Glow Plug Leak

[jrollf]

Lately I've been getting faint smells of fuel so I stopped to check things out today. I noticed a small puddle of diesel around the #4 cylinder glow plug. Strange thing was the #4 injector seems to be completely dry. So I started it and discovered I have a leak around my glow plug by seeing it bubble like crazy around it. Note there was less diesel than what you see in the video, I cleaned up the area around the glow plug before I removed it, then added fluid back around the plug that you see in this video to check for leaks.

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The glow plug was nice and tight, I pulled it and it looks healthy. I cleaned it, cleaned the glow plug bore with carb cleaner and a copper gun brush and still had a leak. To rule out the glow plug I swapped it with the glow plug from the #2 cylinder and no change. #2 is fine and #4 still leaks around the glow plug even after swapping glow plugs. The glow plugs are ZD-9s.

I believe the glow plugs seal at the base, the threads do not provide the seal correct? My bore scope isn't small enough to fit in the hole but what I could see with it the seat in the bore looked ok.

Any suggestions?

 

[Exhumis]

I'm no expert, just getting that out there. Could be a hairline crack? Did you recently overheat the truck? If you have a caliper pull the glow plug and see if the seat is perfectly flat, maybe it warped a bit. Did you clean the seat area around the glow plug? Also, double check connections such as return line and injector with a paper towel to make sure they aren't leaking and dribbling down to the gp. Have you pulled that injector? My understanding is if the top is wet that means it's stuck open.

 

[jrollf]

I fear it's a crack between the glow plug and injector. I recently replaced my injectors and this was the same cylinder that had a crusty injector that looks like carbon was deposited on it from the side not from a leaking seat.

Here is my thread about the injector:
https://www.oilburners.net/threads/injector-problems.87362/

Got a feeling the crack may have been there when I put the new heads on years ago and didn't notice it until I pulled injectors last year...

Now I'm torn on wether to pull the head out or just say screw it and let it live until it gets noticably worse. I know I always felt like there was a slight miss or week cylinder that I could never find, this might be the cause.

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual

 

[Thewespaul]

You can run a compression test to see how its affecting things, I would try installing a new plug or cleaning it some more.

 

[SLC97SR5]

I had an identical issue with my new engine, GP's and injectors.

I thought surely the head was cracked or the GP had an internal leak.

Nope. The injector nozzle to body threads were slightly loose and allowing fuel to fill up the injector bore and dribble overboard into the GP well.

Remove and inspect the return line, remove and re-torque the injector and replace the injector copper washer and put it all back together.

 

[Fixnstuff]

Maybe a previous glowplug was loose for some time and some carbon built up on the seat at the bottom of the threaded hole.
I remember seeing in a manual, a Ford Rotunda brush for cleaning out injector holes and maybe there was one for glow plug holes.

[EDIT]: I CAN'T RECOMMEND THESE BRUSHES FROM FASTENALL = THEY MIGHT HAVE AN ABRASIVE IN THE BRISTLES, I don't know if they do or not but in searching for brushes I saw some aggressive "tube brushes" at Master-Car that do have an abrasive in the bristles so without knowing for sure about these FASTENALL brushes I can't recommend them. They probably do not have one small enough to go into glow plug hole anyway. I will leave the information I wrote about them here as a....
...quotation in case anyone wants to look at them in the store--->>>

You can ignore this as stated above: FASTENALL stores, if you have one nearby sell special cylindrical "tube bushes" for cleaning out drilled holes in concrete before inserting epoxy sealed fasteners (like threaded studs, eyebolts, anchors to attach base plates, building components or machines to the concrete) The bristles on those brushes are white and very stiff. Probably a Nylon formulation. They might have one small enough for a glow plug hole and the twisted wire at the center of the brush, (also the handle) would be small enough to just enter the hole that the heating tip of the glow plug goes through (approximately 3/16 in.) I liked THOSE BRUSHES but I bought ones with less stiff black plastic bristles that were less than half the price of the white bristled ones. I was short on money that day. Back then the white bristled brushes were over $7.00 each. I might go down there today and buy some. I think they will be better than the cheap small flat plastic handled brushes with steel or brass bristles. Those things are like, use once or twice and then throw them out with the household garbage.

END OF EDIT

I would spray a little bit of penetrating oil down the hole (I grew up using WD-40). Let that soak in over night and it should soften up any carbon deposit so it will break up and clean out easier.

Here is a Glow Plug Brush Cleaning Kit from the UK with some taps, brushes and accessories, most made in Germany but NO REAMERS (which is another way to clean and restore the seat) and this kit is VERY EXPENSIVE. The three white bristled brushes the RIGHT side of the kit (steel bristled brushes on the left side) look like the same brushes I saw at FASTENALL <---Cancel that idea per EDIT above.
Enlarged photo of those kit brushes after the posted link)
https://www.lasertools.co.uk/product/6646

You must be registered for see images attach

 

[Fixnstuff]

I just now read your injector topic thread with the photos and I hope that Wes is right about his advice in both topics and that was the cause of the original problem. That crud on the injector could have gotten into the glow plug seat too if the glow plug was loose/not fully seated. I'm hoping for that rather than a crack.
The only way I can see that fuel would come out of the glow plug hole is if the cylinder compression was too low to ignite the fuel and some fuel was pushed through the glow plug seat. Otherwise, if its water that came out and not fuel, a crack somewhere into a water jacket or even a leaking head gasket on that cylinder?
I hope it's a real simple fix.

 

[Fixnstuff]

In case you read my previous post earlier, I just finished editing it TO NOT recommend the particular brushes I describrd at FASTENALL.

I've been searching for good 'tube brushes' and McMaster-Carr has a large assortment, for various uses (983 Products) listed under "Tube Brushes" In the left hand column you can select various specifications to filter the list to fit those specifications. (more below the url):
https://www.mcmaster.com/tube-wire-brushes

The third listing to the right in the first row has tube brushes in the right sizes for cleaning glow plug holes, However, they have stainless steel bristles. I've read that steel bristles are the best to use on iron and steel surfaces and the brushes with stainless steel bristles that I have used in the past, the bristles were fine and a bit too soft & ductile and always tended to bend out of shape under only moderate pressure in a tight area, ruining the brush. THAT would depend upon the SS alloy used. At those high prices at McMaster-Car the bristles had better be a higher strength SS Alloy than the brushes one would buy at the DOLLAR STORE or Harbor Freight! So MAYBE these are good brushes for the job.

In the Vertical columns of specifications (sometimes labelled in-line in the horizontal row) after you have selected the type(s) of brushes you want to see: 'Lg.' means Length of the brush itself, not including the handle and of course 'O-all Lg.' means the 'over-all Length' entire length of the whole brush including the handle.

 

[Fixnstuff]

One last post just for a reference(s). The image below shows what are called 'Fan Tip Tube Brushes' OR 'Radial Tip Tube Brushes.' (for search terms) Try 'Steel Bristle Fan Tip Brushes' (or 'steel bristle radial tip brushes') for search terms. The brushes shown here are are only to show the 'fan or radial tip and these are used to clean test tubes, thus the 'Fan Tip' of the bristles and other glassware used in chemistry labs. The bristles I think are Nylon non-scratch and probably too soft to use in an automotive/engine application.

You must be registered for see images attach

Here are a couple of other good sources for brushes: https://www.justmanbrush.com/

https://www.solobrushes.com/products/pipe-brushes/
ESPECIALLY THESE at that second URL, Solo Brushes. These are available with Carbon Steel, Steel or Brass bristles and they are INEXPENSIVE. I am inclined to try the Carbon Steel bristles and there are all the right sizes for glow plug holes and hope they don't break too easily and at that price if the shipping is reasonable I think would buy a 12-pack of steel ones also. I can't think of an application at the moment where I would need brass bristles. https://www.solobrushes.com/products/steel-stainless-steel-brass-tube-cleaning-brushes-1400/

I haven't searched these last two sites for Fan Tip or Radial Tip tube brushes yet but there are probably some, somewhere, listed on the web.
NOW THEN: What happens if a bristle breaks off and falls down through the hole for the glow plug tip and into the pre-combustion cup??? Any guesses?? With that question in mind I thought, "Use something of the right size to push some grease down into the that glow plug tip hole at the bottom and then if a carbon steel or steel bristle breaks off the grease will catch it and I can pull it out with a strong small magnet. Like a small disk rare earth magnet on the end of a telescoping tube would sure be handy at time like that.
I could also count the bristles on the brush and recount them afterward to see if one broke off, (I know, like, but I have a technical and analytical mind which is why I could probably never be a professional mechanic because I think things out too much)

Anyway, I'M DONE

 

[jrollf]

Thanks for all the info!

Ran out of time this last weekend so i haven't gotten back to the hotel plug yet. Going to find time this week.

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual

 

[jrollf]

Found time Friday to take a look again. I pulled the injector and found the bore around the injector full of diesel... figure my return cap was seeping down through the threads.

Cleaned the bore thoroughly with a gun brush and carb cleaner. I also cleaned up the seat using an injector seat reamer, took my time put no pressure on the tool let the weight of the tool do the work and used it just enough to clean all the carbon deposits off and not cut into the metal.

Also installed a fresh set of o-rings on the return cap and a new copper washer. At the same time I pulled the glow plug and used a gun brush with carb cleaner to thoroughly clean that bore as well.

I used my air compressor to push air in through the glow plug bore to make sure no carbon fell into the cylinder and did the opposite when I cleaned the glow plug.

Short-term results are it looks like the glow plug leak has stopped I've only driven it for about 10 minutes so I'm not sure if the fuel leak has been stopped yet or not, I should know soon.

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual

 

[DaveBen]

jrolif, you should put your truck information, above, in your signature by going to the TOP BLACK LINE and clicking on your User Name and selecting SIGNATURE and do a copy and paste of the info above, to your signature. This will help all of us next time you post something on your truck.

 

[jrollf]

jrolif, you should put your truck information, above, in your signature by going to the TOP BLACK LINE and clicking on your User Name and selecting SIGNATURE and do a copy and paste of the info above, to your signature. This will help all of us next time you post something on your truck.

Strange thought I had it saved in the signature both in Tapatalk and on Oil Burners.

Thanks for the heads up I've got it added on Oil Burners website now.

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual

 

[BeastMaster]

Check Walmart for gun cleaning brushes?

Has anyone used Teflon pipe tape for something like this, or does loctite have high temp sealants for this kind of thing?

 

[jrollf]

My understanding is the threads aren't used to seal, it's the base against bottom of the bore.

1993 F350 Crew Cab Dually
XLT
7.3 Factory IDIT w/Banks Sidewinder
5spd Manual