Citroen AX GT running too hot on WOT

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
jsp
Posts: 303
Joined: 04 Dec 2014, 03:05
x 7

Citroen AX GT running too hot on WOT

Unread post by jsp »

My Citroen ax has a uprated engine, new timing kit and waterpump, new rad hoses and rad.

I have installed a 82C thermostat.

During normal drive the temprature is normal 82-85c.

When I drive WOT its going around 100C

Which thermostat should I use?

I got three options:

73C
75C
78C

Which should keep the engine around 85C when WOT?

User avatar
xantia_v6
Forum Admin Team
Posts: 7314
Joined: 09 Nov 2005, 23:03
x 394

Re: Citroen AX GT running too hot on WOT

Unread post by xantia_v6 »

It doesn't matter which thermostat you use. When it is fully open, it can't open any further.

Your cooling system performance is limited either by coolant flow rate (water pump), airflow (radiator and fan), or the size of the radiator.

It could also be that your engine is producing too much heat because it is badly tuned (especially ignition timing).

User avatar
white exec
Moderating Team
Posts: 6003
Joined: 21 Dec 2015, 13:46
x 990

Re: Citroen AX GT running too hot on WOT

Unread post by white exec »

What are you running in the way of radiator size and cooling fans (one fan or two)?
Are both fan speeds operating - low speed and high speed?

User avatar
jsp
Posts: 303
Joined: 04 Dec 2014, 03:05
x 7

Re: Citroen AX GT running too hot on WOT

Unread post by jsp »

standard radiator size, cooling fan the smallest one. Will upgrade this when the AC goes in.

User avatar
jsp
Posts: 303
Joined: 04 Dec 2014, 03:05
x 7

Re: Citroen AX GT running too hot on WOT

Unread post by jsp »

xantia_v6 wrote:
05 Jun 2020, 20:18
It doesn't matter which thermostat you use. When it is fully open, it can't open any further.

Your cooling system performance is limited either by coolant flow rate (water pump), airflow (radiator and fan), or the size of the radiator.

It could also be that your engine is producing too much heat because it is badly tuned (especially ignition timing).
Thank you this is all uprated already.

Peter.N.
Donor 2020
Posts: 9904
Joined: 02 Apr 2005, 16:11
x 334

Re: Citroen AX GT running too hot on WOT

Unread post by Peter.N. »

If the engine has been uprated you likely need a bigger radiator.

Peter

User avatar
white exec
Moderating Team
Posts: 6003
Joined: 21 Dec 2015, 13:46
x 990

Re: Citroen AX GT running too hot on WOT

Unread post by white exec »

I recently came across this data in relation to Berlingo petrol:
The 1.1i (HDZ) engine. without AC, is fitted with 1 x 120W cooling fan, and a rad of 1700cm².
The 1.4i (KFX) engine, with AC, is fitted with 2 x 250W cooling fans, and a rad of 2300cm².

A 50% increase in rad area, and a x4 on electrical fan power.

User avatar
jsp
Posts: 303
Joined: 04 Dec 2014, 03:05
x 7

Re: Citroen AX GT running too hot on WOT

Unread post by jsp »

I have a K2A at the moment. 73C does its job.


User avatar
kitchD6C
Donor 2020
Posts: 39
Joined: 12 Mar 2012, 22:25
x 4

Re: Citroen AX GT running too hot on WOT

Unread post by kitchD6C »

If it's an issue at WOT, it won't be cooling fan or thermostat-related (unless it's not opening!)

If the engine is highly tuned, it's likely to be an inefficient water pump (different designs have different results, as I've found on our Saxo). The size of the radiator also plays a part, though that's easily rectified by fitting a Saxo VTS unit (about 200mm wider).

To be honest, normally WOT results in better cooling, and it's sitting in traffic that causes issues. If it's WOT that causes it, then it has to be air or coolant flow related. You also shouldn't discount the possibility that it's not tuned correctly, as suggested above. A weak mixture will cause much more heat from the cylinders (at least until it melts something and breaks down).

User avatar
jsp
Posts: 303
Joined: 04 Dec 2014, 03:05
x 7

Re: Citroen AX GT running too hot on WOT

Unread post by jsp »

CO is correctly adjusted 0.8-1.2% its on 1.1% . Timing need to check this week as there is a oil leak on the distributor will redo the timing again.

Cooling is sorted now I think only with 30C+ its 90C thats fine. Otherwise 80C in all conditions.