Rav 4 D4D Cooling Problems: Advice Please?

[Russell W. Barnes]

Hello,

Our 2007 D4D Rav 4 (82,000 miles) has started playing up on the cooling, and I'm seeking advice.

Over the last few months I've noticed the electric fan cutting in more often than usual, although the temperature gauge has always remained around the middle of the scale. I also found I needed to top up the coolant every few weeks, as the level was way down below the 'Low' mark when checked. Mrs B. has also noticed the heater remains cold, even with the temperature knob wound up fully, more often than not.

But yesterday things seemed to be getting worse. With the heater knob wound up, the gauge nearly end-stopped, and no heated air was available. The temperature gauge then returned to normal, at the same time as the heater started to work. This happened a couple of times over a journey of twenty miles.

I bled the system (quite a bit of air in), but still this sluggishness in heater operation, and occasionally a high reading on the temperature gauge. When the heater is wound off to 'cold', the temperature gauge stays mid-scale. It seems that by introducing the car heater and its water pipery to the cooling system , the remainder of the cooling system overheats! I remember as a youth having to wind the heater full-on to mitigate an overheating engine, but it seems to be the reverse is happening here...

Looking this morning, I reckon the coolant loss is via the bleed-spout / pressure relief outlet below the reservoir cap, as the bulkhead and components mounted in the path of it were all wet with expelled coolant.

There's no water in the oil, nor steam from the exhaust. Is this problem likely to be my thermostat sticking or failed? If so, is it easy to change? All advice gratefully appreciated.

[jedi134]

Have you read Charlies 2AD engine topic in the sticky part of the forum :D

[Heidfirst]

it does sound like the headgasket problem - get it checked out at your dealer.

The good news is that you are covered by Toyota for this outside the original 3 year warranty (upto 7 years/112k).

[Tech01]

What does the coolant look and smell like? Clean and right colour? Smoky smell? Any oil in it? Any 'mousse' in the expansion tank?

Have you recently added any coolant/antifreeze to it that wasn't of the same make and type already in there? (Mixing long-life OAT-type with standard antifreeze can produce sludge, goo, gel, crystallization, blockage...)

By all means make use of the warranty to get it all sorted.

But before getting involved with head gaskets (which rarely give trouble, it seems) . . .

- check that the cooling fans are cutting in properly

- check that the radiator gets warm evenly all over (cold spots suggest partial blockage)

- replace the thermostat (cheap and easy)

- flush the system with a proprietary radiator/cooling system cleaner (LiquiMoly products seem good)

- refill JUST TEMPORARILY with tapwater, to test whether you still have a problem (no point in wasting good antifreeze)

- if OK, drain and refill with 30% or 50% antifreeze of specified type, keep the label, and use nothing else without a complete drain and flush-out. Always dilute with demineralized water, NEVER tapwater.

Chris

[anchorman]

Head gasket problems sometimes come from a previous life. If it has been driven hard (or you drive it hard) then it could be head gasket. I think I would start dialogue with a dealer.

[Russell W. Barnes]

Thanks for the input, folks...

Yes, I have added a different brand of coolant recently, but didn't appreciate any potential reaction with existing coolant leading to residue. The top-hose is red hot, and the bottom connection to the radiator is stone-cold. Consequently the steam / coolant escaping from the pipe below the filler cap is a genuine fault, I would say, there being no water passing through the radiator. Some sort of blockage somewhere!

Water pump? No rattles or clanks, and I would expect some trickle of water to pass allowing some sort of thermosyphon cooling if it was knannied. Perhaps it would be best to drain down the system, flush it through, and change the thermostat?

I'm convinced the head gasket is OK, and there are no hairline cracks allowing steam leaks, as there is no evidence of emulsified oil / water on the dipstick.

I shall look on this forum and see about replacing the thermostat and draining down. Thanks again, all.

[Tech01]

Hi Russell,

My money would be on...

1st: thermostat stuck closed

2nd: blocked radiator.

Agree with you - there's no circulation through the radiator. This shouldn't stop the heater from working normally though, unless there's an airlock somewhere too. All sounds like some previous neglect.

Chris

[Russell W. Barnes]

Well...

I removed the thermostat hose, drained it down (sludgy cack) and removed the thermostat. I tested the thermostat by immersing it in a pan of boiling water to check it opened and closed satisfactorily. It did.

I then ran a hosepipe through the radiator hose connected to the thermostat / water-pump end, and got a satisfactory gush of water emanating from the water-pump slot(?) into the thermostat housing: right around the system from radiator thermostat-side hose, through block and heater core, and out through thermostat housing. There was also a good flow through the relief pipe into the header tank. When I blocked this flow off, the water flow through the radiator and block increased.

Re-assembled it all and filled with water / coolant mix. After a while, engine (RHS looking from front) to radiator pipe hot, thermostat-end cold: opposite to how it was before. Temperature gauge rock-steady centre scale and heater working. Took her for a spin and temp. gauge still steady, but heater not as efficacious. Still blowing some water out and slight hiss at pipe below reservoir pressure cap.

Is it possible that this cap, marked 108 kPa, might have lost some of its 'zing' and be weakened? I intend procuring a new cap tomorrow to see if it makes a difference. I can't see how I'm losing coolant anywhere else.

Also... If I disconnect the Battery, will bad things happen?

[anchorman]

You can disconnect the Battery as long as you don't have a tracker.

Trust me, this is not something you are going to cure by conventional means. You need to get it to a dealer.

What part of the country are you in?

[Tech01]

.

[Tech01]

Sounds as if you've done some good checks. There shouldn't have been anything resembling sludge anywhere in the system. Looks like there's still a partial blockage somewhere towards the heater matrix.

Anchorman sounds adamant that you get it to a dealer, so I won't suggest any further checks right now.

Let us know how you get on.

Chris

[igormus]

i 'd visit dealership and claimed as the warranty case.

it is definitely head gasket issue

cheers

[CharlieFarlie]

Read here.. Then go direct to a Toyota Dealer.................Nuff said..

http://www.toyotaownersclub.com/forums/index.php?showtopic=132178

[pcdabbler]

My 2007 was losing coolant out of the header tank breather, with no other symptoms. was running fine, only done 16,000 miles. went in for a service to the Toyota main dealer, came out 9 days later with a rebuilt Engine. Head gasket failure. All free of charge, even a hire car FOC courtesy of Toyota. Impeccable service, and it's been fine since.

[pcdabbler]

My 2007 was losing coolant out of the header tank breather, with no other symptoms. was running fine, only done 16,000 miles. I didn't suspect the head gasket issue. Went in for a service to the Toyota main dealer, came out 9 days later with a rebuilt Engine. Head gasket failure. All free of charge, even a hire car FOC courtesy of Toyota. Impeccable service, and it's been fine since.

[CharlieFarlie]

My 2007 was losing coolant out of the header tank breather, with no other symptoms. was running fine, only done 16,000 miles. went in for a service to the Toyota main dealer, came out 9 days later with a rebuilt Engine. Head gasket failure. All free of charge, even a hire car FOC courtesy of Toyota. Impeccable service, and it's been fine since.

Alan.. That is the lowest mileage that I have heard off for a rebuilt or replacement engine...

Sadly it seems 9 times out of 10 a blown head gasket indicates a replacement engine is on the cards...

Out of interest.. Has anyone heard of a head gasket failure not being related to an engine being either rebuilt (Old policy) Or replaced under the current policy on a 2.2 2AD series engine ??

[anchorman]

As you say in the early days they were rebuilt but head gasket failure could damage the mating surfaces so the policy tends to lean towards engines these days.

[Russell W. Barnes]

Booked in on Friday 13th. Good job I'm not superstitious!

Thanks for all the advice. Will keep you updated.

[Russell W. Barnes]

It was the head gasket.

I went to the dealer who, after a couple hours' investigation, concurred there was CO in the water. Some inherent fault with the D4D 2007 year engine, I was told.

Booked in and partial re-build undertaken under warranty, and all now looking good! Well done, Toyota, and many thanks to all who replied on here. These things happen, I guess, but Toyota had the decency to take it on the chin - hassle-free motoring; a refreshing change.

[Big Kev]

It was the head gasket.

I went to the dealer who, after a couple hours' investigation, concurred there was CO in the water. Some inherent fault with the D4D 2007 year engine, I was told.

Booked in and partial re-build undertaken under warranty, and all now looking good! Well done, Toyota, and many thanks to all who replied on here. These things happen, I guess, but Toyota had the decency to take it on the chin - hassle-free motoring; a refreshing change.

.....AND THAT MAKES TWO VERY RECENT "REBUILD AND REPAIR" SCENARIOS, as opposed to replacement engines, naw ?

Is this the gradual breaking away from the "good will" arrangement as foretold by the prophet Charlie (Book of Knackurt Engines, verses 1 to 3....) ?

Big Kev

[anchorman]

In real terms an engine is overkill for a head gasket - I just hope the so called "techy" knows what he is doing.