What Else Could It Be?

August 16, 2010

Hi Everyone.

I've posted on here before, about a year ago,,,, still have the same problem

We have a Landcruiser Colorado 1998, 3 litre turbo diesel

Over the last year, we have spent a lot of money attempting to fix the overheating problem.

The metal plate on the engine compartment says engine type 1KZ-TE, but when the head for that type was ordered it wasn't correct. We eventually got one called 1KZ-T, which fitted. However, this may be an excuse for ordering the incorrect part by the garage!!

We have replaced the following components,

head (original was cracked at the valve seat in cylinder 2), head gasket, thermostat.

Water pump checked out, is working well.

Cooling fan working OK.

We have also changed the radiator/cap - however, the problem still continues.

Water is trapped in the header tank and spurts out the overflow when the engine gets hot.

The radiator we bought is at least 1cm thinner than the original radiator. We are wondering if this is significant? Is there a difference in capacity between the diesel and petrol radiator versions? Could we have fitted a petrol one by mistake? If we did, could it be the problem?

We are getting pretty desperate now so would appreciate input from you guys...

Cheers

Robin :help:

August 23, 2010

Robin,

I could be way off the mark here,because I am unfamiliar with your model vehicle and the motor,however lets look at the basics with a little experience mixed in.

Is the cap one of the small variety? If so, is the seal aok?(I know you said it was replaced)Does it have a top seal in the cap to work with the recovery system?In other words the right cap for the system? Are you able to test the cap to make sure it is holding pressure.If in doubt with any of these answers,please try another cap. Not necessarily a new one but one off a vehicle you know is ok. The small toyota caps do cause quite a bit of drama and you may have a faulty one.

Your suspicion about the radiator is correct. In the forty years in the trade I have never seen anyone put a smaller radiator into a vehicle as a replacement of an origional one. In general a diesel radiator is a heavier (more solid)unit than a petrol one and being 1cm thinner than the origional, may very well mean that you now have a single row rad instead of a double row.(I am referring here to the amount of tubes in the radiator that carry the coolant.)If that is the case you have effectively halved your radiators' capacity. Hence less efficiency.

Next,can you see the core in the radiator through the cap hole.If so watch the coolant as the engine warms up and see if the coolant is circulating(until the thermostat is open it shouldn't be moving).Can you see bubbles coming up. If you can,you may have a gasket problem (head). Is the coolant stable whilst warming up or does it rise and fall sharply, if it does it may have air trapped in the system.That by itself can cause overheating.Always make sure the heater is turned on when filling the engine with coolant and initial warm up is done.If you have some part of the cooling system (like a heater hose)that is up high on the motor or firewall, disconnect it while you are filling, until coolant runs out of the hose and the fitting it goes on.

If you cannot see the core through the cap hole,you can still see everything as described above except the circulation, which you can still monitor by feeling the temp difference between the top and bottom hoses.When the thermostat opens you will feel the bottom hose suddenly become the same temp as the top.

If you are seeing a lot of bubbles you will have to find someone with a chemical head tester or a sniffer.(Testing for hydrocarbons present in the radiator.)

When the motor is first started cold, listen for the fan noise,it should roar at first and then quieten down.When the motor is at operating temp and not running,spin the fan blades,if they go nearly a full turn or more,replace the fan clutch.

Check the A/C condensor if it has one,(the alloy thing in front of the radiator)if its blocked with dirt or dust or has bent fins,hose it out with reasonably high pressure water preferably or air and sit down in front and spend a couple of hours straightening fins with a little screwdriver.(be carefull).

Lucky last,see if you can research those two engines you mentioned,if both exist and they are similar it is possible that when the head was fitted they may have used a wrong gasket somewhere and it is missing a hole somewhere and is blocking coolant flow, causing the pesky overheating problem.

Hope I wasn't too long winded for you and good luck with it.

Cheers Greg