Temperature Gauge in the red. Toyota Land cruiser 4*4 2001

Jeep?

If the heater is blowing cold, I'd be wondering if you have any circulation. I think your trouble is the water pump. The pump has an impeller inside that is commonly made of plastic. The plastic blades can break off or wear out, the result being that there is no coolant ciruclation, this leads to the engine overheating and the heater blowing cold.

Jeep?

There are several possible causes of the high temperature gauge readings:

The thermostat may be faulty; The temperature sender for the gauge may be faulty; The water pump may be faulty; The radiator and/or AC condenser may be blocked The engine mounted fan clutch may be bad.

The short wheelbase Land Cruisers sold in some countries like the one in this page

is sometimes referred to as a "jeep." Kind of like Escalator, Scotch Tape, Xerox copies, Kleenex, Band-Aid, etc., a "jeep" is a shoft wheelbase utility vehicle in other countries.

Toyota water pumps do not have plastic blades, I have never ever heard of the metal blades in a Toyota water pump breaking off or wearing out. When Toyota water pumps go bad, they leak. You will see a big mess before you have a circulation problem caused by the water pump.

Now, edit the list for things that also result in low temp from the heater.

All that is left is the water pump.

and thermostat.

Hi

Would it be safe to drive the jeep for approx 15 miles to get it to the garage. I noticed the needle moves up and down while I drove it this evening.

Thanks for your help Aidan

aido wrote:

It should probably be OK. If the needle goes up into the red, pull over, shut off the engine, open the hood (bonnet) and let it sit for about 15 minutes, then drive a little more, repeating as necessary.

I was thinking that too, but the tstat housing has a bypass for the heater hose(s) so that the heater gets hot before the tstat opens, and remains hot after the tstat closes. That is, the heater works independently of the tstat in normal operation, so if the heater stops blowing hot, the tstat is not part of the problem because heat should flow to the heater without regard to the tstat being open or closed. And, the OP reported his heater blows cold even though the Temp Guage is pegged to the red zone (I paraphrase his comment). If the tstat was closed and the coolant was circulating properly as a result of the attemps of the pump to operate, the heater should blow hot. If the water pump had failed, then there would be poor circulation and the heater would blow cold even if the engine was actively overheating.

I vote water pump.

Hi All

Your comments have been very helpful. I'll take the jeep to the garage to-morrow. I'll keep you informed. I have pasted a link to a similiar jeep below.

Thanks again

Aidan Brennan (Dublin)

>>>

Your explanation (and vote) is good in theory but not as good in the real world.

In the real world, Toyota water pumps will be leaking coolant all over the ground well before they quit circulating coolant. In fact, I have never seen a Toyota water pump fail to circulate coolant. The OP did not say that coolant is leaking from the water pump so a bad water pump moves down the list of suspects.

I do not know if the engine has a timing chain or a timing belt or how the water pump is driven. If the engine has a timing belt and the water pump is driven by the flat side of the timing belt and the belt is stretched out or the idler is not holding tension, then it is possible that coolant is not circulating, but the fix would be the timing belt's or idler, not the water pump. Also, the timing belt would be making a racket if this is the case.

The lack of heat could be due to a disconnected heater control valve cable, bad heater control valve, air in the system, or blockage in the heater core, or blockage in the cooling system. (assuming the heater fan is working).

I always recommend checking simple and cheap stuff before checking expensive stuff, and checking stuff that fails often before checking stuff that hardly fails, unless it is obvious that the something is broken.

It's true that he did not mention any leaks. But he did mention over heating and a cold heater, and a full radiator. Circulation is the only thing I can think of that fits all three symptoms.

I agree with the Cheapest Stuff First theory in principle. But I have to take him at his word that the heater used to work (eliminating the control valve and blockage in the core). I accept that these are not always safe assumptions, but the coincidence of the tstat and these items both failing at the same time tends to exclude one or the other. Without more information, I still go with the water pump.

PS The water pump is always driven by an external belt, and in my experience it is never driven by the timing belt or chain. The pump is driven by the serpentine belt, not the timing belt. Pray that your timing belt never actually makes noise.

If it were my vehicle, I'd check the thermostat first because it doesn't require tearing open the timing cover, then I'd loosen a few bolts on the timing cover, pry it back a bit, and sneak a peek at the timing belt/chain.

This is incorrect. Look at what is driven by the accessory drive belt drives on a modern Toyota, and look for the water pump. Hint: it is hiding under the timing cover ;-)

Hi LAds

I had our mechanic check the jeep to-day. The waterpump needs to be replaced, it's leaking. The rad was only 1/4 full when he checked it. The water could be seen leaking from the pump.

Thanks again for all your help.

Aidan

Ray O wrote:

New clues! I'm glad you're back on the road.

Ray O

I have never ever seen a water pump driven by the timing chain. Not ever. While there is no practical reason that it can't happen, I've never seen it. Indeed, it seems to that it would be a royal pain in the ass to have a water pump driven off of the timing chain, but engineers make the Big Bucks to create a new pain in my ass.

Your experience with Toyotas must be very limited. All modern Toyota engines that I can think of have water pumps under the timing cover and are driven by the timing belt or chain. OTOH, pushrod engines with camshafts in the block often have external water pumps that are driven by an accessory belt because there is no convenient way to drive the belt under the timing cover.

:-o Ive never seen one NOT driven by the timing chain/belt?!

J

Do you want me to send a picture of my '92 Corolla Wagon's water pump being driven by an accessory belt...not the timing belt?

No thanks, I trust you, i was just fascinated as ive seen a fair few engines in my time and never seen on aux-belt driven. Not sure if it makes sense, design wise, or not really - i presume, by the number of timing driven WPs, that it makes more sense to drive it by timing but it sure would be easier if they were aux driven!.