Toyota 3B Diesel Operating Temperature

[mightymouse2045]

HI there,

I have a Toyota 81' model BJ40 Landcruiser, with a 3B diesel engine conversion taken from a Dyna truck.

No matter what I do this engine runs HOT. If I drive for more than 30 minutes from cold it will reach half way on the temp guage, and if there is heavy traffic with lots of idling it will get to 3/4's on the guage.

I have just installed a new sender unit and, had the radiator overhauled and had a fabricated shroud made up (as there wasn't a shroud when i bought it). But alas it is still running hot.

Is this normal for others out there with 3B diesels or as a friend who has a 13B engine told me it should be running between 1/4 and 1/2 not 1/2 to 3/4's?

Also I have noticed that when it gets hot (the 3/4 mark) and I turn the engine off - the oil pressure has dropped significantly and when I try and start the engine the engine cranks slowly and won't start. I am using a 15w-40 oil and live in the philippines where it is super hot here all the time. Should I be using a 20W-50 oil instead?

Thanks for any info/help anyone can provide

 

[Gun Runner 5]

Are you sure the temp. gauge is operating properly. I also changed my sending unit only to find that the gauge was bad.
I assume you have a new t-stat and are there other indications that the engine is running warm ( other than the gauge...overflow of coolant, smell, etc.)?
......1978HJ45

 

[tmarx]

Don't trust/rely on the OEM guage's readings ..

2c

 

[mightymouse2045]

Are you sure the temp. gauge is operating properly. I also changed my sending unit only to find that the gauge was bad.
I assume you have a new t-stat and are there other indications that the engine is running warm ( other than the gauge...overflow of coolant, smell, etc.)?
......1978HJ45

No it's not overflowing - it seems hot though - and as I said the viscosity of the oil is get high which results in the engine cranking slowly and not starting. WHen I looked in the toyota manual for a 3B engine it says that can be due to the oil viscosity and needing some thicker stuff? When the oil heats up to really high temps it gets thinner - so if I leave the truck sit there for 15 minutes and the engine cools down a little, then it will start.

Does 20W-50 allow running at higher temperatures and should I be putting that in, instead?

Are there other guages you can hook up in place that give a more accurate reading and what is normal operating temp if i do hook another guage up?

I don't have a t-stat believe it or not - which is for warming up the engine in the mornings - and from the 3 other diesels I've seen in the philippines they have all had the t-stat removed as well. I think it's more of a priority to cool the engine here rather than let it heat up quickly by restricting water flow until the engine reaches 80 deg celcius....?

I really want to get a more accurate view of the temperature of the engine because if it really is running as hot as the OEM guage is indicating it's gonna screw my nice (in reasonable nick) diesel engine.

 

[mightymouse2045]

Don't trust/rely on the OEM guage's readings ..

2c

I agree - the oil guage is broken, the fuel guage is incorrect, the amp guage doesn't work at all, the speedo doesn't work at all, and the temp guage is erratic (why i put on a new sender).

I want to replace the whole instrument panel with a new one which i have located for big bucks... in the mean time while i am planning the 4 hour trip and getting the money together to buy it, I want to put something else on if possible....?

 

[Gun Runner 5]

First thing I need to make clear....I am not an diesel engine / cooling system expert! I do live in a climate where 35+ degrees (C) is common through out the Summer and I run a good quality 15W/30 diesel oil with good results. Stock Toyota gauges
(especially if they are old) are notorious for being inaccurate.
I replaced my factory water temp. / oil pressure gauge some time ago and have had good results since.
.......1978HJ45

 

[amaurer]

Hot (thin) oil should make it easier to crank. A hot starter, however, is known to be less powerful. Regardless...

Try to get better temp readings, perhaps by throwing in a cheapy mechanical gauge in the unused head plug on the right hand side behind the tstat housing.

My 3B runs 190F on level ground, 200F on a hot highway run, and up to 210F on big hills.

 

[Radd Cruisers]

You need to figure out what your ACTUAL operating temperature is - use an IR temp gun. The factory gauges are a rough approximation of something that might or might not be happening - good gauges should replace the factory units.

Generally, a thermostat is required for an engine to run at the correct temperature. I would strongly suggest you put in the FACTORY 88C thermostat.

A fan shroud should cover about about have of the depth of the fan blade to be effective. Too much or too little coverage and your air movement decreases.

The 3Bs typically do not run hot, generally they run too cold. A too small exhaust, too much fuel, a restrictive intake can all make it run hot. If your engine is putting out black smoke while you're driving, your engine is getting too much fuel; black smoke = excessive fuel = excessive heat. Engine timing can also dramatically affect operating temperature, also check your valves.

Make sure your water pump is working properly. Every now and then a faulty pump shows up and does not flow the water properly.


~John

 

[mightymouse2045]

First thing I need to make clear....I am not an diesel engine / cooling system expert! I do live in a climate where 35+ degrees (C) is common through out the Summer and I run a good quality 15W/30 diesel oil with good results. Stock Toyota gauges
(especially if they are old) are notorious for being inaccurate.
I replaced my factory water temp. / oil pressure gauge some time ago and have had good results since.
.......1978HJ45

Yeah thanks - I will try replacing the temp gauge and see how I get on

 

[mightymouse2045]

You need to figure out what your ACTUAL operating temperature is - use an IR temp gun. The factory gauges are a rough approximation of something that might or might not be happening - good gauges should replace the factory units.

Generally, a thermostat is required for an engine to run at the correct temperature. I would strongly suggest you put in the FACTORY 88C thermostat.

A fan shroud should cover about about have of the depth of the fan blade to be effective. Too much or too little coverage and your air movement decreases.

The 3Bs typically do not run hot, generally they run too cold. A too small exhaust, too much fuel, a restrictive intake can all make it run hot. If your engine is putting out black smoke while you're driving, your engine is getting too much fuel; black smoke = excessive fuel = excessive heat. Engine timing can also dramatically affect operating temperature, also check your valves.

Make sure your water pump is working properly. Every now and then a faulty pump shows up and does not flow the water properly.


~John

Thanks John,

I'm only getting a small amount of black smoke on starting the engine. Then while driving under load I get some grey smoke but not heaps.

As you said I need to see the actual temp I am running at and from what everyone has said here I can't trust the gauge to be accurate. I will put in a mechanical gauge on the unused plug in the inlet housing and once i know what is happening I will report back.

I'm definitely seeing the water flowing so I am pretty sure the water pump is working, but I will definitely get the timing and valves checked out. Usually that is something that doesn't get done for years in these old cars - so that would be a good thing to have checked for sure

CHeers,
Peter

 

[mightymouse2045]

You need to figure out what your ACTUAL operating temperature is - use an IR temp gun. The factory gauges are a rough approximation of something that might or might not be happening - good gauges should replace the factory units.

Generally, a thermostat is required for an engine to run at the correct temperature. I would strongly suggest you put in the FACTORY 88C thermostat.

A fan shroud should cover about about have of the depth of the fan blade to be effective. Too much or too little coverage and your air movement decreases.

The 3Bs typically do not run hot, generally they run too cold. A too small exhaust, too much fuel, a restrictive intake can all make it run hot. If your engine is putting out black smoke while you're driving, your engine is getting too much fuel; black smoke = excessive fuel = excessive heat. Engine timing can also dramatically affect operating temperature, also check your valves.

Make sure your water pump is working properly. Every now and then a faulty pump shows up and does not flow the water properly.


~John

Ok thanks man

The mechanical says about 190F - that's when it reads 3/4s on my factory gauge.

I only tested that by putting it into the radiator water. I am having it fitted tomorrow to the inlet housing and will be more accurate than that - but still seems to be running hot in my opinion. The locals around here say their cruisers are running at around 150 to 160F, and shouldn't go over 180F...

Also when you say fan blade depth for the shroud do you mean it should only cover half the top of the blade? Because doesn't the original enclose the entire fan blade?

I had another guy here suggest moving the radiator closer to the fan blade?! What would that achieve in a positive and negative sense? In the negative when doing hard off-road driving wouldn't the radiator hit the fan? As it is the fan hits my shroud when going up a steep rocky slope in low 4.

Also another suggestion was if the cylinder head might have excessive rust build up if the truck had been sitting idle for a long time before i actually purchased it, which it had been...?

Thanks for any thoughts because it is getting rather annoying. I will have the timing checked and valves at the same time.

Are there any obvious signs if it's timing issues - ie if the timing is retarded? or it's not easy to know without checking and over heating is just a possible side affect?

Cheers,
Peter

 

[amaurer]

Ok thanks man

The mechanical says about 190F - that's when it reads 3/4s on my factory gauge.

I only tested that by putting it into the radiator water. I am having it fitted tomorrow to the inlet housing and will be more accurate than that - but still seems to be running hot in my opinion. The locals around here say their cruisers are running at around 150 to 160F, and shouldn't go over 180F...

Also when you say fan blade depth for the shroud do you mean it should only cover half the top of the blade? Because doesn't the original enclose the entire fan blade?

I had another guy here suggest moving the radiator closer to the fan blade?! What would that achieve in a positive and negative sense? In the negative when doing hard off-road driving wouldn't the radiator hit the fan? As it is the fan hits my shroud when going up a steep rocky slope in low 4.

Also another suggestion was if the cylinder head might have excessive rust build up if the truck had been sitting idle for a long time before i actually purchased it, which it had been...?

Thanks for any thoughts because it is getting rather annoying. I will have the timing checked and valves at the same time.

Are there any obvious signs if it's timing issues - ie if the timing is retarded? or it's not easy to know without checking and over heating is just a possible side affect?

Cheers,
Peter

The locals are probably full of s***, what has you convinced you've got a problem? 10deg over the thermostat temperature is "normal" operating temp... 3B Tstats are available only in 82 or 88C (179F or 190F), so proper operating temperature shouldn't be lower than that, and is probably more like 189 or 200.

As I said before, my 3Bs run at 190 when relaxing, 200 on the highway. Idling it will drop past 190 as the Tstat closes in cooler weather.

 

[YORSIAN]

engine speed is okay? not increased after the engine warms to operating temperature?

 

[mightymouse2045]

engine speed is okay? not increased after the engine warms to operating temperature?

No the speed is ok when it's warm. It idles normally.

 

[mightymouse2045]

The locals are probably full of ****, what has you convinced you've got a problem? 10deg over the thermostat temperature is "normal" operating temp... 3B Tstats are available only in 82 or 88C (179F or 190F), so proper operating temperature shouldn't be lower than that, and is probably more like 189 or 200.

As I said before, my 3Bs run at 190 when relaxing, 200 on the highway. Idling it will drop past 190 as the Tstat closes in cooler weather.

Yeah i tend to agree with you. What they do here in the philippines is remove the thermostat - so their cruisers are running cooler I'd say and hence the "shouldn't be above 180". Yet as you said the stock Tstats are 82 or 88 degrees celcius 180F is 82C, 190F is 88C - so that is the stock "warm" temp, and as you said operating temp is 10 degs above that. So safe operating temps would be up to 200F, and up to 210F if you are under load.

Hopefully that is where mine is, which I will know today once i get the gauge fitted.

I will have the timing and valve clearances checked today also as suggested and see if that makes any difference. I'm just hoping it's not a cracked head or block, but i think I would see other obvious signs if that was the case.

 

[mightymouse2045]

The locals are probably full of ****, what has you convinced you've got a problem? 10deg over the thermostat temperature is "normal" operating temp... 3B Tstats are available only in 82 or 88C (179F or 190F), so proper operating temperature shouldn't be lower than that, and is probably more like 189 or 200.

As I said before, my 3Bs run at 190 when relaxing, 200 on the highway. Idling it will drop past 190 as the Tstat closes in cooler weather.

ok well it looks like it is running similar to yours. I will know better today after driving it around a bit.

The guys in the landcruiser club here are saying that the tstat temp is the hot temp and that is what it should be running at ie 180F not 190F and 200F. They also say that they buy 76deg tstats and use those instead here in the philippines because it's so hot here, and that the engine shouldn't be running over 180F?!?

I wish there was a clear passage in the toyota manual stating "THIS IS THE NORMAL OPERATING TEMPERATURE RANGE" and give us a figure

 

[Hulsty]

Running no thermostat and lead to the water flowing to fast and not cooling properly in the radiator. I run a totally stock cooling system on my 13BT (new toyota rad cap and T stat) and it is fine in out 40-45c heat.

 

[cruizerbuddy]

Anyone know where to source the 82 C degree tstat?
Tanks