Disaster strikes! help please

[aloshan]

So this morning I decided to fill more oil as my car has been burning oil recently(discussed in another thread)

SO I warmed the engine up , filled oil.

Drove along for about 20min , moderate driving , my temp gauge starts going up

I pull over and there's coolant dripping onto the ground with a hissing sound coming from the cylinders furthest away from the cam gears(towards the back of the engine)

Immediately I thought BLOWN HEAD GASKET

So I let it cool down, popped the radiator cap off and stream of coolant shot out(obviously I didn't let it cool down enough)

Refilled coolant , started engine. Engine temp normal. Drove the car around for 20min , hit boost quite hard...still no temp raise , popped the hood , all seems fine.

Looked at the coolant on the ground , just coolant , not coolant + oil. Checked radiator cap , just coolant , no coolant + oil.

HAD TO use my car to get to work , so I drove to work , 40min in stop start traffic. Engine temp normal , no more coolant leaking , engine seems fine....WHAT THE HELL IS GOING ON?

I know the only way to properly test for BHG is a compression test which I will be doing this weekend. Until then , any thoughts?

Could there have been air trapped in the cooling system somehow that was let out when I opened the radiator cap
Could the oil I filled this morning somehow caused this to happen...

At work and at a loss right now.... and I have to drive another 20km back home.....

[trdee]

could have a BHGbetween cylinders such that you dont get oil contamination but the exhaust gases are pressurising the cooling system. a 40min drive ought to have shown that up though... the other thing it could be is you have a small water leak (such as a cracked turbo water line) which over the course of a few days/weeks etc leaks enough water to cause the car to start overheating

[aloshan]

could have a BHGbetween cylinders such that you dont get oil contamination but the exhaust gases are pressurising the cooling system. a 40min drive ought to have shown that up though... the other thing it could be is you have a small water leak (such as a cracked turbo water line) which over the course of a few days/weeks etc leaks enough water to cause the car to start overheating

hmm that makes sense. but why isnt this problem reoccuring after a 40min drive. temp level seems to be fine. il be pulling hoses of the engine to check on Saturday, until then , any other advice?

[fixeruperer]

HG blown in between will sound like a miss.
you shouldnt use cold water in a hot engine as this will cause some warpage.
what car and engine is it ? could the hissing be coming from a overflow reservoir ?

if all is well, just clean it down and pressure test the cooling system. cold it may leak and when it warms up, the metal expands and seals some what.

compression test will tell you if the gasket is blown in between. you can use a co2 tester to see if the HG is blown into a water jacket. if its bad enough you can see a blow gasket, with how the water acts in the fill up point on the rad.

make sure its all bleed too.

[aloshan]

HG blown in between will sound like a miss.
you shouldnt use cold water in a hot engine as this will cause some warpage.
what car and engine is it ? could the hissing be coming from a overflow reservoir ?

if all is well, just clean it down and pressure test the cooling system. cold it may leak and when it warms up, the metal expands and seals some what.

compression test will tell you if the gasket is blown in between. you can use a co2 tester to see if the HG is blown into a water jacket. if its bad enough you can see a blow gasket, with how the water acts in the fill up point on the rad.

make sure its all bleed too.

thanks for the advice. its a 7mgte as per my dig. a70 supra

hissing was definetly from back of engine not overflow bottle

will do the compression test to confirm ...

[trdee]

if it hasnt overheated again within 40mins then its going to be a slow leak, could easily be a couple pinhole leaks in a cast elbow on a coolant line or a turbo feed line etc.

Get the car up on a hoist and look for dried coolant trails down the bellhousing/engine block etc.

Oh yeah and obviously do a compression test also, but a good comp test reading can still be had with a BHG depending on the way that it has blown, so dont use it as gospel

[lexsmaz]

Dont forget to check the Radiator water / coolant level tonight before you drive off, as has been said its possible it is a small leak, when did you last check the coolant level in the radiator ...

Also after filling the radiator as you did this morning you should let the car run until warm again with the radiator cap off & the heater on hot, as it allows the coolant once the thermostat is open to circulate the cooling system as it will then purge out any trapped air that may be caught, it then may require some topping up of coolant ..

[Jt_70R]

... any other advice?

Sell your car and upgrade to a horse?

[poida]

Could be couple pinhole leaks somewhere in your system as said above. This happened to my aw11 mr2, and trust me you will spring a proper leak if this is the case. I saw coolant under my car one day but couldn't find the leak. It never overheated mind you. Then a couple of weeks later I was sitting in traffic when coolant started spraying out the front of my car. I pulled over and got a tow home. Hole in the radiator bottom tank.

[ajansen]

Take car to reputable mechanic. He will be able to tell you what is wrong and may also be able to do a leakdown test like you were planning. Kill 2 birds with one stone and save some time and money.

[Harreh]

Had the exact same issue vito described.

Exhaust gasses very slowly pressurising the coolant.

Perfect compression across the board and nothing showed up in the TK test - Took upto 60 minutes of driving before it would occur

[Daddio]

Also dont forget if the coolant level is way low, it wont reach the temp sender...temp will appear normal because there is no water getting to it!

Back of motor culprit for water leaks also include banjo bolt fitting at the back of the block...major pain to fix with engine in!

[aloshan]

if it hasnt overheated again within 40mins then its going to be a slow leak, could easily be a couple pinhole leaks in a cast elbow on a coolant line or a turbo feed line etc.

Get the car up on a hoist and look for dried coolant trails down the bellhousing/engine block etc.

Oh yeah and obviously do a compression test also, but a good comp test reading can still be had with a BHG depending on the way that it has blown, so dont use it as gospel

ok , wont use at as gospel (dammit thought seeing a good compression test result would at least make me feel better and get the BHG thoughts outta my mind), will check the car on Saturday for ALL leaks.

Dont forget to check the Radiator water / coolant level tonight before you drive off, as has been said its possible it is a small leak, when did you last check the coolant level in the radiator ...

Also after filling the radiator as you did this morning you should let the car run until warm again with the radiator cap off & the heater on hot, as it allows the coolant once the thermostat is open to circulate the cooling system as it will then purge out any trapped air that may be caught, it then may require some topping up of coolant ..

thanks for the advice , will definitely check the coolant level before i drive off tonight. The last time I checked the coolant level was this morning when I when i refilled it and topped it up. Thanks for the trick ,will try this to purge the cooling system of any air bubbles

Sell your car and upgrade to a horse?

Get the fuck out , if you dont have anything useful to say dont dirty my thread with pointless comments.

Could be couple pinhole leaks somewhere in your system as said above. This happened to my aw11 mr2, and trust me you will spring a proper leak if this is the case. I saw coolant under my car one day but couldn't find the leak. It never overheated mind you. Then a couple of weeks later I was sitting in traffic when coolant started spraying out the front of my car. I pulled over and got a tow home. Hole in the radiator bottom tank.

damn doesnt sound like fun. Hope it will last on the way home today , about 20km. Will properly check coolant for any pinhole leaks on Saturday when im doing compression test

Take car to reputable mechanic. He will be able to tell you what is wrong and may also be able to do a leakdown test like you were planning. Kill 2 birds with one stone and save some time and money.

Man I would LOVE TO. IM EVEN WILLING TO PAY A DECENT AMOUNT OF MONEY FOR A KNOWLEDGEABLE EYE TO TAKE A LOOK. Unfortunately it seems like Sydney is full of wanker mechanics that have no idea about the 7m and all ask in excess of $500 to take a look at anything... and they dont know anything about these engines. They just throw parts at it hoping it goes away and racking up my bill. If someone can PLEASE point me to a reputable 80's toyota mechanic in Sydney.

Also dont forget if the coolant level is way low, it wont reach the temp sender...temp will appear normal because there is no water getting to it!

Back of motor culprit for water leaks also include banjo bolt fitting at the back of the block...major pain to fix with engine in!

Lovely. Another thing that makes the 7m difficult to work on. Seriously , how is the 7m NOT the bane of every mechanics existence

[Supra967]

All the 7M hate didn't come from nowhere

What happenend to your $140 leak down test?

[1JZ-Rolla]

Aloshan, you have another car as a daily driver.

Your supra is a broken shitbox.

Why are you pushing the issue to drive it to work?

Methinks you don't want to go to a mechanic cause they will tell you what you don't want to know, whereas teh intahnets remain ambiguous so you can keep dreaming that there's nothing really wrong, as you troll every Toyota forum here and overseas to "diagnose" your lemon.

What's it gonna take to wake you up?