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School Me In Coolant

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Well, I've noticed that my coolant is brown and thick like a hearty soup. This truck has been sitting for about 3-4 years and it's time for this to be done before I bring it in for a saftey.


Now I would want to flush the system first, maybe pou about 2-3 litres through it and then start to add coolant. But I've heard that these truck have problems taking on coolant.


If I wanted to do a flush were would I want to place my bucket or drain pan?

where would I drain it outta?

Tips/Trick for getting it done?

what could I use to clean the pressure bottle? just more coolant?

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Yes, you need a flush.....


But I don't know your project off-hand so my ideas are going to be for the Renix era closed system.


I generally drain from the lower radiator hose. I pull it at the radiator and that gets the lower end of the block plus the radiator. I aslo pull the heater core lines and drain the pressure bottle.


I have a section of heater hose with a garden house attachment to use as a power flush. I first do the heater core, than I remove the thermostat from the housing, remount the housing and flush the block that way.


To refill the system I start by reattaching all of the hoses, but I remove the upper radiator hose at the engine. I hold the hose as high as it can get and then pour anti-freeze in it. You will get water running out of the water neck as you do this. Once I start to get anti-freeze out there then I know its pretty full. I forgot to mention, my thermostat has the small hole (5/16ths IIRC) drilled in it to prevent massive overheating from thermostat failure. I put the radiator hose back on then, Then I will fill the pressure bottle up with anti-freeze. Then I start the Jeep up and let it warm up. I keep adding anti-freeze to the pressure bottle when the level drops.


Yes, these systems are notorious for getting air pockets and needing 'burped' But this method is the best I've found for minimizing this. Some guys will remove the coolant temp sensor on the back of the block to help get the air out, but I generally haven't had to do it.


Almost forgot, I check the level in the pressure bottle over the next few days of using the Jeep, and make sure i keep the pressure bottle topped off.

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yeah I forgot to mention that it's a 4.0L 1990 so yeah the renix era..


do you happen to have a few pictures laying around that you could show me exactly what you're talking about.. if you don't that's ok.. I'm a noobie at doing coolant..


will this method create quite a mess? if so I'll lay down a few rags..


Is there other method of doing a full system flush, or is that the only way?


someone mentioned to me that I might have to toss the heating switch in the truck to full open, so that I get a complete drain or something of that sort... is that true?


I'm trying to make this as easy as I can.. so any other tips or trick will help alot thanks for the reply bro!

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First, it makes a holy mess. I catch the coolant in a cut off plastic barrell I keep around for it. Once most of the coolant is out, I just let the flush water run down the drain.



There may be other ways, but this is how I do it.


The heater valve is right near the heater core on the heater lines, so that is why I disconnect the heater hoses and flush the core seperately. The vacuum valve likes to stick either open or closed(seems like its always closed in the winter :eek: ) I am planning on removing the valve, as the wheeler Jeep has no doors anyway.


I'm not sure what pictures you need. But I need to flush the cooling system of my wheeler, so I can snap a few pics if you want.

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ok well I've been trying to id those hoses you've been talking about... and I found 2 rigid lines (one mounted higher than the other) that connect to the rad on the drivers side, and run all the back to the passanger side and connect to the side of the transmission? (the behind the area that the starter is connect to) and there is also a large black hose that connects inbetween them at the rad.. and goes to the bottom of the engine (drivers side) what do I do with those? which one do I want to disconnect?



and then there is a large rubber hose (black in colour) from the pasanger side top portion of the rad that goes to a steel tube infront of the valve cover. On either side of that there is 2 other rubber hoses (orange in colour) the one on the passanger side inreferance to the Large Black hose (I assume is the pressure side) that goes to a Tee and from there goes to the bottom of the bottle and also goes to the firewall.


The other orange hose that's on the driverside in reference to the Large black hose also goes to a tee and fom there goes to the top of the bottle (return?) and also into the fire wall too and it is below the one that also goes into the fire wall...



Which lines do I wanna disconnect? and where do I wanna discoonect them?

This is my first time doing this and all I have is bottles of coolant to refil the system.. and all the stores are closed so I can't buy anything else, so if your suggestions could work around that it would be greatly appearicated.. Thanks again for all your help guys.. !!!!! <3

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So In my attempt to get somehting done.. I disconnected the top rad mounts so that I could see what I was kinda doing... and then I disconnected the Large Black hose on the drivers side that was inbetween the two rigid line that connect to the top and bottom of the drivers side rad.. and I disconnected it at the engine beside the water pump.. and whoosh all this coolant come running out... I wasn't expecting that.. I also disconnected the Large black hose that conected to the top of the passanger side rad.. and tried to pour som coolant down it to see where it ended up and it came out the hose that I disconected at the engine.... if I were to run water though that what would I be cleaning out? and what would it leave for me to finish the process? I'm a real noobie at this..

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I do not like to use the petcock valve to flush coolant. I've seen to many radiators start to leak at the valve. So if I never have to touch it, I'm fine with that so I don't have to worry about it ever leaking.


Undo the bottom hose, drain coolant. Take hose and flush water threw the system. I again am not a huge fan of additives to flush the radiator. Water works just fine...

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ok.. so I undid that hose that sits on the drivers side and goes to the water pump.. and I let that drain out... and I removed the Pressure bottle too... would that give me a complete flush? where would I want to attach my garden hose too?


don't I have to do the heater section too? what about the hoses at the bottle what do I do about them.. they are still filled with the old bad coolant!

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Sorry, Family junk got in the way today,..... I've been out shopping for minivans.(That is completely another story though)



Take the hose from the side of the pressure bottle and follow that back to the heater core.(That's where it goes into the firewall) And disconnect that hose. That is where I connect the garden hose and flush out that end of the system. I took a spare piece of heater hose and attached a garden hose replacement end to it for attaching the garden hose. I keep pumping fresh water into the their until I only get clear water out. You need to have the pressure bottle installed for this to work.


I apologize, I didn't realize that you didn't even know which hose was which on the cooling system.


The lower radiator hose is the large black one that goes from the lower side of the water pump to passenger side of the radiator. I also never use the petcock drain unless I am removing the radiator for exactly the same reason. They tend to clog with whatever crap is in the radiator and then either crack, or clog up and you can't get them resealed.


The upper radiator hose I disconnect(after the draining is complete) at the water neck(the part attached to the engine) and hold it up in the air and fill here. If you have reconnected all the other hoses, then the clear water will flow out of the water neck. Once I get the amount of coolant in that I want in, I reattach that hose. Roughly 5qts. is what is recommended here in the northern Midwest. There should be a chart on the back of the anti-freeze jug giving you a recommendation.


The only additives I ever use, is cider vinegar for flushing(per the recommendation of someone here who I have an EXTREME amount of respect for). And I add a bottle of 'water wetter' to the pressure bottle after the flush and fill is complete, to help combat the inevitable heating problems I get every summer.

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so with the coolant I'm supposed to add water? I got a bunch of pre-mixed anti-freeze/coolant is that good enough?


I thought the system took like 11.5Liters.. do you add a lil less and then the rest with water?


the "water neck" is the thing in the front with the 3 hoses that meet infront of the valve cover?

And that hose from the "water neck" when I'm putting in water from the hose that goes to the firewall.. I want the bottle attached and that one large black hose on the top that's at the passanger side attached too as well as the hose from the driver side lower rad connected to the spot beside the water pump which also connects to the drivers side?

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I also disconnected the coolant temp sensor so I could get more fluid out... and I should also mention that the truck is on a bit of an incline too the front is up a bit higher.. I read in some of the other coolant posts that you want to do this...


I don't know if you have Msn messanger, if you do you should add me

Wakka_round@hotmail.com and maybe you could kinda walk me through this in real time..!


And I want to thank you very much for all the help you have given me.. it's greatly appearicated!!

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Now to make everything soo much easier I connected all the lines back up and put the coolant temp sensor back in the only line that I have disconnected at the moment is that one line that runs from the return side of the bottle to that tee where it breaks off and one hose goes to the firewall and the other to the "water neck" it's disconnected at the firewall...



Now when I hook the hose up. where is the water going to come out of to provide the Flush? back into the bottle? or should I have another line disconnected somewhere with a drain pan under it?

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Flush water goes to the firewall connection. the water will run out of the line you disconnected from that spot.


I usually start the flush with the lower radiator hose disconnected to get as much gunk out of the system as low on the block as possible, rather than pushing the junk all the way through the system.


Yes, pre-mix is fine. I don't buy it because its almost twice the price of regular anti-freeze. A 4.0l cooling system holds roughly 12 qts(US) or 3 gallons of fluid. I dug out the FSM, and it shows 11.4l for you darn Canucks 8). Look at the back of the jug, and it should give a recommendation for your particular winter temps. I can't tell you the exact number as there are parts of Canada that are more southern than where I live along the Illinois/Wisconsin border. For my particular needs I need about 5 qts anti-freeze.


You could run straight anti-freeze, but that is a recipe for overheating in the summer and low heat in the winter. Anti-Freeze doesn't have the heat carrying capacity of water.

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