AW11 Overheated - Why?

[AE86less]

So I was was out and about today running some errands. I was giving the car a bit of death through the back streets of Takapuna and the car was fine until I went through the middle of Takapuna and hit the lights at the main intersection. After a couple of minutes of sitting in the sun, running, the engine started making a weird hum and lo and behold: the temp gauge is right off the top. So I turn the car off and push it down a handy driveway.

After a few minutes of waiting for the engine to cool I whipped the coolant filler cap off and got a huge geyser of orange water (I now have several burns on my shoulders and hands), at this point I was able to touch the barely warm rad with my bare hands. I refilled the coolant (took about 3 litres) and turned the engine on and it ran fine with no more overheating.

Did it overheat due to a lack of water?

Also, during the course of my inspection I noticed that even when the engine was running the rad fan wasn't going. Could this be a factor?

[2LTR Rona]

Also, during the course of my inspection I noticed that even when the engine was running the rad fan wasn't going. Could this be a factor?

Assuming you ran it for a while to get back to normal operating temp, then the fan not running would be the first point of call.

why, because in order for the rad to cool it needs air flow, air flow which of course (when standing still) is usually provided via the fan.

Speaking from first hand experiance here, cause I have also been known to forget to hook the fan back up when i rebuilt my engine & a similar thing happened to me.

[AE86less]

Thats what I would have figured.

I'm assuming that the fan comes on at a certain temperature or something? Could it be an issue with the temp sensor or something?

[cat007]

I'm curious as to how you took the rad cap off? Did you "burp" it first to see what the pressure was like, or squeeze the rad hose?

Anyway - sorry that didn't come out right

If there was an air bubble by the temp sensor for the fan it might not have known how hot the water really was?

[AE86less]

lol, na, I just pulled it off then dropped it in the engine bay when my hand got scalded Actually I did try to do it slowly but the pressure kinda blew it off.

The fan still isn't running, even now that I'm home and have refilled the coolant.

[AE82 FXGT]

If a huge orange geyser came out, first up I'd take the rad out get it flushed/rodded, flush the block out.

Check the fan(s) are operating, refill with good coolant.
Replace the thermostat + thermostat gasket (as you're gonna need to take it out to flush).

Then go for a thrash and keep a close eye on the gauge.

[rollaholic]

and for future reference, leave the car for an absolute minimum of 20 minutes next time it overheats, or if you must take it off sooner get a thick rag and turn it very slowly, letting pressure out slowly then tightening cap again when it gets too hot to hold.

[Dell'Orto]

Also, putting cold water into a hot motor is very bad.

[Truenotch]

Sounds like a thermostat to me, or the radiator being clogged.

Do the thermostat first of all, bleed it up well and take it for a drive. Then check the temp of the radiator and leave idling to see if the fans are going.

90% of the time the radiators are at least a bit clogged and need to have the tanks taken off to be flushed. The last one I had done was 30% clogged, and that still cooled well when the car was running.

After those 2 do the water pump... This is a bitch to do in the car but isn't that hard if you pay attention to it.



If you want tips on bleeding it up drop me a PM.

[Mr Revhead]

bled the system.

i usually dont bother with the box breather, but definitly check the rad and heater bleeders

[Dragger_Dan]

Also one big tip with AW11s - make sure you actually fill them right up. They take about 11 to 12 litres of water... but if you don't burp it well enough when you're filling it will stop at about 8 litres and you'll think it's full. I managed about 50km of open road driving, temp guage sitting in its normal position the whole time, before the poor thing overheated because it was still a few litres short. IMO it pays to keep track of how much is going in when filling it up so you know when it is actually full, or still full of air.

[85AW20v]

And jacking the back up when filling and bleeding makes it a lot easier. A 200mm piece of 1/2" heater hose taped into a cut off 1.5 litre coke bottle as a sort of header tank into the filler neck also helps to push out any air. From cold at idle, it takes about 15 minutes to heat all the coolant in the system. The gauge is reading the temp at the head not the radiator outlet.

[matt dunn]

when bleeding air out or a car I usually run them with the cap off til the fan has cycled on and off,

as then the know that the thermostat was fully open and the water has been circulating.

Matt

[Dragger_Dan]

I think the problem with the MR2s tho is that you're not putting water straight into the top of the radiator, you're putting it in a pipe which has a lot of flow through it... I've tried the cap off method but I'm sure you loose more water than air.

[rollaholic]

the cap off method really only works on cars where the cap is the highest point in the system, im not familiar with mr2s but can only presume it is not in this case since they appear to have multiple bleed points?

or is this due to the convoluted piping more than anything

[Mr Revhead]

highest point is the cap
but theres two other high points some distance away, one is the heater tap on the front firewall
the other is on the radiator
you will need to vent them both. have them undone when filling. and fill slowly.

[tsoob]

unlucky sam, kinda sounds like the issues iv just been through, check the fan relay and fuse setup, also if the water was orange give the engine 3 or 4 flushes with clean water run it up close to operating temp in between but let it cool before you flush again., then use glycol. Any probs come by and see us will try to help as best as we can.
Nick

[AE86less]

Cheers guys.

I should probably make an effort to see exactly why this happened, I haven't bothered since it hasn't done it since

Did you get my Txt earlier Nick? The engine is yours if you want it.