engine running cold
- Thread starter basa99
- Start date
Currently reading:
engine running cold
Thermostat stuck open?
John Mc
New member
Another vote for thermostat.
My Marea was fine during the summer last year. Soon as it got cold it barely moved on a 100 mile run.
My Marea was fine during the summer last year. Soon as it got cold it barely moved on a 100 mile run.
Mozella
New member
Me too; thermostat. It's possible to test these things in hot water, but usually the part is so inexpensive that in my opinion it's worth changing it after you go through the effort of removing the old one.
Running your engine too hot is bad for obvious reasons, but running too cold is NOT a good idea either. The more modern the engine design, the worse the practice is. I'd say you should solve the problem as soon as you can get around to it.
Running your engine too hot is bad for obvious reasons, but running too cold is NOT a good idea either. The more modern the engine design, the worse the practice is. I'd say you should solve the problem as soon as you can get around to it.
MrMigs08
New member
- Joined
- Apr 3, 2011
- Messages
- 252
- Points
- 46
Definately a stuck open thermostat, if its too much hassle for you atm, you can try block airflow to the forward rad (Not advised, but it works in this cold weather for me) until you can sort it.
My Marea is running fine with it stuck open, a bit more fuel hungry though so it should be adressed!
My Marea is running fine with it stuck open, a bit more fuel hungry though so it should be adressed!
You don't have to take the thermostat out to test it.
Do the following:
1) ensure car heater matrix fan is OFF and preferably turn the cabin temperature to maximum (you can leave its temperature setting alone or set to cold but max is better as this will reduce the water circulation resistance in the system ) (also not that not all stystems have a heat control water valve and rely just on 'flap' positions to chanel air over the matix or not)
2) open bonnet and locate top and bottom radiator hoses. One of these will go directly to the thermostat
3) remove any loose clothing, ties, jewellery etc. as in a minute you will be holding at least one radiator hose with the engine running
4) start engine from cold and allow to idle. What you should notice over time is that as the engine warms up one of the radiator hoses may get luke warm and the other will remain cooler.
5) when the engine starts to get up to working temperature (you will feel the heat off the engine and all the other little water hoses and hoses to heater matrix will be hot) then the thermostat which up until now should be closed will start to quickly open. When this happens the radiator hoses will very rapidly warm up.
6) if the radiator hoses go from cold and both slowly warm up togther then this is a very good indicator that the thermostat is stuck open
7) Points/steps 5) and 6) are a relative and not exact measurement as there will always be a small water bypass on the thermostat. This is why in step 1) it is better to set the heater matrix temperature and thus hot water flow to maximum.
Do the following:
1) ensure car heater matrix fan is OFF and preferably turn the cabin temperature to maximum (you can leave its temperature setting alone or set to cold but max is better as this will reduce the water circulation resistance in the system ) (also not that not all stystems have a heat control water valve and rely just on 'flap' positions to chanel air over the matix or not)
2) open bonnet and locate top and bottom radiator hoses. One of these will go directly to the thermostat
3) remove any loose clothing, ties, jewellery etc. as in a minute you will be holding at least one radiator hose with the engine running
4) start engine from cold and allow to idle. What you should notice over time is that as the engine warms up one of the radiator hoses may get luke warm and the other will remain cooler.
5) when the engine starts to get up to working temperature (you will feel the heat off the engine and all the other little water hoses and hoses to heater matrix will be hot) then the thermostat which up until now should be closed will start to quickly open. When this happens the radiator hoses will very rapidly warm up.
6) if the radiator hoses go from cold and both slowly warm up togther then this is a very good indicator that the thermostat is stuck open
7) Points/steps 5) and 6) are a relative and not exact measurement as there will always be a small water bypass on the thermostat. This is why in step 1) it is better to set the heater matrix temperature and thus hot water flow to maximum.
