Measuring radiator cooling efficiency (1 Viewer)

[Old80]

I have a 97 80 Series with FZ-1FE engine. I've had it for 13 years and I reckon it has always run a bit hot. Lately it doesn't seem all that hard to get the needle in the top half of the gauge. Eg. cruising at 100kph on highway with or without a load but especially if in "heavy" sand even if slowly. On the highway it recovers after a while if I drop the speed to 90kph. At the moment I'm suspecting the radiator even though it's not the same radiator I've had all the time. Using a scanner type thermometer I get temp at the radiator top inlet at 98-100 deg C and at the thermostat housing 90-92 deg C. That doesn't look like much cooling going on. Presumably the thermostat housing also gets affected by direct engine heat.

Can anyone give me any guidance on what temps I should expect and if there's a better way to measure please?

 

[Desert Dino]

half of the gauge you already coking your motor unless you did the mod to unlock it
use scan tool to see the actual motor temp if it disconnects the AC you are in damage zone

1FZ-FE The Big Overheating Experiment. TESTED SOLVED!!!

ON December 2017 I posted this thread https://forum.ih8mud.com/threads/help-on-the-verge-of-despair-1fz-fe-overheating-on-flat-highway-over-60-miles.1032056/#post-11389186 It was winter time and I didn't like the temperature I was reading on my OBD and the dry contact thermometer installed on...

forum.ih8mud.com

Scan Gauge temp vs Toyota Gauge temp

Coming across Arkansas yesterday, my new-to-me Scan Gauge 2 on my new-to-me truck showed a temperature spike from the normal 184-195 to 220, while the Toyota gauge didn't move. Did I have a steam pocket near the temperature sensor that feeds the ECU? Any idea what's going on here? Once the...

forum.ih8mud.com

 

[SpenserAK]

As mentioned above, the dash gauge in stock form is more of a dummy light, which generally doesn’t move much from center until you are already starting to overheat. Since your 97 should be (?) OBD2, I would plug in a scanner to see the actual temperature while driving, so you know what you’re working with.

Beyond that, need more info. What is your cooling system like, exactly? Which radiator and how old? Age of other parts like thermostat, radiator cap, etc? Condition/function of fan clutch? Water pump? The more info the better

If I were in this position, I’d first confirm temps with a scanner. Then I’d probably check condition of water pump, test thermostat, replace cap if it was old, and check/service fan clutch. If everything checked out, I’d probably be looking at replacing the rad. More or less went through that last year when replacing a cheap rad (from PO) that split a seam. New Koyo rad + OEM tstat & cap, fan & water pump were good, running 184-186F all summer (admittedly not very hot here). Old rad worked before it split, but used to be 194-197F

 

[gummycarbs]

Using a scanner type thermometer I get temp at the radiator top inlet at 98-100 deg C and at the thermostat housing 90-92 deg C. That doesn't look like much cooling going on.

What's the temperature at the bottom of the radiator? The thermostat regulates flow, so its housing should always be near the operating temperature of the engine.

Assuming a warmed-up engine in a moderate climate, the difference between the top and bottom of the radiator shouldn't be drastic. If it is, the radiator is pl usually clogged up, causing the coolant to spend too much time there.

If the temperature at bottom of your radiator matches the temperature at your thermostat housing, then yeah, it sounds like the radiator isn't doing enough cooling. If it's significantly cooler, then it's likely a clogged radiator and/or thermostat that's not opening sufficiently.

 

[BILT4ME]

I have a 97 80 Series with FZ-1FE engine. I've had it for 13 years and I reckon it has always run a bit hot. Lately it doesn't seem all that hard to get the needle in the top half of the gauge. Eg. cruising at 100kph on highway with or without a load but especially if in "heavy" sand even if slowly. On the highway it recovers after a while if I drop the speed to 90kph. At the moment I'm suspecting the radiator even though it's not the same radiator I've had all the time. Using a scanner type thermometer I get temp at the radiator top inlet at 98-100 deg C and at the thermostat housing 90-92 deg C. That doesn't look like much cooling going on. Presumably the thermostat housing also gets affected by direct engine heat.

Can anyone give me any guidance on what temps I should expect and if there's a better way to measure please?

I was recently having temp issues that it would climb enough going uphill (pulling a light trailer) and temp would increase to shut off AC at 226°F, then cool back down to 205°F when I crested the hill.

Discovered my 7 YO OEM T-Stat was not opening all the way. Of course, I changed the fan clutch thinking that was it, then I changed ALL hoses, thermostat, and heater valve and the problem is fixed. Now I run 185°F to 196°F all the time.

So, maybe it's time for maintenance.

 

[Saito]

Any of you running sans thermostat in the summer ? ? I’m considering giving that a shot, even if just temporarily, to see where the temp would be without that restriction.

 

[ChaseTruck]

Any of you running sans thermostat in the summer ? ? I’m considering giving that a shot, even if just temporarily, to see where the temp would be without that restriction.

In Wyoming?? Aren't you concerned that you engine may not ever reach operating temperature?

 

[gummycarbs]

Any of you running sans thermostat in the summer ? ? I’m considering giving that a shot, even if just temporarily, to see where the temp would be without that restriction.

It could help narrow down the cause, but be careful that you aren't just masking the problem.

You'd need to have a repeatable test case, like a long hill that you consistently overheat on in summer temperatures. You'd then need to "warm up" the vehicle (as much as one can without a thermostat) and proceed to drive up the test hill long enough that you definitely see temperatures *stop* climbing.

In other words, if it only takes two minutes to drive up the hill, but it takes three minutes at that load to even get the engine up to normal operating temperature, you haven't proven anything.

I only mention this because it's so common to see people on forums installing colder thermostats to "fix" their cooling problem. All that does is give extra "headroom", a couple of extra minutes under load before you reach overheating temperatures.

 

[BILT4ME]

Any of you running sans thermostat in the summer ? ? I’m considering giving that a shot, even if just temporarily, to see where the temp would be without that restriction.

If you run without the t-stat, you may see operating temps in the 165°F range. While that SOUNDS good, it also keeps your engine in open-loop and overfueling because it's "cold". You will get horrible gas mileage and it will not run as efficiently.

This is an emergency fix only.

We had a 67 Camaro with a 327, 650 CFM carb and 180° dual plane intake that was easily capable of 5000 RPM and built for the short track. We ran it without a t-stat, but it was bored and built with a very lopey cam, so it built a lot of heat. Can it be done? Yes. This car was NOT about being a DD. It was a toy.

 

[80t0ylc]

I have a 97 80 Series with FZ-1FE engine. I've had it for 13 years and I reckon it has always run a bit hot. Lately it doesn't seem all that hard to get the needle in the top half of the gauge. Eg. cruising at 100kph on highway with or without a load but especially if in "heavy" sand even if slowly. On the highway it recovers after a while if I drop the speed to 90kph. At the moment I'm suspecting the radiator even though it's not the same radiator I've had all the time. Using a scanner type thermometer I get temp at the radiator top inlet at 98-100 deg C and at the thermostat housing 90-92 deg C. That doesn't look like much cooling going on. Presumably the thermostat housing also gets affected by direct engine heat.

Can anyone give me any guidance on what temps I should expect and if there's a better way to measure please?

You mention that your current radiator is not what came with the rig. Is your current a copper/brass CSF or other brand? The biggest help with my '94's cooling was switching from OEM style copper/brass to aluminum. Some have been hoodwinked into thinking that a 3 row CSF compared to the OEM (on '95-'97) 2 row aluminum increased the cooling power - wrong! This is especially significant if you're running larger tires and have added weight (armor and other mods). I found that the extra weight and tire size exceeds the capacity of copper/brass to cool the FZ-1FE on hills and higher speeds when ambient temps get extreme, which is when you really need the A/C.

 

[Saito]

Oh, I’m well aware of what the engine will do if the temp isn’t at the correct level. Just wondering if anyone had tried it and what the results were. I’ve got a brand new Tstat ready to go in. My engine runs at about 194° regardless and my cooling system is in top shape. It’s just flush time again and I’ll be dropping an aluminum radiator in with a custom shroud(dual electric fans) and a 70/30 mix. Thermostat that’s in there currently is close to 7 years old now . . .

Wasn’t trying to derail the thread. Just wondering. If I get this done over the next couple weeks and ditch my thermostat, I’ll post the results. I’ll be running up over 14B from Shell to Dayton next weekend so that’ll be a good test.

 

[80t0ylc]

Oh, I’m well aware of what the engine will do if the temp isn’t at the correct level. Just wondering if anyone had tried it and what the results were. I’ve got a brand new Tstat ready to go in. My engine runs at about 194° regardless and my cooling system is in top shape. It’s just flush time again and I’ll be dropping an aluminum radiator in with a custom shroud(dual electric fans) and a 70/30 mix. Thermostat that’s in there currently is close to 7 years old now . . .

Wasn’t trying to derail the thread. Just wondering. If I get this done over the next couple weeks and ditch my thermostat, I’ll post the results. I’ll be running up over 14B from Shell to Dayton next weekend so that’ll be a good test.

I understand the motivation to run 70/30 mix living where the temps drop way below zero in the winter. However, pure water is practically the most efficient coolant when temps get extreme, so you might want to re-think the mixture to 50/50 if you travel into hotter climates very often. There are additives that can enhance cooling efficiency but I like to keep things stupid simple (KISS theory).

 

[CJF]

I understand the motivation to run 70/30 mix living where the temps drop way below zero in the winter. However, pure water is practically the most efficient coolant when temps get extreme, so you might want to re-think the mixture to 50/50 if you travel into hotter climates very often. There are additives that can enhance cooling efficiency but I like to keep things stupid simple (KISS theory).

Hopefully he means 30% coolant, 70% water. Doing the opposite in summer would be a really bad idea.

 

[gummycarbs]

My engine runs at about 194° regardless and my cooling system is in top shape.

Then why would you want to run without a thermostat? If your engine is running at the correct temperature and not overheating under normal use, then running without a thermostat will just mean running your engine cold for no reason.

The '94 FSM says that the thermostat should start opening at 176 - 183F, with 10mm or more opening at 203F. 194F sounds fine to me.

 

[Saito]

194° is fine. I was just curious to see how it would work. The 70/30 mix I was talking about earlier is 70% DI water and 30% antifreeze, not the other way around. Sitting outside at -18° last winter it wasn’t frozen yet . . .and I was wanting to add water wetter to both my cooling system and IC too. Any little thing helps I’m sure.

 

[Old80]

half of the gauge you already coking your motor unless you did the mod to unlock it
use scan tool to see the actual motor temp if it disconnects the AC you are in damage zone

1FZ-FE The Big Overheating Experiment. TESTED SOLVED!!!

ON December 2017 I posted this thread https://forum.ih8mud.com/threads/help-on-the-verge-of-despair-1fz-fe-overheating-on-flat-highway-over-60-miles.1032056/#post-11389186 It was winter time and I didn't like the temperature I was reading on my OBD and the dry contact thermometer installed on...

forum.ih8mud.com

Scan Gauge temp vs Toyota Gauge temp

Coming across Arkansas yesterday, my new-to-me Scan Gauge 2 on my new-to-me truck showed a temperature spike from the normal 184-195 to 220, while the Toyota gauge didn't move. Did I have a steam pocket near the temperature sensor that feeds the ECU? Any idea what's going on here? Once the...

forum.ih8mud.com

Thank you. There's enough stuff in there to keep me going for a year. Where I've got to is this:-

• my radiator is copper/brass and is nearly seven years old. I had incorrectly thought it had been re-cored since then. So, it's a bit long in the tooth;
• I found some notes that, when that radiator was new, the temperature drop from inlet to outlet was approx 20 degrees C ( 35 degrees F) which is more than double what I get now. So its cooling performance is at least half what it was;
• my overall issue is definitely one or more of radiator, fan and water pump;
• it's time for a new radiator or at least for the existing one to be cleaned out;
• I suspect the fan and water pump are not the issue but are easy to check when taking the radiator out anyway;
• any replacement radiator will likely be another copper/brass one because I just don't trust plastic;
• the scan gauges / apps look great but I only have the engine bay OBD1 socket and will need to do some homework on how to connect it all up.

Thanks again for your advice.

 

[Old80]

As mentioned above, the dash gauge in stock form is more of a dummy light, which generally doesn’t move much from center until you are already starting to overheat. Since your 97 is OBD2, I would plug in a scanner to see the actual temperature while driving, so you know what you’re working with.

Beyond that, need more info. What is your cooling system like, exactly? Which radiator and how old? Age of other parts like thermostat, radiator cap, etc? Condition/function of fan clutch? Water pump? The more info the better

If I were in this position, I’d first confirm temps with a scanner. Then I’d probably check condition of water pump, test thermostat, replace cap if it was old, and check/service fan clutch. If everything checked out, I’d probably be looking at replacing the rad. More or less went through that last year when replacing a cheap rad (from PO) that split a seam. New Koyo rad + OEM tstat & cap, fan & water pump were good, running 184-186F all summer (admittedly not very hot here). Old rad worked before it split, but used to be 194-197F

Yes. I've done the split seam bit and of course it was miles from anywhere. A stick of solder got us home on that occasion.

Since my post I've found my radiator is older than I was thinking. I thought it was four years but it's seven. I also found that when it was new it produced a temperature drop more than double what it does now. I have no idea what brand radiator but it's copper/brass. The whole system is standard. Pump is clean, thermostat & cap are new, coolant always kept clean & replaced per service schedule - usually earlier. I did the fan clutch years ago but I think it's still pretty good. If I switch the engine off the fan stops pretty much immediately. There is no coolant loss and system was recently pressure tested.

I'm going to pull the radiator and probably replace with another copper/brass one. Than see what difference that makes.

 

[SpenserAK]

I hear you on plastic, but it’s well documented that aluminum rads cool better.. food for thought

 

[Old80]

What's the temperature at the bottom of the radiator? The thermostat regulates flow, so its housing should always be near the operating temperature of the engine.

Assuming a warmed-up engine in a moderate climate, the difference between the top and bottom of the radiator shouldn't be drastic. If it is, the radiator is pl usually clogged up, causing the coolant to spend too much time there.

If the temperature at bottom of your radiator matches the temperature at your thermostat housing, then yeah, it sounds like the radiator isn't doing enough cooling. If it's significantly cooler, then it's likely a clogged radiator and/or thermostat that's not opening sufficiently.

Bottom of the radiator is hard to get to. I think nearest I got was the bottom hose. I need to go try again just to prove what I got previously. I agree re t'stat housing and engine temp. Interestingly, I found where, when the radiator was new, it measured temp at t'stat housing at 20 deg C less than radiator inlet. That's more like what I was looking for now because otherwise there's no margin for when the engine is working hard. Double checking can't do any harm.

 

[Old80]

You mention that your current radiator is not what came with the rig. Is your current a copper/brass CSF or other brand? The biggest help with my '94's cooling was switching from OEM style copper/brass to aluminum. Some have been hoodwinked into thinking that a 3 row CSF compared to the OEM (on '95-'97) 2 row aluminum increased the cooling power - wrong! This is especially significant if you're running larger tires and have added weight (armor and other mods). I found that the extra weight and tire size exceeds the capacity of copper/brass to cool the FZ-1FE on hills and higher speeds when ambient temps get extreme, which is when you really need the A/C.

It's copper/brass but no idea what brand. I'll probably replace it with similar. I just don't trust plastic to last. Tyre sizes are spec. We're pretty loaded up when we go away whether it's family or a men's fishing trip. Once we get there the load comes off. I previously had a fairly stock 95 80 series doing exactly the same stuff and it had no issues with the same spec copper/brass radiators. There's nothing extreme about my four wheel driving - just occasional days when it needs to work. I'm pulling the radiator and will see where that leads.