Thermostat temp

[clivvy]

hi guys,

I just need to check something with you guys before I start taking everything apart again. Long story short, re threaded a bolt hole on the thermostat housing last night (job went text book by the way :thumbs ) but I had gotten coolant everywhere in the process. I had cleaned the engine bay, but after putting everything back last night and running the car then and this morning to work, the gauge is hardly reaching past starting point. Before all this mess, the gauge would go about halfway, and the heat from the vents was hot! I do have warm air coming through the vents inside, but not hot like it was before (though I have put in my old thermostat, which is 88degree).

so, do I have an air-lock issue here, or is it likely I have damaged my temp sender or coolant temp sensor perhaps??

Rad is getting hot as it should, everything appears ok but im open to suggestions :bow

 

[macabethiel]

Air lock ?

I would have thought an air lock is most likely cause.
Would have thought it unlikely that you have damaged the sender unit.

Check connection to sender is good, on my old r3mR you would get low reading when spade connection was poor as diesel vibration broke contact.

I ended up replacing the spade terminal it was a special one probably designed for engine vibration as it's sort of sprung by a design in the top of the spade had a job finding one ended up at breakers yard and cut one off with a length of cable from an old car.

 

[rustic]

Hi, if the interior heater isn't getting as hot as normal, then you either have an airlock, or the heat is going somewhere else, ie to the Radiator.

The top of the rad shouldn't be getting warm until the engine is quite hot, if the thermostat cover is comfortable to grab, and the rad is warm, then the thermostat is not working, or water is getting around it or through it.
Has the "o" ring slipped out of place? Crud wedging the stat open?

Did you actually drain the whole system when you removed the thermostat?

Some advice re changing antifreeze, whilst we are on a similar topic...
When I changed the antifreeze, I disconnected the rad bottom hose only, not risking shearing off the engine block drain. This procedure only drops half of the 10 litres, and to flush the old antifreeze out, you need to fill again, run the engine, drain and repeat 4-5 times, then you will have cleared out 95% of the old stuff. When filling with new antifreeze, only use the concentrated version that requires 50% dilution, as 5 litres of water is still in there. So yes, you need to buy 5 litres of concentrated antifreeze.
So with this knowledge in mind, when I tried the heater following the change it still worked and there were no airlocks.

If the engine isn't reaching it's normal running temperature, and the gauge is confirming this, then I doubt if the sensor or gauge is faulty.

I have one of those temperature guns, ie you aim it at an object, and it gives you a digital reading. Handy for checking the heat flow in the radiators at home.

I've not actually tried it on the Mav yet.... It will give a clue as to it's normal running temperature.

Rustic

 

[kitchenman]

I got one of those IR temp guns from Aldi or Lidl, can't remember which, around £15 so useful
I used mine to check the pre heater was working etc.

 

[firebobby]

Clivvy, check a posting that Lazy Ferrets put up a few weeks ago, he had the same issues I think, and it turned out to be an airlock.

 

[Ogri]

Here

http://www.nissan4x4ownersclub.com/forum/showthread.php?t=20605

 

[firebobby]

Here

http://www.nissan4x4ownersclub.com/forum/showthread.php?t=20605

You clever dickey you :clap:clap

 

[Lazy-Ferret]

It seems that a few of us have had fun this year... Like the others have said, air lock... I found that you have to run the engine for a lot longer with the higher temp thermostat in, to get it to open, so that you can bleed the system.

Someone suggested parking the car slightly up hill, which is interesting, as when I first got the car, and did all the work, I had the car forward in the drive, and that makes it uphill, but this time, when I had all the fun and games, it was backwards in the drive... we are only talking a few degrees here, but I now wonder if it made a difference.

The other thing is, as Rusty says, the first time, I did a full flush out, and full re-fill but this last time, I only drained it down to the stat.

 

[Ogri]

You clever dickey you :clap:clap

Haha, just got too much time on my hands lol

 

[clivvy]

thanks for the tips guys. To answer a few questions, I didn't empty the system when changing the thermostat - naughty I know, but the first time I changed it everything was fine but ill do it again this weekend. I checked the spade connector and that was wet and mucky, so ive dried and cleaned it. The rad cap is full to the brim still, but looks like it is flowing - how do I actually bleed the system??