hobhayward

Planning on doing a coolant flush tomorrow, using the t fitting method posted here: http://www.xjtalk.com/showthread.php?t=5936 I have a kit that came with the fittings, adapter etc. and am planning on getting a short length of heater tube so that i don't have to cut the tube and after the flush I can remove the T as they are prone to failure over time.

My xj: '99 with 130k, radiator and pump replaced within the last 20k miles by the previous owner, coolant is brownish but not sludgy.

The OCD side of me wants to flush the heater core, radiator and block all separately to avoid gunk from traveling between them, however the lazy side of me wants to just stick a T fitting on there..

Questions:
1. Any reason not to follow this guide?
2. I'm assuming the coolant should be drained into a bucket via the lower tube on the radiator and the system filled with water before starting the engine?
3. The garden hose should not be turned on without the engine running/up to temp so that the thermostat opens to avoid over-pressurizing any lines?
4. Tapping into the heater core return line would mean that all the junk coming out of the block/radiator gets flushed back into the heater core? Unless of course the valve to the heater core isn't opened by turning the heat on until after the rest of the system flows clear?
5. Regarding the above, I could swear I read somewhere that the 97+ models heater core is always running?
6. The FSM and my Haynes manual both say that the air in the system should be eliminated by cycling the engine on and off warming it up and letting it cool so that coolant is sucked in and air is eliminated as necessary via the radiator cap (open system). Is this just as good as 'burping' the system with a funnel in the radiator fill (or just spewing coolant all over as air comes up)?

Sorry for the supremely noobish questions, just want to do this right as I had a friend do it wrong and ended up cracking his head because he didn't pay attention to it overheating. Thanks!

Pelican

The '99 ('97+) doesn't have a heater control valve so no need to worry about that.

I've been using that kit for many years with my '85 and '93 and I just follow the instructions on the card. No need to get creative.

A lot of people say the T-fitting gets brittle. I've never removed one or had a problem but can't hurt to remove it.

I take it that the funnels are convenient but are not necessary. '91+ open systems self burp over a couple of heat/cool cycles. Just make sure you patiently fill the system and have coolant in the overflow bottle for the system to suck up when it cools.

I've never flushed the various components separately but you could do if you feel that you have some really bad crud in there.

MrTowers

woah seem to be over doing it a little.. flushes are cake my friend.

Pop the lower hose off the radiator (catch the coolant of course), then pop the top hose off. Flush both ways. Just use a CLEAN rag to fill the gap between the hose and the garden hose so water actually goes through it.

The "ocd" side of me always replaces the thermostat when doing things like this.. so i'd just take the thermostat housing off and pull the thing out of there! From here you can take the heater hoses off and flush those both ways.

To flush the block, you'll have to put the thermostat housing back on without the thermostat installed so you have somewhere to put the garden hose. Flush both ways. Then re-install everything!

the air in the system thing is correct. To fill with minimal air left over, leave the top hose off radiator and fill through the cap. This gives you a vent path for the air in the system. When water comes gushing out, attach the top hose and top off through the cap. Leaving the cap off, turn the engine over. You will see the coolant get sucked in or swirl around a little, top it off again. After a minute (or sooner.. or later) the coolant will start to heat up and and come out of the cap. When that happens, install the radiator cap. Put a little water in the overflow bottle and call it done!

hobhayward

Thanks guys, I know I'm over thinking it but I'm a total noob and everyone out there has their own way of doing it, on top of no one doing it like the FSM suggests so I keep getting confused..

One thing though, if pumping cold water into the system via garden hose it seems to me that the tstat would open and then close after being hit with continuous cold water? Or that you damage the block by hitting it with cold water, but that's what happens every time you run it after it's cooled off. Reason I'm thinking that is that I also heard it's bad to add cold coolant to a hot system. Here I am over thinking it again lol

Pelican

Firstly, you never add cold water/coolant to an over heated engine that has lost its coolant.

Also, you will not over-pressurize any lines because of a closed thermostat with a normal household water system. You don't have to turn the faucet on full blast if you have really high pressure. You are just trying to back-flush the system which will occur when the water hits the closed thermostat.

If you believe that your heater core is really blocked, there have been threads in the past year about cleaning with chemical cleaners and separately flushing. I guess I've just been fortunate in keeping a reasonably clean system. Every couple of years I clean with the Prestone stuff that you leave in the system for several days of driving before flushing and this seems to really keep the system clean. I would recommend that you do this now if you are not sure what care the PO has given it.

I don't know if this answers your question but come back if you are still concerned.

And again, you will be okay if you follow the directions in the kit.

hobhayward

Some issues came up while I was doing the flush..

Drained from the lower radiator tube where it connects to the waterpump. Did the flush with the T installed in the heater core inlet hose. Coolant actually was pretty much perfect, nice and bright green. I thought it needed a flush because the overflow tank was brown but it was just from dirt in the tank.

When I went to add new coolant I was only able to get 5 qts. pure antifreeze in before it wouldn't take any more fluid. Had been planning 6 qts. pure and top off with distilled water to compensate for leftover fluid in the system. Additionally when I was filling, nothing came out of the T fitting, even when the radiator fill wouldn't take any more fluid.

Temps during a 25 minute first drive were solid at 220 (one tick past 210/the middle). A few hours later my next drive it got to 210 and stayed there. I'm assuming there must have been some amount of air in the system despite the fact that I didn't see a drop in fluid level in the overflow (which was topped up with 50/50).

Planning on driving it 3 hours tonight.. Any ideas why it wouldn't take enough fluid and why the T fitting wouldn't overflow at all? Do you think I have a reasonably appropriate coolant mixture?

Also as soon as the thermostat opened temp gauge on the dash dropped below 100, is that ok?

Thanks!

RTorrez1

You have way to much antifreeze. It is suppose to be 50/50 in the entire cooling system, Not just the over flow.

hobhayward

Its a 12 quart system though, plus the overflow. Therefore 6 qts. pure plus the leftover water in the system should equal 50/50.

From the FSM for 99 XJ:

COOLING SYSTEM
2.5L . . . . . . . . . . . . . . . . . . . . . . . . . 9.5 L (10 qts.)*
4.0L . . . . . . . . . . . . . . . . . . . . . . . . 11.4 L (12 qts.)**
*Includes 2.2 L (2.3 qts) for coolant recovery reservoir.
**Includes 0.9 L (1.0 qt) for coolant recovery reservoir

Pelican

If you did the flush and then put in 5 qts. of antifreeze you should be okay unless RTorrez knows something we don't. I usually run into the exact same situation when refilling except I always have some come out of the T-fitting. In any event I typically get about 5 qts. in during the first fill. Don't know why you didn't get some out of the fitting but can only guess that you didn't have the system as full as you thought. Did you start the engine after starting the fill to get the initial circulation?

Your mixture should be fine. "50/50" is a good average but you will find recommendations ranging from 30% to 70% water/antifreeze.

hobhayward

I did start the engine in order to circulate coolant, however I capped the T fitting before I started it up. I ran it until it seemed to be close to operating temp at which point it was just spewing coolant out the radiator filler. Didn't end up making that 3 hour drive tonight, pushed that till the AM, but another two 25 min drives it stayed rock solid at 210*. I think I should be ok, but I do wish I had distilled water in there instead of garden hose stuff.

cropduster

Your jeep won't care about hose water vs distiller. I just did the same process even though the coolant in there eas only about 15 months old. I bought a Peak flush kit for $4.50 at Pep Boys and a gallon of Peak extended mileage grrn anti- froze plus a gallon of premixed stuff. It flushed out fine. I ran clear water until it hit 210 and flushed until clear cool water came out the radiator cap. Then refilled with coolant, water and topped the overflow off with the 50/50 premix. Holds 210 or slightly under in 96 degree heat.

Snotzalot

If your tap water is as mineral free as distilled go ahead and use it. My well water isn't so we buy one less scratch off and can afford $5 worth of distilled.

Make sure the anti freeze and flush is disposed properly and not just drained into your yard. If you have central sewers you can pour it down the drain.

hobhayward

How much coolant were you able to get in the system?

cropduster

A gallon and the rest water and then filled the overflow tank with the pre-mix stuff.