Twicky Glow Plugs, Pics

[Diesel911]

For about 2 weeks now whey you first turn the Key to the pre-glow position the Glow Plug Light would not go on at first. If I cycled that Key of and back on the Glow Plug Light would come on normally.

I disconnected the Glow Plug Wire Harness at the Glow Plug Relay and used the Ohm Meter to check them. But, they all Ohmed out OK.

Today I decided to remove the Plugs to test them on a Battery and also to ream the Carbon out of the Glow Plug Holes.

The Car is seldom driven on the Freeway and mainly operates within a 10 mile radius of my Home so it is mostly a City car.

The Glow Plugs in the car are Monarks; which are not supposed to be very good and they have were in the Engine for about 2 years. I use the Glow Plugs as often as I can remember to do so even though here in S CA it is not cold.

Connecting the Glow Plugs to the Battery one by one I found that all but one Glow Plug glowed well at the very tip of the Glow Plug. First pic. (And an other one died during the test.)

On that one the complete tip glowed but as you see in the pic it glows at a lower temp. About a month ago on another Forum ForcedInduction described this as a bad Glow Plug.

Oddly during the testing another Glow Plug that had been working died during the test and when I Ohmed it and found it had an open circuit.
I have a bunch of Bosch Glow Plugs so I tested them on the Battery also; all the Bosch Plugs glowed at the tip as they were supposed to and I installed them in the Engine.

The other 2 pics are showing the amount of carbon I got out of 2 of the holes when I reamed them.

In the last pic you can see that the very end of the Tip of the Glow Plug is the part that is going to heat the Pre-Chamber. If the main body of the Glow plug Tip gets hot the Heat goes into the Cylinder Head instead of heating the Pre-Chamber.

Added:I forgot to mention that one of the reasons I was checking the Glow Plugs so completely was because I needed to know if it was the Ignition Switch that was causing the problem with the Glow Plug Light or the Glow Plugs.

With the new Glow Plugs the light is functioning normally.

[johnathan1]

How did the car run with that problem. Was it noticeable on cold starts?

[Diesel911]

Originally Posted by johnathan1

How did the car run with that problem. Was it noticeable on cold starts?

I live in southen California. The temp has been pretty mild in the last 2 weeks.
I had been starting the Car for my Wife in the morning. I had been turning the key and keeping it on until I could hear the Glow Relay shut off.
I have had no un-even idle or hard staring.

Remember one Glow Plug worked but died during the test and the other got hot but the whole tip got hot; so it could be that the one that died was still working on the Engine and that would leave the one that the whole tip got hot on.
On the one the whole tip got hot on it would still put some heat into the Pre-Chamber; just not as much.
So I did not notice any starting issues or idle issues.

I forgot to mention that one of the reasons I was checking the Glow Plugs so completely was because I needed to know if it was the Ignition Switch that was causing the problem with the Glow Plug Light or the Glow Plugs.
With the new Glow Plugs the light is functioning normally.

[layback40]

When I replaced some in my 300D back a while ago, all the new ones (bosch) glowed like pic 2. Car starts fine now.

[Diesel911]

I was not having any starting issues. When I turned the Key the Glow Plug Light would not go one. If I cycled the Key again the Glow Plug Light would go on in a normal manner and the Engine would start normally.
I was not sure it this was a Glow Plug Issue or an Ignition Switch Issue so I decided to Pull the Glow Plugs check them and Ream out the holes.

I checked all the new Bosch Plugs acrossed the Battery and the tips glowed.

How, long did you test yours. The one in pic 2 started of with the whole tip glowing. The others started of with the tips glowing and the heat moved back from the tip. It may be that if they glow long enough the whole thing will get hot.

I was looking for a differance between the Plugs. And, other than the Plug that worked and went dead that the #2 was the one that was different. You can also see it glows at a cooler temp than the #1 does.

The Glow Plug Light Functions normal now so it must have been the Plugs causing the problem.

[espi]

My wagon has a bad glow plug. Is it something that's easy to do on my own?
My mechanic quoted me $100 to replace them.

[Diesel911]

Originally Posted by espi

My wagon has a bad glow plug. Is it something that's easy to do on my own?
My mechanic quoted me $100 to replace them.

On the 617 Engines is most often very straight forward as it is very unusual for there to be a stuck Glow Plug.

On the Engines with Aluminum Cylinder Heads and the longer Glow Plugs it seems to be from what I have read 25% of the people removing the Glow Plugs will have trouble with 1 or more stuck Glow plugs.

Similar to but not as easy as changing spark plugs but easier than doing something like the Brakes.

The job can be done with a 17mm wrench to Remove the Fuel Injection Hard Lines, an 8mm or 5/16 inch wrench or socket to remove the nuts that hold the Glow plug Wires on and a 12mm Wrench or socket to unscrew the Glow plugs.

After that you need something to clean the Carbon out of the Glow Plug holes. You can buy a Glow Plug Reamer or I believe some alternative methods are discussed in the DIY section.

If you removed the Fuel Injection Hard Lines you will need to know how to bleed the air out before Cranking. Simply only tighten the Fuel Injection Hard Line nuts at the Injectors by Hand and back them off a turn or so. Crank the Engine until you see Fuel coming out of all and then Tighten the Nuts.
After that go through your normal starting proceedure and Start your Engine.
(If you ever run completely out of Fuel and had been cranking the Engine trying to start it you will need to do the air bleeding as above (after you have fuel in the tank) except that this time you have to loosen the Hard Line Nuts at the Injectors first.)

Some were in the below links there should be a proceedure.
DIY Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82

http://www.peachparts.com/Wikka/DoItYourSelf

[biopete]

Originally Posted by espi

My wagon has a bad glow plug. Is it something that's easy to do on my own?
My mechanic quoted me $100 to replace them.

Is that including plugs all 5 or just burnt one? Great price if 5 Not really a fun job first couple times you do it . It's one of my least favorite jobs.

[Diesel911]

If the Mechanic in question owns his own shop he will most likely charge for the parts and they will be slightly more than could be bought by yourself loclly.

Some places the Mechanic who works in a shop owned by someone else also gets a percentage of the money from Parts as part of his pay.

Ounce your Car is in the Shop they try to look for more work that they can do quickly like changing Belts or Coolant Hoses.
If they have any sort of equipment like a Coolant Flushing Machine or for gas Engines an Injector Cleaning Machine they will try to talk you into having that done.