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'92 Spi Overheating In Traffic


Best Answer kopi , 31 December 2017 - 07:45 AM

Faulty radiator switch!

I placed both old and new radiator switch on boiling water. The old one remain open even after the new closed.

After fitting the new switch, I plugged in my ACR2 again. The aux fan switches on when coolant temp reading on the ACR2 was at 90. The switch is rated at 82/92.

Thanks again all!

(Bit concerned about my MAP reading 48kpa but thats a topic for another day) Go to the full post


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#1 kopi

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Posted 25 December 2017 - 02:56 PM

Hi all!

 

As the title suggests, my '92 J-Spec SPI's temperature gauge went into the red over perhaps 10 minutes of heavy crawling traffic. I couldn't tell if the auxiliary fan came on but it sounded like it didn't. So here's what I did to test

 

1. I bridged the 2 spade connectors from the temperature sensor switch in the radiator with the engine running, auxillary fan came on. I suppose this the auxiliary fan circuit's / fuses etc. are good?

 

2. I tested the cooling fan relay by measuring the resistance across both pairs of terminals, one 80+ ohms and the other no resistance. Seems to check out. 

 

Any suggestions on where I should look? Does the radiator sensor switch usually fail, it's only been a year since i bought the new minispares radiator that came with it? I apologize but I'm really not sure if the auxiliary fan came on and it still over heated, or if the auxiliary failed to come on at all.

 

Thanks!!

 

Best,

Kopi



#2 cian

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Posted 25 December 2017 - 05:14 PM

Have you tested the thermostat? Any blockages in the system? Heater matrix always clogs up

#3 kopi

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Posted 26 December 2017 - 05:52 AM

Thanks cian. Forgot to mention that once i got up to freeway speeds, the temperatures came down to normal fairly quickly again (like within a minute). So does that suggest my thermostat is working and that the system isn't necessary clogged up? Thermostat's fairly new, but i guess no harm testing. 

 

How should one go about testing for blockages in the cooling system?

 

Kopi



#4 cian

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Posted 26 December 2017 - 06:56 AM

It sounds like the fan is on the wrong way has any radiator work been done recently? There are two hoses that travel through the bulkhead and down to the matrix in the interior squeeze them they should collapse if not they are blocked with crud! ( happened mine )

#5 kopi

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Posted 27 December 2017 - 01:28 AM

Fan's pointed the right way ... and the hoses seem clear. Think i'll test the temp sensors next. Thanks again!



#6 kopi

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Posted 28 December 2017 - 08:14 AM

Ok before I head out to buy another temperature switch, I plugged in my ACR 2 reader after a run. Coolant temperature was reading 95C and aux fan is still off. I guess thats pretty conclusive right

#7 jamesquintin

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Posted 28 December 2017 - 02:05 PM

I would drain the entire system, take the radiator out and back flush it (turn it upside down and run a hose through). Do the same with the internal heater matrix. replace the thermostat, run a hose through the block and al the pipes you can to make sure it flows well

 

How old is the water pump? worth replacing if its 25 years old?

 

Q



#8 xrocketengineer

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Posted 28 December 2017 - 08:35 PM

You might be able to test the thermal switch in hot water. Also, you could let the car idle until it gets hot and then bridge the switch connectors and see if the temperature come down, if it does and the thermal switch has not closed (0 Ohms) then the switch is bad. 


Edited by xrocketengineer, 28 December 2017 - 08:45 PM.


#9 kopi

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Posted 29 December 2017 - 11:18 AM

Hi James, water pumps 3 years old so that should still be good?

 

xrocketengineer, i have a spare switch lying around which i tested in hot water to be good. So i'm gonna swap it out this evening if i can help it. 

 

Plugged in my ACR2 again after a run and geez, the coolant temps were reading 105C (or about halfway between N and H on my gauge). Still no fan kicking in. 

 

Will report back!

 

(side question: can abnormally high temperatures result in inlet air temp and coolant temp sensor fault codes being thrown? because i cleared those yesterday and it surfaced again)



#10 Sprocket

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Posted 29 December 2017 - 11:47 PM

What is the outside air temperature when you are having these problems?

 

From memory with mine, the original factory fitted radiator and thermostatic switch, the fan did not kick in until the temp gauge was in the red. If its not yet in the red, the fan is not yet ready to come on. Minispares radiator should come on a little earlier though.

What you have to remember is the thermostatic switch is on the bottom of the radiator, where coolant is cooler that what the CTS in the bottom of the inlet manifold is exposed to. It's been a while, but I think the original factory switch in the bottom of the rad closes at around 98c and the Minispares one around 92c. Remember, that is in the bottom of the rad, and is not the same temp you'll see at the CTS. It might be as much as 10 or 15 degrees difference.

 

Things to consider

  • What's the coolant condition like?
  • Test or replace the thermostat (should start to open around 88c). Make sure it sits between the sandwich plate and the outlet housing.
  • Test or replace the thermostatic switch (should close around 98c, or 92c if its a Minispares one).
  • Double check the mechanical fan is fitted the correct way round. Solid faced centre side to the engine, open faced centre side to the radiator.
  • check the radiator for obstruction including oil contamination. Thoroughly clean as required.

 

All assuming the cooling system has not been altered from standard in any way



#11 kopi

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Posted 30 December 2017 - 10:02 AM

Hi Sprocket! 

 

That's a relief to hear but i get nervous seeing the needle head towards "H" and not hearing the fan come on! And the key question - is 105C at the CTS within the healthy range at all? And at what temperatures should i really be concerned about cooling capacity then? 120C? 130C?

 

Cooling system standard and unaltered. Outside air temperature usually 28-30C, i'm sure actual road temperature is a fair bit higher. (ACR2 reading of ambient temperature when i'm parked at home was actually 38-40C but i attribute that to the air immediately surrounding the bonnet)

 

I have a 82C thermostat from minispares, less than 2 years old. Radiator switch is a 82/92 i.e. switches on at 92C. The 10-15 degrees difference between the CTS and the bottom of the radiator certainly makes sense, but just to be sure i'll test the thermostat and the radiator switch independently when its out. 

 

Didn't get a chance to flush it today, tropical storm! 

 

Kopi



#12 hungdynasty

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Posted 30 December 2017 - 12:16 PM

This two pictures are from my 98 Japan spi, I changed to six blade tropical fan,88'C thermostat, for your reference.

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#13 kopi

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Posted 30 December 2017 - 01:16 PM

Thanks for that hung! Your numbers are what i aspire towards. Looks like the 6 blade tropical fan is working well too! 

 

May i know what diagnostic tool you're using? Its hooked directly to your phone? 



#14 hungdynasty

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Posted 30 December 2017 - 04:04 PM

Thanks for that hung! Your numbers are what i aspire towards. Looks like the 6 blade tropical fan is working well too! 

 

May i know what diagnostic tool you're using? Its hooked directly to your phone? 

http://memsdiag.blogspot.hk/



#15 hungdynasty

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Posted 30 December 2017 - 04:24 PM

I also have this info from a japanese owner which you may be interested, he tested his spi coolant temperature related to reading position on the gauge.

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