617 glow plug change and fifth cylinder.....
 

Hi all.....

Thanks to the help of all the great info on this forum, I set out to swap out all of the glow plugs on my 84 300SD. They are all changed out to the new Bosch plugs except for the last one -- the fifth cylinder, the one closest to the firewall. This one is a huge PITA and I really don't see how any of you got it out or back in. I did a search for "5th cylinder glow plug fun" and such with no luck.:eek:

Do any of y'all have any tips for that last and final glow plug? Right now I'm thinking that the only way is to remove the oil filter and coolant hose connection.

BTW -- I have removed/loosened all of the injection lines to move them out of the way a little. That helped with the other four but I'm stumped with the fifth one.

Thanks in advance,
.....Dan

it's really not that hard. I do it in 5 minutes with the injector lines on. take an extension and #8 with a wobble and take off the power going to it. hold the wire so it won't break inside the plug because of turning it. then take a gear wrench #12 and put it on the plug. curse some (if you have the lines still on:D) scrape the back of your hand and take it of. you can extend your wrench with another wrench if it' s seized.
you can do it!

I do it with a couple of open-end wrenches and the fuel lines in place, it's not that hard.

open end works good for a well maintained machine, with glow plugs that have some aluminium grease on them:D

Can you elaborate on what your problem is? I have not found the 5th plug to be the hardest. I typically use gearwrenches for them but an open end/box end should work fine.

Sears is pushing some ratcheting wrenches with hinged ends this holiday season.

Looks like they would be ideal for this job.

I think I will tell Santa what a good boy I've been. Maybe he will bring me a set.



Oh, wait, I forgot!!! I'm Santa..... :D

Maybe it's my fat hands that are the problem.

I actually picked up a 12mm gear wrench with the flex angle and that helped immensely on cylinders 1 through 4. But with the oil filter and coolant hose right there nested by the #5 glow plug it is very, very tight. Y'all are making it sound so easy. I actually got the #5 glow plug OUT but have no idea how I'm going to get the new one in. And on top of that I still have to get on all the 8mm wire nuts. Any tricks to that? I was able to not lose any of them -- that was a common theme in my previous searches. I used an extendable magnet to ensure the nut would come out as I unthreaded it off, as was suggested in one of the threads.

.....Dan

I disagree with all of the aforementioned posts. I cannot get my hands between the fuel injection lines and there is no possible way that I can change #5 if I leave the lines in place.

So, my strong recommendation is for you to spend the ten minutes it will take to remove the five injector hard lines. It can all be done with a standard open end wrench and the extra room is a godsend.

When you to to start the engine, press your right foot on the floor. It will crank for about 12 seconds and start.

I agree, you should do whichever is quickest/easiest. I've done the #5 GP several times with the fuel lines in place. Maybe I have smaller hands, but it only takes a few minutes.

I take a 12mm open end wrench, and take it out. Takes me about 2-3 mins to swap glow plug 5, including the wires. :D My hands are not small either....I actually think the order of hardness (I came up with it last time I changed them) is:

From hardest to easiest

4
3
5
1
2

Four is a bear to reach as you can't turn it much each time, takes forever.

I just changed mine recently, while doing the turbo and valve stems, injectors etc. I had my injector lines off. I don't recall the heater supply hose coming out of the block blocking the GP. "IF" I am correct, then maybe someone stuck the wrong hose on there?

It does block the glow plug when its in position, but you can pull it out of the way enough to work on the glow plug pretty easily.

A 12mm ratchet wrench is a huge benefit when doing glowplugs.

Remember, do not bend the injection lines.

When I did the SD GP's:

I did not remove any fuel lines.

I did use gear wrenches.

I did move the heater hose out of the way.

I did remove a clip and loosen the throttle linkage from the firewall, moving it out of the way.

I did cramp up.

I did lose a gear wrench.

I did buy another gear wrench.

It shook it self out a few days later, found it on the garage floor, I now have two 8mm's.

Getting the new GP in, patience.

It sure is, I used one and it speeds up the process enormously!