Nissan Patrol 4x4 (Africa)

So I have been experiencing something strange since December which I cannot find the source of.

By the end of last year, I replaced my copper radiator with the standard TD42 radiator and I have been using my Patrol as n daily drive with no problem.
I have noticed that my coolant was very dirty since I originally used a cheap anti-freeze which did NOT protect the inside of the head and block and the water system was in a shocking condition.

I have since flushed the system twice and am now running Nissan’s very expensive and overpriced antifreeze which seems to be cleaning the head and block very nicely.

Now to get to my actual problem, since my first long trip in December when we went to Hoedspruit area I noticed the one day after an outing that my expansion tank was above the maximum level when the engine is cold. I did not make too much of it as my Patrol was parked at a very steep angle with the water system around 90 degrees and thought the water system sucked in air through the pipe in the expansion bottle.
When I got home I transferred the excess coolant into the radiator and all was well.
When we now did the Dunes trip the exact same thing happened again. Transferred the coolant at the campsite and the next day and made sure the pipe between the radiator and expansion tank was in good order and all was well again and it returned to the full mark when cooled down.

When I got home after the very long drive (about 800km) the expansion tank was again about 500ml over the max when cold and I had to again transfer the excess coolant into the radiator. This is very strange as my Patrol is using zero water and never goes beyond 95 degrees. I have not added water to the coolant system ever and when the excess coolant is transferred back to the radiator the water level is perfect.

This seems to only happen on very long trips where you drive for more than 5 hours or so.

I have replaced the radiator cap with a new original 0.88kpa cap (no joy)
I have put two new clamps on the pipe between the radiator and expansion tank (no joy)
I have now bought a new 1.2 kpa cap from Nissan to test it and see if there is a change.

It seems like the water system is drawing air from somewhere like when there is a hole in the pipe between the expansion tank and the radiator, but I don’t see any leaks and tested it but could not find any fault.

This also never happens around town or traveling to JHB and back…… only very long trips.
I don't suspect a leaky head gasket as I am not loosing any water and the engine is not running hot at all, you really have to abuse it on a hot day to get to 95 degrees and even on the dunes trip where it was SUPER HOT and driving like a maniac it reached 94 degrees only.

So I am baffled

Hi Michael

Interesting problem.
Just a question, but have you checked the pipe to the expansion bottle and the breather ?
A slight kink or blockage might prevent the system from sucking the coolant back to the radiator.
That said, it's puzzling that it only happens on long trips.

Dustin, yes it is very irritating as I don't like these "mystery cases".

I have inspected that pipe, but could not find anything wrong with it. I have also done some reading on the internet and some have found that pipe to be "softened" with age and it cannot maintain its round shape and goes flat when it needs to suck the water back. I could not find anything like this but will investigate it over the weekend.

I think I am going to pressurize the system from the small nipple on the radiator that goes toe the expansion tank and see if the pressure drops over time. I can also do the same from the end of the pipe that connects to the expansion bottle cap.
This way I can test both the pipe and the radiator cap.

If you have some extra pipe laying around, maybe replace the pipe and test it to see if the old pipe is at fault.
If the system is air tight, which I'm sure it is with new radiator cap, then it has to be a pipe or connection in the line.
It one of the ends possibly cracked where it pushes over a nipple ?

Mysteries make a person mad !
It becomes a case of elimination. Start at one end and work your way through until the offender is found.

This used to happen to my zd30. It got progressively worse over time. Eventually my madman started screaming low coolant when at idle. Found a cracked head. Replaced and all was well. 20000kms of bliss. Saturday it started again on my way down to the eastern cape. I'm 99% sure I have either another cracked head or blown gasket.

Exactly as you describe, only long harder trip, normally pushing speed or pulling trailer, no overheating, stable for me under 90degC, when cool push water back into pressure tank with no loss.

Thanks Dale, I have thought about a cracked head or leaky gasket a couple of times, but it makes no sense.....
On a TD42 you loose water with a cracked head and it over heats very easaly. I have replaced a couple and all had the same symptoms.

Will do more tests and see what I find. Im not going to take a head gasket or cracked head off the table, but I have had a Madman installed since day 1 when I rebuilt the engine and the highest ever water temp I had was 105 deg which is not dangerous at all.

Well, I'm stumped. With mine I popped into silverton for a head gasket test and it came out a resounding negative. So gasket is not blown? However it failed the pressure test, at radiator cap mount...! Opinion at this stage is my cap is fine but it doesn't seal to the bottle?

Maybe check yours?

Thanks for the feedback dale, I will have a look at mine because I have been wondering about the top part of the cap.
Makes sense, because if it leaks there it will draw in air on the upper seal.

I did check the pipe between the radiator and expansion tank, but it has no leaks up to 1 bar.
I also installed water cooling pipes to my turbo just before the first long trip after the new radiator so will have a look at thise as well.

My expansion bottle filler neck is oval, this is the suspected cause of my trouble at this stage. I am still unconvinced.

Good luck with your hunting.

M orning Michael....its not nice to battle with an engine overheating or using water....to many unknowns
Michael firstly if your radiator level drops just a little but then stays constant ..its right. The water expands and the excess water is then pushed into the expansion bottle..when cold has a low and full level.
You should maybe (if you haven't yet).fill the radiator when cold and the expansion bottle to the full level,,then drive it for a day or two, if you are not losing water...don't fiddle
If you have to add water then start looking