Cooling System, Erratic idle, white smoke, engine overheat

[petergerasimon Lurker Find all posts View Profile Close petergerasimon]

Hello guys,

I wonder if you can help me with a problem.

My Toyota Prado TX 2001 KZ TE Diesel (200,000km under the belt) is experiencing engine overheating problems.

I first noticed this when towing my caravan, but on on closer inspection I have noticed that the engine tends to stutter now and again when idling. The exhaust emits a white smoke when starting and then whenever the engine stutters, perhaps every four strokes or so.
When I'm not towing the caravan the temperature is not much higher than normal, but probably above usual. It is safe to say the the temperature increases under increased load.

I'm not having any loss in engine power and the fuel consumption seems normal.

I just checked the timing belt tension, which seems to be alright. The belt was changed only 20,000 ks ago. I'm going to loosen the belts to the alternator and water pump to find out if one of these two is creating an obstruction/resistance to the engine.

Any help would be much appreciated.

Regards,

Peter

[Derb Senior Member Find all posts View Profile Close Derb]

Re: Erratic idle, white smoke, engine overheat

Hi Peter. My 1KZ van did about the same thing only with a big rattle before the cloud of white smoke and at about 300 thou. Ended up being a duff head. Funny thing was, it did it whilst I was towing a car on a trailer up a mother of a hill, I backed off the throttle and then thought - what the hell and gave it some more welly and it all went away. Then no more grief or overheating until months later after which I had passed it onto my son and he was towing a large boat. The parts bill made his eyes water a bit. Hope this is not the case with you but these motors have a bit of history with heads, as good as they are. Cheers, Derb.

[petergerasimon Lurker Find all posts View Profile Close petergerasimon]

Re: Erratic idle, white smoke, engine overheat

Hi Derb,

Thank you for sharing your van story, which almost sounds like mine.
After eliminating the water pump, thermostat and fan I am slowly coming to he same conclusion....Head issue.
I rang a Toyota service mechanic who was almost certain this would be the case when I described the symptoms over the phone....including the pressure build up in the water cooling system, bubbles, occasional overflow which requires top up... . Toyota's Head Job...Cost factor.....AUD 1500 to 2500 !!!! cost goes u[p because of head pressure testing, prophylactic new water pump, thermostat and new fan clutch recommended, just in case, which makes seance.
To my surprise, this morning I went for a spin for around 15 Km, headed towards a steep hill and nothing, as tough nothing is wrong with the Prado; full power, temperature normal, no motor stater and when re-staring the motor emits a bit of a brown/black cloud instead of a white one like yesterday. hmmmm I will be monitoring it and report further.

Derb, have a wonderful Christmas in beautiful New Zealand

Cheers
Peter

[Derb Senior Member Find all posts View Profile Close Derb]

Re: Cooling System, Erratic idle, white smoke, engine overheat

Hi Peter. A quick fix for the fan clutch. If you are going to replace it eventually anyway, Take it off, drill a couple of holes straight through and lock it up with a couple of bolts - or fill it up with 2 pot epoxy or a similar product. this will get you through the hot weather without huge expense. No doubt other pradopointers will have similar fixits. have a good one brother. Cheers, Derb.

[petergerasimon Lurker Find all posts View Profile Close petergerasimon]

Re: Cooling System, Erratic idle, white smoke, engine overheat

Yep, probably a cracked head. This happens mainly in number 3. Hairline crack up in behind the combustion chamber plate. Start with a compression test. If one of the cylinders is down in the reading, the head needs to be removed. To diagnos the head it needs to be heated up 80 to 100 degrees C., head specialist job. Only then will this crack reveal itself. The pressure build up in the radiator is exhaust gas leaking into the coolant. If you drive your Prado (1KZ) you run a risk of the chamber plate letting go into your cylinder walls and or the top of your piston, much bigger repair job. I am sorry to be the bearer of bad news, I hope it is not this, but this is a classic problem with the 1KZs. If it is the problem make sure as part of the job that you flush your block and use Toyota coolant 50/50 demineralised water. The drain plug is located oil cooler side (passenger) just below your oil filter, 10mm, use a good quality socket, it's brass. Change your water pump (Toyota Gen. kit) and thermostat/gasket.
Good luck and I hope this helps.

Hi ##########,

Thanks for your helpful post.
I the meantime I did some work. Since I installed a new Water Pump and a new thermostat I made roughly 200 Km and the engine runs like clock. I must say though I haven't tried it under load like towing a caravan. All the symptoms I described in my first post are gone. May be a little bit of pressure in the coolant container when radiator cap removed in the morning. The water level remains steady. No bubbling. No water traces in the oil. Everything seems to be perfectly normal.
Could it be that the fine crack has been sealed by some stuff in the coolant?............ Like Heal-A-Seal, which may be the previous owner added to the coolant for obvious reasons....? I started to suspect that this could be the case is when I found traces of white powdery looking stuff when the overflow coolant, which spilled around the 2nd battery, dried up.
I experienced head gasket problems previously with other cars, but in non of the cases was the problem gone. It was always a progression to the problem becoming stately worse, specially when it comes to compression.
I have to add too....I have a D-Gas system installed on this vehicle. Could this contribute to the problem?

Cheers
Peter