Stalling and low coolant

[Mrs Sunshine]

1997 Nissan Micra Vibe, 1L petrol

My old car runs really smooth until it heats up. It isn’t overheating (never gets past half way on the temp gauge) but after about 5 miles then it starts sounding like a bag a spanners and regularly stalls when I push the clutch or idle, it also dips power now and then at that point.

My coolant in the overflow tank seems to be going down quickly but can’t locate any leak.

If I put my hot fan on constantly (keeping the temp gauge at about a quarter) I can get a longer journey out of it before the problems ‘kick in’.

Any thoughts? Could it be the radiator? A bust thermostat? Also, I go over a few nasty speed bumps to work, maybe the fuel filter is getting clogged up? I was told by a garage it may be the dizzy misfiring (but he didn’t notice my empty coolant) and that is a big cost to replace! Timing belt, sparks, air filter all seem fine.

It is an old car though!

Many thanks for the help

 

[Burnerman]

If the coolant level gets low, some of the sensors are exposed, and not immersed in the coolant and can therefore give incorrect readings to the engines electronic control unit.
Therefore, if the coolant level is correct, all should be well for a while until the level drops again.
A common Micra leak is from the main radiator, on either bottom corner.
A common Micra fault, if the car just wont tick over at all, is a faulty throttle body - and there arent any left in scrapyards......however, first things first! Splendid wee cars, these.
John

 

[Mrs Sunshine]

Hi John

18 years of pretty much hassle-free motoring from my Micra, great little car!

Thanks for your info, it is so very much appreciated! It also got me thinking. I did some research and found some basic checks. One of these is to check it’s triggering the fan. I can’t remember the last time I noticed the fan on so I got it up to temperature and left it idling for about 15 minutes and I can’t seem to get it to trigger. Interesting! The temp gauge is at half but never goes past that (which I would expect it to move a bit, revving it while stationary, then the fan would kick in and the temp reduce slightly?) – sensor could be faulty after the lack of coolant? Giving a bogus reading? Car seems quite warm.

I have kept an eye on the coolant since and it’s not low. Fan fuse looks OK. Not ruling out the fan itself is bust.

I think the sensor may still be a likely culprit though? at least that’s cheap enough to try and replace.

Thanks!
Tez

 

[SpecialK]

Im sure mine had a similar fault, this was a long time ago!

The solder joint in the throttle body goes bad due to heating cooling, You can strip it and redo the joints. Might be this as the throttle body has coolant flowing through it so fails when warm?

I wouldn't worry about the fan if its not overheating...

Maybe leave some cardboard under the car to locate the coolant leak, or look for a white crust in the areas mentioned by burnerman?

 

[Burnerman]

I think your priority Tez is to identify and deal with that coolant leak.....if the car overheats due to lack of coolant then the cylinder head gasket will fail for sure, and that is expensive!
With the engine cold, check for oil traces in the coolant expansion bottle - hopefully that will be clear.
The belt that turns the alternator also spins the coolant pump - check around there for any crusty deposits as leaks arent unknown.
If coolant is leaking there will be a distinct smell around, some think its like curry -but for sure it isnt normal. Micra radiators dont repair, only replace but changing them is easy enough if it is leaking.
If the car is starting well and accellerating without any great hesitation and then returning to idle without cutting out then the throttle body is fine.....similarly I dont think the fan is an issue at this time. If the car was seriously overheating then water would be being forced out of the expansion bottle.
John

 

[SpecialK]

Do the symptoms go away when the coolant is topped up? How long does it take for the coolant to go down from max to min?

 

[Mrs Sunshine]

Hi all

Everyone is being really helpful, thanks so much!

The coolant, I refilled it and it seemed to go down a bit but seems to have stopped now. I can’t see any leaks and is about half full (checking it after each journey!). I may be just being paranoid as I don’t want to ruin my engine. Or maybe the level goes down a bit if it’s circulating? Apologies on my lack of knowledge here!

Car doesn’t appear to be overheating, it runs great (smooth as anything) until it gets up to a certain temperature (needle on half way) then it starts sounding rough and that’s when it starts stalling on stop (engine warning light may pop on momentarily when it stalls). Exhaust seems to rattle more too, bit smoky. Once I get into 3rd/4th gear it seems a bit happier.

I will point out that I travel only 6 miles to work, it just about gets up to temperature, the problems start on the last road into work but that’s usually heavy traffic and it stalls quite a bit then (have to keep a foot a bit on the accelerator to stop it stalling)

I realise my car is pretty underused, I’m often stuck in traffic and it rarely get a good motorway blast, I have had that cause an issue previously!

Many thanks

Tez

 

[Burnerman]

This sounds like the coolant temperature sensor isnt doing its job.....the black smoke at the exhaust would indicate over fuelling, or ‘rich mixture’ - like having the choke on in the old days.
This sensor is in the thermostat area - follow the radiator top hose to the engine and its a single wire component which screws in to the engine block. Its worth checking that the wire terminal is tight before replacing the thing.
At the same time, check that the air filter isnt black with crud!
John