I think I killed my glow plugs..?

Brian Rages · Post by **Brian Rages** » Fri Mar 14, 2008 8:38 am

I had a recent ordeal with some fuel starvation issues. Trying to limp home, I ended up killing the car a few times and having to do some extended cranking on a warm engine to restart. Now, I think the glow plugs are always on when cranking.

So I wonder if I burned mine out.

After this ordeal, my car has been very difficult to start in the mornings. It takes several minutes of cranking. While it is cranking, it will begin smoking grayish smoke from the tailpipe, but I won't feel any cylinders really "hitting". Eventually, one cylinder will start to hit a few times, and then within a couple of seconds the motor catches and begins running on all cylinders.

I'm thinking I killed my glow plugs. It's apparently getting fuel (hence the smoke). And it runs fine once it starts (good power, no smoke), so I don't think my timing is off.

Also, my dash lights don't seem to brighten when the glow plug relay kicks off... this may be the "smoking gun"...

Does this sound right?

idhoho · Post by **idhoho** » Fri Mar 14, 2008 9:07 am

Did you check the g.p. fuse on the firewall? Test the glows to see if they have continuity.. will they complete a circuit with a multi-meter. If you don't have a multi meter you can take out the easy ones and test them with your battery charger. If the system was working OK before you ran out of fuel, I doubt that you have "burned up anything other than the starter. Try not to react emotionally panicked to mechanical malfunctions/problems. I know that it is hard to stay calm but cranking the living sh%& out of your starter is not wise. Find the problem and correct it as you will cause more damage that will cost you more time and money

Live an learn my man.... Hopefully this has been a cheap lesson on the importance of fuel in your vehicle, eh?

There is much discussion on glow plug removal, testing, operation, etc. if you search this forum.

Post by **Fatmobile** » Fri Mar 14, 2008 11:44 pm

Try not to react emotionally panicked to mechanical malfunctions/problems.

It can sense your fear.
Maintain a calm cool composure at all times.

You have to be prepared, better than the people who built this car ever intended you to be.

A vacuum gauge on the fuel line will warn you ahead of time when there is a clogged filter, gelled fuel, a clogged vent line,... clogged check valve or new check valve that has a large opening pressure.

The light on the dash is just a dummy light, it doesn't mean the glow plugs are on, it's for people who don't want to count to 10 or 20 before they start it. Another light, that only powers up when the glow plugs are actually connected to the battery will let you know when the fuse is bad or glow plug relay stuck in the on position.

A manual rad fan switch for when it trys to overheat in rush hour traffic,...
it's happened several times in the Fatmobile.

There are probably a few other modifications you can make to your car so when it tries to mess up your day you flip a switch and laugh.

Brian Rages · Post by **Brian Rages** » Sun Mar 16, 2008 4:58 pm

It turned out to be the fusible link... the previous (original) owner had a couple spares taped to the front of the owner's manual, so it was a quick fix!

Still scratching my head to find the connection between blowing the fusible link and fuel starvation...

Vincent Waldon · Post by **Vincent Waldon** » Sun Mar 16, 2008 5:28 pm

My guess would be your fuel issues mean you are using your glow plugs for extended periods... causing the fuse to heat, thin over time, and then eventually fail.

The plugs draw about 48A cold and it's a 50A fuse, so it's on the edge to begin with.

Brian Rages · Post by **Brian Rages** » Sun Mar 16, 2008 6:45 pm

My theory is that I did some cranking while the engine was still running, before it died. 14.4V into 1/4 ohm is 58 amps...

Vincent Waldon · Post by **Vincent Waldon** » Sun Mar 16, 2008 6:58 pm

A good theory for sure.

Having said that, the plugs are actually designed to run while the engine is on... on my 94 Jetta they stay on for about 3 minutes *after* the car starts to improve cold weather drivability.

The secret is that their resistance is dynamic and temperature-dependent... they draw the full 48 amps initially when stone cold but draw a fraction of that once hot (either by themselves or because the engine is running).

mattbondy · Post by **mattbondy** » Sun Mar 16, 2008 7:49 pm

I find that when my car has warmed up just a little and I shut it off the glow plugs dont want to come on. This is a bit of an issue on colder days as it will take 10-20 seconds cranking to start. Maybe Im just a little too paranoid but I want the starter to last as long as possible (I have the auto tran.) I also have constant problems with v-belt tension (I really should remove the non-working AC) so I worry about killing the battery. I have been contemplating a fix so I tried disconnecting the coolant temp sensor on the front of the cylinder head. This did not seem to have any effect. I was hoping I would be able to throw a switch in there. If Im at home and I have the time I just open the hood and let things cool down. Otherwise I dont want to give the impression Im having any problems.