increases low temperature sludge along with the lower temps. Hotter greatly increases engine life.

Change antifreeze once a year? Yes, if you have money to throw away. I change it every 3-5 years depending on circumstance and using old school green coolant like older cars use. I don't use extended life coolant as most of them take up to 6 months to develop full corrosion protection, the old school has that instantly. I've experienced corrosion with the extended life coolant and the old school lasts almost as long even though they will not tell you that.

There is no 'getting fluid from behind the stats', flushing like I said will open the stats slightly and ALL of it comes out, part of that is slowly dropping back the hose amount of fresh flushing water to make the engine temp come up to open the stats. You can tell them open or shut, the water coming out of rad drain will be stone cold or warm if stat is open. Careful, don't burn yourself.

You will NEVER get an engine bone 'dry' of coolant, all engines will keep at least a quart in various crevices and pockets even with block drain plugs removed. It is not possible to remove all of it.

If you follow my method of flushing you WILL (if competent) drain and clean 100% of every thing in the engine, just don't expect it in 5 minutes. Won't be anything left behind except clean water. Of course, if the rad was corroded inside the engine block passages will be too, no chemical cleaner you can buy and safely handle will remove more than a light amount of that.

Finish flush and drain as much as will drain and then add the full gallon of straight AFZ first, likely all will go in, then fill the rest with water. Most cars are set up (by luck or design) to come pretty close to 50/50 when you do that, bigger trucks won't.

Waste of time filling final fill unless you have all parts back together. Fill and start engine and stay over it watching level to drop (you'll get a big one as soon as engine starts) until the stats open, there will be another slight level drop when that happens. Full then until you drive around say 5-10 minutes at higher engine speeds to purge the system and then another final check, check levels again in a couple more days. Why I love the Fords, they add extra hoses to auto bleed the system, by the time the stat has opened the engine is 100% bled of all air. I have never has to use any tool at all to ever fully bleed a car and lots of them when at the garage.

The first time I do work on mine I intend to remove the inlet stat completely, I want to see if it works. My Fords use the exact same cooling system schematic as my Nissan except that Nissan wants a second stat for some reason. The Ford has nothing there. I suspect the second one is to make a cleaner signal to the ECM as to time to go closed loop from open, I intend to test that idea out. 2 stats are just too much, double the chance of an overheat and a really stupid way to lose an engine. I may restrict the as-cast cooling tunnel from the outflow stat to the block intake as well, that worked fine on the Fords and makes it harder to overheat one.

Stat tricks.....................any stat that mounts with the circle vertical needs to have a small (1/16") hole in it with the hole facing straight up 12 o'clock to bleed air out easier. Some stats have them and some don't. Make a hole with drill if none (carefully consider how far in your sealing gasket fits while deciding how far out to make the hole. You want hole out as far as it can be without compromising gasket seal there. Some have a little 'piddle valve' I call it that wobbles in the hole, I remove them always or they tend to rust in place and then you lose your bleed hole. You CAN put a hole in a horizontal mounted stat but not as effective because the hole is not at the highest point to bleed air. It WILL bleed some air out though with stats shut. The hole can go a long way toward fully bleeding the engine of air.

I should write a book.............
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Last edited by amc49; 03-02-2019 at 09:54 AM.
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