Blown head gasket???

[matt90prado Lurker Find all posts View Profile Close matt90prado]

Hi Gurus,

I've a 97 RV6 with a TRD supercharger.

After a recent 400 odd km trip towing a mid size box trailer my Prado began spewing boiling hot
coolant out of the overflow bottle. Temperature slowly (about 20 mins) rises to the top of the gauge and I stop. Coolant continues to pump out of the bottle for about 5 minutes. I pulled out the overflow hose and steam was pumping out. As the motor cools it sucks the overflow bottle dry. It takes about 2 litres of water to fill the radiator again.

There is no oil in the coolant and no coolant in the engine oil.

I ran the engine with the radiator cap off and doesnt seem to be bubbling a lot.

I've done some searches on pradopoint and cant find a definitive answer. I've been to my mechanic and had him stumped. The radiator pressure tested fine as it the compression.

I went to a radiator specialist who reckons it could be a blocked radiator. But I cant see how a blocked radiator could cause air in the system??

At this stage im sourcing a reco motor or second hand with 80000 km.

Questions
1. Anyone have any ideas on what could be causing my radiator to pump out coolant.
2. If it is a head gasket any advice on a reco or second hand

Any help appreciated.

Oh and its running like a bit of a dog but has been since before the cooling issues. (feels underpowered).

[tassie tiger Advanced Member Find all posts View Profile Close tassie tiger]

The only real thing to do is pull the heads and have a look.

The fact it was running like a dog probably meant that the gasket between the cylinders had started to leak and now its gone into a water jacket.

Could also be a crack in the head or cylinder.

[Leethal Advanced Member Find all posts View Profile Close Leethal]

I would do some more tests before replacing the engine myself.
There are tools available which will detect the presence of CO gas in your coolant, most good workshops should be able to do that for you.
I would also change the radiator first as well, if that fixes your overheat problem .. great, if it doesn't then you have a good radiator to go with your "new" or rebuilt engine.
The poor running and the overheat might be twwo separate issues.

Lee

[letsgoplaces Advanced Member Find all posts View Profile Close letsgoplaces]

Hey,
I had the same issue last year. While the radiator was about 70% blocked, the boiling from the overflow bottle still happened after having the radiator fixed. After a lot of head scratching, turns out that the radiator cap was no longer holding pressure. Replaced the radiator cap and the problem stopped
Start small and work your way up and like Leethal said, if you do need a new engine at least you'll already have the radiator
I'm no mechanic by any stretch of the imagination, but i would think you will see signs of oil/coolant mixing if you have a cracked head/cylinder

[Brett1979 Avid PP Poster! Find all posts View Profile Close Brett1979]

I'd replace the radiator first. Will cost approx $700 for a radiator specialist to do it. I had the same problem a long time ago in my Prado and my radiator had a blockage. The standard Prado radiator hit the 10 year mark which is when they tend to let go by a decade long build-up of crap in the small horizontal fins. As for your car running a bit sick, it wouldn't be because of a warped head as that shouldn't affect performance of the car in my experience with having a previous car with a warped head. If the head was warped or cracked you have a milky white residue under the radiator cap and your radiator would be bone dry after 10-15 minutes of driving. So it'd take much more than 2 litres to refill it. You car running sick could be anything from an old fuel filter to old ignition leads and spark plugs or even dirty injectors. I'd recommend the radiator replacement first with any radiator specialist or even Toyota, and while Toyota are at it they can use a diagnotics tool to find out why your car is running sick. They'll know your Prado well so you can get a diagnosis and quote to have it fixed at a later stage.

[tassie tiger Advanced Member Find all posts View Profile Close tassie tiger]

Temperature slowly (about 20 mins) rises to the top of the gauge and I stop. Coolant continues to pump out of the bottle for about 5 minutes. I pulled out the overflow hose and steam was pumping out. As the motor cools it sucks the overflow bottle dry. It takes about 2 litres of water to fill the radiator again.

This is the worrying bit. Its not like 'the motor gets hot when I am driving and if I slow down again it drops' which is indicative of poor cooling.

To keep pumping water out for 5 minutes after stopping means it was REALLY REALLY hot and the water just keeps on boiling and pressurising beyond cap pressure or had been pressurised by compression from the cylinders.

Agree with doing the radiator. In fact, upgrade it seeing as it has the supercharger fitted.

Good luck

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

I had a similar problem a few years back, so I replaced the rad, thermostat, and rad cap, never had the problem since. However if yours got as hot as you said, you may have hurt the heads/gaskets, get it tested while your at it.

[matt90prado Lurker Find all posts View Profile Close matt90prado]

Thanks everyone for your advice. I've replaced water pump, thermostat and radiator cap. I'll replace the radiator and see how I go. Just got to source a 2 or 3 core.
Thanks

[croozza Avid PP Poster! Find all posts View Profile Close croozza]

Get a 3 core