78 300D - Loop glow plug question
 

I have had this car for 2 years and I have no idea when the GPs were last changed. Car has been more difficult to start in the cold weather (although changing the oil to a synthetic 5W40 belnd has seemed to help with that). I have had very noticeable smoke on start up and under load and I am using oil at approx 1 qt per 500-100 miles, depending on the type of driving. I seem to use it more quickly during interstate, 70 mph driving.

Anyway, this prompted me to change out the valve stem seals and in so doing gave me an opportunity to pull the GPs and look them over. Valve stem seal job going well, although I'm not sure how to tell if the existing ones are bad??? Regardless, I'm replacing all of them, but I sure would like some confirmation that I am fixing A problem!

I have attached a picture of the GPs and they look fine to me - no carbon crud, nothing broke, although #5 loop looks a little distorted. Again, I have no idea how long they have been in there, but I read an old post by Larry Bible that indicated these loop plugs hardly ever break and need replacing. They get 'crudded up', but mine did not have any crud on them. Should I change them anyway? I have 5 new Bosch plugs, but I'm not sure why I would replace these? When I reinstall, should I use some antiseize? No way to get a torque wrench in there, so just snug them down??


BTW, a Flex head 13/16 Gear wrench made pulling the GPs very easy!

ryan

Replace them with the retrofitted pencil type plugs designed to replace the loop type. Their performance is so superior, you won't regret it. You can buy just the plugs and make jumper wires to go from plug to plug. Just disconnect the ground from the last plug at the front of the engine and hook the first one up the same way the loop plug was connected.

Thanks for the reply, but I have already purchased 5 loop style plugs and had already decided just to stick with the original style. Just doesn't get that cold here that often and I really don't see the need to upgrade.

ryan

One reason to upgrade is that if one of the loop plugs fails, they all stop working. Not so with the pencil plugs.

Also the loop plugs take about 6x the time to pre-glow.