You forgot that your not running antifreeze...but water and some sort of cleaner...boils a lot closer to 212 than green coolant, even when dirty

 

I bypassed the heater core and didn’t tighten one of the house clamps so the coolant was leaking from the valve

 

OUCH - there is a freeze plug at the back of the engine close to the firewall that could be leaking or a head gasket. I assume you already looked at the heater hoses and that assembly.

 

I think im leaning toward the head gasket, when i was burping it before there was a very steady stream of small bubbles coming through the neck of the funnel used for burping. and then after driving it to work i let it idle in the parking lot, in the reservoir there is a steady stream of the same bubble every 1-2 seconds. I guess i can try an emissions tester. not sure about doing the headgasket job myself. Ive done lower intake manifold gaskets on a 5.7 vortec which was very involved so maybe i could handle this.

but i should point out like someone else did i am still running only distilled water and thermocure so maybe the water is just boiling.

 

Head gasket is easy. I did one in about 16 hours of work over a few days last Thanksgiving time off work. The head bolts in the back of the head can be a pain to get to since they are under the cowl. You'll have to tape one of the bolts while its pulled up so you can slide the head out, if I remember correctly. It was a pain for me to torque because I have a digital torque adapter and it was too tall. If you have a regular torque wrench it probably fits under the cowl. I have IN/LBS AND FT/LBS torque wrenches, but the in/lbs wrench doesnt go high enough, and the ft/lbs wrench starts too high for the head bolts.

A thick radiator can also work against you at low speed. If you use a thicker one it cant be full of the tubes that the coolant flows through, which is what will block air flow to the rows in the back of the radiator. So you'd really only be getting good air flow to the first 2 rows of the radiator, then essentially heating up the rows in the back. I'm not sure how to choose the proper radiator when getting a thick one, but the airflow through the fins and coolant tubes is the issue at hand. That's just what I've read. But changing back to the OEM radiator was a good idea I think. I've read that the OEM coolant system is very good when it is taken care of.
If you want to get super OCD about cleaning out the system, you can get much more distilled water than you need to run through after the flush to make sure you get out all of the garden hose water and flush chemicals. If you plan on just running water without anti-freeze there in southern Cal., water wetter will help with the water surface tension and allows better cooling. But it does no good if you mix it with antifreeze.

 

Can read here too.

https://bobistheoilguy.com/forums/th...e-help.385505/

Seems to work for some, not for others. Probably depends on the condition of your coolant system and if its filthy or not.

Great all around website.

 

Since last I posted I refilled with just peak universal 50/50. We finally got another heatwave so i was able to drive it in stop and go traffic, No AC this time and i had bypass the trans in the radiator and just used the aux cooler. I installed a trans temp gauge and a secondary coolant temp gauge that is located in the upper radiator hose. I also swapped the temp sender / switch on the back of the block with a new post style connection from an older XJ because my connector the blade style was pretty crispy and loose and you cant buy a replacement easily. I snipped the old connector and crimped on a ring connector to the post.

so driving home stop and go traffic outside temp was 95-100F No AC this time, in sections of being stopped for long periods on the freeway dash gauge would show 220-230 Secondary gauge showed 210. I turned on the electric aux fan but temps didnt lower but also didnt continue to climb but even i turned the fan off it seems like the electric fan makes zero difference on the temp. Once speeds picked up and i was moving for more than a few minutes at 50mph+ temps would finally start to lower on both gauges dash guage showing just a hair under 210 and secondary gauge below 210 maybe 195

As soon as i got off the freeway and got into side streets temps started to climb again back to the same spot. I confirmed when i got to my driveway with the IR gun.

Im going to send my oil to blackstone labs to test for coolant. and do the exhaust gas test to check for headgasket. Oil is always normal, coolant isn't showing oil either but in the radiator fill neck there is a collection of rust flakes again and shiny silver flakes? also if im losing coolant in the system its a tiny amount because its never low. another noteworthy thing is every cold start the exhaust coughs out quite a bit of condensation with this black grime mixed into it. this stops after a few minutes of idling. If it is the headgasket its gotta be like the smallest leak right?


this picture is from behind the thermostat looking inside after thermocure flush looks way cleaner then the previous image. If im still getting rust flake build up in my radiator filler neck do i just need to keep flushing, do another round of thermocure? the coolant stays clean looking minus those flakes that seem to collect there.

 

I’m starting to chase down my own over heating issues on my stock 2001 XJ with 4.0 and automatic trans. Reading through your thread confirmed a lot of what I’ve already been checking on mine. Have you resolved your issue? Any more troubleshooting steps that you’ve taken?

I saw one guy say that the harmonic balancer could be a possible culprit. It’s the first time I’ve heard this so I’m not sure how accurate it is. In any case here’s the link so you can judge for yourself. If anyone that knows better watches that video I’d love to hear your thoughts.

 

Good point..... Most people find that problem when the balancer weight takes off into the radiator.. The belt was the only thing keeping it in place...Glad you found the problem but not before fixing the symptoms....
I'm surprised the charging system didn't show a decline with all the belt driven accessories...

 

Hey Corky,
I haven’t checked my balancer just yet. This was just a video I found in my research for less common causes of overheating. I can’t take credit for the video or the info. Definitely something I will be keeping an eye on though. I didn’t even know this could detach and I don’t want to find it in my radiator, lol.

Jksnevets

 

Ok boys im back with another update since its been awhile, Ive flushed the coolant again and this time i installed a coolant filter on the heater hose bypass to collect all the rust particles. So far its keeping the coolant clean. I also installed hood vents and the hood vents made a huge difference in temps. We have yet to have a really hot day yet in so.cal but so far in testing my temps have been really good. One thing to note though is my temps without the AC remain really good never any issues its really only with the AC on my temps start to go past 210 and keep climbing. But like i said im waiting for a hot day to come around to really test it. I feel confident the hood vents will make a big difference. I also took off the hayden 2737 fan clutch and went back to the stock fan clutch. the power difference for me is noticeable. Hopefully my temps on the hot days are good so i dont have to go back to the ZJ fan clutch.

 

Hi Algebraic429,
When you were researching hood vents did you come across any mentions of concern with rain? I live in southern Louisiana and we get a lot of rain. I’m just wondering if water making its way on top of the engine could cause more problems than it solves.

Jksnevets83

 

This was a concern of mine as well but probably less so for me then you because here in southern California we dont get much rain. Recently we had a lot of rain and the jeep did fine no issues, it was parked outside in the rain and i drove it to and from work no issues. I went with hood vents made by rodlouvers so i called up the shop and asked if i should be worried about rain intrusion and according to the owner of this small fab shop in 20 years of making and selling them only one person has ever had the issue of rain water causing problems in the engine bay, and it was mainly because that person had some worn out exposed wires or something. With all that being said if i lived in a place like you that got real real storms i might consider a smaller style hood vent and maybe fabbing some sort of catch pan. an engine bay is designed to be "water proof" to some degree so some water getting in there shouldn't hurt anything. Im talking water spray not submerging an engine in water like a high water crossing.

The hood vents for me became a last resort type of deal. Ive done everything your supposed to do, replaced everything, multiple flushes and i still got temps i wasnt happy with.

if you go with smaller hood vents you could place them in the most ideal location to avoid any potential for water issues. If this isnt your daily driver and you dont have to drive it during horrible weather id say its well worth it, Im not too concerned about driving and getting caught in an occasional rain storm even a severe one.

 

Algebraic,
Thanks for all of the info. I really appreciate it. I’ll be doing a flush this weekend. Based on how the thermostat housing looked when I changed the thermostat I wouldn’t be surprised if I have some rust in the radiator. In its past life mine was a farm truck in Missouri. Not known for getting top of the line maintenance. I plan on a new radiator soon and possibly a new heater core.
Sucks you’ve had all these problems but I’m glad you documented them here. The last Cherokee I had presented similar issues. I was able to correct it simply by putting in an upgraded aluminum radiator and an upgraded electric fan. Also found out that the computer had been swapped and the new one was not for the correct year. I’m not sure I’ll get so lucky with this new one.

Jksnevets83

 

One item to check is the siphon hose to the overflow tank. I chased down this issue when my XJ started to run warmer than usual. When the siphon hose is plugged with dirt like mine was, it will allows the excess pressure in the radiator to escape into the reservoir. However when the engine cools and creates a vacuum, it's not powerfull enough to pull back any fluid. I found the upper radiator hose was collapsed a little showing that there was indeed a vacuum, but there was no liquid drawn back from the reservoir. Opening the radiator cap releived this vacuum.

I did a flush and refill, replaced the OEM thermostat replaced thebsiphon hose and burpped the system, or so I thought. I found that even if you attempt to burp all of the air out of the system, there remains quite a bit that takes time to remove. The simplest way to remove this air is by repeated heat and cool cycles like the cooling system is designed. I over filled my reservoir a little and during the course of a week it dropped about a half gallon and then stabilized. This would not have happened with the blockage in the siphon hose.

My slight over temp issue was resolved after this. I still have the stock radiator, fan clutch and e-fan.