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Hello, this is my first post. I recently acquired a 1985 Toyota Celica Supra (2.8l i6).

I'm currently fixing up the engine, can someone please help me identify these parts?
  • The electrical plug appears to be part of the coolant system.
  • The 2nd part is attached to the A/C system.
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Second one is the AC EPR Valve. It regulates pressure in the evaporator.

On the switches on the coolant neck. The one of the right is the EFI coolant temp sensor. The one on the left that is broken is the cold start time switch;

 
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Thermo timing switch on Thermostat housing...
 

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Hey thank you for the help. The Supra starts up fine, so at least the amateur fix on the cold start sensor still works.

The AC EPR valve was frosting up when I attempted to add freon, I don't know if that indicate it's bad; but the AC did not blow fully cold. There seems to be a restriction when adding freon, so I am waiting for my Denso AC expansion valve to come in the mail soon. Also, I replaced the AC compressor with a refurbished one.

Another thing that concerned me was the oil meter was very low when I was idling at a stop or red light. It will go up when I pressed the gas and the vehicle moves. I replaced the oil pressure sensor and changed the oil/filter. I won't know if that fixed it until the AC system is put back together. Other than that, it drives just fine.

Btw, it has 99,000 miles.
 

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Freezing could indicate air or water in the lines. Make sure you do a proper vacuum pull on the AC system before adding freon. The stock system does not have a high pressure shutoff for the A/C system. If the evaporator is icing up due to water or air this could lead to a burnt compressor in the near future. A frosting EPR valve does not strictly indicate the evaporator is freezing internally but is one indication. Depends on outside humidity.
That is somewhat normal that the oil press will drop at idle. The oil pump is rotating slower and not putting through as much flow at higher rpms. For how low is too low we may need to see a pic of the gauge with rpms to compare.
 

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What weight oil are you using?? 5Ms like 10/40...thats a bit low IMO...
 

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What weight oil are you using?? 5Ms like 10/40...thats a bit low IMO...
I don't know what kind of oil the previous owner put in it. While working on the AC, I also changed the oil and the oil pressure switch. I won't know if that fixed the issue until I put everything back together.

I used the following oil as recommended by my local auto parts store:
Mobil 1, High Mileage, Advanced Full Synthetic Oil. (10W-30)

If this doesn't fix it, could this mean the engine is bad?
 

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Oil pressure is one of those things that can worry folks needlessly and I've seen one gauge read 20% higher than another, so definitely not an empirical measure of motor health. A thinner synthetic can definitely run pressures this low though, so I'd move up to a 10w-40 and then drive the car. Keep the oil full and doubt you'll ever see issues out of it.
 

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Our 5MGE's typically have very low oil pressure at idle when warm. It will come right up at 2 K rippem's.
On my very tired 5MGE, I ran 20W-50.Only in summer. It leaked and blew oil out of the ass end.The oil pressure was a little higher at idle, IN GEAR. Auto tranny.
 

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Discussion Starter #11
Well it looks like it didn't fix it. When I started it, the oil meter did not rise at all. It only risen when I pressed on the accelerator.
 

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It's pretty normal for an M series motor. If you're that worried about it remove the oil pressure sender and install a tester gauge to compare against the Toyota requirements.

 

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Discussion Starter #13
Oil pressure gauge does not move 80% of the time. It only moves up a quarter when I floor it, and then goes back to zero when idling at higher speeds. Could this be a faulty oil pump? I will attempt to replace that next, where can I get an OEM oil pump? Are aftermarket parts good?

I drove it for 15 minutes with the AC on, and it ran fine.
 

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Maybe instead of throwing parts at it maybe do the simple test like I mentioned? These motors won't last long if you run them low on oil pressure.
 

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Discussion Starter #15
Maybe instead of throwing parts at it maybe do the simple test like I mentioned? These motors won't last long if you run them low on oil pressure.
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What do you think? I installed an aftermarket oil pressure sensor, and the oil gauge is still low. I suspect the oil gauge on the odometer may be off or faulty.
 

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I'd worry more about where its at with warm oil at 3000 rpm, but its probably fine. Note that you have to drive the car for 30+ minutes to get the oil warm.

If it's me I'd suspect the aftermarket part first since they are often cheap crap, but since you changed it does it read the same before and after? You also put the correct one in right? The digidash cars just have a switch. You could always buy another used cluster to try and see if it reads better. If it is the cluster you'll probably have to disassemble both and swap parts.
 

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Discussion Starter #18
did u get a replacement cooler expansion valve?
I am still looking
part number
88515-14050​
VALVE, EXPANSION​
No, I didn't replace the cooler expansion valve.
I bought and replaced this part:


It's located behind the glove box compartment. Once I replaced the AC expansion valve, the AC drier, and AC compressor, it's blowing cold air again.
 

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One contributing problem, your idle is too low! Yes you can can run a 5m as low as 650rpm or so, but they don't really like it when they get old. Especially in hot weather, when its fully warmed up bring up your min idle to at least 800rpm. Check with a timing light with RPM readout, again don't trust the cluster. There is a big slot screw behind a black plug on the throttle body you adjust to set your base idle when its fully warmed up.
 
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