z31 temperature issue


New Forum User
i just bought an '88 z31 turbo today. on the way home it was fine from glasgow to dundee on the m'way then going through dundee the temp guage went up to the three quarter warning mark and it started blowing cold air through the vents. then back o the dualler it went back to normal but the oil temp. guage went up a notch.
then i got to the country road that takes me home and the water temp. went back up and the cold air started again. and it was doing this on and off when i took it for a run around town.
its got a pretty bad misfire that should be fixed with ht leads but has anyone got any idea what the crack is with the temperature lol?
and please dont say something expensive lol


The first simple check on the Z31 is to see if the two cooling system caps have been mixed up. The engine should have a plain (not sprung) cap and the expansion bottle should have a radiator style pressure cap.
Mixing them up can cause overheating symptoms.

Also check for water loss - leaks from hoses or the radiator which is quite tucked away.

Is the electric fan coming on when up to temperature? Possible switch failure if not.

Get the system checked for combustion gases in the water - colour change to yellow on the test fluid may indicate a blown head gasket...:unsure:


Well-Known Forum User
Well I'm no mechanic, and know nothing about Z31 turbos. But twice in my life I have had cars (not Datsuns) that have shown high temperature on the guage, couplde with the heater fans blowing cold, and on both occasions it was the cylinder head gasket that needed replacing . . . which was not cheap. Hope it is something easier to fix!

Rob Gaskin

Staff member
Site Administrator
Hi Dan, sounds like it might be low on water to me.

My reasoning being that the temp gauge sensor and heater can't work properly without water. A hot engine i.e. the metalwork will heat the lubricating oil giving the high reading.

If it is low on water, why is it low.

Can you have airlocks in these cars and is there any special filling procedure. Fell foul of this on a Pug 306 Diesel where the heater is much higher than the engine.