Over Heating Engine

john432

Car is 2003 Nissan Almera 1.5 petrol.
Gauge went above normal, getting close to red mark, while driving a steady 70mhp, been on road for 1 hour.
Stopped before gauge actually got into red area.
The reservoir expansion tank for the radiator was over expanding the coolant through the overflow.
When left to cool, level dropped down in expansion tank.
Afer 4 hours ( thats how long it took the RAC to come out ), the level in the expansion tank is now on the min mark.

So, thoughts please....

PS. Engine runs normal, as driven onto and off flatbed.
Also, their is no evidence of coolant leaking, only when it got warm, through the overflow.

Thankyou.

forgotmyname

Failed thermostat, But with the expansion tank hot, Possibly not.

Failed waterpump, Does it have plastic blades or driven off soemthing like the steering pump?

Headgasket?

john432

Thanks for your reply.
Don't really know about the water pump, other than the engine sounds absolutely normal, no extra noise like bearings going.

Oil level is normal, no evidence of water in it.
The coolant is the blue stuff, although it is not so blue now. But it has been like that for months, hoping their isn't any oil in it. Will check this properly in the morning and post back.
Thanks.

missing_link_2

john432 wrote: »

The coolant is the blue stuff, although it is not so blue now.

Usually,exhaust fumes in the expansion tank is a tell tale sign of HG failure.
Most cars have electric fans. Possibly the fan switch is dead,relay needs replacing,or fuse has blown.

reeac

missing_link wrote: »

Usually,exhaust fumes in the expansion tank is a tell tale sign of HG failure.
Most cars have electric fans. Possibly the fan switch is dead,relay needs replacing,or fuse has blown.

Unlikely to be a fan problem as the overheating occured whilst driving at 70 mph..

cb1979

Maybe the Radiator need flushing as they tend to block in time if not flushed out at regular intervals

BertTheRaccoon

I would recommend taking it somewhere you trust and seeing if they can do a "sniffer" test on the coolant. This will detect if there are exhaust gases in the coolant, which would be an immediate sign of head gasket failure.

Otherwise it has the possible hallmarks of either water pump or thermostat failing to open, but I would advocate it would be boiling itself up much sooner if the thermostat was stuck shut.

Strider590

It's probably the thermostat, the expansion tank should still be in circuit whether the thermostat is open or closed.

The thermostat allows water into the radiator once the engine has reached operating temperature (allows for faster warm up times).

You can check by seeing if the radiator gets hot or not.

john432

Thanks all.

Coolant is dark colour, not sure if it is cantaminated with oil.
Engines fans are working, but agree with above post not relevent as had been doing 70 for a while.
Yes will be taken it to a garage that I can trust.

My problem tomorrow morning will be getting it to my choice of garage which is 12 miles away. The RAC will want to charge me £85 because it will be another callout with the same problem.

Anyway, will post back when I know what the actual problem is.
Thanks.

anotherbaldrick

Thermosatats usually fail in the open position. With the engine cool remove the cap from the reservoir, start the engine and after a minuite increase the revs. If the contents of the reservoir froth up it is a blown head gasket

forgotmyname

Not all thermostats fail in the open position.

Depending on the system the main bulk of the cooling maybe fairly cool when the engine starts to overheat.
Water trapped in the engine block.

At least you spotted it and took action,

Usually the posts are my engine has cooked itself to death. Its been getting hot for some time and had no water in it. Whats wrong.. Well it may have been a thermostat but bow you probably need a new engine.


In your case the repair should be a lot cheaper.