Winter Glow Plug Modification?

[StevenPH]

Has anyone ever removed the glow plug temperature sensor so they will just remain on indefinitely? On cold winter mornings i end up needing three or four cycles to start, and i'd love to just turn the key and count to 30 or so, rather than keep turning and returning the key every 7 to 10 seconds.

Any danger in doing so? I assume they have a heat maximum, correct, so if they are left on for 30 to 40 seconds they won't just continue to heat up until they fail, right? I'm so used to the timing so well that i'm not worried about over using the plugs when the engine is warm, and i'll plug the sensor back in as soon as the winter is over.

[82vdub]

Older style glow plug systems de-energized the glow plug relay when the starter was engaged. The newer systems (maybe starting with the Mk2) left the glow plugs on for a little while after the engine starts.

However, removing the wire to the temp sensor will only make the glow plug circuit energize, every time you turn the key on. It starts the glow plug cycle, which is controlled in the relay. So, it will not leave them on indefinately, but only start the cycle, and will even turn the glow plugs on when the engine is hot.

If you jumpered things out to keep the glow plugs on all the time, they would not last long at all.

Are your glow plugs new and/or have you tested them this fall? Cheap one's don't last a summer.

[TylerDurden]

I would install a 12V LED in the cabin, connected to the GP buss, it will indicate how long the GPs are actually energized - which is usually much longer than the stock lamp in the dash stays illuminated.

Taking off the sensor wire will fool the relay into always acting as though the engine is cold. Not a problem, if Bosch Duratherms (or equiv) are used.


More important is the reason the engine needs more than one cycle... In good tune, it should light-off first shot unless the temperature is very cold. I'd check the current-draw of the GPs to verify they are all working, check compression and check for air in the IP.

[StevenPH]

Everything is as it should in there, the gp draw, compression, IP, and under normal circumstances it needs only one cycle. I'm only taking about starting in under 5 degrees F ( cold here in Minnesota), when I can't plug in. Usually two or three cycles does the trick, but I'd rather lean on my glow plugs than burn out my starter, so I usually do 3 or 4 cycles when it's below zero. I replace them every fall with Bosch duratherms.

If I disconnect the temp sensor, the glow plugs will still turn off after the engine is running correct? That's really all i think I'm concerned with. I know the engine well enough to know how long the plugs need depending on the engine temp, and I'll plug back in the sensor in the spring when I only need one cycle again.

[TylerDurden]

If I disconnect the temp sensor, the glow plugs will still turn off after the engine is running correct?

Yep, you got the picture.

I agree with your position - a longer glow could be better than killing a starter, particularly if you refresh GPs every fall.

[Dakotakid]

Why not just forego the relay and run the glow plugs with a push-button? I've done it a bunch and never regretted it. Just keep it fused.....no problems. I started the practice in late '79.