I'm Gonna Slash - Overheating Saga - Yes, Still!!!

[ParadiseMJ]

Thanks fellas, the only reason I ask is to figure out which hose goes OUT of the t-stat and/or WP TO the core.

 

In other words if the hoses were off, where would coolant come out of the engine?  The water pump pipe...or the small t-stat fitting?

 

Weird question but it is relevant

[Exgrayxj]

I dug out my FSM.

Coolant flow is out the thermostat nipple, to the bottom heater connection, returns from there to the ... duh ...other nipple.

I also went out and looked at my mj, and that is the way it is.

I have eliminated the heater control valve also.

 

BTW, not that it helps you any, but I found my temp sender to be defective, reading about 100 degrees plus high!

 

Notice it the other morn, turned the switch on to run the fuel pump before cranking, noticed that I already had temp! And hadn't even started it yet!

 

This is the SECOND replacement sender since the gauge swap, with the same symptom.

So far, I am back to normal ... for now.

 

As an aside, I am not sure it makes a difference on the heater flow if there is NOT a control valve, I THINK it may have something to do with filling the core from the bottom, exiting the top. 

 

On a '64 Plymouth I once had, reversing the hoses caused heater core failure, not just once either ... got sick of changing them 'til i Figured out what I had done.

[HOrnbrod]

The image below is from the 1997 XJ parts manual. It shows how the heater hoses are supposed to be run w/o the water control valve. The supply hose goes to the top fitting on the heater core. Eliminating the water control valve is what we are emulating, si?

 

[Exgrayxj]

Is this perhaps a Renix/HO thing?

 

My fsm is '89, my mj is '90, and I do not have the long stand pipe for the return /nipple.

 

Not capable of scanning the fsm, and can't find my Chilton.

[ParadiseMJ]

I dug out my FSM.

Coolant flow is out the thermostat nipple, to the bottom heater connection, returns from there to the ... duh ...other nipple.

  

On a '64 Plymouth I once had, reversing the hoses caused heater core failure, not just once either ... got sick of changing them 'til i Figured out what I had done.

 

Thanks for researching for me.  Read the below after the second quote.

 

The image below is from the 1997 XJ parts manual. It shows how the heater hoses are supposed to be run w/o the water control valve. The supply hose goes to the top fitting on the heater core. Eliminating the water control valve is what we are emulating, si?

 

 

Si...correct.  The heater valve has been gone for a couple years.  Whether I routed the hose correctly, and whether it matters

 

The reason I ask the question is:

 

I seem to have a flow problem.  The coolant exiting the t-stat nipple makes sense since INSIDE the small hole in the water pump there is a deflector which is apparently there to deflect coolant DOWN into the pump.  That deflector, on my pump, is corroded and therefore not necessarily directing the coolant the right way.  I don't know if that matters either, but it's the ONLY odd thing I've been able to find.

 

So, if routing the hoses correctly eliminates the possibility of any air pockets in the core and any cavitation at the pump or at the compromised "deflector" that's one less possibility to eliminate. 

 

My next step is to replace the pump with an OEM pump (can't justify the Hesco) and take the flippin' radiator to a shop and see if a.) it's clogged or b.) if they can do anything about it (cost effective).  Thanks to everyone adding their input here and in my previous uber long thread. 

[HOrnbrod]

We all have the same heater core and the supply comes in at the top, from the thermostat nipple. I doubt it makes any difference, but that's how it is.

[Keyav8r]

Maybe I'm looking at it wrong, but jpnjim's photo shows the flow going through the hose from the thermostat housing, splitting to go into the top connection on the pressure bottle and to the lower heater core tube. The hose connected to the water pump shows flow from the upper heater core tube and from the bottom of the pressure bottle going towards the water pump. That's how I installed the hoses on my 88 but I haven't driven it enough yet to see how well it cools.

[Oyaji]

Since you are insistent that you have a coolant flow problem (and you may well be on the right track there), here is one more thing for you to consider: by being geared over 30% too tall, your water pump is spinning 30% slower too. This results in reduced coolant flow - perhaps reduced MUCH more than 30% (because hydrodynamic flow is not linear in response to change in pump RPM.).
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I cannot stress how much a favor you might be doing yourself to simply try dropping down a gear for all your driving. Remember, the AW4 you installed to replace your 5-speed manual was paired originally with 3.54 final drive - yet you kept the 3.07s... and then jumped to 33" tires too! [correction: reading back in the other thread I see you jumped ~15% to 31" tires, not 33" - in combination with a 16% change by keeping the 3.07s instead of compensating for the AW4's 3.54 ratio, for an overall change of ~31%.] Not only are you overloading the engine by demanding the same (or more) power normally delivered when it is running ~30% faster, you are also asking it to cool itself with reduced flow at the same time.
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At least on the way to the radiator shop, drive there using one gear lower. If you note normal running results, you'll have the chance to save yourself some money... money you could put toward new ring and pinion sets!

[MancheKid86]

oyaji,

he is not overloading his engine to the point to over heat due to any spark issues, tire size, gear size,

he states that INCREASED RPM will induce the over heating, INCREASED RPM IS A PARTIAL RESULT OF DROPPING GEARS!

SO OBVIOUSLY HE WILL OVER HEAT FASTER if he drops gears every where like you suggest, as well as you state that driving in second will save him money,

NO, you are driving slower with way more rpms, more rpm's = more fuel being burnt = more gas consumed

 

heck, if that were the case my truck would over heat every day, 3.55 gears with 35" tires, but it doesnt, it runs actually around 150,

so do us (or me atleast) a favor and stop posting on this topic, you are disregarding every input, and making it seem like they have no idea what they just typed,

 

save every one the grief

 

i apologies to every other participant in this thread for my outbreak,

but this dude drove me nuts just reading this, I'm sure your all going nuts too

 

paradiseMJ

 

have you tested your tsat?

just toss it in a pot of water and boil it until it opens,

make sure to have a thermometer handy to see the temp it opens

 

like jimoshel asked, have you pulled your frost plugs out?

 

and don't know if this applies, ive read about the 3 row radiators having lots of overheating issues where the owner swapped back to a oem single row with no issues afterwards,

could this maybe be the same with your 2 row?

 

thats all i got, good luck

[Oyaji]

Dropping a gear costs nothing at all to try, and addresses an issue that no one here has yet commented on.

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If the issue of lugging is not well understood,  once again I reiterate my advice to go google up some info from engine manufacturers who doubtless do a better job of explaining it than I have done.

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I have read all posted here  by both the original poster and all contributors in both  his overheating threads, multiple times. The fellow with the overheating problem is running out  (has run out) of alternatives to try, having already been through great expense trying out things from all helpful readers. I wish him all success in his ventures to solve his problem.

[ParadiseMJ]

Just to clear the air here.  I thank you all for your attention and suggestions.  I would have never even gotten this far without the sage wisdom, knowledge and experience. 

 

I am not lugging it.  I know lugging. I'm not running 33" tires, they're 31's (that measure out at the curb to an "actual" 29.75) I normally run in 3rd unless I'm on the freeway going 65-70.  Always have with the 3.07's... My immediate need to get smaller tires (235's) until I can re-gear is being worked on.  The RPM's normally run ~2200 to 2400 at 65 on flat ground (just like my XJ with AW4, 231, 265's and 3.55 gears.  Running up the hill in 3rd the tach gets anywhere from 2800 - 3200 or so...certainly not overtaxing the engine OR the tranny and my MPG's are really fine.  The tranny temps are fine...130-170 and all the way to 250 if I'm pulling a load or driving slow up a steep hill (10-11% grade).

 

The cat is new, the exhaust is clear.  My brakes aren't dragging, my bed is empty, my shocks are in good shape, all my lights, accessories and my radio works...and I just washed it.

 

P.S. Keyav8r I don't have a pressure bottle.  It's an been open system conversion since day 1.  The picture in the pic section is a closed system Renix.  Thus the confusion.

[Oyaji]

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth."

[metrictonner]

Odyssey is right.  I'll repeat the three word advice I took a few years ago from someone after years of diddling around and thinking I had to live with it: replace your radiator.  It worked for me.

[Exgrayxj]

Just sayin ... I don't think it is the tires, and I wouldn't bother swapping/spending that cash for smaller ones ... 31/10.50s aren't that much taller than 235/75s ...

 

I am running 265/75/16 on mine (though it is 3.55 gear) it is not a problem, only time I even notice it is under light throttle and seeking a mild increase, a little nudge or a pull down one notch and good to go.

 

And, now with the new rad, open system to get rid of the pain of the closed system, and a correct switch, I am good to go.

 

For now.

 

Now that fall is upon us, I am going to fix the a/c.

[Oyaji]

Honestly I don't think it is just the tires either  - I think it is a combination of tires,  5-speed-to-AW4 swap while retaining 3.07 final drive, (and to add  3 guesses as well)  uncorrected speedometer, driving style/high speed driving, and maybe also accessories that add aerodynamic drag (a picture would help). Below follow some of the posts I read here that lead me to this conclusion:

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In red underlined text below is a practical definition of lugging:

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ParadiseMJ, on 20 Apr 2013 - 22:18, said:

I did smell some hot metal smell...and it seem to plateau out at around 65-68 mph. It was hard to push it faster than that, which was also unusual. 

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These don't actually define lugging, but are symptomatic  of it:

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ParadiseMJ, on 24 Apr 2013 - 17:15, said:

Then when I hit the hills, it slowly creeps up to 220-230 and stays there until I get up riding along the relatively flat ridge and into slower traffic in town, up and down small hills. Still, going 45-50 in town or stopped at a light, it's right at 195-200.

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ParadiseMJ, on 01 May 2013 - 07:10, said:

Goes to 195+ then drops off as the t-stat opens for about 30 seconds. Then it evens out at just under 200 for the level ground freeway trip...driving along at 65-70mph for 20-30 miles, until I get to the hill. When I get about half way up, the gauge starts climbing past 210, 220, 230...til I get to the top.

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ParadiseMJ, on 24 Apr 2013 - 17:15, said:

It's not overheating in traffic or creeping while idling...it actually cools off when idling.

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ParadiseMJ, on 18 Jun 2013 - 14:48, said:

Mileage...don't know yet...taking a trip tomorrow, about 200 miles one-way, I'll see how it goes. I was only getting about 15 overall.

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ParadiseMJ, on 10 Jul 2013 - 23:27, said:

Sooo, took my trip, still overheating under load on hiway.


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[ParadiseMJ]

I bought a new radiator yesterday

[cruiser54]

Hopefully that's it.

 

Would be interesting to have the "old" one checked out by a radiator shop.

[87Warrior]

 The tranny temps are fine...130-170 and all the way to 250 if I'm pulling a load or driving slow up a steep hill (10-11% grade).

 

This threw up a red flag for me. Are you sure the torque converter is locking up? A slipping torque converter will add slot of heat to the system. Regardless, all of the hot transmission fluid is heading straight for the radiator.

 

Which leads to this:

Odyssey is right.  I'll repeat the three word advice I took a few years ago from someone after years of diddling around and thinking I had to live with it: replace your radiator.  It worked for me.

I too had a high load/speed cooling problem with my TJ. It has 5.13 gears and 35's, so it is not lugging by any means. After replacing everything but the radiator it was still having problems. Bought a Griffin radiator and it hasn't had a cooling problem in 4 years.

[ParadiseMJ]

Hopefully that's it.

 

Would be interesting to have the "old" one checked out by a radiator shop.

 

I was thinking that when I had some extra $$ laying around (as if) to take it to the shop.  Seeing as how it's younger than my last set pair of shoes.  Back in the Old Days I used to just take my Chevy C-10 to the rad shop and have it "rodded out" and re brazed for $40.  Do they still do that, or just replace it with an aluminum OEM model from AutoZone?  Had that truck when I was 16 until I was 30

[ParadiseMJ]

 

 The tranny temps are fine...130-170 and all the way to 250 if I'm pulling a load or driving slow up a steep hill (10-11% grade).

 

This threw up a red flag for me. Are you sure the torque converter is locking up? A slipping torque converter will add slot of heat to the system. Regardless, all of the hot transmission fluid is heading straight for the radiator.

 

 

No I'm not absolutely sure that the TC is locking up, but like I said, the tranny temps are good according to my trans temp gauge. I have the tranny "cooler" in the radiator bypassed...as in, the tranny fluid does not go thru the radiator since I live in sunny California and it rarely gets colder than 30F here even in the dead of winter.  The aux. HD tranny cooler is installed remotely, away from the radiator, so I don't believe the engine cooling system is affected at all by the tranny fluid temps.

[Oyaji]

Let me preface this comment by noting that, since your overheating is occurring at an indicated 65-70mph, you could  just drive at 55-60 mph instead. It is also worthwhile to consider the increase in true speed (and the additional aerodynamic drag load that comes with it) by driving at an indicated 65-70 mph with a speedometer uncorrected for your bigger tire size. You never did mention if in fact your speedo is corrected for the 31"s you are running, and if your tires are 15% bigger in diameter over stock, your true speed at 70 would actually be 80.5 mph. The additional  aerodynamic load  alone might be enough to cause overheating at that speed, even before considering additional problems.

There are  just 2 possible root causes of overheating: failure to reject heat within the original capacity of the cooling system (i.e., a fault in the cooling system), and addition of heat beyond the capacity of  a perfectly functioning cooling system to reject (i.e., an overloaded engine). Besides normal wear and tear/breakage degrading the cooling system, but (as you can read below form the list of repairs made) in this case this can be discounted as a cause. I suggest the next place to look are at what has changed from stock, since modifications to a vehicle can result in overheating resulting from either or both of those root causes mentioned above.
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I remembered reading that there had been some problems with the AW4 swap, so I went back and dug up the following  (items I thought pertinent I highlighted in red - all below are quotes by the original author):
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There is no rust in the system. The coolant is bright green, no sign of rust, oil or contamination. I have no heater valve, the cooling system was swapped over to an open system from the get go when I built it. The water pump is relatively new (miles wise) and coolant is circulating well. That is the reason I hadn't mentioned the water pump...and it is the correct R flow pump. Every pump I've had in any of my Jeeps have been fine on the impellers.

So...I've fixed and tested the following within the last 2,000 miles months: I'm not just throwing parts at it...this has all been part of the total build.
New radiator
Water pump
Hoses, upper, lower, heaters (and just the other day a new LOWER hose with a spring in it [thanks again Cracker])
T-stat (195) twice
New t-stat housing (the old one had a hairline crack in it)
New catalytic converter, it was partially clogged
New downpipe flange donut
New temp sender
New rad cap (Super-stat 16 lb.)
Flush & fill with new coolant, twice
Ext. Tranny cooler
1997 ten blade curved e-fan...on a switch
Harmonic Balancer
Alternator
P/S pump

...A/C is not operable at the moment, so it's not adding any heat to the mix. How hot does it get? Anywhere from just barely over the 210 mark to just before red-line. Test says no exhaust gases in coolant.

I'm down to this:
I swapped in an AW4 after the BA-10 gave up the ghost. So, my gearing is still 3.07's...I'm also running 31" tires. What I'm thinking is that the engine has to work too hard to move those axles, so it's doggy, and when it's doggy is when it gets hot.

 

Did this running hot start when you swapped in the AW4? Or before?

It did overheat, even when it had the BA-10 in it. It also had the 31's. Don't think 31's are a deal breaker for a D44 with 3.07's...but since I won't be doing the Rubicon anytime soon...anyhoo, the AW4 has never been quite right (which I can only attribute to my OWN work) electronically. I still can't get a reading on the TPS. Tried to, drove it, tried, drove, and so on. But still, driving down the highway it seems to do fine.
I did all the cooling system swapping before, and it ran a some cooler.

>>>>>>>>I could see the 3.07s adding to the prob. I know with 3.55's and 32s my mj is sluggish to say the least. I had a lot of over heating probs and did pretty much everything you have done. they are not as bad. but still get up there on hot days. I added the e-fan and it will drop the temps from the red to normal within 5 mins of turning it on at a idle.


My overheating thread. Maybe there is something in that that will help you? :???:
http://comancheclub.com/topic/35395-mj-still-overheating/

My trans cooler is directly in front of the e-fan.. .in front of the radiator. Once it starts climbing, even the e-fan only helps a little. I'll read your thread and see if I missed something, but it sure is frustrating.

[ParadiseMJ]

I corrected the speedo for the tire size when I put in the t-case with the AW4.  As far as driving style and speed goes...I'm pretty conservative.  I take it rather easy on the skinny pedal...I don't drive like a teenager...but I don't drive like an old lady either.  :thumbsup:

 

During all of this I relocated the trans cooler to just above the front skid plate (that post is 2 mos. old).  I'm not really worried about whacking it there, "since I won't be doing the Rubicon anytime soon"...and it actually works fine there and eliminates it as an issue in the cooling system.  I am replacing the radiator today or tomorrow.  If the radiator doesn't do the trick...who knows.  :???:

 

Maybe I'll get a Toyota :yes:

[Oyaji]

I corrected the speedo for the tire size when I put in the t-case with the AW4. As far as driving style and speed goes...I'm pretty conservative. I take it rather easy on the skinny pedal...I don't drive like a teenager...but I don't drive like an old lady either. :thumbsup:

 

During all of this I relocated the trans cooler to just above the front skid plate (that post is 2 mos. old). I'm not really worried about whacking it there, "since I won't be doing the Rubicon anytime soon"...and it actually works fine there and eliminates it as an issue in the cooling system. I am replacing the radiator today or tomorrow. If the radiator doesn't do the trick...who knows. :???:

 

Maybe I'll get a Toyota :yes:

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Reading the above, one thing jumps out at me: that you corrected the speedo for tire size, but you did not mention if you also corrected the speedo for the 3.07 final drive. Remember, the AW4 is expecting a 3.55 final drive, but you still have the 3.07 instead. If left uncorrected, that in itself is a 16% difference in indicated speed versus true ground speed. That may not sound like much, but because aerodynamic drag is proportional to the square of the speed, that means a 34% increase in power needed [1.16^2 = 1.34, or 34%] - and the heat rejection capacity required may be beyond the volume delivery that your water pump provides at your engine RPM at indicated cruise speed of 65-70 mph.

[ParadiseMJ]

 

Well, I'm about 17.3% convinced that at least 1/2 of the stuff I've done might fix 88.9% of my problems.  I'm sure that if I reduce my speed by 14%  I'll probably get .00397% benefit in my tire wear.  If I reduce the tire size by 22.496% I'll probably take the Ranger to Jackson Hole...depending on the size of the first pot hole I hit on Hwy 97.

 

EDIT:  What I really meant to say was ... Duh! What?? So, In one sentence, what should I do to fix that...in another sentence...Why is it that I see completely neglected P'sOS driving down the highway doing 75 with a meth head behind the wheel with all their windows rolled up and their A/C blasting towing a fishing boat with 4 inner tubes tied on top and they are NOT over heating?!?

[cruiser54]

 

Well, I'm about 17.3% convinced that at least 1/2 of the stuff I've done might fix 88.9% of my problems.  I'm sure that if I reduce my speed by 14%  I'll probably get .00397% benefit in my tire wear.  If I reduce the tire size by 22.496% I'll probably take the Ranger to Jackson Hole...depending on the size of the first pot hole I hit on Hwy 97.

Pure frickin genius!! Did you use a slide rule? I'm about 99% sure all this mathmatical stuff is 100% bull$#!& regarding your issues with overheating.