engine almost over heat error code says..... (1 Viewer)

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engine almost over heated, maybe did? just happened this morning on the way to work.
heres whats going on:

* coolant dial gauge says its getting hot, then I let off throttle, it cools down to normal temp range in a matter of 20 to 60 seconds..sometimes.
* low coolant, when i top off the radiator and to the full line of the overflow cont. the overflow bubbles or boils? cant tell but it seems hot.
*rough idle, ( like at stop lights) but at cruising speeds of 35 to 50mph it runs smooth.
* following error codes: P0306, P0133, P0103 ( 133 and 103 talk about O2 sensor, 306 says #6 misfire)
* lower Radiator hose is luke warmish/slightly Luke. Top Radiator hose much warmer/hot. when i pull over to let it cool down a little i heard bubbling.
* coolant in engine bay, but i think it boiled out of overflow cont.
**total miles driven like that 30 miles and not any more until problem solved.

1FzFE FEFZ...you know which....inline 6, standard 4.5 L

the question: whats causing the overheating? thermostat or the misfire?
 
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flintknapper

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I'd wash down the engine bay so you can detect any NEW coolant losses or deposits there.

IF your radiator cap is not new-ish and NOT OEM....then replace it. . Replace thermostat and gasket. Top off radiator and overflow bottle then watch carefully.

Best to have some monitoring system other than the factory dash gauge for coolant temp. The factory gauge has a HUGE dead spot in it.....and by the time you see it rising into the red you are already overheating or about to be.

Number six misfire is not good news. Could be an injector, plug or plug wire, but the head-gaskets on the 1FZ-FE are known to fail at that spot more often than anywhere else (mine did).
 
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I'd wash down the engine bay so you can detect any NEW coolant losses and deposits there.

IF your radiator cap is not newish and NOT OEM....then replace it. . Replace thermostat and gasket. Top off radiator and overflow bottle then watch carefully. Best to have some monitoring system other than the factory dash gauge for coolant temp. The factory gauge has a HUGE dead spot in it.....and by the time you see it rising into the red you are overheating or about to be.

Number six misfire is not good news. Could be an injector, plug or plug wire, but the headgaskets on the 1FZ-FE are known to fail at that spot more often than anywhere else (mine did).


owned the LC for 7 years, never replaced the Rad cap. most of coolant that needs to be sprayed in on the passenger side
 

flintknapper

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owned the LC for 7 years, never replaced the Rad cap. most of coolant that needs to be sprayed in on the passenger side

Get an new OEM cap. If the system is not properly pressurized the coolant will boil at much lower temperature. Can also be your source of coolant loss. There are several sources on the passenger side that could be leaking. Cleaning that area might reveal if that is the case.
 

flintknapper

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but why the o2 sensor code? any guess? should i worry about o2 sensors last?

What causes the P0133 code?
  • A faulty O2 Sensor
  • A leaking exhaust manifold
  • An engine vacuum leak
  • An open or short in the wiring of the O2 sensor
  • Soot or oil buildup on the O2 sensor (excessive buildup will clog the ports the sensor uses to measure the air fuel ratio)
  • A dirty mass air flow sensor
  • Incorrect fuel pressure

What causes the P0103 code?
The MAF Sensor high voltage output to the ECU may have several causes:

  • The source of the problem is the sensor voltage output is higher than normal or required by the ECU to function with other sensor signals.
  • The wiring or MAF sensor may be too close to higher voltage consumption components, alternators, ignition wires, etc. causing inaccurate output signals.
  • The air intake system from the air filter assembly may have a large leak like a bad vacuum hose, air intake hose, loose hose clamps or other intake leak before the MAF sensor.
  • MAF sensors must operate within specific ranges to send correct signals for the ECU to adjust correctly and in conjunction with other sensors for proper engine operation.
 

flintknapper

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damn! o_O wow thats alot to considered...uhh!

Faulty 02 sensors could conceivably cause a 'lean' condition which could result in the engine running hot.

Look at your air intake tube that goes from the air cleaner box to the throttle body. Very common for there to be a crack in the bottom side resulting in a vacuum leak (MAF) will be affected.
 
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jbee

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"Best to have some monitoring system other than the factory dash gauge for coolant temp. The factory gauge has a HUGE dead spot in it.....and by the time you see it rising into the red you are already overheating or about to be."

Agree. You can buy one of those cheesy bluetooth or wifi OBD 2 things on amazon that will send to your phone the actual readings, actual temp, rpm, and maybe even MAF Sensor data in real time. My old Harbor Freight wired scanner will do it. If your gauge is wonky you could miss a 210+ degree temp = too late.
 
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Faulty 02 sensors could conceivably cause a 'lean' condition which could result in the engine running hot.

Look at your air intake tube that goes from the air cleaner box to the throttle body. Very common for there to a crack in the bottom side resulting in a vacuum leak (MAF) will be affected.


do you mean the rubber boot/ tube ? its 4 years old, i replaced it when i caused a crack in the rubber.
 
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i did a boil test on the old Thermostat, sadly it works. i was hoping that was it. opened around 180 or 190...one of those. i put the new thermo in, going to have a neighbor run me to get coolant, new sparkplugs and new SP wire and cap and rotor. if that doesnt work...o2 sensors..upper and lower?
 
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"Best to have some monitoring system other than the factory dash gauge for coolant temp. The factory gauge has a HUGE dead spot in it.....and by the time you see it rising into the red you are already overheating or about to be."

Agree. You can buy one of those cheesy bluetooth or wifi OBD 2 things on amazon that will send to your phone the actual readings, actual temp, rpm, and maybe even MAF Sensor data in real time. My old Harbor Freight wired scanner will do it. If your gauge is wonky you could miss a 210+ degree temp = too late.

after 210*F head warps?
 

jbee

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after 210*F head warps?
I don't know if that's the real temp or if the head will warp; point is that it's good to see the real temp all the time.
In a few drives you'll get a feel for where your truck likes to run.
I'm driving a new to me LX450 (newly engine swapped) now and the shop loaned me a supergauge (ultragauge?) to watch the temp all the time.
It likes to run around 190 but it's cool out (phoenix; 40 degrees-75 degrees) If engine temp spikes by 10 degrees for no reason I know to stop, open the hood, and poke around.
 
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AC shuts down at engine temp of 226. Gonna be hotter than that to warp a head.

However, that's not always causes a head gasket to blow.

I think @flintknapper is walking you through proper diagnosis so you can isolate it to a blown HG.

Any maple syrup smelling exhaust cloud when running?
 
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AC shuts down at engine temp of 226. Gonna be hotter than that to warp a head.

However, that's not always causes a head gasket to blow.

I think @flintknapper is walking you through proper diagnosis so you can isolate it to a blown HG.

Any maple syrup smelling exhaust cloud when running?

There's definitely a coolant smell as its in part of the engine bay. i rinsed the main source. do you think it is a blown HG? havent refilled the coolant yet, dont have penfrost asian coolant stuff yet
 
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There's definitely a coolant smell as its in part of the engine bay. i rinsed the main source. so you think it is a blown HG? havent refilled the coolant yet, dont have penfrost asian coolant stuff yet
Do you know the maintenance history of the head gasket on this truck?

How many miles?

Follow what he's telling you.

Next will be compression tests,
Exhaust gas test on the radiator,
And inspecting the spark plugs.
 

richardlillard1

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AC shuts down at engine temp of 226. Gonna be hotter than that to warp a head.

However, that's not always causes a head gasket to blow.

I think @flintknapper is walking you through proper diagnosis so you can isolate it to a blown HG.

Any maple syrup smelling exhaust cloud when running?

My record high was either 260° or 270° when the belts failed on the highway once.

In addition to checking for exhaust smells, performing a block test and smelling the coolant overflow bottle can often be very revealing. If exhaust gases are being shoved into the system the block test fluid will change color and the overflow bottle will smell like exhaust.
 
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i dont mean to dismiss anyones advice ive been spoiled with this LC and my maint / diagnosing has suffered ..and this is my only vehicle...so theres that pressure, my apologies
 

Tachycardic

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Not saying that it is your head gasket, but my original HG started going bad at 260k miles. If you plan on keeping the truck for a while, you should be saving up for a new HG job at this point, or just get it done now for peace of mind. These trucks are tanks, but a quarter of a million miles is a lot regardless.
 

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