Diagnose Engine Health from Glow Plugs (1 Viewer)

Joined
Apr 19, 2021
Messages
44
Location
Tasmania, Australia
Hi Guys,
Replaced the glow plugs in my 2H for the first time yesterday and noticed that the way each of the old ones came out was quite different, some fairly clean, some oily, some coated in carbon and some dipping oil.
I know that you can tell a bit about petrol engines from the used spark plugs, and I wasn't sure if you could do the same sort of thing with glow plugs?
I had a look at some other threads and they said the oil on the plugs is nothing to be worried about. I just thought it a bit strange that they were all quite different.
Plugs in the picture are in order of cylinder 1 through 6

IMG_20210420_172311.jpg
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
7,434
Location
Victoria, BC, Canada
Hi Guys,
Replaced the glow plugs in my 2H for the first time yesterday and noticed that the way each of the old ones came out was quite different, some fairly clean, some oily, some coated in carbon and some dipping oil.
I know that you can tell a bit about petrol engines from the used spark plugs, and I wasn't sure if you could do the same sort of thing with glow plugs?
I had a look at some other threads and they said the oil on the plugs is nothing to be worried about. I just thought it a bit strange that they were all quite different.
Plugs in the picture are in order of cylinder 1 through 6

View attachment 2651549

I'm not familiar with the 2H, but the oil is most likely coming from the top (valve cover gasket leak?), not the inside of the engine (combustion chamber). You really just have to look at the very tip of the glow plug only. A better test might be pulling the exhaust manifold an looking in the exhaust ports. Or better yet, just do a compression test while those glow plugs are out. You're half way there!
 
Joined
Apr 19, 2021
Messages
44
Location
Tasmania, Australia
I'm not familiar with the 2H, but the oil is most likely coming from the top (valve cover gasket leak?), not the inside of the engine (combustion chamber). You really just have to look at the very tip of the glow plug only. A better test might be pulling the exhaust manifold an looking in the exhaust ports. Or better yet, just do a compression test while those glow plugs are out. You're half way there!
Thanks mate, makes a fair bit of sense, the ones that are oil soaked are dirty all the way to the top which would indicate that they are getting oil from the rocker cover (which on a 2H is very close to the plugs) and leaking down. Compression test is a good idea, I'm not worried about my engine at all. Was just interested if there was such as thing as 'glow plug diagnostics'
 
Joined
Dec 5, 2006
Messages
969
Location
Vancouver BC
My glows are like yours, a mishmash of oily, sooty or both. This was before and after my rebuild. Ive stopped trying to determine cylinder health with the glows...
Nice avatar picture BTW :) we've got the HJ60 temperature extremes covered...
 
Joined
Apr 19, 2021
Messages
44
Location
Tasmania, Australia
My glows are like yours, a mishmash of oily, sooty or both. This was before and after my rebuild. Ive stopped trying to determine cylinder health with the glows...
Nice avatar picture BTW :) we've got the HJ60 temperature extremes covered...
Yeah seems to look like trying to determine cylinder health is grasping at straws.
Thankyou muchly. Yes it seems so, your picture is quite nice.
 

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