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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Anti-freeze is colorless and a dye is added. Some dealers buy bulk which is colorless and a dye is added. It could make it any color. But generally they stick to colors that designate type.
It was a good move to flush it out and re-do. One big issue with anti-freeze is pH, which changes over time. B/c your Jeep has Iron, Copper, Aluminum components mixed together and they each have a 'happy pH' they like to live with, there's a narrow range where you can satisfy all 3 w/o scavanging the metal. The aluminum heater core is perhaps the weakest link. You get out of the range and the anti-freeze can literally 'eat' the thin aluminum away.
So, now that the job is done, double-check the pH. I'd adjust it so it's in the 9.2 range perhaps, or whatever the center range is for all the metals in your system.
Pure distilled water has a ph of 7.0. A solution of 9.2 seems very alkaline to me. Better alkaline that acid I suppose.
Wrong pH will eat away at metals. It's what science proves. Professional manufacturing knows it, and I've seen neglected pH cause untold damages to big equipment. Ever wonder why so many XJ owners are replacing their AL heater cores??? I doubt it's all b/c of age. The al got eaten away. All metals get eaten away eventually, but they just make blocks and water pumps heavy enough to allow some sacrificial decay. Heater cores and radiators don't have any 'meat' to them. Add a little sodium hydroxide to get it up higher (drain cleaner), or lemon juice to lower. Use an inexpensive ebay pH tester to measure. Just something to be aware of. Lots of writing about it online. Here are a couple articles I found in a quick search, but there are detailed white papers on the subject. When you get into large industrial cooling operations for food processing and industrial boilers (steam/hot water), water chemistry really matters. Not trying to preach, just point something out to help XJ owners get the most out of their equipment. I never used to pay attention to it either.
I had the water pump on my 1996 XJ 4.0 replaced last year, or 2 years ago at a shop. Turned out the only thing leaking was the gasket. Had them put the new one on anyway. Original factory pump lasted about 349,000 miles, and I have been horrible about replacing my radiator fluid, but it is still green.
Have dye in it this week checking for leaks and from this thread I now know to look at the radiator with the UV light too.
From time to time I've sprayed the hoses with plastic safe silicone spray. Still has original hoses except for radiator, which was replaced in 2004ish. Only coolant leaks I've had was from the heater valve, and I just replaced that a week ago again, third one total on this Jeep. And the overflow hose was leaking up near the cap, which was a weird one. Took a day or so to track it down. Came close to overheating "bad" twice.
If I catch any leaks, I have a full set of hoses and a thermostat in the Rock Auto shopping cart ready to order.
Last edited by 318SixPack; 08-08-2019 at 10:45 PM.
Reason: misspelling
I've been a toolmaker all my life and am very aware of metallurgy, but not too much knowledge of the corrosion factors except for salt water electrolysis and dissimilar metals in contact. Do you think it would be advisable to add a zinc anode somewhere in the system or just keep the ph in the "sweet" zone and change the coolant regularly? I've never paid much attention to the chemistry involved in cooling systems. I have had a problem once with a flathead Ford V8 that someone had put aluminum heads on it and used the original studs. They was so corroded we had to start it up with the head nuts loose and "blow" the heads loose! Then crank out the studs with vise grips.
If you're running low or high pH, why bother ....your aluminum heater core will become your sacrificial element!! ha, ha.
Seriously, though, there's lots of info on the web per commercial water heating situations. But it applies to vehicle cooling as well.
In the older cars that had copper heater cores and radiators, the pH range where metals were still 'happy' was a lot wider. You could get away with more neflect back then, they could stand more neglect.
Last edited by Jeepwalker; 08-09-2019 at 09:56 AM.
If it were me I would simply flush the hell out of the system then refill with distilled water and coolant of your choice. As long as you fully flush the system before you add in a new coolant you should still be good to go. Mixing coolant types isn't something I would do even if the bottle says "mixes with all coolant types". Getting it wrong can be quite costly and time consuming to repair even in your own garage. You can quickly turn your cooling system into a jellified mess.
I can see the draw of going with a HOAT or OAT coolant for extended change invervals though. Just be careful. Id' be careful going by color as well. There are colors that are the same between the various types and again it's not something you want to mess up. You really need to KNOW what's in the system and KNOW what's in the bottle you are filling it up with.
Wrong pH will eat away at metals. It's what science proves. Professional manufacturing knows it, and I've seen neglected pH cause untold damages to big equipment. Ever wonder why so many XJ owners are replacing their AL heater cores??? I doubt it's all b/c of age. The al got eaten away. All metals get eaten away eventually, but they just make blocks and water pumps heavy enough to allow some sacrificial decay. Heater cores and radiators don't have any 'meat' to them. Add a little sodium hydroxide to get it up higher (drain cleaner), or lemon juice to lower. Use an inexpensive ebay pH tester to measure. Just something to be aware of. Lots of writing about it online. Here are a couple articles I found in a quick search, but there are detailed white papers on the subject. When you get into large industrial cooling operations for food processing and industrial boilers (steam/hot water), water chemistry really matters. Not trying to preach, just point something out to help XJ owners get the most out of their equipment. I never used to pay attention to it either.
I just picked up some coolant test strips at the Cummins shop here in Knoxville. Less than $2 each. They have them in bulk too, but didn't see the need in spending $50 to check mine out.
Wrong pH will eat away at metals. It's what science proves. Professional manufacturing knows it, and I've seen neglected pH cause untold damages to big equipment. Ever wonder why so many XJ owners are replacing their AL heater cores??? I doubt it's all b/c of age. The al got eaten away. All metals get eaten away eventually, but they just make blocks and water pumps heavy enough to allow some sacrificial decay. Heater cores and radiators don't have any 'meat' to them. Add a little sodium hydroxide to get it up higher (drain cleaner), or lemon juice to lower. Use an inexpensive ebay pH tester to measure. Just something to be aware of. Lots of writing about it online. Here are a couple articles I found in a quick search, but there are detailed white papers on the subject. When you get into large industrial cooling operations for food processing and industrial boilers (steam/hot water), water chemistry really matters. Not trying to preach, just point something out to help XJ owners get the most out of their equipment. I never used to pay attention to it either.
The test strips I picked up at the Cummins service center are Fleetguard brand, part number CC260B, each card contains 1 test strip. Tests for Freeze Point, Molybdate (MoO4), and Nitrite (NO4).
5 strips/cards just over $9 with tax.
Is the Molybdate (MoO4) something diesel specific, or is it something to watch in gasoline engines too?
Just used a Fleetguard strip and followed the instructions to the letter (longer description of process below). Looks like I am good to -30 F (agrees with my Prestone float tester too), however the other two test pads did not match anything on the card.
Longer description: Drove out for some errands, returned home and parked nose up hill. Let it run with heater on for about 20 minutes. In the recent past, I thought i was catching a whiff of coolant in the morning right after start. No odd smells today.
Shut down and let system cool off for a couple hours. Checked and temp gauge was a touch over 100F, ran engine for a sec to check if temp was accurate, shut down. Cap felt hot, left hood open and came back later.
After all cooled down (Fleetguard says to use strip at room temp), set up camera and tested according to instructions. It says the coolant is good to -30F, but the Molybdate (MoO4), and Nitrite (NO4) did not match anything on the chart. BTW, Prestone tester agrees and says high side I am good to 265F.
So I guess I should find some of those PH strips from Walmart to get some usable results.
Big plus is it sounds like the heater core is still good, so when I change this fluid I can stop at changing fluid, since hoses still look great too after over a week of dye in the system and no hint of leaks.
Edit: Extra big plus. Oil analysis from WIX just came back, no coolant in the oil and water <0.05%. The rest of that sample was normal too. One year and 3K between changes. Guess I will take a sample in 18 months and see what's up there.
Last edited by 318SixPack; 08-17-2019 at 08:52 PM.
My cinematography skills were not their best today. Here is a still of the card and the strip. Strip reads from top pad, matches with top row of card. Middle pad reads left side of card. Bottom pad reads bottom of card. Wish I knew how to resize these pix for this forum. Test strip reads top to bottom in this view. Full chart.
08-08-2019, 09:21 AM
