Can it be a BHG?

[IJ.]

Only time the undertray missing makes a difference is at highway cruise you'll see +5c temps, most cars if the rest of the cooling system is working and in good repair can cope with this.

I prefer to have mine run on the TStat at cruise.

 

[jtran8]

I ran my 89 sup without under tray for 3 years and temperature gauge never went more than half way and never lost coolant either . but if out side temperature more than 80F degree , coolant fan shround is a must . without coolant fan shrould , coolant fan won't be able to draw cool air through radiator fins caused coolant boil up quick ; if coolant fan clutch went bad , it won't alow coolant fan spool up at higher rpm when it needed . what i think is that you need to change thermostat , install a new or good used coolant fan shrould , check coolant fan clutch ( it should not spin by itself at all unless you turn it ) . wait until engine dead cold or early in the morning ; fill up your radiator and fill reservoir to full mark . if that not fix your problem then you might have to check coolant and oil to make sure they're not mix .

 

[AJ'S 88NA]

^^You're an exception not the standard.

I thought IJ was THE standard.

 

[MaNNy919]

theres no leaks what so ever only problem is that the resevoir tank is empty by the end of the day...in the morning i filled it up with water but never thought about squeezing the upper radiator hose so maybe like bigaaron said that can be why it seems like im lossing water and the resevoir tank gets empty after a while of driving...im just hoping that its not a BHG...

i need some help on the sogi foglight rewire...i did it but i used electrical tape to join the wires together...the car is a 89' and for some reason my fogs dont even come on no more i had just replace the bulbs couple days ago...what did i do wrong? i did exactly what this tutorial did...
http://gallery.sanitylapse.com/v/supra/Foglight+Rewire/

 

[jgcable]

theres no leaks what so ever only problem is that the resevoir tank is empty by the end of the day...in the morning i filled it up with water but never thought about squeezing the upper radiator hose so maybe like bigaaron said that can be why it seems like im lossing water and the resevoir tank gets empty after a while of driving...im just hoping that its not a BHG...

The same exact thing happened to me. It was the head gasket. Most likely what is happening is that your coolant is passing into your exhaust jacket and burning out of the tailpipe.
My overflow tank would go empty once a week. This lasted for a few months. Eventually the car began to heat spike so I did a leak down test on it and sure enough... blown head gasket. I could see exactly where it was leaking. The #6 cylinder down into the exhaust port. I never lost a drop of coolant on the outside and the car ran perfect right up to when I took it apart. If you check the past history in the threads on this subject you will see that your symptoms are exactly like all the rest of t he Supra owners with a failing head gasket.

 

[Quin]

Compression testers are right around thirty bucks at Advanced, go get one and give it a go (very useful tool to have anyway, if you're friends with a lot of gear heads you may be able to borrow one). Are you getting any white smoke at all?

Btw, redo the fog light mod and use crimp connectors or solder + heat shrink this time.

 

[bigaaron]

The block test is a better way to check for a bhg. The compression can be just fine on the compression tester, and the headgasket still could seep compression into the coolant passage when the engine is running.

Here's a "block chek" kit so you can see what I am talking about:
http://www.blockchek.com/instructions.htm

 

[jgcable]

The same exact thing happened to me. It was the head gasket. Most likely what is happening is that your coolant is passing into your exhaust jacket and burning out of the tailpipe.
My overflow tank would go empty once a week. This lasted for a few months. Eventually the car began to heat spike so I did a leak down test on it and sure enough... blown head gasket. I could see exactly where it was leaking. The #6 cylinder down into the exhaust port. I never lost a drop of coolant on the outside and the car ran perfect right up to when I took it apart. If you check the past history in the threads on this subject you will see that your symptoms are exactly like all the rest of t he Supra owners with a failing head gasket.

Another thing... all the time we were losing coolent in the overflow tank we never noticed any steam, or sweet smell coming out of the tailpipe. The car ran perfect. All that time I thought it could be a radiator cap or a high pressure coolant line leak. The one time the temp did spike my son put the heat on full blast and the temp went right down. When he got home I replaced the T-Stat and the radiator cap and the car ran perfect at normal temperature for another 3 weeks (although he was still adding a pint of fluie once a week) until the temp spiked again. Thats when we brought it to the shop for a full leak down test.