Overheating in 4wd mode

[dannypatrol]

I made earlier a topic on overheating during sanddriving and I decided to do a coolant flush. I also found that the spring in the cap wasnt working so replaced that.

Today I went to duck creek road (awesome place!) And was driving on gas in 4wd mode (4h). Half way we stopped and the coolant was boiling and coming out the radiator while the temp gauge never moved. After cooling down, the car didnt start right away. I decided to continue on petrol, it was only a couple more km till the end but in the end the coolant wasnt boiling so not sure if it was the gas mode or coolong. The engine still didnt start at once while I now start at petrol mode. The gas system is checked in oktober 2013 when I bought the car.

Another thing I noticed yesterday that the car the first 5min didnt had much power when I was driving on gas but I thought it was just a cold engine so not sure if this is related.

From this it might be good to get the cooling and gas checked out. My scare obviously is a high bill, in addition i am not learning much if i just bring my car to a mechanic. Because i will do a big lap, i like to be able to solve as many problems by myself as possible. so I am wondering if anyone on this forum from around brisbane has any experience that might be useful for this and like to help me out (a cold beer will be waiting).

Some details: nissan patrol gu, 1997, auto, 4.5l lpg/petrol, last service in oktober 2013, coolant flush and change month ago

[MudRunnerTD]

Dod you do the coolant change yourself? Are you sure it was fully bled of air? Interesting that the gauge did not show hot yet it boiled? Does the gauge function normally?

[Bloodyaussie]

These cars are shocking for bleeding properly and it is advised to jack the front of the car up to allow for air to escape.

Sometimes it can take a couple of days of allowing the car to cool right down and then the next morning topping up again.

It is hard to explain about warming up the car with the cap off and when the thermostat opens the level will drop , you then rev the engine up and fill with coolant then quickly close the cap.

[dannypatrol]

The gauge was showing hot when I was sanddriving. My driveway is steepish so I did the rev wo cap thing to bleed for air. But not 100% sure it is done properly. Having said that, the sand issue was before I did a coolant flush so I read that as that the cooling issue isnt coolant related.

[Alitis007]

The 4.5 has a bleeding point on the heater hoses on the firewall which make them easy to beed out. Only problem is you will need to bleed the converter then heater to get all the air out.

I would recommend having the gas mixtures checked to make sure they are within the specific tolerances ( roughly 2.5% Co2 ) on a gas analyzer, that should solve the lack of performance also check the timing. Incorrect timing and fuel mixtures can cause an overheating fault when the motor is pinging / pre igniting but is rare. Unless you have a stoichiometer of a gas analyzer you won't be able to adjust the fuel mixture on lpg.

When you flushed your cooling system did you have the tanks removed and the core cleaned out of did just reverse flush it with the hose?

[Bloodyaussie]

So does it over heat??? when you say coolant comes out the radiator does it fill the overflow bottle??

Does the temp rise and fall quickly or does it get hot and stay there... if it fills the overflow bottle does it suck it back after it has cooled???

[dannypatrol]

I didn't remove anything. Just flushed it with water through the radiator followed by coolant. I am not experienced enough to take it apart.

The coolant in the overflow tank was boiling and steam came out of the radiator (I guess because it was to hot to open the bonnet, but green liquid was around the cap after cooling. The coolant stopped boiling after 20min or so. So far it only happens in 4wd mode, slow driving and on gas for sure, petrol unsure. Radiator is so good as new. The fans are on as well during driving.

I am unsure what the lpg inspection is when you buy a car 2nd hand (as part of rwc).
Maybe I should get that checked out if that only can be done by a mechanic

[Alitis007]

I didn't remove anything. Just flushed it with water through the radiator followed by coolant. I am not experienced enough to take it apart. The coolant in the overflow tank was boiling and steam came out of the radiator (I guess because it was to hot to open the bonnet, but green liquid was around the cap after cooling. The coolant stopped boiling after 20min or so. So far it only happens in 4wd mode, slow driving and on gas for sure, petrol unsure. Radiator is so good as new. The fans are on as well during driving. I am unsure what the lpg inspection is when you buy a car 2nd hand (as part of rwc). Maybe I should get that checked out if that only can be done by a mechanic

The lpg is inspected for leaks and for correct operation and to make sure the tank is within its 10 year safety inspection during a rwc check.

The radiator has to be taken to a workshop to be cleaned because of special tools needed to re connect the tanks aswell as new seals after it is pulled apart.

Firstly you need to make sure you don't have any water leaks, without a pressure tester you can inly do this by monitoring the water level and a visual inspection of all the hoses and fitting and also on the cylinder block around the welch plugs.

Which fan are you talking about ?? The viscous fan on the motor or the electric one for the A/C? The electric thermal fan should only come on if the a/c is on OR if the engine coolant temp is 96* or higher as a back up, NOT ( normal operating temp) is around 90*C.

To me imho it sounds like you have a circulation fault, be it the radiator cap allowing the water to fill the overflow bottle when it expands but not return which over time will make the water level become lower than the tank and not allow it to circulate, a partially blocked radiator, stuck partially open thermostat or a viscous fan clutch fault because it only overheated when you where laboring the motor at slower speeds in 4h.

If there is a water leak the gas converter will freeze over and stall the motor because the coolant is used to heat up and vaporize the lpg.

A test you can do yourself is, start the motor and raise the idle to about 1500 - 2000 rpm by holding the accelerator cable near the throttle body. If the viscous fan is working is should make alot of noise and make alot of wind for up to a minute then not blow as hard. After that let the motor idle until it is at not and race the motor again, you should hear it engage and disengage. That test will point point us in the right direction to eliminate your fault. The other test will most likely need to be done by a mechanic.

Please try and be specific so we can get a better understand of whats going on with your motor so we can help you out the best we can

[04OFF]

When was the last time the Valve clearances got checked ?

[dannypatrol]

Thanks everyone for helping out! This is my first car so I am a noob on many specifics but will look into it to answer all questions so that we can maybe target it to a more specific problem.
I just checked the radiator coolant level and it was too empty. I topped it up with 5l of coolant. Not sure if it was an airbubble or I lost 5l of coolant out of the radiator. The overflow is a bit fuller so it might as well be that a big part of the coolant went into there. I follow the coolant procedure as noted in the manual.

With the fan, I ment the fan on the inside of the radiator. I will do the test tomorrow Alitis007

I bought the car in oktober 2013 and didnt check the valves, I will have a look at the logbook.