[Mk2] [Turbo] Car runs too cold

[drift88]

Hi all
Hope someone can help, problem is temp gauge. On a good long run gauge only manages to creep up to just under quarter. I have boost problems sometimes, I say sometimes as the car can boost ok then after two or three hard boost runs their is a hesitation and a boom noise and no boost, after that happens the boost is ok once or twice then it happens again.
I have checked all the hoses as i have a manual boost controller, no problems their, also I have adjusted the boost controller so the boost is only 0.7 bar this does not make a difference.

Back to the temp gauge problem, the intercooler fan seems to come on to early when in traffic but the gauge is barely above the c mark.

I have had the thermostat changed, no difference, the sensors (or senders if that's what they are called) have also been replaced, no difference.

When I do hit max boost the gauge plummets below the c mark surly this is doing damage to the engine!!!

Please can someone help as I am out of ideas

[Quigonjay]

your boost problem sounds like you are just hitting fuel cut
what sensors exactly have been changed? the gauge gets it reading from the water temp sender

[DeusMR2]

The intercooler fan is unrelated as it's switched on by an air temperature sensor on the engine lid.

Do you get hot air from the cabin vents?

[drift88]

Engine Coolant Temperature Sender and the Water Temperature Sender were changed along with the thermostat.

I thought that the fuel cut defender was their for over boost safety measure, and I am no were near over boosting.

It seems to happen when I am feathering the pedal and the boost gauge is near 0.5 and the stutter happens, but if I give it loads it boosts ok.

The main concern I have is why my engine does not run up to the usual mark on the temp gauge which should be just below half way. The needle doesn't even manage quarter of the way up.

To answer DeusMR2 nope don't have any problem with hot air in cabin but sometimes their is a smell of coolant that comes and goes doesn't matter if it's first thing or a good run, it is an irregularly problem like the boost.

I will just point out that the car runs at this same temperature come hot or freezing weather the needle always points just above the C mark.

Faulty Gauge?

[DeusMR2]

Could be a faulty gauge but best to rule out engine problems first.

I presume you are not losing any coolant (including whats in the expansion tank).

To check that the coolant is getting to the right temperature (therefore ruling out engine/cooling problems), use the Coolant Temperature Sender with a multimeter to check that the coolant is being heated up.



Check the resistance when cold - it should be between 1.5 and 3 Ohms according the graph.

Check the resistance when hot - water temp should get to around 80-90 degrees after a while (~0.2 Ohms according to graph) - if it does then your cooling system is OK and your temp gauge is most likely at fault.

You could of course just use a thermometer but I'd advise against it!

[drift88]

thanks DeusMR2, very informative image. I will update soon thanks again