coolant

[gazgore]

hi i am new here 

I have a 2006 rav4 t180 it was blowing white smoke and coolant was low 

had a test and was told head gasket on way out. Got a mechanic to replace hg and it seems to have stopped the smoking but coolant is still coming out the header tank and getting low

I have been told a number of things from various people from faulty thermostat, bad water pump, inlet manifold leaking and need a new engine 

can anyone help shed some light on this 

many thanks

[alan333]

When a cylinder head or a head gasket fails then any of three things can mix - oil, water, and combustion (exhaust) gas.  It seems you had symptoms of two things mixing: the water was getting into the combustion chamber thus blowing white smoke while it burned off, and combustion gas was getting into the water thus pressurising and heating it until it threw it out the header tank, thus giving you low coolant.

Assuming the head to be ok, then in theory a new head gasket should cure it.  However, from reading on here, apparently Toyota say that particular diesel engine can't be cured by fitting a new head gasket, and when they fixed these engines under the extended warranty they fitted a new engine (or actually a new short motor I believe).  On the other hand I've also read of at least one person being successful by fitting a new gasket.

If water is still coming out your header tank then it's either under pressure or it's boiling (or both).  There could be various causes for this - duff fan, water pump, radiator, thermostat, cylinder head, cylinder head gasket.  I can't think how a faulty inlet manifold could cause it tho.

Remove the header tank cap and start the engine from cold.  Beware the water could be under high pressure and/or be very hot very quickly so don't get yourself scalded.  See if there's any movement in the water in the header tank, see if it changes when you rev the engine a bit.  If there's movement then it suggests that the problem is there even when the engine is cold, which should rule out the fan, radiator, water pump and thermostat.  And it would point towards a continuing problem with either the head or the head gasket.

Probably the best thing to do would be get a sniff test done and find out if there's any exhaust gas present in your water.

 

[daveh_rav4]

Hi Gareth, welcome to the forum... I seem to remember that after many years of head gasket free trouble the Toyota bean counters decided to change the format and or material on later Toyota engine head gaskets thus causing them to fail.  You might want to do a search on that...  Normally a mechanic charged with replacing a head gasket would check the block face and head surface for distortion or 'burn'.  If the surfaces are not true and or within spec then replacing a head gasket would probably only be a short term fix.  The thermostat and water pump should have been checked and replaced as necessary while the head gasket was being replaced?  You might want to ask if that was done... 

Perhaps you need to ask the mechanic concerned exactly what he found when he had it stripped down.  Service receptionists in garages don't always have the full picture!

One thought, I have had air locks in cooling systems causing header tanks to blow coolant out after a top up; so, again... a trip back to that mechanic is in order. Also ask if the latest (good) spec gasket was used?

[gazgore]

2 hours ago, alan333 said:

When a cylinder head or a head gasket fails then any of three things can mix - oil, water, and combustion (exhaust) gas.  It seems you had symptoms of two things mixing: the water was getting into the combustion chamber thus blowing white smoke while it burned off, and combustion gas was getting into the water thus pressurising and heating it until it threw it out the header tank, thus giving you low coolant.

Assuming the head to be ok, then in theory a new head gasket should cure it.  However, from reading on here, apparently Toyota say that particular diesel engine can't be cured by fitting a new head gasket, and when they fixed these engines under the extended warranty they fitted a new engine (or actually a new short motor I believe).  On the other hand I've also read of at least one person being successful by fitting a new gasket.

If water is still coming out your header tank then it's either under pressure or it's boiling (or both).  There could be various causes for this - duff fan, water pump, radiator, thermostat, cylinder head, cylinder head gasket.  I can't think how a faulty inlet manifold could cause it tho.

Remove the header tank cap and start the engine from cold.  Beware the water could be under high pressure and/or be very hot very quickly so don't get yourself scalded.  See if there's any movement in the water in the header tank, see if it changes when you rev the engine a bit.  If there's movement then it suggests that the problem is there even when the engine is cold, which should rule out the fan, radiator, water pump and thermostat.  And it would point towards a continuing problem with either the head or the head gasket.

Probably the best thing to do would be get a sniff test done and find out if there's any exhaust gas present in your water.

 

hi yes it only smoked every now and again 

the mechanic checked the head and said it all looks good 

I had a chemical test on the tank and it never changed colour to indicate gasses getting into the header tank? This was confusing as it was pressurised the mechanic checked the star and pump and said they seem to be working correctly as it does not over heat and fluid is coming back into tank 

I was told the inlet manifold could have a leak causing it to fill with pressure? But not sure on this as not mechanically minded.

I will try the cap off and see what happens 

[gazgore]

2 hours ago, daveh_rav4 said:

Hi Gareth, welcome to the forum... I seem to remember that after many years of head gasket free trouble the Toyota bean counters decided to change the format and or material on later Toyota engine head gaskets thus causing them to fail.  You might want to do a search on that...  Normally a mechanic charged with replacing a head gasket would check the block face and head surface for distortion or 'burn'.  If the surfaces are not true and or within spec then replacing a head gasket would probably only be a short term fix.  The thermostat and water pump should have been checked and replaced as necessary while the head gasket was being replaced?  You might want to ask if that was done... 

Perhaps you need to ask the mechanic concerned exactly what he found when he had it stripped down.  Service receptionists in garages don't always have the full picture!

One thought, I have had air locks in cooling systems causing header tanks to blow coolant out after a top up; so, again... a trip back to that mechanic is in order. Also ask if the latest (good) spec gasket was used?

hi toyota told me to replace hg before i needed a new engine? 

and the head and block was checked he is a jaguar technician and knows his stuff 

the pump and stat were checked but told were in working order 

how could i tell if air was in system/ remove it please

and yes i believe it was the new gasket set as was about £200 

 

[daveh_rav4]

Well, it sounds like Alan is suggesting that Toyota know something else about these engines if they are advising a replacement short motor if the HG fails to fix!  Perhaps these diesels engines use piston sleeves that have an issue with the water jacket side of the engine block? 

Again I am not familiar with your engine... but to purge an engine with a coolant system 'air lock' we used to remove one side of a heater feed pipe, run the engine for a short time until any air had been expelled, reconnect, then top up as required.  Trapped air will contract when cool (you then top up), expand when the engine gets hot and pump coolant out of the header.  Obviously if there is a combustion gas leak from a sleeve, block or block/head face then combustion gasses will have the same effect. i.e. pressurising the coolant system beyond the set level.

[Heidfirst]

see 

 

[daveh_rav4]

WOW!  @-@  

I didn't read all twenty odd pages on the above thread, but it appears carbon build up on top of the pistons caused by (supposidly) crap UK diesel fuel that damages the head.  It also seems Toyota are not exactly say why this happens, but it must have been seriuos enough for them to hold their hand up for a seven year (110kn) warranty.  I am glad I detest diesel cars... Seems like you are out of Toyota's extended seven year warranty Gareth if the problem persists. :(

My next car will be a fourty to fifty year old classic... without all these emmission sensors and digital crap. I just need a car with a starter button, simple petrol engine, spark ignition, light switch and wind up windows. KISS  LOL

[Doosan]

Hi, Gareth, This is well documented on here. Have a read of this.