Running Hot

[iansplatinum]

Why are you idling so low with the AC on @ 650? My rig idles around 800-1000 with AC on. Lower idle, means lower fan speed and less air being pulled across the radiator for cooling. I'd check on your IAC valve to get your idle to bump up some and beyond that you may look into an aux fan to boost your idle cooling.

When I'm in park w/ AC on, it does jump to about 900 rpm. But in gear it's at 650rpm. I thought this was normal?? Can anyone else confirm?

AC on, in Drive: 650 RPM
AC off in Drive: 650 RPM
AC off in park: 650 rpm
AC on in park: 900 RPM

I have not looked at my IAC, will check on it today.

 

[baggar11]

That sounds about right. I'll check later today on my rig. I think you just reminded me about my weird driving habit too. I usually pop the transmission into neutral when I'm at a stop light. I think it's a habit I carried over from the early days of driving a stick shift.

 

[GeoRoss]

In drive with the AC on the idle should be 1000-1100. At least that is what mine does.

 

[iansplatinum]

In drive with the AC on the idle should be 1000-1100. At least that is what mine does.

Seems a little high, like the car would want to lurch forward? If i'm in drive and keep my foot on the brake, 1100 rpm would be a good bit of force to overcome.

Think we need some more data to figure out how it's supposed to be...

Also, does IAC modulate the idle-up function when AC is on? Or is there some other valve?

 

[baggar11]

Just went for a drive. I'm seeing about the same numbers you are at idle with the AC on/off and the foot on the brake. You might consider an aux fan to supplement air flow at idle.

 

[jpoole]

An aux fan may be your best/easiest option here and an asset in tough, rock crawling situations where there's lots of hot-engine idling and you want more control of air flow.

That said, the stock cooling system should be keeping things cool for you in the scenarios you are reporting based on my understanding of them, my experience with my own 80 and understanding of what other folks see as well.

A few questions:

When you changed your fan clutch oil did you test/check the port opening temps and adjust/set those? I'm not sure how this may impact your idle specific cooling issue but there are multiple dynamic systems playing together here so it might.​

​

How clean are your condenser and radiator? Have you cleared the fins for airflow and also washed them with a coil cleaner of some sort (or are they newish)? to make sure you are getting good airflow and heat exchange?​

​

Have you tested wetting the condensor/radiator (w water hose) or pushing more air (leaf blower/external fan?) while idling hot to see how the engine temps react, to get a sense of where the limitation(s) is/are? This may not tell you much, but could also yield easy to get and interesting feedback or point to insufficient coolant flow (if that happens to be an issue, which seems unlikely given how it cools when you are moving).​

If your cooling system is truly up to snuff maybe there's a tuning issue with the engine? That seems pretty unlikely without associated error codes or other issues but I assume it's possible. In any case, something doesn't seem to add up as I've pushed my 80s engine in a variety of situations, out west at elevation, at sea level, towing, etc. and it stays cooler than you are reporting. Of course, unless we were running side by side and checking with the same temp gauges, etc. there are a lot of conditions that could vary and be leading to the understood/reported temp differences.

Good luck,

 

[iansplatinum]

An aux fan may be your best/easiest option here and an asset in tough, rock crawling situations where there's lots of hot-engine idling and you want more control of air flow.

That said, the stock cooling system should be keeping things cool for you in the scenarios you are reporting based on my understanding of them, my experience with my own 80 and understanding of what other folks see as well.

A few questions:

When you changed your fan clutch oil did you test/check the port opening temps and adjust/set those? I'm not sure how this may impact your idle specific cooling issue but there are multiple dynamic systems playing together here so it might.​

​

How clean are your condenser and radiator? Have you cleared the fins for airflow and also washed them with a coil cleaner of some sort (or are they newish)? to make sure you are getting good airflow and heat exchange?​

​

Have you tested wetting the condensor/radiator (w water hose) or pushing more air (leaf blower/external fan?) while idling hot to see how the engine temps react, to get a sense of where the limitation(s) is/are? This may not tell you much, but could also yield easy to get and interesting feedback or point to insufficient coolant flow (if that happens to be an issue, which seems unlikely given how it cools when you are moving).​

If your cooling system is truly up to snuff maybe there's a tuning issue with the engine? That seems pretty unlikely without associated error codes or other issues but I assume it's possible. In any case, something doesn't seem to add up as I've pushed my 80s engine in a variety of situations, out west at elevation, at sea level, towing, etc. and it stays cooler than you are reporting. Of course, unless we were running side by side and checking with the same temp gauges, etc. there are a lot of conditions that could vary and be leading to the understood/reported temp differences.

Good luck,

Fan clutch ports open as expected when heated with hairdryer. When I opened the fan clutch, it was about 95* in the garage, so the ports were already half open. Put bimetallic in temp monitored water, rechecked opening and closing operation. Set to half open at 95* as many do.

Radiator brand new TYC unit, clean as can be. Condenser 1 year old denso unit, cleaned it off a month ago. Was a little dusty prior but fins are straight, clean now, with no corrosion.

I'm suspecting thermostat or engine tuning issue as well. Going to investigate timing this weekend. Anything else worth checking?

 

[iansplatinum]

Fan clutch ports open as expected when heated with hairdryer. When I opened the fan clutch, it was about 95* in the garage, so the ports were already half open. Put bimetallic in temp monitored water, rechecked opening and closing operation. Set to half open at 95* as many do.

Radiator brand new TYC unit, clean as can be. Condenser 1 year old denso unit, cleaned it off a month ago. Was a little dusty prior but fins are straight, clean now, with no corrosion.

I'm suspecting thermostat or engine tuning issue as well. Going to investigate timing this weekend. Anything else worth checking?

Also I mentioned this in my forst post- what does this mean? Is it normal? Blackish coating/discoloration on inside of old water pump. Does not scrape off with finger nail.

 

[jpoole]

5 pages in and I've not read it all so I'm at high risk of repeating previous ideas, asking dumb questions and wasting time!

My initial response to your last post is wondering if your temp numbers are correct but I'm sure that was suggested earlier in the thread and you probably responded with multiple temp checking methods of verified accuracy... My other thoughts move to timing, air leaks/unmetered air (air fuel ratios) and similar universal engine temp areas.

In any case, you are in uncharted waters for me on an 80 and I don't have more ideas that I have specific experience with on an 80 at this point. Makes me glad that once I covered the basics (clean the cooling system, setup the fan clutch, foam gasket the rad) my 80 temps fell right into line! I hope you've just overlooked something easy but at this point it seems more like you've been really thorough and frankly, have done more to address these high temps than I had to do.

I'll keep reading along to see if you turn up some new findings/ideas in these areas as you proceed.

 

[GeoRoss]

Seems a little high, like the car would want to lurch forward? If i'm in drive and keep my foot on the brake, 1100 rpm would be a good bit of force to overcome.

Think we need some more data to figure out how it's supposed to be...

Also, does IAC modulate the idle-up function when AC is on? Or is there some other valve?

When the compressor kicks on the idle increases when in drive. Maybe it is closer to 900, but it does't stay ~650. I don't know the up idle circuit off the top of my head.

 

[jpoole]

I've driven around in the 80 some this weekend, which has seen temps in the low 90s here with high humidity.

This weekend driving up mountains, on the interstate, in city traffic, etc. coolant temps never broke 190 and were in the mid 180s most of the time per the odb2 feed.

Idle with AC on and in drive was around 700 and in neutral around 900. I'm pretty confident that my 80 is running/performing well and that these idle numbers are good at least based on drive ability and engine temps.

I'd guess it feels hotter for people here, because of the humidity, than much hotter temps do out West. I also assume that humid air moving through the radiator is more effective at moving heat than the same amount of air with less humidity would be so perhaps it feels cooler for the 80 here than it would out West. I have seen higher temps in my 80 when driving out West vs in the humid East. Last Summer in NM and CO for instance I saw temps go into the 200s pretty regularly when towing in the mtns. Back in the East getting into the 200s, even towing in the mtns, is rare for my 80 (lower elevation and higher humidity seem like big factors). My 80 runs a good bit cooler when not towing and I don't know those numbers as I don't usually watch them as closely.

I still think you are running hot and have an at idle cooling issue but maybe folks in your region can share their numbers as those may be a more direct comparison.

 

[iansplatinum]

Tested new aisin thermostat side by side with toyota unit, both performed about the same. I think factory spec is 10mm open at 203*F, both met this criteria.

 

[80t0ylc]

After reading through this thead again, seeing your progress through the testing and troubleshooting, I've come to the conclusion that you are seeing a much more active temp gauge now that it's modified and reading more accurately. If I'm correct, you've modified it recently and that's when you noticed the temp creep with A/C on while idling. Bringing rpm's up will drop the temp which is normal. Sounds like you've upgraded the fan clutch fluid to 30K and checked opening temp of both clutch and now your thermostat. I don't think the dark coating on the water pump housing was significant and if you've sealed up the gaps around the radiator and shroud you should be good to go for Wyoming. That's a good pull from Dallas and fair elevation change. It took me a while to get comfortable after modifying my temp gauge, (it's been 13 yrs now) but it helped me when I understood what I was missing before. I even saw it barely go into the red (briefly) climbing a few passes towing my trailer. You gotta remember it's a 6 cylinder pulling similar weight of what a lot of other rigs have a V8 with more displacement and cooling capacity. So, you'll be running slower and hotter. I've found that lugging the engine on grades really brings the heat. Slower rpm's just to keep the engine noise down with the 1FZ on hills doesn't cut it. You'll want to keep the rpm's up - at least 2800, and 3200 - 4000 on long pulls and you will see the difference now on that gauge.

Let me post some facts, JIC you're unaware:

(From Tools-R-Us) 1FZ RPM peaks - Torque = 3200 rpm; HP = 4600 rpm

(From Ravi's thread) Modified temp gauge guide:
Pegged hot = 244*
Top of red = 227*
Bottom of red = 217*
Center = Approx. 189*
Cold line = 160*
Pegged cold = 150* or less

I printed this on a card and put it in the clear pocket of my sun visor for reference - it helps me at times:

 

[Malleus]

Fan clutch ports open as expected when heated with hairdryer. When I opened the fan clutch, it was about 95* in the garage, so the ports were already half open. Put bimetallic in temp monitored water, rechecked opening and closing operation. Set to half open at 95* as many do.

Radiator brand new TYC unit, clean as can be. Condenser 1 year old denso unit, cleaned it off a month ago. Was a little dusty prior but fins are straight, clean now, with no corrosion.

I'm suspecting thermostat or engine tuning issue as well. Going to investigate timing this weekend. Anything else worth checking?

You've done everything I've done and neither of us is having any success. As I stated earlier, my heating problem is very likely the source of the earlier blown headgasket. I inherited a CSF all metal radiator, which I took to a local shop (many thanks to Terry at The Cooling Center) who tested both the OEM and the aftermarket. The OEM was installed when I was seeing 200+°F, and I have not yet installed the brass tank model. The flow tests on both were good, but just for kicks, I had the metal tanks removed, the tubes rodded and the tanks resoldered. I'm replacing the fluid in the OEM clutch and pulling the water pump later today. I have no idea what the film inside yours is; I've never seen that in any Land Cruiser pump I've pulled. It looks like the oxide coating my parts get after I leave them in EvapoRust too long. It's chemically bonded and has to be wire-wheeled off.

I do not think the modded gauge is the problem. It's certainly not mine, and my temps are similar to yours.

At this point, I'm hoping Mr. Wizard is listening...

 

[iansplatinum]

After reading through this thead again, seeing your progress through the testing and troubleshooting, I've come to the conclusion that you are seeing a much more active temp gauge now that it's modified and reading more accurately. If I'm correct, you've modified it recently and that's when you noticed the temp creep with A/C on while idling. Bringing rpm's up will drop the temp which is normal. Sounds like you've upgraded the fan clutch fluid to 30K and checked opening temp of both clutch and now your thermostat. I don't think the dark coating on the water pump housing was significant and if you've sealed up the gaps around the radiator and shroud you should be good to go for Wyoming. That's a good pull from Dallas and fair elevation change. It took me a while to get comfortable after modifying my temp gauge, (it's been 13 yrs now) but it helped me when I understood what I was missing before. I even saw it barely go into the red (briefly) climbing a few passes towing my trailer. You gotta remember it's a 6 cylinder pulling similar weight of what a lot of other rigs have a V8 with more displacement and cooling capacity. So, you'll be running slower and hotter. I've found that lugging the engine on grades really brings the heat. Slower rpm's just to keep the engine noise down with the 1FZ on hills doesn't cut it. You'll want to keep the rpm's up - at least 2800, and 3200 - 4000 on long pulls and you will see the difference now on that gauge.

Let me post some facts, JIC you're unaware:

(From Tools-R-Us) 1FZ RPM peaks - Torque = 3200 rpm; HP = 4600 rpm

(From Ravi's thread) Modified temp gauge guide:
Pegged hot = 244*
Top of red = 227*
Bottom of red = 217*
Center = Approx. 189*
Cold line = 160*
Pegged cold = 150* or less

I printed this on a card and put it in the clear pocket of my sun visor for reference it helps me at times:

View attachment 3080579

this thread has largely been me questioning whether I'm chasing a non-issue.

Which btw, I looked again today and there are significant gaps on the side supports of the radiator. Will have to pull fan shroud to get to them. This could be why I didn't see any difference between the TYC unit and brass radiator. I didn't put foam on the TYC unit, because the 80 didn't have foam from the factory, you know?

Based on the raventai gauge guide though, I routinely hit about 210* just going through a long drivethru with AC on. Others don't hit this unless they're towing up grade it seems.

 

[Malleus]

When your measurements indicate you have high engine temperatures, how hot are the fenders and hood? Are they warm to teh touch, or so hot you can't keep your hand on them?

 

[Marco Lau]

this thread has largely been me questioning whether I'm chasing a non-issue.

Which btw, I looked again today and there are significant gaps on the side supports of the radiator. Will have to pull fan shroud to get to them. This could be why I didn't see any difference between the TYC unit and brass radiator. I didn't put foam on the TYC unit, because the 80 didn't have foam from the factory, you know?

Based on the raventai gauge guide though, I routinely hit about 210* just going through a long drivethru with AC on. Others don't hit this unless they're towing up grade it seems.

My rig don't even hit 210 when climbing 7% grade with 3 ppl and AC blasting in 95F heat. Something is not normal.

 

[iansplatinum]

When your measurements indicate you have high engine temperatures, how hot are the fenders and hood? Are they warm to teh touch, or so hot you can't keep your hand on them?

From memory, pretty dang hot. Cats are brand new as well and still getting hot floor boards on long highway drives, despite installing an inch of styrofoam.

Checkin timing next. Retarded spark timing could definitely lead to hot cats, hot exhaust, hot engine...

 

[Malleus]

FWIW, I don't think you're chasing a non-issue.

Timing's the last thing on my list, too. The cool '95 80 I have runs 190°F all day, every day; the fenders and hood get warm, but definitely not hot. The '95 problem child gets so hot you'll get a 1st degree burn leaning on the driver's side fender, unless the hood's open, then it's just really, really hot. The cool kid's timing is right on 3° BTDC at idle, which is pretty stable at 650 rpm, ±10 rpm. I have the whole cooling system apart right now, so I have no idea where the timing is.

Also, on the hot rod, I checked the exhaust manifold temps, when it was really hot, and they were pretty stable at 300°F, same as the other 80 I have. The down pipe, just below the manifolds checked in at 190°F.

It seemed to be just the top end that was outrageously hot, on mine at least.

 

[iansplatinum]

FWIW, I don't think you're chasing a non-issue.

Timing's the last thing on my list, too. The cool '95 80 I have runs 190°F all day, every day; the fenders and hood get warm, but definitely not hot. The '95 problem child gets so hot you'll get a 1st degree burn leaning on the driver's side fender, unless the hood's open, then it's just really, really hot. The cool kid's timing is right on 3° BTDC at idle, which is pretty stable at 650 rpm, ±10 rpm. I have the whole cooling system apart right now, so I have no idea where the timing is.

Also, on the hot rod, I checked the exhaust manifold temps, when it was really hot, and they were pretty stable at 300°F, same as the other 80 I have. The down pipe, just below the manifolds checked in at 190°F.

It seemed to be just the top end that was outrageously hot, on mine at least.

Tested timing, it was about 4-5* at idle with diagnostic port jumped. Which is acceptable.

Tested vacuum, needle flutters between 20-21 Hg, which is a healthy number for my elevation. Not sure what the flutter is, but doubt it's related to the heat.

My fenders are hot but I can hold my hand on them for about 10 seconds before I need to take it off.