I thought Land Cruisers didn’t overheat ever

[Eiji73]

My LJ73 (2LT diesel) sometimes overheats (well at least the temperature gauge reaches the red zone). It does that if I drive fast (~100km/h) for a while on a motorway that goes uphill (even not so steep). I usually either ease off the accel and take it easy (70-80 km/h) for five-ten minutes to get the temp back in the normal range (middle) or sometimes if that doesn’t work I stop and let it cool down engine off before getting on my way again.

Any pointers?

 

[Reinhardtius]

Please take a look on this forum for 2LT blown head gaskets issues, as this may be a starting point for you. You can conduct tests and visual inspections to see if your overheating is a function of a blown head gasket.

You may also wish to evaluate your cooling system and whether it is doing its work as it should

 

[Tigris]

My LJ73 (2LT diesel) sometimes overheats (well at least the temperature gauge reaches the red zone). It does that if I drive fast (~100km/h) for a while on a motorway that goes uphill (even not so steep). I usually either ease off the accel and take it easy (70-80 km/h) for five-ten minutes to get the temp back in the normal range (middle) or sometimes if that doesn’t work I stop and let it cool down engine off before getting on my way again.

Any pointers?

As you likely know, you have an IDI diesel engine, which means they have pre-chambers. So heat transfers from the cylinder head into the coolant more readily, compared to an equivalent DI diesel. This is not a flaw per say, just a thing any IDI diesel would have. Both DI and IDI have their advantages and disadvantages.

I don't know what your driving conditions are other than spreed and type of vehicle. But generally speaking, if your cooling system is in tip top shape, and your injection system and timing are equally perfect, you should not see any drastic changes in coolant temps under most driving conditions.

To me (and this is just an opinion), any deviation from normal operating temps is no good, and you'll bet that I won't be driving around with my gauge rising to near red until I get to the bottom of it. Also, these gauges tend to be on the dull, laggy side, so realtime momentary heat spikes might even go undetected.

More info on the driving/vehicle condition might help. Are you blowing smoke? Things like that.

Cheers

 

[Eiji73]

As you likely know, you have an IDI diesel engine, which means they have pre-chambers. So heat transfers from the cylinder head into the coolant more readily, compared to an equivalent DI diesel. This is not a flaw per say, just a thing any IDI diesel would have. Both DI and IDI have their advantages and disadvantages.

I don't know what your driving conditions are other than spreed and type of vehicle. But generally speaking, if your cooling system is in tip top shape, and your injection system and timing are equally perfect, you should not see any drastic changes in coolant temps under most driving conditions.

To me (and this is just an opinion), any deviation from normal operating temps is no good, and you'll bet that I won't be driving around with my gauge rising to near red until I get to the bottom of it. Also, these gauges tend to be on the dull, laggy side, so realtime momentary heat spikes might even go undetected.

More info on the driving/vehicle condition might help. Are you blowing smoke? Things like that.

Cheers

Thank you! Appreciate the education around indirect and direct injection. It’s always good to have this sort of background. I don’t think it’s the head gasket, my truck is being maintained by a good mechanic and he would have detected that, surely. He thinks one of the fans doesn’t kick in, or that it’s a thermostat issue. As for the other vehicle and driving conditions: truck works fine all the time. No temp deviation under normal daily use: 50-90 km/h on country roads, trips of length anywhere from 2km to 100km, etc. All hoses recently changed, oil changes regular, it’s got 210k km on the odo. Smoke of exhaust is a bit black when I start up and when I force it e.g. downshift to third to climb an incline, or I accelerate full throttle in fourth or fifth gear. No smoke coming out of engine bay at all (eg steam / coolant etc).

 

[Eiji73]

Please take a look on this forum for 2LT blown head gaskets issues, as this may be a starting point for you. You can conduct tests and visual inspections to see if your overheating is a function of a blown head gasket.

You may also wish to evaluate your cooling system and whether it is doing its work as it should

Thank you, I think my mechanic would have caught a head gasket issue but I’ll take a look. My mechanic tends to think it could be an issue with a fan belt or fan that doesn’t come on when required (presumably one such fans only comes on when the engine is being sollicited a lot e.g. high speed / high load / incline) — I don’t know much how cooling systems work

 

[Eiji73]

To me (and this is just an opinion), any deviation from normal operating temps is no good, and you'll bet that I won't be driving around with my gauge rising to near red until I get to the bottom of it.

I think you’re probably right…

 

[coldtaco]

First off these old diesels weren’t designed for extended hwy speeds. That said an engine in good shape will behave at 100kph all day, as long as you don’t do long climbs.
As to the water temp gauge, don’t rely on the factory gauge. More important is learning what normal indications are and investigate any deviations from them. I added a aftermarket/separate water temp sensor and gauge and when my factory water temp gets to middle or slightly above the aftermarket gauge showed water temps around 245F which is too hot, so imagine how much hotter it is when the factory needle sits at 3/4.
Signs of cracked head/leaking head gaskets come in many different forms. When my 2H head started cracking it didn’t show itself until I drove faster than 55mph on level ground and relatively cool summer ambient temps. So, you may have a cracked head or bad head gasket even if it seems normal. May have to do different tests.

 

[coldtaco]

Also, replace the fan clutch or the fan clutch fluid with a higher viscosity fluid if in doubt

 

[4runnermods]

Also check the turbo and vacuum lines. I installed an electrofan on the LJ73 to help with the air flow.
The 2LT likes to overheat while doing up hills. As long you don't push it should be fine.
My LJ70 has big mud terrain tires and it does fine in highway, maintain 100k/h traveling, I just slow down up hills and let go a little bit the trotle.

 

[jayp2]

Thank you! Appreciate the education around indirect and direct injection. It’s always good to have this sort of background. I don’t think it’s the head gasket, my truck is being maintained by a good mechanic and he would have detected that, surely. He thinks one of the fans doesn’t kick in, or that it’s a thermostat issue. As for the other vehicle and driving conditions: truck works fine all the time. No temp deviation under normal daily use: 50-90 km/h on country roads, trips of length anywhere from 2km to 100km, etc. All hoses recently changed, oil changes regular, it’s got 210k km on the odo. Smoke of exhaust is a bit black when I start up and when I force it e.g. downshift to third to climb an incline, or I accelerate full throttle in fourth or fifth gear. No smoke coming out of engine bay at all (eg steam / coolant etc).

Does it consume oil or coolant?

 

[Tigris]

@Eiji73

These details certainly help. Thanks!

Question: when you say 'one of the fans' I would assume that you are running electric fans or a combo of OE/electric fan as to my knowledge, your engine came with a single mechanically driven fan. Running the OE and electric fan is not a bad thing if they were setup right to work with each other, but relying on two electric fans may be effy if the setup was not thought through well.

I have only the OE mechanical fan on my KZJ78 (very similar DNA) and I would not switch to an electric setup unless 1. I have no choice, and 2. I have the absolute highest CFM, shrouded brushless fans money can buy .

I'm sure that you can appreciate the fact that many things could be involved in temp spikes. Start with the basics, do a non invasive HG test, evaluate your radiator and radiator cap, check when your thermostat opens, when the fans kick in, airflow through radiator, etc and if you are still having issues, maybe consider rebuilding and flow testing the injectors, but I would start with the cheaper easier stuff first. Installing a quality coolant temp gauge is always a terrific idea as stated above.

Tip: you can always motivate people here with some pictures of the truck!

Cheers

 

[Waikato Willy]

keep it simple do the viscous fan hub upgrade with 10,000 or 15,000 silicon oil ( from a hobby shop) , if you cant hear the fan then it aint working ,trust me , the noise and sudden strain on the motor will tell its working especially up a hill , the amount of air these move is impressive and will kick any thermo fans ass , before my rig got written off even though its was a 1KZTE its almost exactly the same cooling system , overloaded up a hill flat out the fan was almost constantly on , you could hear it over the 3" exhaust .
dont bother with a new hub as most are not serviceable unless you get a genuine but its super simply to pull apart the original one , clean it up , fill with oil , use a heat gun with a temp guage on it (dewalt do one) and set the thermo spring to the desired temp , I set mine around 85 Deg C from memory , search the forums , a few write ups on the process with pictures

 

[Felde]

Hi
Before going into any guts: Have the basics been checked?
Coolant level Ok and coolant clean? Cooler gets equally warm on entire surface? Thermostat OK? Thermoswitch for the e-fan(s) OK and fan(s) kicking in? (Can be tested with a barbecue thermometer and a pot of hot water).
I'd rather suspect the cooling system than the engine.
Good Luck Ralf

 

[Eiji73]

Does it consume oil or coolant?

No

 

[Eiji73]

@Eiji73

These details certainly help. Thanks!

Question: when you say 'one of the fans' I would assume that you are running electric fans or a combo of OE/electric fan as to my knowledge, your engine came with a single mechanically driven fan. Running the OE and electric fan is not a bad thing if they were setup right to work with each other, but relying on two electric fans may be effy if the setup was not thought through well.

I have only the OE mechanical fan on my KZJ78 (very similar DNA) and I would not switch to an electric setup unless 1. I have no choice, and 2. I have the absolute highest CFM, shrouded brushless fans money can buy .

I'm sure that you can appreciate the fact that many things could be involved in temp spikes. Start with the basics, do a non invasive HG test, evaluate your radiator and radiator cap, check when your thermostat opens, when the fans kick in, airflow through radiator, etc and if you are still having issues, maybe consider rebuilding and flow testing the injectors, but I would start with the cheaper easier stuff first. Installing a quality coolant temp gauge is always a terrific idea as stated above.

Tip: you can always motivate people here with some pictures of the truck!

Cheers

Thanks Tigris. Here’s my truck. To my knowledge it only has the one mechanical fan. Oh and my dog, she is a big fan. I don’t think I understood my mechanic’s explanation properly — Dutch can be hard to follow

 

[Tigris]

Beautiful Cruiser and scenery!

Yes just ease off the skinny pedal going uphill until we get to the bottom of this overheating issue.

BTW if you haven't already, consider changing to a Toyota low temp thermostat. If your overheating occurs while you are moving at a good speed (say above 50km/h) then the incoming air volume and speed should be sufficient for adequate cooling. But that's only if the coolant, radiator, cap, thermostat, pump and passages are in very good shape

Keep us updated.

 

[Sethsquatch1]

keep it simple do the viscous fan hub upgrade with 10,000 or 15,000 silicon oil ( from a hobby shop) , if you cant hear the fan then it aint working ,trust me , the noise and sudden strain on the motor will tell its working especially up a hill , the amount of air these move is impressive and will kick any thermo fans ass , before my rig got written off even though its was a 1KZTE its almost exactly the same cooling system , overloaded up a hill flat out the fan was almost constantly on , you could hear it over the 3" exhaust .
dont bother with a new hub as most are not serviceable unless you get a genuine but its super simply to pull apart the original one , clean it up , fill with oil , use a heat gun with a temp guage on it (dewalt do one) and set the thermo spring to the desired temp , I set mine around 85 Deg C from memory , search the forums , a few write ups on the process with pictures

I came here to say this, just had a new head on my 1hz, mechanic says it's running a little warmer than he'd expect. Into the forum I go and find a post about the viscous coupling, told him, he put 2 tubes (no idea what size) into it, said it was bone dry, now the temp gauge hasn't broke a quarter up. Easy fix!

 

[joekatana]

Thanks Tigris. Here’s my truck. To my knowledge it only has the one mechanical fan. Oh and my dog, she is a big fan. I don’t think I understood my mechanic’s explanation properly — Dutch can be hard to follow

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Contact Marc at Garage Eyckens in Houthalen Helchteren , best toyota guru I know in Belgium and his kids played around a lot with 2LT’s

 

[Eiji73]

Not with my truck right now, will join him again after Sunday and will do a check on the fan clutch operation. Following your advice, very thankful by the way, I read up on what the heck is a “viscous” and how a fan clutch operates. Got it. I think it could well be that because I have not really noticed a higher revving fan noise before, and it’s obvious that I probably should. These articles helped me understand the operation of the fan clutch.

Engaging Efficiency-Viscous Fan Couplings - Part Info

Fan Clutch Replacement - https://www.popularmechanics.com/cars/how-to/a302/1772922/

 

[o8ko8k]

You're close, but you had it backwards, "I thought Land Cruisers didn’t overheat ever" should say "I thought Land Cruisers regularly overheat always". Keep it under 60mph and it will be fine, if you want to drive faster, do an engine swap with an LS motor, make sure point A to point B is always downhill, or get a different vehicle. --Land Cruiser Fact of life #372 (LCFOL)

HA!, ok seriously, but actually I was being serious, but that's not actually all the helpful. So, to be helpful...

I added about a 3/4" to 1" spacer (made from a poly cutting board I had laying around) between the hood and the hood mounts and the hood, which puts a big fat crack along the downwind side of the hood, lets more air through (yes it works). This actually helped more than all the other suggestions de-jour, granted I did all the other stuff first so maybe it just all added up. But it still adds up to keep it under 60 and it won't overheat, otherwise... see LCFOL #372.

Suggestions de-jour referenced in this thread faithfully and in the link below.

HOT 2H tune up

Ok so i have a 84 HJ60 with the 2h with about 270000km on the odometer. I have owned it since it had 267000Km on it. I noticed it was running kinda hot (stock needle right under "H"). BTW i live in arizona and this is the month of record temps 116F is not unusual. its been about 108F our or...

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