Skyline running to cold?

[unlimitedpower]

Right datsun guys help me out.
I have a mate with a 435wkw rb30 skyline. Thing is nuts. Now heres the problem
He brought the car and was told it had no thermostat in it. As had a big raditator fitted i think (i don't know full story behind that)
its had a problem of running real cold to the point where it fouled up the plugs and ran so bad was having massive flames and then wouldn't even start.
I cleaned up the mega expensive plugs and she was running pretty mint again. Starting better than ever etc.
So first thing i do is say right we fitting a thermostat and some new coolant.

So that was yesterdays mission. All done.
It had a thermostat in there already !!!!!!
So replaced it anyway and it warms up nice and smoothly now way faster than it did before.
So i was thinking excellent thermostat must just have been buggered (the other day i started it from cold with the cap off and the water was circulating round the radiator this gave me the impression of no thermostat).
With new thermostat we didn't get the water circulation etc when cold with the cap off (like it should).

But he txt me last night and says, That when diving the temp falls right back down off the gauge again.

Any ideas?
My understanding is it doesn't matter how big your radiator is etc its the thermostat that controls the water temp of your car.

Im totally lost now. Not even Google is shedding any light on this one.

Who has problems trying to keep an engine warm? Especially one cracking out 435 at the wheels.

Brett

[disruptiv]

does the car run a link?

[DJZ]

What fan(s) is it running? As above, what computer is it running? If it's a Link is he looking at the dash gauge or the temperature the Link thinks it's running at?

Correct thermostat? Correct seal?

[niccy]

Has it even had a tune?

What plugs are in it? Iriduims? Scrap them and get NGK, RBs love them.

Maybe his radiator is way too big, that's a huge problem with a lot of cars. Maybe get him to drive it without a fan for one drive and see what happens? Maybe something as simple as that.

Is he checking the water etc after its been running for a bit? Could just be a faulty sender lol

[unlimitedpower]

Car is running iriway 8s NGK plugs. Is fully tuned on a Stinger ECU runs real smooth now i have cleaned up the plugs massive power to burn. Tune seems spot on dyno graph is tidy so tune looks good. Guy who tuned it has just closed his workshop and gone into the concrete trade with his dad rumor has it. So he hard to get a hold of.

If you sit and idle then the temp comes up nice on the gauge, Fan is an electric one and ive never heard it come on yet. Round town its on the gauge which it wasn't before really with old thermostat but open road drops right off.

Car actually apparently runs real nice now,
Im thinking of trying to talk him into swapping out the tridon thermostat to a Gen Nissan one. But money is a little tight right now as he took it for a wof today and they notice it wasn't certed for the RB30. Everything else is certed but was done before the engine swap.

In my opinion radiator size can never be to big. As if the water is to cool flowing past it then the thermostat should close and allow temp to build to the point where will open again and also that should be around 2/3-1/2 reading on the gauge.
My opinion could be wrong though so please correct me if so.

It is better with the new thermostat but im wounding if its maybe a little on the piss.

Running electric fans haven't heard them come on yet.
Car warms up when idling no probs so i assume gauge and sender are fine.
Its just when driving open road that it cools right down. Doesn't blow flames and back fire now like it did before i cleaned up the plugs. Runs way better than before. But with it running real cold i guess its just a matter of time before it fouls them up again.

Im thinking of trying a 150mm strip of cardboard across the bottom of the radiator this should maybe stop the water getting real cold just before it flows through the thermostat and enters the engine.
I'll keep a very close eye on gauge and also get a thermo gun from work to double check the temps as best i can,

[niccy]

In my opinion radiator size can never be to big. As if the water is to cool flowing past it then the thermostat should close and allow temp to build to the point where will open again and also that should be around 2/3-1/2 reading on the gauge.
My opinion could be wrong though so please correct me if so.,

Fair enough I just know in my last skyline, it has a fairly big alloy radiator and it barely ever got over 1/3 warm...
eh lol

[Bartman]

I'd try fitting another temp gauge.
One which has an actual scale in Degrees C.

[brocky41]

Id try a factory radiator - if the radiator is too big it'll be cold all the time unless its sitting there idling (which by the sounds of it is what its doing?) and the thermostat will be closed constantly - my CA'd 120y was doing that for a while but later found the thermostat was a 89 degree instead of an 82 degree. Does the heater work properly - nice and hot all the time or does it die off with the position of the gauge?

Id also try a new water temp sender for the ecu (not the gauge one) as that may eliminate your fouling up on the plugs ( remember when plugs foul they are not 100% from then on but i know the iridium's and platinum's are expensive and that's what the manufacturer recommends) I have heard that you can run the same heat range standard plugs thou as the plat/iridium ones are designed for fuel economy and longevity - 100,000kms etc). makes it cheaper to replace until u get it right.

just my 2c but may give you some ideas.

[torqued]

I'd just run more boost and drive it harder.

What's the point having all that power with a functioning coolant system and not abuse it.

NKG plugs are cheap who cares

[dan1200sss]

that is the PERFECT solution