Heat Guage Probleem

[J@coBez]

Kan iemand my sê hoeveel sensors het 'n 4.8 Patrol wat die water temperatuur monitor?
Gaan die sein na die gauge of na die computer?

My probleem is dat as ek lang pad ry lyk dit of my Patrol warm word en kook as ek stadig ry of stop. Sodra ek versnel kom die naald van kook af tot normaal in n paar sekondes.
Dit frustreer my, want jy weet nooit of daar werklik iets fout is nie en die lugreëling skakel af. Ek het nou al die een sensor geruil, die verkoeler laat deurgaan maar sien niks fout nie.
Tydens my laste 4X4 roete met temprature van 32deg. het die naald nie beweeg van normaal af nie. In die stad word hy ook nie warem nie en is die naald altyd op normaal.

[Peter Connan]

Jaco, I don't really know the answer to your question, but this sounds like the viscous coupling to me.

[Wheels]

The engine coolant temp. sensor feeds back to the ECU. It also uses input from the accelarator pededal position sensor. There are also two outside electric fans for additional cooling when you are running the aircon and when the car is getting too hot.
It seems as if your viscous coupling might not be working.
You should hear the fan when you start the car cold and after a few minutes it should not make any more sounds. When it heats up past normal you should hear the fan again.

[J@coBez]

Four weeks ago the heat gauge started bouncing again coming from Ellisras, going to Elisras no problem.
I just reach my house in Elarduspark as the heat gauge staid on max. Switched the Patrol off and checked the cooling system, the Patrol was not boiling and the water in the fill up bottle was still full.
Tried to start it again after a hour or so but the engine light was on and it missed like hell. the next day after work I filled the radiator that took about 2 lt of water and started the Patrol again, engine light was off and it ran like it was just Dino-tuned. Just to mention that my Patrol was withe Nissan in Centurion for two days the week before I went to Ellisras and according to them I don't need to worry about the heat gauge there is nothing wrong with the car.
I took the car to Dastek so that they can do tests as every body else tells me there is nothing wrong withe the car. Dastek determinant that it was loosing water some were, they pulled the head and it seems like the head gasket is blown, the head was pressure tested and there is no cracks. I drove the Patrol with the problem for about 17 000km and it never overheated. Only problem now is that Nissan SA only have two new head bolts in stock and we need 14, needles to say my Patrol is still with Dastek as thy cannot fully assemble with two head bolts.
See pic below



What is your take on this?

[ricster]

Yeah it does look like there was a little water bypass happening there.

Head bolts.... hmmm tricky one that. They say you can reuse a head bolt once after it has been used once from new, and that is even on a diesel ( 22.5:1 compression ratio), so I would say that you should be ok using the existing headbolts again. Check the length of each bolt as there is a limit to how much they are allowed to stretch. Torque settings are very important!!

This is my opinion only and I'm not telling you that must do this.... but use a Genuine Nissan Head gasket as I believe there is a quality difference.

I know on the diesel 4.2 motor, which is also 6 cylinders, the sleeves must sit either flush with the block or sit 0,07mm proud of the block. I don't know on the petrol motor if it is the same. Maybe you can PM Frans (Tour de Frans) as he is quite the GURU with motors.

While you have the motor sortof stripped... get the radiator flushed and cleaned. Definitely get the viscous checked out, as this may have been the start of the problem. When refitting radiator etc, replace with either Genuine Nissan antifreeze ( best choice) or a very well known brand.... DON"T GO CHEAP ON THIS !!!

Hope this helps a bit