Back to the Pug 406 2Litre Estate
Owners were complaining lack of engine temperature, noticing badly on short runs, compared to how it used to be, even on a longer run, it never got up to the middle of the gauge (90 degree in this case) where it used to sit
So at this point there is only 1 culprit that usually causes a lack of temperature to occur, the thermostat
It sounds like the thermostat has gone lazy and failing to regulate the coolant flow by opening or closing the flow, or it was in the stuck open position
Since the vehicle didn’t overheat, it certainly wasn’t in the stuck closed position
So i left the vehicle running, till the coolant fan kicked in and out, the gauge sitting at the happy point of 90 degree’s and didn’t move till, i started to drive the vehicle on the main roads.
Soon as i was driving along at 30mph, it had already dropped to roughly 80degree’s
Moved onto a dual carriageway, and the temperature dropped to 70degree’s while at 70mph
Classic symptoms of thermostat gone lazy, instead of reducing the flow as the temperature of the coolant drops, it stays at the same place, resulting in excessive cooling. He stated the vehicle hasn’t had a thermostat changed in his ownership
So getting 15 years without issue is not bad going 🙂
Since the cooling system was to be opened up, the owner stated he’s like the vehicles coolant changing as well. Since it hasn’t been changed in a while.
Locating the radiator hose vs the drain cock, as the cock would be much slower at draining AND flushing the system
Popping the spring off – and let the coolant drain out, refit and refill with water, open bleed valves and wait till water gush’s out. Run the engine to allow the coolant to flow. After some mixing, drop the coolant again and repeat.
Swapping the stat is a case of air-box removal, 1 clamp and 2x bolts
The facing needs a clean before refitting
The thermostat didn’t require are gasket sealer or paper seals, as the thermostat has a flush fit seal that seals the thermostat to the block, a gentle nip on the 2 bolts to ensure there secure
Refit and secure the parts all back in
The bottom hose had some large scabby rust, a quick sandpaper removed that, before refitting bottom hose
Refilling using a plastic bottle with a DIY Masking tape seal
Ensuring the coolant flows air free out the 2 bleeder valves and the heater set to hot
Once refilled, run the engine up-to temperature to allow the coolant to flow and to ensure no trapped air or overheating issues by waiting for the cooling fan to kick in and out
A quick spin up and down the road, confirmed the temperature gauge is sitting happily at 90degree’s with no movement and fan kicking in to regulate the temperature
Final check once the vehicle has cooled to top up the coolant level to max (bottom of the inner neck)
And to check the strength of the anti-freeze mix, showing a strong mix protecting down to about -40 Degree Celsius
bbautorepairs 