Mysterious over-heating on idle even after full engine rebuild (1 Viewer)

[BajaSupreme]

Hi folks,

3 months ago I started experiencing overheating on idle in the desert heat of Dubai with ambient temperatures reaching 50C sometimes. I know for a fact that shouldn’t warrant LC100 with 1Fz-fe engine to hit redline on the temp gauge so I wanted to fix it asap.

I created a thread in r/LandCruisers but after trying everything mentioned, it still overheats. But thanks to that thread I found another owner who has the same exact problems as mine, even did the same fixes as mine before reaching out to me.

Here’s what I replaced to attempt fixing the issue:

1- Custom made brass tank copper core radiator. Replaced again with aftermarket aluminum radiator.

2- Replaced the fan clutch and fan.

3- Replaced radiator caps and flushed the coolant.

4- Replaced the two coolant temperature sensors on the engine.

5- Replaced Waterpump, replaced again with aftermarket WP.

6- Added additional auxiliary cooling fan since GCC version came with only one fan, this made no difference to the overheating issue.

7- The Previous owner removed the thermostat so I added again but it made no difference. Now I have it removed so that it doesn’t interfere with issue.

8- Replaced the idle bearings and checked the belt, everything was fine.

9- Removed external trans cooler that I added cuz I thought it wasn’t letting air into the rad.

10- Added foam around the radiator so there’s no air leaks and noticed improved A/C cooling but the car was still overheating.

After doing all that and not having any changes to the temp, we decided to replace the head gasket even though I didn’t have any symptoms of blown head gasket like white smoke.

So I ordered the full replacement kit that came with all the gaskets needed for the engine. We replaced almost everything that had a gasket even the engine oil cap cuz that was leaking XD.

IT STILL OVERHEATES ON IDLE.

The garage wanted to pressure test the head, it came out fine but the main engine block has minor errors so they are skimming it.

I don’t think that’s going to make any difference though.

When we replaced all the gaskets the Throttle body sensor’s connector was in poor condition, replaced that the car started to idle at 1000-13000RPM during this time the overheating issue was gone. Obviously I can’t let the car idle at those RPMs since it’s usually below 800RPM so when we fixed it, the car started overheating on idle again.

This leads me to believe the issue lies somewhere with the circulation of the coolant, even though we checked all the coolant flow paths and cleaned it.

I don’t know what I missed at this point since we basically replaced every part of the engine that’s responsible for cooling the engine.

This isn’t a faulty temp gauge though cuz both of with with our cars can’t stand infront of the hood when it’s overheating, I can barely even breath when it starts overheating.

I searched even this website and found similar threads but no solid fix, it seems like people with this issue magically disappeared from the face of the earth.

Everyone on those threads said to replace Tstat, rad, head gasket, WP, all of which I’ve already done.

Sorry for the long thread but I’ve been going crazy for the past two months due to this issue and just wanted to let it all out. Please let me know if you need any other additional info and I will reply asap.

 

[94SRUNNER]

Even though you have a 100 Series, becasue it has the 1FZ-FE in it, you may want to cross-post this in the 80 Series forum.

Symtoms of overheating just appeared one day or was there something leading up to it?

That said, what fan clutch did you install? OEM or an aftermarket?

 

[GremlinMobile]

Is that a pair of pliers and screwdriver laying inside the cylinder? Aren't you worried you'll scratch the walls and lose compression?

 

[azusa]

Hi folks,

3 months ago I started experiencing overheating on idle in the desert heat of Dubai with ambient temperatures reaching 50C sometimes. I know for a fact that shouldn’t warrant LC100 with 1Fz-fe engine to hit redline on the temp gauge so I wanted to fix it asap.

I created a thread in r/LandCruisers but after trying everything mentioned, it still overheats. But thanks to that thread I found another owner who has the same exact problems as mine, even did the same fixes as mine before reaching out to me.

Here’s what I replaced to attempt fixing the issue:

1- Custom made brass tank copper core radiator. Replaced again with aftermarket aluminum radiator.

2- Replaced the fan clutch and fan.

3- Replaced radiator caps and flushed the coolant.

4- Replaced the two coolant temperature sensors on the engine.

5- Replaced Waterpump, replaced again with aftermarket WP.

6- Added additional auxiliary cooling fan since GCC version came with only one fan, this made no difference to the overheating issue.

7- The Previous owner removed the thermostat so I added again but it made no difference. Now I have it removed so that it doesn’t interfere with issue.

8- Replaced the idle bearings and checked the belt, everything was fine.

9- Removed external trans cooler that I added cuz I thought it wasn’t letting air into the rad.

10- Added foam around the radiator so there’s no air leaks and noticed improved A/C cooling but the car was still overheating.

After doing all that and not having any changes to the temp, we decided to replace the head gasket even though I didn’t have any symptoms of blown head gasket like white smoke.

So I ordered the full replacement kit that came with all the gaskets needed for the engine. We replaced almost everything that had a gasket even the engine oil cap cuz that was leaking XD.

IT STILL OVERHEATES ON IDLE.

The garage wanted to pressure test the head, it came out fine but the main engine block has minor errors so they are skimming it.

I don’t think that’s going to make any difference though.

When we replaced all the gaskets the Throttle body sensor’s connector was in poor condition, replaced that the car started to idle at 1000-13000RPM during this time the overheating issue was gone. Obviously I can’t let the car idle at those RPMs since it’s usually below 800RPM so when we fixed it, the car started overheating on idle again.

This leads me to believe the issue lies somewhere with the circulation of the coolant, even though we checked all the coolant flow paths and cleaned it.

I don’t know what I missed at this point since we basically replaced every part of the engine that’s responsible for cooling the engine.

This isn’t a faulty temp gauge though cuz both of with with our cars can’t stand infront of the hood when it’s overheating, I can barely even breath when it starts overheating.

I searched even this website and found similar threads but no solid fix, it seems like people with this issue magically disappeared from the face of the earth.

Everyone on those threads said to replace Tstat, rad, head gasket, WP, all of which I’ve already done.

Sorry for the long thread but I’ve been going crazy for the past two months due to this issue and just wanted to let it all out. Please let me know if you need any other additional info and I will reply asap.

View attachment 3700439

View attachment 3700440

Do have pictures of the head gasket, both sides. #1 cylinder doesn't seem to be sealed in the front.

 

[azusa]

Did it get a combustion chamber leak down test before teardown?

 

[BajaSupreme]

Do have pictures of the head gasket, both sides. #1 cylinder doesn't seem to be sealed in the front.

Hi here’s the pic:

And no the combustion leak down test was not done, I wasnt aware of suck tests, when I took the car to the garage they looked at the engine coolant intake hose and said there’s pressure in the engine.

 

[BajaSupreme]

Is that a pair of pliers and screwdriver laying inside the cylinder? Aren't you worried you'll scratch the walls and lose compression?

I honestly didn’t notice it at the time, but the block has since been completely removed and inspected. The report came back as perfect condition for both the head and the block. So I think it is fine.

 

[BajaSupreme]

Even though you have a 100 Series, becasue it has the 1FZ-FE in it, you may want to cross-post this in the 80 Series forum.

Symtoms of overheating just appeared one day or was there something leading up to it?

That said, what fan clutch did you install? OEM or an aftermarket?

Good idea, I will do that thanks!

Yes it just appeared this summer after overhauling the transmission since the previous owner completely recked it.

And as for the second person who has the same issue as mine, he noticed the issue after flushing the radiator.

 

[94SRUNNER]

Good idea, I will do that thanks!

Yes it just appeared this summer after overhauling the transmission since the previous owner completely recked it.

And as for the second person who has the same issue as mine, he noticed the issue after flushing the radiator.

If it was noticed after a coolant flush, then I suspect one possibility would be air in the coolant system. There are good coolant bleeding details in the 80 Series section, but you want to part with the front end elevated as you bleed the coolant system. Make sure they thermostat is installed with the jiggle valve in the 12 o'clock position. Make sure the heat is set to high on the climate control. You can also use a vacuum bleeder to help

 

[AARONTLC]

Good idea, I will do that thanks!

Yes it just appeared this summer after overhauling the transmission since the previous owner completely recked it.

And as for the second person who has the same issue as mine, he noticed the issue after flushing the radiator.

First off, I am really sorry this is happening. These vehicles almost become a member of the family.

So a couple weeks back on this forum there was a gentleman that was having an overheating issue after doing some repair work and long story short it was a shop towel that was left in a hose or inlet or something. I guess where I am going is could it be possible that some thing is clogged or blocked. The other guy had an issue after a flush, (something broke free and plugged a port?), you stated after a transmission rebuild. Did they pull the motor to do that and maybe left something plugged? Just talking out loud here. Since you are so vested, can we remove some hoses and put a hose on your water passages and take a look at flow? Wish you the best!

 

[azusa]

The first picture of the head gasket, number one cylinder near the timing chain between 11:00 and 12:00. Doesn't look very good can you take another picture. The engine block needs to be cleaned with a wire wheel, then you can inspect it for pitting. The wire wheel will take off any remnants of the head gasket material, it's difficult to see the pitting unless you use a high speed wire wheel. The blocks that I've come across have never been warped. If that's what they're calling good that it's not warped, you need to check again for pitting. Around the firing ring and around the water jackets. Also inside the water jackets is there excessive buildup of scale and rust?

 

[azusa]

Every time I refill the cooling system, I do vacuum refill of cooling systems. Buy a vacuum tool and fill coolant this way, it will avoid trapping air which probably destroyed your engine.