Flushed coolant, still a click above 210?

Hey guys,



As the temps have gotten hotter in the south, I've started to notice my 2001 xj run a little hot. All winter long it's been running at 210 with no issues.

Yesterday I used a prestone flush and fill kit to give the system a good flush.

Refilled with 50/50 and parked it on a slope to let burp.

On the drive home, it got up to a click above 210 and stayed there. I originally thought it was the fan clutch, but it seems to not overheat at idle, but does when there is a load.

The radiator / 195* stant thermostat / gates water pump and hoses are all 4 months old. The heater core is currently bypassed.

Any idea what could be going wrong? Would really like to solve this issue soon.

Thanks for your time and any advice!



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It should run about 195-215*. Have you confirmed temperatures with an IR temp gun pointed at the thermostat housing ? I might consider a new fan clutch and a fresh 16 lbs radiator cap as preventative maintenance.

Your electric fan should be kicking in at that temp, is it?

By "load" are you saying climbing a long grade on the highway? Go to Advance Auto Parts and borrow one of their code readers and see what the PCM says the temperature is. At least on my 2001, the gauage is "dumbed down" past 210F. My electric fan kicks on at about halfway to the first tick mark past 210F. Make sure your electric fan is working and that you plugged it back in after you did the radiator job. ;-) The 2001's also had the minicats which can create a lot of heat. Do you have any fault codes for O2 sensors/cat efficiency?

I have not verified it with a temp gun.

The electric fan is definitely on and it sounds like it's doing overtime to try to get it down to 210.

Yes, it actually runs hotter on the highway. Which is odd to me.

I also just read that open cooling systems are self burping.


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Verify the actual temperature.

Consider that the new parts aren't moving coolant like they should. Defective thermostat not opening all the way?

In another thread you mentioned an oil sheen in the coolant reservoir.

Check the plugs for evidence of a head / had gasket leak.
Check for hydrocarbons in the cooling system for evidence of head / head gasket leak.
You may also wish to look into a leak down test for evidence of head / head gasket leak.

It ran fine for the past 4 months, unless the thermostat failed within this time period?

If the headgasket was an issue, wouldnt I see bubbling when I look inside the radiator cap at idle? I will do a contamination test to be sure.

Also, as a side note... I took it for a short drive this morning. The fan clutch felt the same when the car was hot compared to when it was cold. Not easy to turn. No free spinning at all.

Thanks again for the input.

Time for a radiator

Digger87xj said:

Time for a radiator

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True or have a shop do the flush. Service should be done on rads every 5 to 6 years. Normal temps out in the desert ( Palm Springs CA ) during summer is over 100 an my jeeps run around 200 and with AC on 210/215.

I would've suggested a radiator but he says he changed it within the past 4 months.

Head gaskets/heads can fail in multiple ways. If its minor you may get the oil sheen like you had and some warm/hot running but no bubbles.

erykv1 said:

Yes, it actually runs hotter on the highway. Which is odd to me.

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My 96 did this and I thought it was weird. It was the pump.

I know your pump is new, and so was mine. It took a little while to find but after all the work I went through, I never assume new equals good.
It was such a time consuming pain in the ass, I keep the Napa replacement pump part number in my wallet TFW42005.

md21722 said:

I would've suggested a radiator but he says he changed it within the past 4 months.

Head gaskets/heads can fail in multiple ways. If its minor you may get the oil sheen like you had and some warm/hot running but no bubbles.

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Radiator.

If you got one that's all metal, aluminum, super fancy or magically wonderful, get yourself the plastic tank/aluminum $100 one at the parts store.

Get the free loaner tool for testing the radiator coolant for a head gasket leak. It is bubbler device that tests for CO2 combustion gas. You will need to buy the test fluid (simple color change) for about $8/bottle. It will sniff out very tiny head gasket leaks of exhaust gas getting into the coolant. Those gasses can change the pH of the coolant and cause silicates in the green coolant to precipitate and clog radiators.

Get an IR temperature tester and check the inlet and outlet and top and bottom sides of the radiator for temperature differences. If the inlet is 210 F or higher and the outlet is something like 160 to 170 F at 2000 rpm, then there is too little coolant flow, thus a clogged up radiator. Cold top side, hot bottom is air in the radiator. Odd cold spots are clogged tubes.

Could also be a tiny coolant leak lurking around.

These are the tools I use for isolating ht spots and testing head gaskets.

http://www.harborfreight.com/hand-tools/thermometers/infrared-thermometer-93984.html

http://www.nationaltoolwarehouse.com/Combustion-Leak-Detector-P58326.aspx

Verify with IR gun before doing anything, could just be a defective sensor

RedHeep said:

Radiator.

If you got one that's all metal, aluminum, super fancy or magically wonderful, get yourself the plastic tank/aluminum $100 one at the parts store.

Click to expand...

I have seen those junk ones on Ebay lately for $40 to $50.

I have about 10 years now on my first CFS 3 row all brass one I paid $160 for. My second Cherokee has about 6 years on the new CSF radiator now. And they both use the Renix closed system plastic bottle with no bottle failures since I came up with the two simple mods years ago for the bottle and cap (use a volvo cap). My OEM Renix radiators never leaked, still have them, they just need roding out, if I ever need them again.

My saturn is on its third POS plastic/aluminum radiator in 8 years. Last one started leaking transmission fluid externally at the plastic tank bulk head fitting as the tank bellowed out a nice curve where it needed to be flat to seal.

Ronbo said:

My 96 did this and I thought it was weird. It was the pump.

I know your pump is new, and so was mine. It took a little while to find but after all the work I went through, I never assume new equals good.
It was such a time consuming pain in the ass, I keep the Napa replacement pump part number in my wallet TFW42005.

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One possible issue if it is a bad new pump, is the wrong impeller on it as I recall, thus the wrong pump. IIRC the wrong pump fits and seems to work, but is some how reversed and is used on the Grand C 4.0s?

IIRC!!!! Or they screwed up and miss labeled/boxed the pump. Easy to check for flow at the top of the radiator on closed system radiators, HO jeeps. Very hard to check flow on the older Renix, closed systems. That was why I switched to using the IR temp gauges. Found found about 50% of the tubes in the middle of my 20 year old OEM radiator were cold, no flow using the IR Gauge

Ecomike said:

I have seen those junk ones on Ebay lately for $40 to $50.

I have about 10 years now on my first CFS 3 row all brass one I paid $160 for. My second Cherokee has about 6 years on the new CSF radiator now. And they both use the Renix closed system plastic bottle with no bottle failures since I came up with the two simple mods years ago for the bottle and cap (use a volvo cap). My OEM Renix radiators never leaked, still have them, they just need roding out, if I ever need them again.

My saturn is on its third POS plastic/aluminum radiator in 8 years. Last one started leaking transmission fluid externally at the plastic tank bulk head fitting as the tank bellowed out a nice curve where it needed to be flat to seal.

Click to expand...

I played the overheating game for 2 years with a 3 row CSF. Did the whole cooling system, did all the temp checks, etc. and it would heat up on the highway and cool down at idle. Everyone said head gasket, so I changed it (twice, because I'm the guy that tears the first gasket).

Still did it. Bought a mopar radiator and it runs exactly at the thermostat all day when it's 100 degrees outside. Tossed the 3 row magic answer in the scrap pile.

We all have our own stories I guess.

RedHeep said:

I played the overheating game for 2 years with a 3 row CSF. Did the whole cooling system, did all the temp checks, etc. and it would heat up on the highway and cool down at idle. Everyone said head gasket, so I changed it (twice, because I'm the guy that tears the first gasket).

Still did it. Bought a mopar radiator and it runs exactly at the thermostat all day when it's 100 degrees outside. Tossed the 3 row magic answer in the scrap pile.

We all have our own stories I guess.

Click to expand...

Did you swap T-stats or just the radiator? If there wasa head gasket leak, the CO2 from the exhaust quickly reacted with the silicates in the antifreeze and precipitated the equivalent of concrete scale on the tubes that cut off heat transport through the tubes (reduced cooling) and that is not reversible even with descaler snake oil flushes, or a new head gasket. New head gasket may have saved the Mopar radiator from the same fate.

It is best to descale/flush and clean the entire system as best as possible, verify no head gasket leak ALL before replacing radiators. Radiators do not clog up over night for no reason.

I chased a night mare over heating issue for 3-4 years that I got manageable with all the typical upgrades but never really solved it (it was still peaking at 235 F on a 105 F Houston summer day), until I discovered that the exhaust manifold to pipe flange donut was bad and there was exhaust at freeway speeds getting out and super heating the oil pan, oil and causing my oil leaks and over heating. Found that out when I swapped out the transmission and had to drop the exhaust pipe. Two muffler shops swore there was no leak there, but replacing that donut solved my overheating at cruising speeds and oil leak problem.

Had the same problem with my sons Ford Taurus not long again, but it was oil leaking...... All the engine Trany mounts were bad and the movement at high way speeds made the exhaust flange move and blow hot exhaust right on the oil filter, 96 Ford Taurus 3.0...superheating the oil at high MPHs for 30-40 minutes on the freeway. Replaced the engine and Tranny mounts and the oil leak problem vanished.

The source of some cooling and oil leak problems are not always obvious. The really odd thing about the Taurus exhaust leak issue was that after a 40 mile freeway drive, and parking it, it would pour about 1/2 quart of engine oil out of the tranny bell housing (front wheel drive abortion). Every one said the rear crankshaft seal was gone. But I could run it leak free at idle for 2 hours in the drive way or 0-35 MPH for an hour in stop and go driving with ZERO leaks. The Highway operation exhaust leak (that vanished at idle.....etc) was thinning the oil and overheating it to over 300 F to where it would take a dump when the engine was turned off right after a 40 minute freeway drive at 70 mph.

FWIW, I make a living solving these kinds of non obvious problems in industrial processes that are covered by the service manuals. Wish I was good at welding and custom mechanical stuff as many of the inhabitants here.

I love this quote from the Karate Kid..... Mr Miyagi ..." Answer only important if ask right question "

I always ask my self when a simple repair turns out not to be simple
Am I asking the right question?

I got an IR thermometer and a Hayden 2625 fan clutch coming in today (I know I know, don't throw parts at it until I know whats wrong... but I figured at 150k miles it cant hurt to replace it)

Will report back with what I find. Thank you all for the input.