since the last time i asked for help on here with an autobox problem and thanks for all the help but it cost me just over a grand to get sorted with no help from the robbing bastards at optimum autos.ive now got a new problem OVERHEATING if i drive about 15 miles pull up for a couple of mins i can hear water bubbling out of the rad cap into the expansion tank the engine is turned off at this point fire her up again all strange noises stop and she drives fine for 5 miles then the temp gague goes up not wanting to stop till it hits the top pull up let her cool down for 30 mins put some water back in and away she goes no problem at all now ive done about 1500 miles with this problem happening and id of thought if it was a head gasket problem then they would of blown by now and ive had a co meter in the top of the rad for over half an hour and no traces of co in the system could there be a blokage in the heater matrix and ideas please if anyone is sure they know what the problem is please ring me 07989411656 rick

Rick- some ideas - sorry if any is stating the obvious.

 

Have you checked that the radiator cap is sealing properly and that it is the correct one? If it does not pressurise the system properly it will boil up in this hot weather and eject water anyway or eject then boil up. Squeeze the top rad hose when its good and hot. It should be firm and burny hot hot!

 

If its soft then your cooling system is not pressurising or leaking somewhere. If its firm then the problem is elsewhere. Maybe a furred up radiator core.

 

You should also have a feel at the radiator core when warmed up - engine-off of course. Feel for it being warmed up all over its area. Means reaching inside the shroud. If its well cold then it points to it being furred up. The top hose is the engine outlet and the bottom is the cooled water from the rad back to the engine. You might feel the temp difference. The bottom one should be cooler.

 

Also try starting from cold- leave ticking over and keep feeling the top hose. It should suddenly warm up just as the thermostat opens. Should only take 10 minutes or so in this weather even at tickover. If the engine gets hot but the hose stays cool it could mean a stuck shut thermostat. If it warms up straight away gradually then the stat is stuck open. Unsual to be a bad stat though.

 

Also is your leccy fan coming on as well? If you've aircon on then the leccy fan will come on too when good and warm in addition to the engine driven one.

best of luck

Willie

Mine was very similar to yours before i replaced the water pump, turned out that it was just the seal on the pump and not the pump itself, but while i was in there i replaced it too, i also did the two little water pipes that you cant see untill yo take it all apart, the thermostat, top hose etc.

 

The problem with alot of these leaks is they dont do it at idle they only do it under propper load/high revs so they can be difficult to find, at idle they tend to suck air in then not dump fluid till after shut off.

 

Could even be someting as simple as an air lock in the system, when you fill it (with the engine OFF) undo the bleed screw on the left hand side of the rad and top it up slowly, when it gets full, leave it for a min or so then try to get more in, keep doing this till no more will go in without it comming out the bleed hole, then do it up put the rad cap back on run it up to temp, let it cool back down and repeat.

 

If you need any help locating the bits in there feel free to give me a bell on 07966 891954.

:D:D

thanks for the help and im quite sure ive located the problem now being a mechanic doesnt help because u allways look to deep and never gave it a thought that the numbskulls at nissan have given me the wrong or just faulty rad cap pressure checked it last night and its blowing off at 2psi not 15psi no wonder its throwing a lot of water out thanks anyway rick