I've tried changing the thermostat, and flushing out the rad fluid, pressure tested the cap and rad and no leaks there. The heater comes out cold when econ is off. And now i only get half of the boost on the stock guage. I could be driving and its all good and then, BAM! straight to the 'H' mark! Any ideas would be greatly appreciated.

Also when that happens the fluid overflows from the overflow tank.?

I think the ecu will cut boost if it senses a high temperature.

Tiny holes somewhere will only leak if under extreame pressure when hot and running....

This is one of the worst problems on a zed in my experience...

It could be a whole list of things....

I wouldnt like to say anything in particuler as its plaging me at the mo and have replaced hoses and rad caps and getting w.pump soon...

 

you could try adding extra antifreeze to the system and seeing if it leaves a white trail anywhere and you will smell it when it leaks....others use talc sprinkled on the connections....

or put a bit of cardboard under the car just as you pull up and switch off...this should show any drips after the heat soak and pressure build.

..the most prone ones to leak are a fooker to get to...down the back of the engine or by the tubs.

 

In extreame cases it can be the HGasket but lets not talk about that :nelson:

if it was youd probably get high pressure in the water system...white smoke form rear(doesnt always) or even water in oil or vice versa.

 

So...i dont really know but persiverence and carefull systermatic checking should reveal eventually.

search is your friend ... try it ...

I've tried changing the thermostat, and flushing out the rad fluid, pressure tested the cap and rad and no leaks there. The heater comes out cold when econ is off. And now i only get half of the boost on the stock guage. I could be driving and its all good and then, BAM! straight to the 'H' mark! Any ideas would be greatly appreciated.

 

 

,the reason for half boost is safety boost,because of the overheating the engine is going into safety mode change the temp sensor but symptoms point to HG failure do acompression test

Try to refill the radiator from the rad cap and are you sure you don't have an air block in the system, have you taken out the radiator and checked that it isn't blocked, when you did the flush?

 

The head gasket could be the culprit but a compression test isn't a reliable way of testing for it, ask a local garage if they have an ultraviolet leak detector, they add an ultraviolet dye to the coolant, put a pair of UV specs on switch on an ultraviolet light and see if it is coming from the exhaust if it isn't they then look at the engine bay.

 

Lastly buy a new rad cap from Nissan they are too cheap and too important not to replace on a regular basis!

Try to refill the radiator from the rad cap and are you sure you don't have an air block in the system, have you taken out the radiator and checked that it isn't blocked, when you did the flush?

 

The head gasket could be the culprit but a compression test isn't a reliable way of testing for it, ask a local garage if they have an ultraviolet leak detector, they add an ultraviolet dye to the coolant, put a pair of UV specs on switch on an ultraviolet light and see if it is coming from the exhaust if it isn't they then look at the engine bay.

 

Lastly buy a new rad cap from Nissan they are too cheap and too important not to replace on a regular basis!

 

correct a compression test wont indicate HG failure but it will indicate whether or not the engine is in good health,you obviously know that yourself :tongue:

 

i seen HG failure yesterday and once the engine was up to temp the plenum was impossible to touch and the pressure was that high in the systym the top rad pipe bulged 3times its size along with milkshake in the radiator :eek:

That comment wasn't directed at you greg just trying to help Joe with his problem!

 

A head gasket failure on a 300 can also hardly be visible in the normal way, i.e. mayonaisse in the rad or oil filler cap, if you leave the rad cap off and let the engine warm up a fine stream of bubbles can be seen coming up from the radiator opening, as fine as the bubbles on the side of a glass of lemonade or beer!

 

Another way of testing HG failure and cheaper solution is to buy a head gasket tester kit, which tests for combustion fumes coming from the radiator opening, costs about 25ish pounds sterling.

When you replaced the thermostat did you make sure you put it in with the arrow pointing up? If not then you are going to have problems bleeding all the air out, thus causing possible overheating.

That comment wasn't directed at you greg just trying to help Joe with his problem!

 

A head gasket failure on a 300 can also hardly be visible in the normal way, i.e. mayonaisse in the rad or oil filler cap, if you leave the rad cap off and let the engine warm up a fine stream of bubbles can be seen coming up from the radiator opening, as fine as the bubbles on the side of a glass of lemonade or beer!

 

Another way of testing HG failure and cheaper solution is to buy a head gasket tester kit, which tests for combustion fumes coming from the radiator opening, costs about 25ish pounds sterling.

 

i know you wasnt

I've tried changing the thermostat, and flushing out the rad fluid, pressure tested the cap and rad and no leaks there. The heater comes out cold when econ is off. And now i only get half of the boost on the stock guage. I could be driving and its all good and then, BAM! straight to the 'H' mark! Any ideas would be greatly appreciated.

 

Others have already given great advice but as you are not getting any water to the heater matrix (no heating) are you sure that there is no water leak inside the car ie in the footwell as a blown heater matrix would cause the symptoms that you are having

 

A compression test would not show up the symptoms your having but as mark has said there are two types of dye test the easiest to use is the one you put in the rad that changes colour when it comes in to contact with combustion gasses but i still think if you have no heating your matrx has a leak

 

Ryan

Others have already given great advice but as you are not getting any water to the heater matrix (no heating) are you sure that there is no water leak inside the car ie in the footwell as a blown heater matrix would cause the symptoms that you are having

 

 

Could also be this as well, it is usually accompanied by an acrid smell inside the car, but just for info on people using search in the future, no heat from the matrix is one of the first signs of low coolant levels.

i appreciate all the info so fast!! But, i did install the thermostat correctly, and i installed a nizmo rad cap(1.3 kpa). There are no leaks in the footwell. No odors inside the car. ECU code 55. The right side precat makes noise when i let off the accelerator only when the car is warmed up.

 

I live in Aviano, Italy so i havent found anyone that knows how to work on Zeds. I will try to take it in and see if they can put the dye in.

Correction to the radiator cap: 0.13Mpa sorry

i appreciate all the info so fast!! But, i did install the thermostat correctly, and i installed a nizmo rad cap(1.3 kpa). There are no leaks in the footwell. No odors inside the car. ECU code 55. The right side precat makes noise when i let off the accelerator only when the car is warmed up.

 

I live in Aviano, Italy so i havent found anyone that knows how to work on Zeds. I will try to take it in and see if they can put the dye in.

 

try fitting a standard new nissan cap sometimes aftermarket caps wont seal properly causing lack of pressure in the systym,you say you getting cold air when heating is on that does point to heater matrix,but try the cheapest options first like rad cap

I already had a new cap on and i also cant find any leaks other than the catch tank overflowing. Thanks for the help.

I already had a new cap on and i also cant find any leaks other than the catch tank overflowing. Thanks for the help.

Are you sure you have no Airlocks?

Very common and easy to happen on these motor's

I normally use the old Raising the Gravity method of filling the radiator up with coolant via a large funnel or coke bottle with just the bottom cut off,keeping the funnel over 3/4 full at all times until you think the system is full of coolant with the engine running.

Cause's the coolant to be forced down under higher gravity and air gets forced out of the system easier...I worked in a few garages and most of us mechanic swear by this method of getting airlock's out of stubborn cooling system's...

Lot's of helpfull advice here from other experianced people!!!

It's just going to be a process of elimination here starting with the most simplest thing's first.... :)

Could also be this as well, it is usually accompanied by an acrid smell inside the car, but just for info on people using search in the future, no heat from the matrix is one of the first signs of low coolant levels.

 

Sorry Mark gonna have to disagree here mate you would have to have next to no water in the system for it not to reach the matrix , if you had low levels the heater would still work which is why if your car overheats due to lack of coolant you can bring the temp down quicker if you turn the heating on full and turn the fans on full to try and get rid of some of the heat

Sorry mate we will have to agree to disagree!

 

The heater matrix is one of the first items to suffer from an air block, which is why they say have your heater on running full blast and raise your zed front end up high when refilling your zed coolant,

 

If there is a leak/low levels in the system there is a fair chance it is gonna put air into the heater matrix as the next dump point is the rad.

 

Overheating is not necessarily the same as having low coolant levels, which is why they advocate running your heater on full blast, as it gives you an extra point for heat to escape.