scillyman Posted November 30, 2022 Share Posted November 30, 2022 Hi I have a 2003 Freelander TD4. I have replaced the glow plugs. The heater light lights for 3-4 seconds. Attach a volt meter to a plug lead. I switch on ignition, volts read 11.8 volts for about 10 seconds. Switch off and back on same results. Start engine, volts rise to about 13.8 volts for aprox 2 minutes the drops to zero. Is this normal? can anyone tell me what is happening? Regards. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted November 30, 2022 Share Posted November 30, 2022 Yes it's normal, in a generic style for diesel engines with any sort of electronic control. Basically, full battery voltage is applied to the plugs, and the dash lamp is lit, this is pre-heating. The dash lamp is darkened but battery voltage is kept on the plugs. As the engine starts the voltage changes from 'just' the battery value to the alternator value, which is what you have seen and reported. This is 'post-start heating', it's purpose is to improve the burn, giving smoother running and less exhaust smoke while the engine is cold. Generally it's all controlled by time rather than temperature, although extreme cold may extend the pre-heat and the post heat periods. Regards. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 30, 2022 Share Posted November 30, 2022 Yes, perfectly normal. Glow plug light is not actually that, it is telling you when it is ready to crank. The glow plugs on more modern diesels stay on for a while after start to smooth things out and ensure ignition. Quote Link to comment Share on other sites More sharing options...
scillyman Posted November 30, 2022 Author Share Posted November 30, 2022 Thank you for your replies, sound logical, puts my mind to rest. Cheers Quote Link to comment Share on other sites More sharing options...
scillyman Posted December 1, 2022 Author Share Posted December 1, 2022 Hi. Another question on a similar theme. My Freelander starts quite quickly in the morning when it is cold, glow plugs working ok. During the day when the engine is warmer and the air temp is higher it takes a good 15 seconds with the starter churning fast. I feel like I could do with the glow plugs running a lot of the time. Could the temp sensor be faulty or is there a safe way to over ride the sensor to manually activate the glow plugs. Any thoughts? Regards Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 1, 2022 Share Posted December 1, 2022 I doubt that's down to the glow plugs, I'd suspect maybe a sensor. Quote Link to comment Share on other sites More sharing options...
Escape Posted December 1, 2022 Share Posted December 1, 2022 If it's anything like it's big brother BMW diesel in the P38, it could be down to wear in the injection pump. Hot starts uses as little diesel as possible to reduce emissions, as the engine ages that's not always enough to guarantee a quick start. It is possible to bypass the temperature sensor (with a timer) so the ECU thinks it's colder when starting, works a treat. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted December 1, 2022 Share Posted December 1, 2022 13 minutes ago, Escape said: it could be down to wear in the injection pump. Was my first thought too.... sorry. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.