Excessive (maybe) white vapour from old micra K11

My ancient (but still useful) Micra K11 is blowing what seems excessive white smoke. Is worse in this cold weather and when engine is cold. It does seem a lot though. The amount does get much less when engine is warmed up to normal.

Temp gauge indicates normal and engine starts and runs perfectly (60k miles even though is a very old car).

The only thing I know to be broken is the coolant header tank has a huge hole in the top of it! There is still some coolant sitting in the bottom of that tank though. Could this be the reason for the white vapour? (Does that tank need to be pressurized?). I can get one on ebay if would fix the problem.

Am on the point of scapping the car if this is head gasket etc - so much appreciate your expert advice on this many thx

Reply to
dave
Loading thread data ...

If it is steam rather than white smoke this will be much more apparent in cold dry weather, such as we had last week in the south-east of England. Once warm - after at least a 10-mile drive - it should disappear

60k isn't any great mileage - 160k would not be unreasonable.

The cooling system should be pressurised - otherwise it will boil dry in a few dozen miles. If this has actually happened then all bets are off

- could be warped cylinder head, gasket ...

Once you can pressurise the system you can find out whether the head gasket is leaking - not sure how you would do so otherwise.

Reply to
Graham J

It sounds as though the car is fine, many Japanese cars use an UNPRESSURISED header tank and have a conventional (as in old style) pressure cap on the radiator itself. The header tank just has a loose fitting cap, often similar to a washer bottle cap. The lack of a cap is not a problem. There should be coolant in the header tank, about half full to allow for overflow to be stored, which gets sucked back in to the rad. when it cools. Due to evaporation the level in the header tank will reduce over time and should be checked on a regular basis.

Reply to
MrCheerful

One of my cars produces an embarrassing amount of steam. It seems to be a function of that model - made worse by the aftermarket stainless steel exhaust. other owners with the same combination have remarked on it too.

The system is pressurised to raise the boiling point of the coolant. Although the dash gauge may show below 100C, local areas within the engine

- like round the cylinder head - might well be a great deal hotter.

I've never known any car with a pressurised system which could be used safely unpressurised.

First replace the header tank.

Reply to
Dave Plowman (News)

Ah - that explains why it hasn't blown up. ;-)

Reply to
Dave Plowman (News)

Mant thanks all. I'll replace that header tank. The temp gauge always sits just below half way when engine up to temp.- as it always has. It has never gone above that even with this shot header tank.

good to have it explained why what I thought was a pressurised system hasn't blown up - and why there is still some coolant in the open-to-atmospeher header.

Reply to
dave

So long as the crack/hole isn't down the the "MAX" mark, Gaffer tape will do.

Reply to
Peter Hill

The rad should be brim full.

For external non pressurised header tanks Nissan use a 2 way pressure cap on the radiator. There is an inner suction valve with very light spring. This allows the engine to suck coolant back from the expansion tank.

Proof that the system is working is when the level in expansion tank rises about 1cm when warm and drops back when cold.

If there is air in the rad header then it air locks and stops working so you can have a dry rad with full expansion tank. This has lead to the demise of many Nissan's. The expansion tank is a liar, always check the rad is full.

In 2003 I bought a 1989 200SX for £150. Had "rattly cams" and a "full" expansion tank. Took 2L of coolant to bring the level of brown mud in the engine up to the rad filler neck, didn't stop the big end knocking from a spun shell. It's called "donor".

Reply to
Peter Hill

How would the air get in? A failed head gasket is the only likely answer.

Reply to
MrCheerful

For an engine that has been OK for 65K miles probably. If it's had a coolant change, was it done by someone that understood the filling procedure?

Many Nissan engines don't have air bleed points on coolant system for filling. You fill the system, run it until warm, when the stat opens the air collects in the rad, let it cool and then top up the rad.

Reply to
Peter Hill

"They all do that, sir."

Very regular problem on that Micra - but not the cause of your promble.

Reply to
Scott M

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.