Turbo 3B Overheating (1 Viewer)

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Dec 12, 2020
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Victorville
I put at GT20 turbo on my 1985 3B BJ70 and I’ve been having overheating issues since I did that. If I drive over 70Km/hr, or up a hill for more than 30-45 seconds (rpm’s over 2000) the temp gauge shoots up to the red and coolant spews out the overflow. I’ve burped it countless times due to the high temps shooting out so much coolant, replaced the thermostat, checked the water pump is working, installed an intercooler, replaced the clutch fan with a 3000 cfm electric fan, and had the radiator rebuilt. There isn’t any coolant in the oil or oil in the coolant. I’m out of ideas. Is there anything I’m missing?
 
Did you install a pyrometer when you did the turbo install? If not, stick one in pre turbo, and add a boost gauge if you don’t have one. Those two gauges will speak volumes as to how your engine is running. Also, I would highly recommend ditching the electric fan and going back to a mechanical one, just make sure the fan clutch is in good condition (you should hear it really roar when it first starts up). A mechanical fan will move way more air at reasonable engine speeds than any electric one.

Have you had your radiator checked out? If it’s original it is probably due for a good flush, or better yet have it rodded out.
 
Did you install a pyrometer when you did the turbo install? If not, stick one in pre turbo, and add a boost gauge if you don’t have one. Those two gauges will speak volumes as to how your engine is running. Also, I would highly recommend ditching the electric fan and going back to a mechanical one, just make sure the fan clutch is in good condition (you should hear it really roar when it first starts up). A mechanical fan will move way more air at reasonable engine speeds than any electric one.

Have you had your radiator checked out? If it’s original it is probably due for a good flush, or better yet have it rodded out.
Yes I have a pyro and a boost gauge. The way I drive it to prevent it from overheating, the EGTs stay below 650/700, and if I floor it I get 10 psi max. I’m not sure what you mean by “A mechanical fan will move way more air at reasonable engine speeds…” bc the electric fan is full speed as soon as I turn the batteries on, regardless of engine speed. How much air does the mechanical fan pull? The radiator rebuild was on the list of stuff that has been done already in the first post.
 
Maybe I should refrain from trying to answer questions at 2am, I completely missed the part about your radiator being rebuilt! :doh: At idle your electric fan will definitely be moving more air than the stock mechanical one, but when driving at 2000-3000rpm the mechanical fan could easily be operating at double the CFM of the electric one. However, it sounds to me like the rest of your cooling system is in good shape, so I would start looking into the possibility of a cracked head. Check your coolant for combustion gasses at idle.
 
Sounds like a cracked head to me. I don't think you can get OEM new ones anymore, but I believe there might be some aftermarket ones out there still.

In a nutshell, IDI's don't do that well when turboed when it comes to heat. That's why Toyota never made any factory IDI turbo diesels for the heavy duty cruisers. All the heavy duty turbo diesels are direct injection. It's also why the 2LTE and 1KZTE have heat issues and a bad reputation. The pre-cups dump tons of heat into the coolant when the motors are under load.

I agree with AirheadNut above regarding the fan situation. Mechanical fans can move several hp worth of air (you can actually feel engine power loss when the clutches are fully engaged). An electric fan will be limited to the power from the alternator 1/2 hp or less probably. Power is power. I know electric fans are more efficient etc., but it doesn't make up the difference.
 
Maybe I should refrain from trying to answer questions at 2am, I completely missed the part about your radiator being rebuilt! :doh: At idle your electric fan will definitely be moving more air than the stock mechanical one, but when driving at 2000-3000rpm the mechanical fan could easily be operating at double the CFM of the electric one. However, it sounds to me like the rest of your cooling system is in good shape, so I would start looking into the possibility of a cracked head. Check your coolant for combustion gasses at idle.
Dang, a cracked head is the last thing I want. Thanks for the insight on the fan!
 
Sounds like a cracked head to me. I don't think you can get OEM new ones anymore, but I believe there might be some aftermarket ones out there still.

In a nutshell, IDI's don't do that well when turboed when it comes to heat. That's why Toyota never made any factory IDI turbo diesels for the heavy duty cruisers. All the heavy duty turbo diesels are direct injection. It's also why the 2LTE and 1KZTE have heat issues and a bad reputation. The pre-cups dump tons of heat into the coolant when the motors are under load.

I agree with AirheadNut above regarding the fan situation. Mechanical fans can move several hp worth of air (you can actually feel engine power loss when the clutches are fully engaged). An electric fan will be limited to the power from the alternator 1/2 hp or less probably. Power is power. I know electric fans are more efficient etc., but it doesn't make up the difference.
So was it a bad choice to install the turbo then?
 
So was it a bad choice to install the turbo then?

I wouldn't say that exactly. It does depend on the previous condition of the motor, and how you use the vehicle. If the 3B is in good solid shape, and you just use it for regular driving it should be ok with a turbo. If the 3B is tired, or you're trying to do heavy towing, then you'll have problems for sure.

I just remembered that sometimes turbo can take out the OEM head gasket on these motors. Maybe your cylinder head will be ok, and the gasket will be out. Won't know until you dig into it more. Could start just with a compression test.
 
I wouldn't say that exactly. It does depend on the previous condition of the motor, and how you use the vehicle. If the 3B is in good solid shape, and you just use it for regular driving it should be ok with a turbo. If the 3B is tired, or you're trying to do heavy towing, then you'll have problems for sure.

I just remembered that sometimes turbo can take out the OEM head gasket on these motors. Maybe your cylinder head will be ok, and the gasket will be out. Won't know until you dig into it more. Could start just with a compression test.
Ok. That makes sense. I can pick up a compression tester easy enough to check that out.
 
Could just be the headgasket as others have stated. If it is the original, then it's the composite style that will fail. Upgrade it to the MLS which will be much stronger.
 
@OGBeno

What would you suggest to upgrade to?

Modern that has available parts. I’m not being sarcastic. I’ve been thinking about this lately. Curious on your perspective.
 
Your question is loaded as was my response.

Lots of parameters to consider. Different for you, different for me.

That said, anyone trying to waste time on a 3B is wasting time on a 3B. :meh:
 
@bcsteel I know you didn't ask me, but I would go for a 2UZ/1UZ if it were me. Those run forever, have good power, parts everywhere and you can pick up used ones for dirt cheap. It would keep it all Toyota, however it would be "harder" than a chevy swap of some sort where a lot of the conversion parts have been hammered out and tons to choose from.
 
I think it would be sad to take a diesel cruiser and make it a petrol one. You could drop a 1hd(f)t(e) in that would be an ideal upgrade. Not as many parts available as the HZ for example, but the HD is a native turbo and direct injected is quieter and more efficient.
 
I guess I’ll just remove the turbo and go back to naturally aspirated. I’m not sure I can afford an engine swap, and I definitely don’t have the experience for that either.
 
Your 650/700 EGTs are in °F right? Cause if we're talking °C, well...
Something has gotta be going on, I hear 3Bs can run hot, but there wouldn't be so many people running turbos if it was a terrible idea.
I wish I could help out more. I'm turboing my 2B this winter so I'm curious to see what you figure out.
 
Your 650/700 EGTs are in °F right? Cause if we're talking °C, well...
Something has gotta be going on, I hear 3Bs can run hot, but there wouldn't be so many people running turbos if it was a terrible idea.
I wish I could help out more. I'm turboing my 2B this winter so I'm curious to see what you figure out.
Yep EGTs are in Fahrenheit. I assumed the engine would run a little hotter with the turbo, but it’s pegging out the gauge and spewing coolant. Hopefully you have better luck.
 
650/700 F is nothing, even if it's Post turbo. I can't imagine the EGTs run that low, even factory doesn't run that cool so I'm definitely questioning that reading.

I'm guessing something might be blocked in the head or cracked or something. There is no way there should be coolant spitting out at 70kmh. That would lead me to believe that coolant isn't flowing right and getting cooled at all.

Can you go back to the original fan/clutch setup with shroud?
I would replace that waterpump. You said you checked it, how did you do that? You can fix everything else but if that water isn't circulating from the pump, it's going to overheat quickly.
 

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