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The car was topped up with water via the rad cap twice, but it overheated in a matter of 5 - 10 minutes of driving at 60 MPH. The strange thing was the car would normally return to normal temps if you were at the right speed and RPM, but oh no, the temp just climbed.

At one point I thought I would have made it home with the needle WAY past the red, and I was very wrong! I felt a thump under the bonnet and a huge spray of steam from under the bonnet - I drove another 2 miles with an exploded radiator untill she grinded to a halt. Oh well.

I popped the bonnet and found the top of the radiator cracked and nearly separated from the top core, steam and hissing sounds and probably a soaked battery (hence I couldn't start it up)

Once the car was home, I had a look at the thermostat, completely rusted and in the "closed" position. I tested the thermostat by boiling the hell out of it but I looks like *it* was the cause to these problems.

Now the car can start up, but it will not idle. Apply gas and let go, but the revs will drop straight down to 0. I had a code 31, so I swapped back my old AFM, but still the same issue. Anyone have any ideas about this one?
 

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Severe head damage for sure, probably headgasket failure, possible bearing damage, the list goes on and on. Why some people think they can continue to drive a car with the temp gauge pegged is beyond me - especially one with an aluminum head. You just likely turned a problem that would have cost you $7 into a multi-thousand dollar ordeal.
 
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Hey Anh, sorry to hear about it.
If your head is craked, let me know. I have a spare head you can have for cheap, thats been machined, and had the valve seats recut.
 

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That sounds like a question my wife would ask me. Why wont it start anymore it only got real hot once, I didn't think that needle meant anything and that the C and H were only for decoration. Just messin with ya sorry to here about your misfortune and hope you have the funds to get it back on the road.
 

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ouch man... {insert random owned pic here} not a good idea on the driving w/ no coolant... theres gotta be alot of thermal damage done but u are gonna have to crake that puppy open to be sure...gluck
 

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Sorry to hear about your car. I had the exact same failure a few weeks ago. You probably had a head gasket problem even before the 'event' happened. It sounds like you were filling it on a regular basis. The 'cycling' of the temperature was due to air being trapped in the cooling system, probably from a slow head gasket leak. A bad thermostat can do this as well, but not quite in the manner that you described (it wouldn't care so much about speed and once it opened it would stay open and you would be OK). At pressure, the air pockets can prevent the coolant from circulating properly and the temperature rises. The pressure will force air/coolant out to the recovery bottle as the temperautre rises, but reaches a point where it can no longer sustain pressure and starts to flow again. The problem is that if the coolant level gets too low then you don't have enough thermal capacity to maintian normal temperature. That's where the fun begins. Now you have the possibility of high pressure, combined with the radiator plastic upper cap seeing super high temperature water/steam at the inlet. The steam over-heats the plastic and combined with pressure... game over.
I drove my 89 for about three years and with a small hg leak from cylinder to coolant. Coolant loss got to be too big of a problem though, and I got trapped in the fast lane at rush hour one day. When I got over to the side I dumped the clutch and started coasting to try and cool it down (it was almost in the red) and it must of created a huge temperature/pressure spike. That's when my radiator blew up.
Other than the head work that you probably needed anyway, the super high temperatures could have damaged some of the sensors(02, etc) and also sent the engine computer into a maximum retarded ignition timing due to engine knock. The super-retarded timing may cause the car to not idle. I would replace the head and hg, check the sensors and reset the computer. Good luck.
 

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ownage...1st rule of mk3...when the temp climbs to even 3/4 of the guage, shut it off immediately...Chances are you blew the HG, cracked/warped the head, fried some seals, obviously blew up your radiator and probably a whole slew of other things. Good luck and have fun...JDM 7M anyone?
 

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...heading for 500+ RWHP
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1. take off old head
2. remove all valves(if they are still useable)
3. place thermostat next to radiator and old head
4. beat all three peices with a sledge hammer until all your frustration is gone....then time to get new head, MHG, high-perf. rad. and new thermostat!! ENJOY!!
 
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