MIDAS blew up my Jeep ...

[Ecomike]

Yes, you reuse the stock fan.

I forget the height difference. It is covered in old threads here. If you have a huge 1" gap from the stock fan clutch face to the radiator then you should have no problem. Mine was already down to about 1/2" or less gap, and the ZJ clutch moved it to about 1/4" away, but mine is renix (like yours) and I have the largest fattest radiator on the market, so you should be OK to go that route if you need to.

I would test the current clutch first!!!! Hot water pan, boiling water, set the face of the clutch in the boiling water for say 15 seconds, then see if it is still easy to turn, or very hard to turn. You can use your IR gauge to verify how hot the clutch is, it needs to reach about 160 F IIRC to lock up to nearly direct drive.

- I'll have to start to get up to speed on this topic. Can you use the stock fan with the ZJ clutch?

- I don't know whether my rad is thick or thin, I don't have anything to compare with.

- The jeep stayed in the garage today. Tomorrow I'll go out and I'll put back on the original rad cap and get some new measurements.

 

[FlyNNN]

Yes, you reuse the stock fan.

I forget the height difference. If you have a huge 1" gap from the stock fan clutch face to the radiator then you should have no problem.

I would test the current clutch first!!!!

OK, good on the stock fan. I just checked and I have 1" clearance. Also noted aluminum looking grills on rad. I think you may have asked earlier about plastic or metal rad.

I see we have a number of ZJ's in the local pick'n'pull. I think I'll go tomorrow and get a fan clutch. I'm thinking that if I go through the motions of testing my existing unit I might as well do a replacement and be done with it. Then I can evaluate its performance. I don't know about any local suppliers here for a HAYDEN 2737, but I could get one off eBay for $60. I have $US dollars in my PayPal account looking for something to spend on.

 

[Ecomike]

One thing I would not grab at a junk yard is a used fan clutch. Test the one you have before you bother looking for one, it may be fine. Also, the test result, will confirm if it is, or is not part of the problem. Takes all of 5 minutes to test it.

Or just get the jeep good and hot, shut it off and see if the clutch is loose or tight (spins easy or not).

A hair dry can be used to get hot it hot too!

 

[FlyNNN]

One thing I would not grab at a junk yard is a used fan clutch ... Or just get the jeep good and hot, shut it off and see if the clutch is loose or tight (spins easy or not).

I thought you might have a comment on my plan ... and make me reconsider. Thanks. Shouldn't have a problem getting the jeep good and hot. Now that I'm up to speed on the HD clutch, I may just go with it for the added benefit anyways, stock good or not. I'll ponder.

 

[FlyNNN]

Well, at least I'm able to drive my vehicle now, thanks all to who have participated. The engine is not back to normal but at least we are going in the right direction. Today's findings;

1) put back on original bottle rad cap - no problems, OK.

2) seems to be running a little cooler @ 30mph than last drive. In my business heat is the enemy, although not use to seeing the temp gauge on the left side of center. There is quite a swing from running at speed to no movement idle. This is the new norm right now. It was not always like this, it use to sit dead center all the time. See picture below.

3) I cleaned the engine bay on the weekend. Hot coolant deposits started to attract dirt. I then noticed some new sweating/leakage around the head, up front. See second picture below.

4) I ordered a Hayden HD clutch from RockAuto for $47 shipped. I have not tested the existing fan clutch yet.

4) Took some new IR measurements;
upper rad hose - 77 --- 81
lower rad hose - 50 --- 57
head, front - 118 --- 129
Thermostat - 80 --- 88
bottle - 50 --- 50
dash temp - x --- 110-115 (3/4 mark)

5) Since the "incident", I'm now starting to hear a "chattering" noise of sort from around passenger side, front. Almost a little like a diesel engine clattering. Audio a little hard to make out but its all I got to share. It seems to cycle about every 1 sec. See link below for mp3 (850k).
http://tinyurl.com/jeep-audio

 

[Ecomike]

Have you checked the EGR valve? How hot is it? How hot is the intake manifold?

The noise might be a loose exhaust mount bracket.

The T-Stat data contradicts the dash gauge data. Can you get an ohm meter reading of the rear head Temp sensor when the engine is good an hot? Pull the connector off, and read from the brass pin on top to the brass body.

 

[Ecomike]

These two measurements,

upper rad hose - 77 --- 81
lower rad hose - 50 --- 57

Indicate some reduce coolant flow at idle to me, or I just have better flow at idle with my 3 row brass radiator, but you have enough flow while driving so it can not be serious.

 

[FlyNNN]

Have you checked the EGR valve? How hot is it? How hot is the intake manifold?

The noise might be a loose exhaust mount bracket.

The T-Stat data contradicts the dash gauge data. Can you get an ohm meter reading of the rear head Temp sensor when the engine is good an hot? Pull the connector off, and read from the brass pin on top to the brass body.

I only visibly inspected the EGR and it looked good. Of course not good enough information I know.

I just went for a spin around the block. The clattering was constant at idle and disappeared once I got moving. I'll get a better handle on its behavior now that I'm paying attention to it. Its near the front of the engine and sounds like its around the harmonic balancer (which was replaced last year as well). I'll check up on your questions and post my findings tomorrow.

 

[FlyNNN]

These two measurements,

upper rad hose - 77 --- 81
lower rad hose - 50 --- 57

Indicate some reduce coolant flow at idle to me, or I just have better flow at idle with my 3 row brass radiator, but you have enough flow while driving so it can not be serious.

Checking previously collected data before the thermostat change, it appears to be less of a delta between the two by about 10*.

 

[Ecomike]

Check the CAT (do you have one?) for the rattle!!!!! A bad CAT, loose guts can cause overheating, randomly!


http://www.naxja.org/forum/showthread.php?p=245921323#post245921323

Originally Posted by 8Mud
My 96 heats up at low speeds, traffic. New fan clutch, a good two row radiator etc. EcoMike tipped me off to look at exhaust leaks blowing on the side of the block, ParadiseXJ tipped me off on one of the better ways to spot the leak.

I sprayed some oil down the TB and could see the clouds of white exhaust smoke in my engine bay. I need a new exhaust manifold, mine is beyond repair.

Worth a look.
........

Less likely but possible.

The heater valve moves some coolant around the thermostat, it's possible to have a plugged heater valve.

What happens is a pulse of relatively cool coolant ends up near the thermostat and fools it into thinking you have just started a a cold motor and it closes. That glob of cool coolant heats up from the rear, slowly, until the the thermostat opens again.

The bypass through the heater valve (either to the heater core or the bypass) around the thermostat, keeps a portion of the coolant moving and helps avoid this.

Putting the wrong gasket behind the thermostat housing can also cause this, the universal gasket that comes with most after market thermostats plugs off the heater/bypass coolant supply. An OEM (type) gasket is the only way to go.

Generic thermostats are a no no, the Jeep thermostat has a lower profile than say an early Chev thermostat does (they look the same, the difference isn't a lot) you can crush a standard thermostat a little in a Jeep Renix thermostat housing. I'm not sure about the late models and clearance. I'm careful about which thermostat I buy. The Stant catalog has addressed this, but your parts place may have an old data base,

 

[FlyNNN]

These two measurements,

upper rad hose - 77 --- 81
lower rad hose - 50 --- 57

Indicate some reduce coolant flow at idle to me, or I just have better flow at idle with my 3 row brass radiator, but you have enough flow while driving so it can not be serious.

Thinking about this, I recall the thermostat gasket was not an exact match to the port configuration on the head. It was on the right, heater hose port that the gasket slightly over lapped. I maybe should have cut out any of the over lap. Think this might have something to do with the high temp idle?

Have not tested the EGR yet. What brought about this in your thought process? This unit was replaced around 10 years ago. I was familiar with its failure symptoms. Nothing like that now. I do have a few spares here.

No cat here. That blew up on me years ago as well. Familiar with its failure symptoms. Resonator in place of.

Have not done any checking for exhaust leaks yet.

Did some research on the e-fan switch. Looking at my IR data, its no wonder that fan is never kicking on. If the switch is suppose to switch on at 92c(198F), my last temperature data for the lower side rad hose was 57c. I did find some threads of using a 79 Peugoet 504 switch ($20 at Amazon) that would open at 82c(180F), but even then that threshold is too high. It makes sense to me that one would want a large delta between input and output. That means a lot of cooling going on. Yes/No?

 

[FlyNNN]

I think this MIDAS train wreck has run its course. I have a vehicle that is operational and I didn't have to shell out $3800 for repairs. Thats a WIN! Thanks N-A-X-J-A! If available EcoMike, we could take any follow up off-thread.

 

[Ecomike]

On the Renix -E-fan switch in the cold side of the radiator:

That was changed in 1991, so it is only a Renix, 87-90 issue. At low flow rates (Idle) and with blocked tubes in the radiator, causing low flow rates, the coolant moves too slowly (so it gets too cold) to trip that E-fan switch. On Renix that switch turns on at about 185-190 F (new) and off at about 170-175 F measured at the radiator cold side.

1996 OBD-II seems to turn on the E-fan at 220 F and off at 212 F ( apx) at the T-Stat housing (which is a different location, and usually the hottest location, while Renix used the coldest location (which was an engineering design flaw!!).

OBD-I, 1991-95, used the OBD-II location, but I suspect the on/off temps may have been lower than OBD-II?

IIRC, one possible repair mistake on rigs with the vacuum actuated heater valve is to flip flop the the two heater core hoses, and thus blocking T-Stat by pass flow to the coolant bottle during warm up!!!!

If the EGR valve is stuck a little open, not closing completely, it can make the engine run lean and too hot for even the best working cooling system. Also a partially clogged fuel injector can make a cylinder run lean and thus too hot!!!

Coolant hose (like the radiator hoses) temp readings will be about 30 F cooler than the coolant inside of them, as the rubber is a heat insulator. So if you are taking the hose temp, and not the metal temps they will under report the actual temperature.

Check the intake manifold temp near the EGR and EGR temps when the jeep is warmed up. Mine run about 165 F at the most.

I use a manual bypass toggle switch on my E-fan as do many others on .

 

[FlyNNN]

On the Renix -E-fan switch in the cold side of the radiator:

That was changed in 1991, so it is only a Renix, 87-90 issue. At low flow rates (Idle) and with blocked tubes in the radiator, causing low flow rates, the coolant moves too slowly (so it gets too cold) to trip that E-fan switch.

IIRC, one possible repair mistake on rigs with the vacuum actuated heater valve is to flip flop the the two heater core hoses, and thus blocking T-Stat by pass flow to the coolant bottle during warm up!!!!

If the EGR valve is stuck a little open, not closing completely, it can make the engine run lean and too hot for even the best working cooling system. Also a partially clogged fuel injector can make a cylinder run lean and thus too hot!!!

Coolant hose (like the radiator hoses) temp readings will be about 30 F cooler than the coolant inside of them, as the rubber is a heat insulator. So if you are taking the hose temp, and not the metal temps they will under report the actual temperature.

Check the intake manifold temp near the EGR and EGR temps when the jeep is warmed up. Mine run about 165 F at the most.

I use a manual bypass toggle switch on my E-fan as do many others on .

Thanks Ecomike for your details. The weather around here has not been conducive to working outside under the shade tree lately. I have done some follow up to some of your previous questions. As the days have gone by, the dash temps on the low side have even been moving to the left a little, settles in around the middle and stays there longer than before. Sitting, idling in the driveway for 5 minutes and it moves to the right just before the red.

- measured 98.5 ohm on the dash gauge temp sensor.
- EGR valve seems to be working. Tugged on it during idle and engine stumbled. Will check temp.
- I made sure that I did not cross my heater lines (heeded your earlier warning).
- Got a thermostat gasket from the dealer and will compare with one installed (looks similar, cost about 300% more).
- I did order a Hayden fan clutch from RockAuto.
- I noticed that my hose temps and rad temps only varied by a couple of degrees. I have been targeting a metal spot on the rad when taking those measurements.
- I installed new, Jeep Liberty injectors last summer.
- Thanks for debunking my thoughts on the radiator being to cold as ideal. Seems like you are leaning towards a clogged radiator. That was new last summer as well. Looking at some video I shot during the work, it does look plasticky on the sides.

 

[Ecomike]

100 C is 185 ohms, is the highest reading on the FSM data table, 70 C is 450 ohms.

I still wonder, even more now, if that dash temp sensor is bad?

Can you pull it, and put it in boiling water and retest the ohms? At ambient pressure it should read 185 ohms at sea level (near sea level) as water boils at 212 F.

If you replace it get a dealer one, I have about 5 aftermarket ones that are junk!!!
Also, do not put sealer on the threads, it grounds through the threads.

I suspect your radiator tanks are plastic (like rubber they do not conduct heat well, and read cooler on the surface that the coolant is. The IR reads an area, not a pin point temp, so hard to get spot temps that are exact, but it spots huge differences real well! Keep in mind my delta T posts I made were degrees F, not degrees C, so divide my delta Ts buy 1.8 if you are using degrees C on delta temp calcs!!!!

What is the flow rating on jeep liberty injectors at 39 psi? Renix prefers about 19 lbs!!

Keep in mind the new radiators have thinner tubes than we used 30 years ago, they plug up a lot faster, and if junk was still in the block, calcium scale from PO insults, it may have disolved and migrated to the new radiator tube inlets.

Or if there is, was a head gasket exhaust leak, the CO2 in exhaust gas precipitates a concrete like scale out of coolant chemicals that can block radiator flow. It can be a slow progressive process, or sudden.

 

[FlyNNN]

I still wonder, even more now, if that dash temp sensor is bad?

Can you pull it, and put it in boiling water and retest the ohms? At ambient pressure it should read 185 ohms at sea level (near sea level) as water boils at 212 F.

What is the flow rating on jeep liberty injectors at 39 psi? Renix prefers about 19 lbs!!

Or if there is, was a head gasket exhaust leak, the CO2 in exhaust gas precipitates a concrete like scale out of coolant chemicals that can block radiator flow. It can be a slow progressive process, or sudden.

- I'll check my parts box, I should have another JY pull. I'll see what I can do about getting some test results.

- 21.1 lb/hr for the Liberty injectors.

- "slow progressive process", this statement reinforces how this situation came to be. Overheat at MIDAS. Dash gauge temp slowly rising over the following days.

 

[BulletMaker]

100 C is 185 ohms, is the highest reading on the FSM data table, 70 C is 450 ohms.

I still wonder, even more now, if that dash temp sensor is bad?

Can you pull it, and put it in boiling water and retest the ohms? At ambient pressure it should read 185 ohms at sea level (near sea level) as water boils at 212 F.

If you replace it get a dealer one, I have about 5 aftermarket ones that are junk!!!
Also, do not put sealer on the threads, it grounds through the threads.

Didn't we go over the coolant temp sensor almost 2 weeks ago? I said check it because it's a cheap part and easy to replace!

 

[Hypoid]

We didn't even verify coolant loss. It did not get mention, it must not exist.

 

[Ecomike]

Didn't we go over the coolant temp sensor almost 2 weeks ago? I said check it because it's a cheap part and easy to replace!

He did not run the exact test I suggested. He tested the sensor while mounted at operating temp, but we have variable IR data that is all over the place as to what that coolant temperature really is in the head. I wanted to see if that sensor read 100 C (in ohms) at 100 C (in terms of the FSM spec for ohms at 100 C), i.e. in a boiling pot of water which is exactly 100 C at sea level for pure water (not coolant).

Once that is done, he can take the ohm meter reading he took earlier at operating temp to verify if the gauge is reading properly. We need to verify the sensor first, then the ohms at operating temp (which he did already), and then we need to use those data points to verify the dash gauge is reading out what the sensor sends out.

The data he supplied was not conclusive as to the whether or not the sensor is off by about 20 C or not.

 

[FlyNNN]

We didn't even verify coolant loss. It did not get mention, it must not exist.

There are no coolant leaks. It has never over-heated or spewed any coolant since the unit was returned to me.

Didn't we go over the coolant temp sensor almost 2 weeks ago? I said check it because it's a cheap part and easy to replace!

Yes, you did mention. I posted IR data that confirmed a match with what was reading on the dash. I have since done a few comparison checks and they continue to match. So, at the time that idea was put aside. When taking my IR measurements, I try to get as close as possible to the target area.

Looks like a revisit is in order due to the resistance measurement. I was searching my parts bin for another sensor but was unable to find. Another thing to add to the list on the next pink'n'pull run. In the meantime, I will pull the sensor and test (as per Ecomike).