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Discussion Starter #1
I have a '83 Celica Supra witch may or may not have a blown head gasket. The problem is that I think it sends mixed signals!
After a long drive (and a shorter one too) I had brown-ish 'gunk' under the coolant cap and some in the expansion reservoar, but NO foam or 'mayo' under the oil filler cap!
I can't se any coolant traces on the dipstick either.

The car emptied the reservoar after the trip, but has not repeated that since then. I did refill some, but not 'full'.

Is it possible that the oil might seep into the water but not the other way? I mean, the oil pressure is about 4 Bar 'some places', but the water has 1 Bar pressure for quite a longer time?
I will try to clean and refill to see, but I fear it's head-job time. The car sees about 1000km's a year, so it's not 'heavy' use.. :p

I have not run compression test, but the car runs flawless as normal. No smell of coolant or excessive steam from the tailpipe either.

Any thoughts?

Any good source for head gasket kit? I haven't found any metal HG, bot that doesn't mean they do not exist..

Unable to post pictures yet due to low post count.. :p
 

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Sounds like the head gasket is going. It will get worse if you keep driving it.
 

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I would start with a flush of the cooling system, then pressure test, then add new coolant..

New radiator cap as well...and when was the last time the thermostat was changed out??

Lastly is the fan clutch working??
 

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There are inexpensive block test kits to check for a BHG...
 

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If its not overheating and using coolant the headgasket is probably fine. The cars typically just blow between the combustion chamber and the cooling jacket so it doesn't go into the oil pan. The most definitive test is to do a compression test.
 

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Discussion Starter #6
Thanks for all the suggestions!

I will first do a flush and get a compression tester, although I don't think I'll see something in the numbers..

the car is not being used now, I have others for daily use..

The cap and thermostat has never been replaced as far as I have known the car, and my dad got it in '89! But the temperature gauge is always on the mark, and it has never used any coolant except when the heater core blew. Still on the mark when I lost the contents of the reservoar. That really makes me wonder, since the engine was still full when it cooled down..

I replaced the coolant with ordinary 'blue' type in 2016, as my local Toyota dealer discontinued the yellow type some years ago. I was sure to flush it good, so there was no discoloration or contamination afterwords.

I'll order a new thermostat and do all the belts through the winter anyway, and it might be high time for a HG and valve stem seal replacement after 35 years! :)

I'll certainly keep you postet of my findings!

Thanks again!
 

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I have had a similar experience. The brown-ish gunk seems to be unavoidable, I have flushed and refilled coolant several times, but it's just comes back. I did have a coolant leak, but that was due to a leaking radiator. I changed the radiator, never had a problem since... but new coolant still turns brown right after a coolant change.
 

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I was fearful of a BHG as well. Coolant CAN get into the oil,after engine shut down.There is pressure then, to seep past the head gasket.
The "Overflow" tank will get dirty stuff in there. Normal.
You can try a(safety) pressure relief style of radiator cap.When you park it,relieve the pressure.
https://www.allpar.com/fix/engines/cooling-caps.html
 

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Discussion Starter #9
Thanks for all the suggestions.
I took out the car this other day, and saw there was still gunk under the cap. It seems not to be very oily, but smells a bit like iron, so I guess it's rust of some sorts mixed with something sticky.
I don't understand why the car expelled the overflow reservoar completely, and then seems to retain all coolant still in the engine. The level is up to the cap..

Time for a complete flush (I'll try to source the yellow coolant somewhere) and then I'll get it checked for exhaust fumes just to be safe. There's still no sign of coolant in the oil, and the oil level is still the same.

I'll be back.. :p
 

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As mentioned, replace your thermostat and radiator cap. Since buying my 85P new, every few years it starts to intermittently overheat some. EVERY time, it's been the radiator cap. These seemingly simple devices perform multiple functions and cooling system pressure testers only test one of them. They're great for determining if your cooling system can hold pressure, but simply aren't able to fully test caps. Radiator caps are cheap and simply don't last very long.
Here's what happens. After a hot shutdown, the coolant expands some and is pushed past the radiator cap into the overflow tank. When the engine cools down, the coolant contracts creating a vacuum which, if everything is working correctly, sucks coolant from the overflow tank back into the engine. For this to work, not only must the radiator cap work correctly, but there must be a good seal from the radiator to the overflow tank. Make sure that the hose from the radiator to the overflow tank is good and that the rubber seal in its cap is there. Also, if there's any coolant leaks, a good vacuum won't be created and less coolant than needed, or more likely none will be drawn back into the engine when it cools. A pressure tester will confirm if your system can hold pressure and will therefore also be able to create a vacuum to suck coolant back from the overflow tank.
When the radiator cap fails, on shutdown some coolant will still be forced into the overflow tank. But when the engine cools, it won't be sucked back into the engine. Then the engine will overheat sooner and more. I'm sure you can see that it doesn't take long before this becomes a much bigger problem.
Another potential problem area is the screw type hose clamps. They're known to loosen up over time. Yes, you can use Loctite on them. But I finally removed all of them and replaced them with the original spring clamp style ones. They don't loosen over time.
Thanks to ddd228, I've also added a simple cooling system bleeder to the top rear heater hose, the one from the center rear of the engine to the heater control valve. It's the highest point in the cooling system and bleeding all the air out of the cooling system after a coolant change or whatever is MUCH easier and faster than raising the front of the car, etc. Dave used a cheap garden hose repair kit to do this. These come with a male and female barbed hose fitting and clamps and are typically used to repair a hose with a cut or tear.
So after having this issue a few times, I started using a Sharpie to write "Check Me First" on my radiator caps. No matter what Sharpie claims, it's NOT permanent, not even close. The last time this happened, it had been quite a few years. I checked everything and when I'd ruled out everything except the radiator cap, upon close inspection, I could faintly see a couple of letters of my Sharpie note to myself. DUH! So on its replacement, I used some black touch up paint and painted "Check Me First!" on it. Hopefully, this will help should brain fade happen again, and it surely will!
If your car only overheats in stop and go traffic or when idling for a while, your fan clutch has probably failed. They can usually be brought back to proper operation by replacing the fluid in it. It seems that over many years, some of the fluid can leak out and once enough does, it'll fail to couple when it gets hot. There's articles on the net about how to properly do this. One important note is that you don't have to use Toyota specific fluid for this although it's still available. The silicone differential fluid for RC cars is exactly the same, much cheaper and easily available. The proper viscosity is 3000 cSt. It's available in 2 ounce (59ml) bottles which should be enough to completely replace the fluid although this should be verified.
Why bother doing this vs just picking up a new one? It's much cheaper and of 3 replacement units I've had experience with, they all either had problems out of the box or quickly failed.
Another possible issue is with the nylon fan itself. Over time, these tend to soften and individual blades will start to warp from heat. With the engine running, it'll appear like the fan is wobbling. But looking closer, the water pump bearing and fan clutch are just fine. Eventually, one of the blades will bend forward enough to catch under the top rear edge of the top radiator tank and / or the fan shroud. The fan is NOT sucking the shroud backwards although it can appear that it did. This can happen even without the shroud in place. The fan bends forward trying to pull air through the radiator and the hotter everything is and the higher the RPM, the more likely this is. The solution is to replace the fan.
FYI, there's a lot of reasons why nylon fans are a good thing vs metal ones. Should you ever get a hand in one, you'll likely end up with a bruise or two and maybe a cut at worst. But you'll still have all of your fingers! And I've never heard of nylon fans losing blades either. Hope this helps.
 

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Discussion Starter #11 (Edited)
Thanks for the thorough write-up and great heads-up! :D
As I said, I have not seen any overheating issues, and the cap seems to work as intended, the radiator top is always full, even if the reservoar has been close to (or even) empty.
But, I will check the reservoar and plumbing again for sure!
As you say, the cap has failed me on other cars as well, so I have had it on my mind. I think you might be onto something regarding the thermostat, though. Even if the gauge usually is spot-on, I have seen some highs and lows this last year, and as far as I know, it's the original one too. :p
The fan clutch is immaculate, loose when cold, and rigid as a seized bearing when hot.



Parked alongside a $100' E-type, but my Celica Supra is actually a less common car.. :p
 

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Discussion Starter #12 (Edited)
Just to conclude..
In May I took out the car to go to a friend's house some 25 kms away, and the car ran good one way. I heard some of the now somewhat familiar belching into the reservoar, but as there was no puddle when we checked later, I didn't worry much. The temperature was normal.

When we returned home, the temperature suddenly soared, and I had to rev it to have it go down. This repeated itself some times.
Well, we got home, and some days after, I pulled the (I believe original) thermostat. It opened at 87-89 degrees, but not very much. After boiling it for some minutes, it still wasn't as open as I would have it to, but then it did not close completely either. Still, I thought i should have been enough.

I ordered a new, and since it just runs in the summer, i chose one with 82 degrees.
Opening the housing, i _had_ to break a bolt, and pretty fed up and still thinking the HG was blown, especially after the overheating, I postponed the bolt removal job for some time. (Some time=2.5 months. I said I was fed up..)

I had to weld FOUR nuts and lastly just a washer to get enough leverage to yank out the bolt, that was one tough bolt!

Making a new gasket and removing the worst pitting of the hose flange, I reassembled and started up. 20 minutes idling later, the needle had not budged past 'half', and a test drive confirmed that a lazy thermostat could cause many problems. :rolleyes:

Well, now it's back on the road again, and I'm off to my MOT/EU test today.

https://www.instagram.com/p/B1UCal7ohJC/?utm_source=ig_web_button_share_sheet
https://www.instagram.com/p/B1Zwz5YoO_g/?utm_source=ig_web_button_share_sheet
 

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Bhg? Nooooooo!

NO BHG? Lucky dude.
It got really hot!
Any trouble with "burping" the system? I always have trouble with that last air bubble trapped in the cooling system.
Anti-seize is your friend.

You Supra looks...AWESOME!
I did this with a couple of water hose couplings. The rear heater hose traps the air inside.
By the fire wall.Recommended addition,as mentioned by Ray85p.
If the system is not properly burped,that trapped air can CAUSE a BHG. Most late model cars have some burping bleed valve. Smart. The air bubble will not allow coolant to circulate in that back few cylinders and it gets REALLY hot.:sadsmilie

Another way to burp is to park it facing uphill and rev the SNOT of the engine to force that bubble to the front. The reservoir tank will go down a little. Fill it back up.
Yes,the hose and cap and connections need to not leak vacuum going to/from the reservoir tank.:thumbsup:
Normal!.. for the tank to fill with gunk-that is how the system works.

When you do the M.O.T. test,be sure that the engine is fully warmed up-hotter the better. I'm exempt in my State,but it has passed the emissions test in the past.1995.
 

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Discussion Starter #14
Thanks, I also think it looks good, even if it has some things here and there. :) Your engine room looks immaculate, though!

I just refilled, and I have driven a bit. (Well, I admit i did som WOT runs.. It's a Supra, after all! :p )
I heard some burping, and the reservoar now is a bit fuller than when I started.. I'll just keep an eye out, I'm about to flush it again anyway!

Norway has a 2.4% CO limit for these old cars without catalyzer, so my 1.6 was well within limits.
 

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YAY! You passed the MOT/EU.

I can't keep my hands out of my engine compartment. I try to make improvements to the original design.
There IS a pretty aluminum intake tube under the shiny bubble wrap.
The master cylinder has a desiccant bag on top to collect any moisture.
I use Evanscool and will NEVER have a pressure-related coolant failure.
I tossed the thermostatic fan assembly-a mistake.I use a small fiberglass fan.
The water pump is over driven from the crankshaft by about 30 %,IMO.
I thought that my fire wall was transferring heat to the passenger compartment,so I added some insulation.
The strut tower braces are from a big trucks extended mirror brackets.They don't get in the way at all.
I also did the BIG THREE with fatter wires.

The 5 MGE loves to be wound out!It's just an Italian tune-up.
 

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Discussion Starter #16 (Edited)
Sweet mods, Dave! I tend to keep mine stock, but as everything slowly deteriorates, I will eventually have to modify things.

Yes, approved for two more years! :) (Of course.. I have driven it some 2200km's in the last two years, nut much happens during that time!)
 

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Discussion Starter #17
It never ends.. :p
On our way home from a party, the charge light started shining..
It clearly has low state of charge, ([email protected]) and opening the generator revealed perfect brushes.
I suspect I've blown the regulator, so I'll just replace that first.
Stay tuned! :D
 

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OH NOOOOO!
This Chinese cigarette lighter volt meter saved me from being stranded.
I drove for 1/2 day until I could get the entire alternator replaced.I did it the hard way: from the top. DOH!
[url=https://imgur.com/49fuRDu][/URL]


Yes,I have a back up (stock) alternator,when it happens again.
An 8 gauge wire was added.

I was thinking that the slip ring got wet from coolant,but no.
A dead battery will ruin any party mode vibe.
 
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