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Radiator flush

dcampbell98XJ

dcampbell98XJ

NAXJA Forum User
Location
Western Connecticut
I have a 98 classic and the PO neglected the whole jeep. My heat stopped blowing hot about 3 weeks ago and am planning to do a back flush of the heater core. I also noticed it looks like there is sludge built up in the overflow bottle and plan on doing a radiator flush once it warms up a bit. I purchased the Zerex super flush kit that you apparently leave in for 3 to 6 hours of driving. Has anyone used this product and if so what we're your thoughts and did it clean out your cooling system? I'd like to flush as much crap out as I can so my heater core doesn't fail or get clogged. Any input is appreciated. I also will be replacing hoses and thermostat at the same time.
 
Good choice.

Those radiators CLEANERS work a whole lot better than the 15-minute flushes.

I would run the cleaner through the system first, THEN attempt the backflush of the heater core.
 
No experience with Zerex, but I used Peak's flush/cleaner. Drained the coolant, ran the engine while filling/draining with a garden hose for a couple minutes, let all the that water drain out, & ended by filling the system with the flush/cleaner & tap water. I ran with that in the system for about a week (30 minutes to work, 30 minutes home = 1 hour a day), then drained it, spent a little time blowing out all the tap water out with compressed air, overhauled EVERYTHING (minus radiator), & filled with distilled water & full concentrate coolant.

While you're at it, even though you're not having overheating issues, you might as well replace the radiator cap too.

My temps are awesome. Haven't seen it touch 210 & I dont think my electric fan has turned on since the overhaul.
 
There are a number of different "strengths" of cooling system flushes/cleaners.

Mild cleaners include citrus and other ingredients.

Stronger cleaners are recommended for obviously poorly maintained systems. Pick your product wisely; go stronger if you're on the fence. I agree with Joe Peters on how it should be approached with cleaning the cooling system, THEN thoroughly backflushing the heater core (both ways) with moderate, not high pressure water stream.

Replacing ALL hoses and thermostat is a great idea. I highly recommend the Mopar 195 degree thermostat. It's the one your XJ came with and can't be beat for reliability and maintaining a stable coolant temperature.

Also examine your serpentine belt as that is ground zero for everything on it's route. Replace it if glazed or older; it's money well spent. I like the Goodyear Gatorback belt for a replacement belt.

Don't forget a new 16 pound radiator cap! Only about $5.00 and should not be overlooked.

Good luck!
 
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I was definitely going to replace all the hoses, thermostat and cap. From what iv seen in the overflow bottle I do not want anything like that in my cooling system. I was planning on doing the heater core separately so to avoid damage or clogging it entirely. I was thinking of just bypassing it for the radiator flush. The flush kit I bought calls to fill the system with water and the cleaner but with the weather being in the low 20's this week and next I don't want to risk freezing cracking the block.
 
Yea, I wouldnt be comfortable with only water/cleaner in the system with freezing ambient temps.

Some people have had luck with running CLR through the system, something like 15 minutes or so. Could get it done in a day & then replace stuff when it gets warm out

How would you do the heater core separately? I would assume the fact that you dont have heat has something to do with the heater core being clogged.
 
I have slight heat just not what it was like a few weeks ago. I was going to back flush the heater core and possibly use the CLR trick. As for the radiator flush I might join the heater core hoses together so none of the crap gets into the core
 
That's a start, atleast for now to get you thru the rest of the winter. Clamp & disconnect the heater hoses, back flush the heater core, & clean out the reservoir. See what that does for you. Just sounds like you got gunk starting to clog your HC up.
 
Yeah I should have done it a few months ago and haven't gotten the chance. Short on time and sleep between work and a 10 month old baby. Now that it's below freezing and my heat started blowing luke warm I wish I made the time
 
xj^REMY said:
Yea, I wouldnt be comfortable with only water/cleaner in the system with freezing ambient temps.

Some people have had luck with running CLR through the system, something like 15 minutes or so. Could get it done in a day & then replace stuff when it gets warm out

How would you do the heater core separately? I would assume the fact that you dont have heat has something to do with the heater core being clogged.
Click to expand...

Just to clarify clr should only be used on the core, isolated from the rest of the system, then Flushed out really well

Do just the core by pulling the lines off of it and doing just the core. I bought some clear flex tube I jam in the hoses so I can direct the fluids into a 5 gallon bucket, and see what kinda crud comes out
 
That was the plan. Iv seen people say to use muriatic acid and iv seen why that can do so I'm skeptical about using chemicals on the radiator
 
I'm very lazy an took mine to a shop to have this done for under 100 bucks.They flushed everything and added new anti freeze when they finished.I had no crap to clean in the driveway or street.Dropped it off in the morning and picked it up a couple hours later on the same day.(went to breakfast)Plus he gave me a NEW cap cause mine was bad.I have a closed system in my jeep.Still runs cold(195/200) in a 110 with AC on out here in the CA desert
 
dcampbell98XJ said:
That was the plan. Iv seen people say to use muriatic acid and iv seen why that can do so I'm skeptical about using chemicals on the radiator
Click to expand...

Muriatic is also know as hydrochloric acid, a strong acid, it eats iron, aluminum and copper. One of the worst choices there is. The OTC heavy duty cleaners have mild acids that are gentle on the metal but dissolve calcium from tap water, and iron and other metal oxides, then the chelating agents like EDTA keep the metals and calcium in solution till you flush. Vinegar (acetic acid) is a poor mans version, but it does not have the other additives. CLR works well but may need a water pump lubricant, that I suspect is in the OTC radiator flush cleaner formulas already.
 
Yeah i worked for a pool company years ago and we sold muriatic acid and I use to get calls all the time from people trying to clean a stain with a aluminum pole. And getting a shower with it when the reaction happened and exploded everywhere like a fire hose. I'm just waiting for some warmth to do this at this point. Thank you everyone for the advice and tips hopefully all goes well.
 
Im hoping that is a stab at the bimmerjeeper guy. iv found his posts to be very entertaining
 
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