Weird water issues...

OK this is a really long story, but I'm looking for some insight into possible causes....

Basically I have a 1994 supercustom, 4x4 1KZ-TE model. I do a fair bit of towing with it. I bought it off a mechanic mate who bought it off a client when it had a cracked head. He fixed it up with new head and everything then when he went overseas i bought it off him. The head is about 3 years old...

I started having issues last summer, in that after driving home from work and parking up and shutting down, 3 minutes later water would be bubbling out the overflow bottle. We found the radiotor cap was a bit buggered, and a blocked hose from overflow bottle to top of radiator. fixed those, it went ok for a bit then did it again. So i had everything checked, radiator flushed, pressure tested ok, everything tested mint. So My mechanic assumed a cracked head... He put some irontite in and set that up couple fo flushes etc, and afterward i had no probs for 10 months.

A while ago towing again, the van was running mint uphill etec no probs for 3 hours. I then stopped at a servo and left the motor running, within about 2 mins of sitting there idling the temp started to skyrocket. I dont think the fan was running at this stage. I drove it onto the road and tried to cool it by getting airflow through the radiator, but it didnt come down. It wasnt red hot, bout halfway between normal and red. So i shut it down, turned the key on and the fan was running. At this stage it pissed all its water out the overflow bottle again. Luckily this happened beside a workshop, and so we waited till it was cool, flushed the radiator and put good coolant in. No problems after that or since...

1 - I suspect the fan is dodgy maybe what caused the above problem. I am fixing that this weekend.
2 - Now it uses a tiny amount of water, like a capful each week.
3 - what would have caused the initial problem of it blowing waterout the overflow when stopped?
4 - is it likely to be a cracked head, or should i take the radiator out and get it checked properly?

Bear in mind the ONLY time it has been warm is with the above when i was towing and stopped. When the initial issues were happening it never ever got warm, nor has it done since.

I would appreciate any advice, I'm at my wits end with it!!!

Hi Datman,

A dodgy thermofan could cause (or have caused) most of your problems. The last vehicle I saw spit it's water out when stopped (in my driveway) was a mitsubishi van with a newly fitted thermofan and a new thermostat. The guy came to fix my home heater but ended up fixing his van instead. As soon as you stop or drive slowly it will boil if the fan hasn't kicked in. Knowing if or when the fan has failed can be difficult to find out, especially if it is an intermittent fault. A non operating fan could cause overheating and contribute to a blown head gasket or cracked head. In your case it could simply have caused the repeated boilings and there may be no damage to the head. The current water loss may be a small leak.


2 & 4 - possibly does now have a head/head gasket problem but I would check for leaks first. I once had a leak at a hose connection to the radiator which wouldn't leak until the temperature dropped below about 15 overnight. Then there was a small pool of water under the car. Any warmer than that and no leak at all.

I have used chem-i-weld on my falcon which has done about the last 100,000k's (out of 400,000) just fine after developing a water jacket to cylinder bore leak. I could identify it easily by looking at the spark plug but that's a bit impossible with a diesel. Irontite is basically the same thing and will fix all sorts of leaks as long it is water leaking out to somewhere else.

1 & 3 - likely thermofan problem in the first place. Did you happen to disturb the thermostat or wiring and inadvertantly fix the issue when looking for the problem? It's possible. The one dodgy connection can do that.

In short fix the thermofan and check for a leak first. If no leaks you could try more irontite as is seems at least not to have done any harm the first time round.

Good Luck

Cheers, Dave

Datman,

One last thing - I presume you have a thermofan but you didn't actually state it now that I look again. You say it ran again after turning the ignition on again soi I thought it must be. You could replace it with the conventional viscous coupled belt driven one and not have to worry any more about that side of the equation.

Cheers,
Dave

Thanks for the advice Dave, very helpful! The fan is a viscous belt driven unit. Do these run without the motor turning over? I'm damn sure the fan was running after it got hot and i shut the engine down, but i must be mistaken... My local toyota dealer reckons if the viscous fan is dodgy, just to replace the fluid inside the viscous unit. He's given me some of the fluid but im yet to do it.
We never found any leaks first time round but it will be worth checking again. How hard are the water pumps to do on these btw?

I'm also thinking if i get the problem fixed i should really be installing an oil and trans cooler because i will be doing lots of towing my rally car. Dont know where to start with these, ill do some searching.

Hi Datman,

My presumption was wrong about the type of fan. It just happened that this week the guy turned up with his overheating van with non std thermofan.

The standard fan will not run without the motor turning over. The viscous fluid causes the fan to engage more (slip less related to the drive pulley) as it heats up. I can't recall a typical failure mode for these fans but if it hasn't been running the effect is the same as I was talking about a thermofan not running. I don't know if these can fail intermittently. You could try and turn the fan when cold and compare it to when the motor is hot.( engine not running ;-) it should have some resistance in both cases - more when hot. If it doesn't have any resistance then it's busted. From memory these need to be stored on the side or face down to prevent fluid leakage.

If the fan is running it may be some other coolant system problem like you investigated last time which is preventing flow so checking water pump, radiator, thermostat etcetera may be necessary.

Good luck,

Cheers,

Dave

I'll start with the fan anyway, because in the last week i did lots of hard running and never heard the fan once. Even sitting in traffic on a hot day after a thrash i never hear the fan roaring. I mean its spins, but only like its freewheeling, not actually engaging.