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Ke30 overheating - excessively purging from overflow


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Hey guys, so I'm currently driving my ke30 up to Dubbo for mysterybox rally. 

Had a bit of trouble yesterday with overheating. 

Managed to encourage her through a 500km trip, 35 degree heat. Most of the time she ran fine, but she over heated twice. 

It seems there is excessive purging out the overflow bottle, then coolant gets too low and it overheats.

Has a new water pump and new thermostat, plus good coolant. 


I'm hoping maybe it's just the radiator cap is a bit faulty? Don't want to think about a head..


cheers for some advice!! 


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Hi Madelaine,

                        There is nothing like a good long country run, to allow any gremlins to surface, in an olde engine. You said, "she only overheated twice".   What were the driving conditions during when there was these two occurrences ?  Going up over a range or mountain ?  Stuck behind a big truck ?  Forced to drive in a lower gear ? The circumstances might give us an idea of what it might be going on.

As she ran fine most of the time, I would tend to discount the horrible head scenario. Inspection of spark plugs directly after a run, will usually indicate whether water has entered a cylinder, with a very clean plug, in the offending cylinder.

If it was me, I'd be removing the thermostat for the day, & see if that makes a difference.  If it was a 35 deg C day, it should not make any difference, as I would expect the thermostat to be open most of the time under those conditions.  Removal of thermostat is an easy 10 min. job.    Just check the specs of the radiator cap, usually stamped into the metal, on top.  Even relatively new thermostats have been known to fail.

My guess is the run has loosened some crapp inside the engine, & it has created a blockage somewhere, "throttling" the flow of coolant. My other best guess, is a partially blocked radiator, that has enough flow to run under normal conditions, but not enough to handle an extreme day.

Maybe just take the bottom hose off, and put a hose in the top spout.  Turn the tap on full, and check the radiator gets it all through to the bottom.  If the radiator overflows at the intake at top, it may indicate a reduced flow, due to partial blockage, or build up internally.  Cleaner, run, then flush, could fix it, but the safer bet is to get a radiator shop to check & flush, or give it a core clean.

Lets know what you find.

P.S. I assume, you have checked the fan belt tension. Does your dash temp guage work OK ?   Was it running hi all day, without going into the red zone, when she was running fine ?

Cheers Banjo



Edited by Banjo
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Firstly see if the thermostat is working, so take it to the local cafe and ask if you can put a pot on the stove to test if it opens.  They should have a thermometer for you to use to see what temperature this happens at.

What kind of cooling fan do you have?  The old clutch fans are inefficient and they cost many HP, up to 1/5 of your power can be eroded. so a thermofan would definitely help if you dont have one.  You can just wire it up to a switch, so that it is easy to use when it gets hot you can boost it up.

If you're out on the road and need a quick fix overnight, Id look at adding some muckowt descaler for the next hundred ks of driving, that will descale the cooling system, and then dump the water from the block, do the mandatory unblocking of the block drain and let or pick all the crud out, same for the radiator, maybe even physically remove it and invert it with running water.  Then just put it back together and run it with a garden hose in the top of the radiator and the hot hose disconnected for ages letting the aged coolant, muckowt and scale be flushed out.  Then put it back together and bleed it up.

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yeh agree with banjo. all my 4k overheating events are from gunk nesting in the downtubes of my radiator, and i have no thermostat.

the gunk causea two things.

1. heat cannot conduct into these blocked parts of radiator and

2. the blockage forcea water to accelerate through the unblocked tubes which causea a decrease in heat transfer to those good areas, so a little bit of gunk has a multiple stage affect on cooling.

i clean out my system with acidic flush once a year because every ml of water i can get my hands on is laden with lime and causes exactly the same symptoms u are referring to. the lime attacks the rust, the rust falls off and the calcium glues it to the copper radiator tubes. a standard alkaline radiator flush will not suffice.

go for tectaloy hd2 flush

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