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Running down running hot issue

ParadiseXJ

NAXJA Forum User
OK guys,
I've been running hot on grades at highway speeds and slow going on uphill treks on dirt or crawling. Here's what I've done.

1990 4.0 RENIX with open cooling conversion. Been fine for the last 2 years. HD trans cooler directly plumbed, trans/cooler/trans, not thru the radiator.
  • New fan clutch (has resistance when I spin it when it's hot) 3 months old and less than 1,000 miles).
  • New 195* fail-safe t-stat. Well, 2 months old, tested it on the stove before I installed it.
  • Triple flushed entire system (block, rad, heater core) - twice.
  • New 16# cap (ported).
  • New 50/50 mix coolant.
  • Heater Control valve is operational and not clogged. Been thinking of deleting it altogether.
  • Coolant looks brite green and clear (but there is a bit of crud on the inside of the cap, not oily stuff, just cruddy). Oil fill cap looks good. No crap or film in overflow.
I thought I had it narrowed down to the water pump (4 years, and about 25K miles old) so I went to change it out this morning, thinking I'd find corroded or wasted impellers (they're in perfect shape). There is no play in the shaft or bearing but it does give a little resistance when I turn it. I have good circulation. When I open the flush n' fill port, coolant shoots out when running.

Everything works fine except this one issue. So, any ideas?? I have it apart right now and I need it on the road tomorrow. I could just button it up with the older parts but since I'm already half way ther I'd like some input on which way to go.

Thanks
 
Water pumps are relatively inexpensive. I would absolutely change it out as long as you are tore down. If you don't replace it and continue to have symptoms, you'll keep wondering about the pump. Pumps can fail prematurely; happens all the time.

Replace it.
 
Life on a water pump is 4-6 years on average. DON'T buy reman, go with new.

That said, how "hot" is "hot"?

Your fan clutch--standard or ZJ upgrade?

Is there an efan, and if so, is it working?

Is the trans cooler mounted in such a way that it is restricting air flow?
 
Life on a water pump is 4-6 years on average. DON'T buy reman, go with new.

That said, how "hot" is "hot"?

Your fan clutch--standard or ZJ upgrade?

Is there an efan, and if so, is it working?

Is the trans cooler mounted in such a way that it is restricting air flow?

  • Hot is over 240 to just shy of the red. As soon as the grade is over it cools back to 200-210. Haven't gone into the red yet. Could my fail-safe t-stat be toast at those temps??
  • Standard fan clutch. As a side issue, I got an HD ZJ clutch. It didn't fit, and my trusty guy at NAPA said having an HD clutch and a standard fan blade, it works against itself, so I went with a standard. It blows hard when hot, and also much harder to spin when OFF and hot.
  • There is an e-fan, it's on a switch. I flip it on when over 210. Works great when the temp creeps up, except when I'm pulling a grade, then all bets are off.
  • The trans cooler IS mounted so that airflow MIGHT be restricted. Half of it is in front of the e-fan and half in front of the mech fan. Its about 8" x 10".
  • I also have Le Baron hood vents. It also helps when the outdoor temps are 90-100*
So, today I'm replacing the pump and t-stat, deleting the heater valve and might look at the trans cooler and a possible mounting options.

Off to NAPA!!
 
As for the ZJ clutch, did they try and sell you the MAX cooling fan clutch? It won't fit.

The difference in the fan clutch is 60-70 percent of shaft speed for the standard, 80-90 percent of shaft speed for the HD, regardless of the FAN's shape, it flat out moves more air--that parts guy was blowing smoke up yours or talking out of his.

Is the trans cooler mounted flush with the radiator? You could try moving it forward to put a little space between them and see if that helps.
 
New water pump installed along with t-stat (195 Super Stant), heater control valve deleted (trial basis).

They did sell me the MAX, it didn't fit (do you have a p/n for the HD?). This parts guy is usually right on, but I think I agree with you. I'll hunt one down tomorrow.

Looks like I'm driving the Camry to work.

The cooler has a 3/4" spacer, then the condenser, then the radiator.
 
The only thing you haven't replaced is the radiator. You could probably test coolant temp in and coolant temp out. I think Ecomike posted some numbers during his search for cooler running.
 
the pn i have is 272310 and is a NAPA number. i got it off this site but have yet to get one.

zedpapa

That is right number, $44, direct fit.
 
The only thing you haven't replaced is the radiator. You could probably test coolant temp in and coolant temp out. I think Ecomike posted some numbers during his search for cooler running.

Oops, yes, I did replace the radiator last October - CSF 3 row - forgot to mention that. Thanks for the p/n, I'll be hunting that down today.
 
So it's all put back together with the ZJ HD clutch added (sounds like a turbo). Lots more wind!!. When warm and OFF I have to push the fan, no free spin. Also, with the heater control valve deleted everything works fine and cleaned up the engine bay alot, just makes more sense (best $5.00 upgrade yet).

Hard to know whether I needed the water pump (it was in OK shape) or just a new fan clutch, the weather here changed from 101 to 75*F and down to 34*F in the morning. Hard to test out. I'm going for a camping trip and trail run tomorrow for the weeekend, we'll see how it goes.

Thanks for the input.
 
Let me know how you like things with the coolant valve removed. I have been considering this but have been concerned over heat in the cabin--I hate the smell of rendering fat! LOL!
 
Hahahah - Hey Joe (I heard you shot your woman down... Oh ....wait.... wrong Joe)
I removed my blend valve about three weeks ago- mine was starting to leak at the bottom so when I put in the Macs aluminum coolant bottle in.
I have had no issues with heat in the cabin while the controls are off.
(Remember to cap off the vacuum line that controls the old valve too)

I went to the local plumbing supply house bought a "3 way" copper "T" - 3 new hose clamps and spent no more than $7.

It's a keeper.
 
Hahahah - Hey Joe (I heard you shot your woman down... Oh ....wait.... wrong Joe)
I removed my blend valve about three weeks ago- mine was starting to leak at the bottom so when I put in the Macs aluminum coolant bottle in.
I have had no issues with heat in the cabin while the controls are off.
(Remember to cap off the vacuum line that controls the old valve too)

I went to the local plumbing supply house bought a "3 way" copper "T" - 3 new hose clamps and spent no more than $7.

It's a keeper.

Ok, sounds like I got a new item on my to-do list! Appreciate the info. :wave1:
 
Let me know how you like things with the coolant valve removed. I have been considering this but have been concerned over heat in the cabin--I hate the smell of rendering fat! LOL!

My first test today, outside temp 82.

From work, elev. 130 ft. to home elev. 1950 ft and about 8 miles of 5-6% grade. Air on.

Before: I'd be running at 240
After: On the low side of center - about 200+/-
No heat from core until I asked for it. So deletion of heater valve working fine.

Tomorrow going from here to elev. 6600. Everything copacetic.
 
So, all weekend (wheeling, towing trailer, pulling grades, dirt trails, slo-n-go, highway/freeway speeds) my temp never got over 210 and never below 200.

I believe my cooling problems MAY be over.
 
So, all weekend (wheeling, towing trailer, pulling grades, dirt trails, slo-n-go, highway/freeway speeds) my temp never got over 210 and never below 200.

I believe my cooling problems MAY be over.

Glad you got it worked out.

I've got the coolant control valve deletion on my list. If I can just stop breaking things while working on my XJ I will get around to it.
 
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