Nissan Note Owners Forum banner
1 - 13 of 13 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Hi all,

Got a recurring fault with my 2016 1.5dCi Acenta - the heater blowers run fine, but there is no heat at all unless I'm running the engine quite high, and even then it is really weedy and just a bit warm. Air-con works fine.

It happened once before when under warranty and the dealer replaced a thermostat, now six months later the warranty is over and the problem has returned.

Any ideas what the problem can be? It took 2 diagnostics, fluid changes, new cap and thermostat to fix it last time, and now it's buggered again!

Thank you all in advance.
 

·
Registered
Joined
·
1,139 Posts
Go for the thermostat again.
A cheap easy fix and one you can do yourself.
I would also drain the entire coolant from the car and refill with new antifreeze / water mix as it degrades after a year or so.
 

·
Banned
Joined
·
58 Posts
Thermostat is fine mate. High revs is the elephant in the room for me here. This indicates you have air locks in the coolant, though the elephant is that your water pump is the cause, indicated by high RPM operation only providing you with heat. A faulty thermostat doesn't just work out of nowhere, you know?

Replace your water pump immediately and timing belt whilst there (you'll cry if you don't!). The impeller blades may be worn so much that they only pump coolant at higher RPM's. Alternatively, this can happen in an airlock situation inside your heater matrix deep down in your dashboard. It may also be blocked.

Drain coolant, replace with a different coloured fluid completely. Once the thermostat opens, the new coolant will flow through the heater matrix and back into engine. Let it cool down and remove the hose from matrix back to engine, do you see the new coloured coolant? If yes : water pump. If no : blocked heater matrix.

Hope this helps Dan
 

·
Banned
Joined
·
58 Posts
I forgot to add that the air coming into the system may be from a poor coolant replacement before, or from the water pump itself. With the engine running, and filly heated up, check for any residual / slow leaks coming fro your water pump. It is covered by a plastic case which you will not be able to remove, though any water leaks will be noticed from the bottom of the casing. If you see no water, you should see coolant stains. You will find its location here "WP"

Nose Eye Eyebrow Human body Ear
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #5 ·
Thank you both for your replies, much appreciated.

I've been looking through car paperwork and have a few details to add -

1 - When the problem first came up Nissan replaced the fluids and heater core, which didn't fix it. Then the second mechanic replaced the thermostat.

2 - A couple of months back for its MOT the coolant was identified as low. They topped it up, but it is low again.

So, I think the problem may be a coolant leak somewhere? Is this something better dealt with by a Nissan dealer or would an independent mechanic be better?

thanks again
 

·
Banned
Joined
·
58 Posts
Thank you both for your replies, much appreciated.

I've been looking through car paperwork and have a few details to add -

1 - When the problem first came up Nissan replaced the fluids and heater core, which didn't fix it. Then the second mechanic replaced the thermostat.

2 - A couple of months back for its MOT the coolant was identified as low. They topped it up, but it is low again.

So, I think the problem may be a coolant leak somewhere? Is this something better dealt with by a Nissan dealer or would an independent mechanic be better?

thanks again
Avoid the stealer-sharks aka Mr Arnold Clark etc at all costs. Take your car to a local Renault specialist, as this engines Renault, this will be their bread and butter.

All they are doing is getting the engine up on a hoist, checking for leaks between cylinder head and engine block, checking for leaks between coolant hose pipe unions. This will be easy peasy as coolant leaks leave stains.

The reasoning for the water pump was due to the RPM only correcting the issue. If you recall old top gear when Hammond drove across water at speed in a big offroader jeep racecar thing? It was the dig of the wheels at high rpm which made it stay afloat. This is exactly the same force at play inside a water pump with worn impeller blades. high RPM to feel the heat aka the coolant flow, and as you bring RPM back down, its back go square one.

You can verify operational thermostat by checking with your hands, feeling the hoses on both ends of thermostat. If one coolant pipe is noticeably warmer than the other side's pipe then that's an issue, though I don't believe the thermostat is the fault here.

Let me know how things work out for you Dan, I'd be keen to know as that's certainly an interesting issue you have there
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #8 ·
Avoid the stealer-sharks aka Mr Arnold Clark etc at all costs. Take your car to a local Renault specialist, as this engines Renault, this will be their bread and butter.

All they are doing is getting the engine up on a hoist, checking for leaks between cylinder head and engine block, checking for leaks between coolant hose pipe unions. This will be easy peasy as coolant leaks leave stains.

The reasoning for the water pump was due to the RPM only correcting the issue. If you recall old top gear when Hammond drove across water at speed in a big offroader jeep racecar thing? It was the dig of the wheels at high rpm which made it stay afloat. This is exactly the same force at play inside a water pump with worn impeller blades. high RPM to feel the heat aka the coolant flow, and as you bring RPM back down, its back go square one.

You can verify operational thermostat by checking with your hands, feeling the hoses on both ends of thermostat. If one coolant pipe is noticeably warmer than the other side's pipe then that's an issue, though I don't believe the thermostat is the fault here.

Let me know how things work out for you Dan, I'd be keen to know as that's certainly an interesting issue you have there
Finally got around to trying to sort this - have taken it to a local garage who have gotten back tome to say that they believe it is an issue with the Thermo-plunger, but they'll need to take the bumper off to have a look. I've told them to go ahead. Does this sound plausible to you? A quick Google and it looks like it makes sense to me. A bit. I guess?
 

·
Registered
Joined
·
995 Posts
Thermo plunger !!
Sounds like a new fangled tool that a plumber uses lol.
Never heard of it myself, so cannot comment to the op post above.
I thought it was a Northern name for a thermostat a bit like 'windythropter' for helicopter but i just googled it, and there is such a thermo plunger heater used on the coolant system of some diesel vehicles
 

·
Registered
Joined
·
1,937 Posts
I had to google thermo plunger too!

Maybe the garage think that it is blocked up, it is just an inline electric heater that helps the defroster blow warn air quicker, it should be off when the engine has warmed up.

My old (Nissan engine) diesel Terrano used to blow cold air all the time in Winter, the thermostat used to stick open.
It was a special Nissan design feature, because undoing the housing to remove it made it close (so it was always closed when I took it out, and worked perfectly in a saucepan of water on the stove), and new ones went the same way after a month or so. The housing must have distorted the thermostat somehow when it was tightened up, but I could never see anything wrong.
 
  • Like
Reactions: Jymmer
1 - 13 of 13 Posts
Top