Overheating diagnoses - loss of power HELP request! (1 Viewer)

[Gascan]

Need MUD’s brain trust help here…

The specs:
97’ LX450 with 352k miles.
Eats a bit of oil
Aluminum radiator 2.5 years old
OEM Thermostat 3 years old

The situation:

In Florida, it’s hot! Was low on fuel (likely 1 gallon away from fuel light coming on when down to the 21st gallon) stopped at a questionable gas station in the middle of the agricultural nowhere and filled approx. 6 gallons to get me to civilization.
35 miles later, I start going up a steep incline (Sunshine Skyway for the local folks) and feel a loss of power. Skinny pedal is in the floorboard and the RPM’s are high; a/c cuts out & engine temp starts to climb for the first time in my life with my trusty Cruiser (over a decade ownership). I crest the hill before reaching the red-line on the temp gauge and crest the way down. Lower RPM bring the temp gauge back to normal. I stop when safe (at bottom of bridge) and plug an OBD2 scanner in. Engine temps are around 200°F. Continue on to a “good” gas station and top off the tank; all the while monitoring the coolant temps. Long story short. High RPM are causing it to overheat.

Got home and checked what I could out:

Oil is good

Trans fluid is good

Fan clutch is good (nearly took my hand off!)

Coolant overflow tank was normally high when hot and normally level after it cooled down.

Coolant isn’t bubbling to indicate blown gasket; both with radiator cap off and overflow tank

Was thinking bad gas retarded timing and caused loss of power/overheating… now I’m thinking maybe the cats went tits-up with oil consumption and using Rotella 15-40 for the last 100k. Here are my O2 sensor readings and timing at high RPM. What do you fine people of MUD think and or suggest? This is my daily and I’m sort of in a bad shape if I can’t fix this ASAP.

 

[weaponoffreedom]

So, in a nutshell, it seems that you think that 200 degree water temp is "high".

I do not think this is that case.

Why are you at 4500 rpm at 0 mph? Might cause a spike in temps for sure. Either way, 200 is not too hot for the engine.

"in the red" could mean many things, it could be the gauge is bad.

Your data screenshot does not mean much as one would need to see live data. Sensor 2 is what you need to be looking at for a clogged CAT. Voltage readings should be steady and not fluctuate like sensor 1.

Not sure of the skyway incline, but it maybe that you were running out of gas in the incline, and that had an effect. Never heard of bad gas causing "in the red" water temps.

Does it over heat now? just normal driving?

 

[jpoole]

a/c cuts out

That indicates you got up to around 220 degrees F or higher as that's when the temp based AC cut off occurs.

I don't see a clear/single issue from your description but will say that if the ODB2 scanner isn't convenient to use I'd buy one of the bluetooth odb2 sending units, install it, and then run the torque app on a phone so that it's easy to monitor temps in real time whenever you drive it until you figure out what's going on. You should be able to get a sense of current operating temps and then see what impact changes you make have on temps, etc.

Have you driven it much more since this event? How much fuel have you run through it and how is it performing now? If you've got an issue it's going to keep coming back which will make it easier to diagnose as you gather more info, just don't run it over 220 more than you have to (opinions vary on the safe max temp, I aim for sub 200 but don't really worry til around 220).

If it was just bad fuel you should be able to relax after you run a few tanks through it without seeing more temp spikes and power losses.

 

[Gascan]

So, in a nutshell, it seems that you think that 200 degree water temp is "high".

I do not think this is that case.

Why are you at 4500 rpm at 0 mph? Might cause a spike in temps for sure. Either way, 200 is not too hot for the engine.

"in the red" could mean many things, it could be the gauge is bad.

Your data screenshot does not mean much as one would need to see live data. Sensor 2 is what you need to be looking at for a clogged CAT. Voltage readings should be steady and not fluctuate like sensor 1.

Not sure of the skyway incline, but it maybe that you were running out of gas in the incline, and that had an effect. Never heard of bad gas causing "in the red" water temps.

Does it over heat now? just normal driving?

Sorry, I was unclear, 200 was after temp gauge dropped down to normal and I limped my way home. Coolant temp climbed to over 233f at high RPM (when I revved the engine while traveling on the highway. The screenshots are of the live data after I brought the engine up to operating temp and revved the engine in my driveway while testing the fan clutch.


The Skyway is a very tall bridge with steep inclines on either side, I still had plenty of gas when going over it. The reason I initially thought that it was bad gas/retarded timing/overheat is:

 

[Gascan]

That indicates you got up to around 220 degrees F or higher as that's when the temp based AC cut off occurs.

I don't see a clear/single issue from your description but will say that if the ODB2 scanner isn't convenient to use I'd buy one of the bluetooth odb2 sending units, install it, and then run the torque app on a phone so that it's easy to monitor temps in real time whenever you drive it until you figure out what's going on. You should be able to get a sense of normal operating temps and then see what impact changes you make have on temps, etc.

Have you driven it much more since this event? How much fuel have you run through it and how is it performing now? If you've got an issue it's going to keep coming back which will make it easier to diagnose as you gather more info, just don't run it over 220 more than you have to (opinions vary on the safe max temp, I aim for sub 200 but don't really worry til around 220).

If it was just bad fuel you should be able to relax after you run a few tanks through it without seeing more temp spikes and power losses.

To clarify, I did mean a bluetooth OBD2 gauge with an app on my phone to view realtime data is what I used. Yes, coolant temp went over 233 F. I've driven it approx 6 miles since filling the rest of the tank with good gas. Let it idle in the driveway and even then, revving the engine caused coolant temp to shoot up to 217 F.

At this point, I suspect it's not bad fuel and is something mechanical, which is making me think clogged cat leading to high EGT which causes high engine temp. But I'm honestly throwing at the wall.

 

[weaponoffreedom]

Sorry, I was unclear, 200 was after temp gauge dropped down to normal and I limped my way home. Coolant temp climbed to over 233f at high RPM (when I revved the engine while traveling on the highway. The screenshots are of the live data after I brought the engine up to operating temp and revved the engine in my driveway while testing the fan clutch.


The Skyway is a very tall bridge with steep inclines on either side, I still had plenty of gas when going over it. The reason I initially thought that it was bad gas/retarded timing/overheat is:View attachment 3721072

Ok, so has it happened again since this event?

What is "high rpms on highway"?

Does it still overheat at the same temp?

Also, how clean is your AC condenser? Can you see through it?

 

[Gascan]

Ok, so has it happened again since this event?

What is "high rpms on highway"?

Does it still overheat at the same temp?

Also, how clean is your AC condenser? Can you see through it?

Yes, it's still overheating when raving the engine.

Hight RPM is over 3,000

A/C condenser is a brand new Denso unit from earlier this year. Clean as they come.


I should note: there are no trouble codes.

 

[weaponoffreedom]

Yes, it's still overheating when raving the engine.

Hight RPM is over 3,000

A/C condenser is a brand new Denso unit from earlier this year. Clean as they come.


I should note: there are no trouble codes.

And not revving the engine yield normal temps?

Driving at highways speeds, it still overheats?

 

[Gascan]

And not revving the engine yield normal temps?

Driving at highways speeds, it still overheats?

Driving highway speed, as tested when I drove home after topping off the fuel tank at gas station, yes it would still overheat when engine was consistently revved at higher RPM.
Not revving the engine yields normal temps based on that drive home and driveway tests. Have not driven it since I got home a few hours back.

EDIT: I should note that driving it back at lower speeds and not revving the engine too high, the coolant temp was around 210-213 f.

 

[weaponoffreedom]

Beyond engine mechanical, like a blown head gasket, I would say the thermostat is the culprit, even though it was newer. It is the cheapest thing to try aswell. I think it is a stretch to call engine timing the cause of this overheating. Maybe in an older, non electronically controlled engine, but not yours.

The proper way to test for exhaust gas in the coolant is with a kit like this:

BT-500 Universal Petrol & Diesel Block Tester / Gasket Combustion Leak Test Kit | eBay

KIT Includes: • Block Tester® combustion leak tester. Block Tester® is a complete combustion leak tester. Works with virtually any liquid-cooled internal combustion engine or generator with a closed cooling system including: gasoline, diesel, propane, natural gas and other alternative fuels.

www.ebay.com

The bubble test really requires a special radiaotr funnel, and even then, it is not 100%. The above test kit is 100% conclusive.

Keep me informed, I am interested to know what it is.

 

[Gascan]

Update:

Replaced the thermostat, it idles fine but maintaining RPM around 4k for over 20 seconds and the coolant temp climbs past 220°; so issue is still unresolved.

Can the fan clutch lockup at temp but still be faulty? I noticed that it did not “roar” on a cold startup.

 

[weaponoffreedom]

Update:

Replaced the thermostat, it idles fine but maintaining RPM around 4k for over 20 seconds and the coolant temp climbs past 220°; so issue is still unresolved.

Can the fan clutch lockup at temp but still be faulty? I noticed that it did not “roar” on a cold startup.

you just replaced the thermostat this morning?

 

[Gascan]

you just replaced the thermostat this morning?

Yes, popped my old one in (it was good when I originally replaced it as a PM).

 

[mudgudgeon]

Yes, popped my old one in (it was good when I originally replaced it as a PM).

I would suggest testing the thermostat by heating it in a pot of water, check the temperature when you first see it start to open, and again when it looks to be fully open.

Unless it's brand new OEM out of the box, I'd keep the thermostats on the suspect list until verified as good
Its easy to test and verify if a thermostat is good or not.

Next suspect would be fan clutch.

Then head gasket.

If cats are blocked, in my experience you'll see a loss of power, or a stumble/ misfire.

Does the radiator have foam seal around the edges?
New ones often don't come with the foam, and allow air to escape around the sides

 

[mudgudgeon]

PS . . .

In Florida

a steep incline

Does not compute!

 

[jpoole]

To help rule out a number of possible issues you can test misting / lightly spraying water on the radiator when the engine is hot. If this causes a quick drop in temps then you will have pretty much confirmed that the tstat is opening and coolant is circulating through the radiator properly. There could still be mild constrictions or cooling system issues but if cooling the radiator cools the engine then the cooling system is functional for the most part.

You can also turn on your inside heater(s) to see how they impact coolant temps. If these blow heat really well and also drop engine temps you've again confirmed decent coolant flow and at the same time should have a sense of the engine creating "normal" or excessive amounts of heat.

I do think that the fan clutch is a suspect here as it will impact temps while driving at some speeds and while stationary. In my experience there is a band of speeds where the fan clutch is less important that I'd guess runs from 20mph to 55mph, roughly. If you drive it in those temps and it stays relatively cool but then it gets hot above/below those temps then insufficient airflow from the fan becomes a more likely cause for the issue.

If your fan clutch is a decent quality unit (like an Aisin blue hub) and it's not rusty/crusty or otherwise damaged you can change the oil, set the opening temp and get it going without spending much time or $$ on it. Search the forums for the details on oil to use, how to set the temps etc. It's been covered repeatedly.

How is power output? Does the rig generally drive/feel the same as it did before or is it sluggish? Is the power loss, if present, more noticeable at higher or lower temps?

 

[SHIfTHEAD]

A couple things come to mind; 1) these engines are notorious for running hot at high RPM. The way I've mitigated this problem is to install two 3D printed spacers at the hood hinge that creates a 1" gap at the rear of the hood, essentially making it a big louvre. Since then I've never seen the temps beyond the low 220's. I'll paste a link below of where I bought them. 2) could you have a water pump going bad?

FJ80 LX450 FZJ80 Hood Vent Risers - Etsy

This Car Parts item by SolveFunction has 67 favorites from Etsy shoppers. Ships from San Mateo, CA. Listed on Jul 22, 2024

www.etsy.com

 

[Malleus]

Need MUD’s brain trust help here…

The specs:
97’ LX450 with 352k miles.
Eats a bit of oil
Aluminum radiator 2.5 years old
OEM Thermostat 3 years old

The situation:

In Florida, it’s hot! Was low on fuel (likely 1 gallon away from fuel light coming on when down to the 21st gallon) stopped at a questionable gas station in the middle of the agricultural nowhere and filled approx. 6 gallons to get me to civilization.
35 miles later, I start going up a steep incline (Sunshine Skyway for the local folks) and feel a loss of power. Skinny pedal is in the floorboard and the RPM’s are high; a/c cuts out & engine temp starts to climb for the first time in my life with my trusty Cruiser (over a decade ownership). I crest the hill before reaching the red-line on the temp gauge and crest the way down. Lower RPM bring the temp gauge back to normal. I stop when safe (at bottom of bridge) and plug an OBD2 scanner in. Engine temps are around 200°F. Continue on to a “good” gas station and top off the tank; all the while monitoring the coolant temps. Long story short. High RPM are causing it to overheat.

Got home and checked what I could out:

Oil is good

Trans fluid is good

Fan clutch is good (nearly took my hand off!)

Coolant overflow tank was normally high when hot and normally level after it cooled down.

Coolant isn’t bubbling to indicate blown gasket; both with radiator cap off and overflow tank

Was thinking bad gas retarded timing and caused loss of power/overheating… now I’m thinking maybe the cats went tits-up with oil consumption and using Rotella 15-40 for the last 100k. Here are my O2 sensor readings and timing at high RPM. What do you fine people of MUD think and or suggest? This is my daily and I’m sort of in a bad shape if I can’t fix this ASAP.

View attachment 3721040

View attachment 3721041

Just so I understand what you're describing, your engine rpm increases while driving uphill and simultaneously losing power/speed?

And you're sure it's an engine power problem? As opposed to a slipping transmission?

As noted above, the 1FE-FZ heats up at high rpm, due to the cooling system design. It appears that 3500 rpm is the operational happy high point; anything above that and it has a hard time keeping up.

 

[Gascan]

I would suggest testing the thermostat by heating it in a pot of water, check the temperature when you first see it start to open, and again when it looks to be fully open.

Unless it's brand new OEM out of the box, I'd keep the thermostats on the suspect list until verified as good
Its easy to test and verify if a thermostat is good or not.

Next suspect would be fan clutch.

Then head gasket.

If cats are blocked, in my experience you'll see a loss of power, or a stumble/ misfire.

Does the radiator have foam seal around the edges?
New ones often don't come with the foam, and allow air to escape around the sides

PS . . .




Does not compute!

Placing an order on a new OEM fan clutch and thermostat now. No I don't have the foam on the radiator, but it has not been an issue in over two years. I'll note that with the old thermostat I popped in this morning, the lower radiator hose began to get warm when the coolant temp went over 82F, same as the OEM thermostat rating, indicating that it's working.

Lol, I knew it wouldn't makes sense when I mentioned Florida and steep incline in the same post but the Sunshine Skyway bridge, spanning over the mouth of Tampa Bay with its 4% grade is steep by local standards.

To help rule out a number of possible issues you can test misting / lightly spraying water on the radiator when the engine is hot. If this causes a quick drop in temps then you will have pretty much confirmed that the tstat is opening and coolant is circulating through the radiator properly. There could still be mild constrictions or cooling system issues but if cooling the radiator cools the engine then the cooling system is functional for the most part.

You can also turn on your inside heater(s) to see how they impact coolant temps. If these blow heat really well and also drop engine temps you've again confirmed decent coolant flow and at the same time should have a sense of the engine creating "normal" or excessive amounts of heat.

I do think that the fan clutch is a suspect here as it will impact temps while driving at some speeds and while stationary. In my experience there is a band of speeds where the fan clutch is less important that I'd guess runs from 20mph to 55mph, roughly. If you drive it in those temps and it stays relatively cool but then it gets hot above/below those temps then insufficient airflow from the fan becomes a more likely cause for the issue.

If your fan clutch is a decent quality unit (like an Aisin blue hub) and it's not rusty/crusty or otherwise damaged you can change the oil, set the opening temp and get it going without spending much time or $$ on it. Search the forums for the details on oil to use, how to set the temps etc. It's been covered repeatedly.

How is power output? Does the rig generally drive/feel the same as it did before or is it sluggish? Is the power loss, if present, more noticeable at higher or lower temps?

My clutch is original with 352K miles on it, placing an order on a new OEM fan clutch and thermostat now. Power output went down significantly during the aforementioned drive. Have not driven it since I got home last night. Just spit-balling but maybe the timing was retarded due to high temps, leading to decrease in power (most noticeable when going up inclines like the highway on-ramp)?

A couple things come to mind; 1) these engines are notorious for running hot at high RPM. The way I've mitigated this problem is to install two 3D printed spacers at the hood hinge that creates a 1" gap at the rear of the hood, essentially making it a big louvre. Since then I've never seen the temps beyond the low 220's. I'll paste a link below of where I bought them. 2) could you have a water pump going bad?

FJ80 LX450 FZJ80 Hood Vent Risers - Etsy

This Car Parts item by SolveFunction has 67 favorites from Etsy shoppers. Ships from San Mateo, CA. Listed on Jul 22, 2024

www.etsy.com

Noted, but the cruiser's been running without any overheating issues in Florida for over a decade. My understanding from reading MUD is that the water pump failure is very noticeable when it happens.

Just so I understand what you're describing, your engine rpm increases while driving uphill and simultaneously losing power/speed?

And you're sure it's an engine power problem? As opposed to a slipping transmission?

As noted above, the 1FE-FZ heats up at high rpm, due to the cooling system design. It appears that 3500 rpm is the operational happy high point; anything above that and it has a hard time keeping up.

Yes, the RPM were increasing because I was gunning the engine after realizing I was losing speed on the incline; I'm positive it was not slippage.


I appreciate everyones support. Since the last update, I've tightened the alternator belts (I installed new ones maybe a month ago) but that did not resolve the issue.

 

[mudgudgeon]

One thing to be aware of. Things fail slowly. You get an accumulation of issues, that are degrading. At some point, you get to a critical condition.
Could be, no foam around the radiator, thermostat not opening fully, fan clutch not fully engaging, steep speed bump across Tampa Bay, hot day, transmission not as efficient as it once was, engine down on power due to normal wear and tear, and suddenly you have an issue that's been 30 years in the making.

I've tested old and new thermostats in the last to compare. I had an old I've that started to open about when it should, but only opened about half as much a the new one. Thiscan be a big restriction on coolant flow