New Zealand Datsun Club

NGK Iriway 8s arnt cheap not even close to ever being classed as cheap.
Id like to throw a hotter set of plugs in a 7 would be a good start but i never tuned it im not a tuner and have no idea how that would affect things with the tune etc, Would hate to melt a $20,000 engine.

Im still lost someone please explain to me how its possible to have a radiator thats to big which makes the car run cold. Was talking to tony whiter about this and he shares exact same view as i do on that theory.

If temp in the cylinder head is cold where gauge and senders are located then thermostat is shut this makes head warm up and up goes gauge. It doesn't matter if i have 500L of cold water on the other side of the thermostat with it closed its not circulating so the other side gets warm. Cool water from bottom of radiator hits thermostat before it enters head so that would actually keep it closed longer than it should be (id say this was covered in design stages and allowed for).

Im not trying to be a cock and ignore you guys who say rad is two big i just can't see how logically that could be possible..

On a different note it doesn't actually matter anymore as guy lost his license today. Complete dick head managed to get it back for 2 days!

Im only interested in solving this issue due to i don't like stuff getting the better of me ive been trying to get him to sell it before he takes himself of someone else out with that car,

I did talk to him today and he said temp only drops down now on open road. Round town its not to bad.
Bearing in mind this guy lucky to know the fuel gauge from the temp gauge.

Throw away those long life plugs. Just get standard

take it for a drive and feel if the water is hot or cold, top and bottom rad pipes?

As far as i can tell they don't make that style of plug in 8.

Im aware of the pros cons and etc of copper vs iridium and platinum etc.
I don't think the plugs are really the problem,
I don't want to change to copper plugs of a lesser heat range as the tuner specified them for a reason. (not cos he wanted to make money as he didn't supply them) Tuner is very well known up here and has built and tuned some very hi spec cars he does know what he is doing. If i was to change plugs and it resulted in a poorer quality burn then that would be a step in a backwards direction.

I more leaning towards a possible plumbing issue that is resulting in some water by passing the thermostat or a slightly faulty thermostat. Tridon don't have the best name for being 100%
Got ages to ponder it now as car will be parked up in a shed not doing anything.

ok this is an interesting thread, I started my working life as a radiator repairer, (atomotive coolant engineer) you are correct in your assumption that the thermostat controls the temp of the engine coolant, you could in theory run 500 litres of cold water on the radiator side of the thermostat and, should still see consistant coolant temp on the guage.
there have been some very good suggestions made, especially, is the heater pumping hot air?
I would surmise that there is either a faulty, new thermostat opening early, or its got the wrong thermal range on it, and not suited for the car, some imports also ran 2 thermostats, cant remember which make and models and have been out of the game for many years now, but the second thermostat was tucked in the bottom radiator hose ,where its meets the block, check to for a electric solinoid on the inlet manifold, that may allow water to circulate through for cold start etc, and may be stuck open etc.
I would also advise purchase of genuine nissan thermostat.
perhaps the sender that tells the ecu the temp is faulty, as previously mentioned, or there may be an earthing issue somewhere causing temp to read incorrect.
best to also check temp guage reading compared to actual water temp when engine idiling and stationary, with cap off insert mecanical thermometer into coolant and check against guage on dash.
if i think of anything else ill post again.

Put a genuine nissan/nismo thermostat in it, Dont trust a factory gauge on the dash, the distance between the first bar and hot on a temp gauge is f all and not even worth worrying about. My Z runs near 95-100deg thru ecu sometimes thrashing around hills and the temp gauge reads half still. Has it got an external oil cooler(prob has with that power)? If so is it temperature operated or working all the time?

Thanks for your feedback.
I know what your saying about the factory gauge etc. Id like to fit an aftermarket one if i can somehow. (man not even my car i just hate being out smarted by a machine). What does get me about the factory gauge is that it does read right up to the normal level when you let car idle etc. So its range of movement does actually seem correct.
I have access to a thermo gun so when i can get out to the car again i'll try take some readings of the housing when gauge is reading normal at idle and after its been taken on a short open road drive,

Heater i need to double check on for sure as stupid as this sounds (i'll prob get flamed for this) when we changed to new tridon thermostat i forgot to put heater on when we refilled with coolant.
I got him to do it the next day when he drove car into work, Didn't actually ask if it was hot or not.