Austarion

Firstly, my problem is with a 1991 Toyota Corolla, but the advice should filter true to the Starion!

Ok, said car is overheating! It's boiling the water in the overflow bottle. It eventually gets so bad, it totally overheats and spits coolant out of the overflow, which is full at all times!? So, as a first port of call we checked the waterpump, which seems to be working, replaced the thermostat and gave the car a new radiator cap and hoses.

I should point out at this point that the overflow bottle was also full of a brown grease\sludge material, but we couldn't find traces of it in the radiator. We did however find this crap in the engine when we opened the thermostat housing! The O-ring was completely eaten away. We flushed the radiator and engine out with a high pressure hose and re-asssembled. The temp sender in the thermostat housing was also corroded, so I cleaned it with a wire bush and brought it back to new!

Car also got new oil and filter and of course new coolant. Car was driven for two days, just locally with no issues. Car was then re-checked for oil and water and all was fine. Car was then driven for a week, just locally without issue.

Here's the point... I then took the car on a longer drive, about 100kms, at speeds varying from 60km to 100km. Car was fine until the 100km mark. At this point, I smelt coolant, and it began to "rain"! I instantly pulled over, killed the engine and...

Car has NO radiator cap. Water is spraying from the radiator about 2 feet in the air in a steam with water droplets kinda way. Overflow bottle is full, and the temp guage in the car never moved above normal. I then poured the overflow bottle contents into the radiator, which gurgled momentarily the spewed the contents out as before! Remember, the engine is off at this point!

So, I'm asking, firstly what do you guys think the original issue was?
Secondly, do you think I took the correct steps?
Thirdly, what happened to the radiator cap? If it was loose or not on properly, would it not have come off much, much earlier?
And Fourth, what do you think is the issues are now?

Any help or suggestions really welcomed! This is not my car, but my housemates! :?

Head gasket or cylinder wall?? I had a 180B that popped a head gasket and used to blast water out of the radiator, got pretty bad towards the end. That is reinforced by the oily sludge in the overflow bottle.
I know of a Magna that got a reco motor put into it. It was contantly ejecting water from the rad, was worst on the highway. Checked over everything and couldn't find the problem.. In the end it turned out to be a weird one.. There was a hole in the cylinder wall letting combustion gasses into the water jacket.. took a bit to find but made a huge fountain on the freeway.

To your question though, it does seem like it could be a leak between the hot gassy bit and the steamy soggy bits in the engine..

Do the thermo fans come on properly. Id assume before a engine goes to the level of head gasket failure other componants have to be fail before finishing of the gasket, so having said that, did the thermo fans activate, did your previous thermostate open.??

Fans are functioning! As for the other thermostat, I never bothered to check, just replaced!

Mate, at this point we would be pulling the radiator out and getting it prof. flushed. I have had this problem thinking it was a head/thermostat/pump only to be the radiator being blocked in lots of places internaly. Also a pressure test when this is done will put you at ease.

Other symptoms notwithstanding: local, slow-ish driving being ok but overheating at higher speeds may point to an airflow problem. Is the radiator core free of leaves, debris, etc? Is there anything blocking the airflow to the radiator?

Radiator airflow is fine, fans operate normally etc. Core being blocked? I don't know, it emptys and fills fine and we hit it backwards and forwards with a high pressure hose.

It's just that now my housemate has got her cousin around to look at it, who is a Toyota mechanic (Bitch could of mentioned this before we decided to help her), who got on his high horse spouting the "Well, at Toyota..." routine and he's somehow convinced her that I broke her car and should pay for half of the repairs! Granted, I was driving it the second time, but I shut the engine down within 800m of the coolant spraying out! She would have kept driving! I don't feel I'm at fault, and before we started any work on her car I urged her to go somewhere to have it checked, which she declined. I then told her, after extensive research on the net that she may have a blown head gasket, which was aslo declined as a valid answer!

Mr. Toyota is claiming that a radiator cap can't just "blow off" which may be true, however that does not explain how the car got around for so long if the cap wasn't on properly! It's either on or off, right!? He's pretty much claiming that because I tampered with the cap, I broke her car and that I should pay!? Do you think this is fair!?

Mr Toyota is a nut.
Tell your housemate she owes me 20 bucks for loosening the cap so they can all blame you.

thats the thanks you gat chunk!!??
thats why i dont look at other peoples cars anymore, just comes back to bite you on the arse......

sounds like sediment or rust and shit has built up in the core

Tell her if you get a second opinion from an independent Mechanic, on what is/has caused the problems, and if they come back saying it wasn't your fault, will she pay you the fee the mechanic charges for his/her report ?

:beer