How do I check glowplugs on a 6.2? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**rs74** · 10-30-2013, 10:04 AM

Can I just turn the key on and use my test light? Connect to ground and see if there is power at the glow plug? Going to start troubleshooting on the no start issue. I would like to start there that way if I need to replace then I will have a full working set to start with. And how loud is the glow plug relay/solenoid/controller on the inside fender supposed to be. It buzzes a couple of times when keyed on.

**Corts60** · 10-30-2013, 10:13 AM

I would start at that relay. If it is buzzing, the contacts have more than likely failed. It should only click once when you turn the key on.

**rs74** · 10-30-2013, 10:18 AM

Quote:

Originally Posted by Corts60

I would start at that relay. If it is buzzing, the contacts have more than likely failed. It should only click once when you turn the key on.

Thanks. Answer me this. With the key off I should have power on the battery side. Now when keyed on I should have power on the other pole right? I had no power yesterday there when I tried but that was before it started to make noise. I even took off the flat connector below it and checked across and nothing. I would still like to check the glow plugs too and make sure they are good if you have any thoughts on that.

**rs74** · 10-30-2013, 06:47 PM

Quote:

Originally Posted by Corts60

I would start at that relay. If it is buzzing, the contacts have more than likely failed. It should only click once when you turn the key on.

Got it running today. Not sure but I think the controller was buzzing due to low batteries. After I got it running and warmed up I then shut it off. Every time after that I started it the controller just made a click. So as of right now I am chalking it up to low batteries.

57ToyBox · 10-30-2013, 10:22 AM

A good glow plug will produce a small amount of resistance.
Disconnect the wire and do a continuity test. High resistance indicates a bad glow plug

D13 · 10-30-2013, 11:43 AM

You will have power on the far side of therealy (to the glows) for 10-15 seconds after key on, with the engine cold. Best thing I ever did for the 6.2 was put a manual override in parallel. When I turn the key the old realy clicks on, I hit the override, and hold it an extra 10-15 seconds afte the relay kicks out. never had a start issue when I have fuel (next - spin on Racor filters with air bleeds and an electric fuel pump).

Best way to test glows is to pull them and activate them and look for the tip to get hot.

Absolute best thing to do is pull them and replace them with 60G's, self limiting so the tips don't burn and swell (common failure on the 9G's), then add the override and give it the extra time and it'll be happy.

chengny · 10-30-2013, 07:04 PM

These might help. Glow plug trouble shooting guide - from the military's CUCV manuals:

crashz · 10-31-2013, 12:57 PM

D13 nailed it. Couldn't be said better.

His comments on filters and fuel pump are on as well. Got my e-pump and will be installing spin on Mack filters (primary and secondary as I have a full set) for the 87.

crashz · 10-31-2013, 01:02 PM

BTW - if you pull/replace the glow plugs, remember they can swell and will pack with carbon. Take you time with them and do not break off the ceramic tip inside the head.

Mine came out hard on the 87 but plenty of penetrating oil disolved the carbon and allowed them to slide out. They were getting stuck well past the threads, so I was able to unthread and pullout a 1/4" before getting stuck. Pull very gently!

10-30-2013, 10:04 AM	#1
rs74 Senior Member Join Date: Jun 2010 Location: Illinois Posts: 2,957	How do I check glowplugs on a 6.2? Can I just turn the key on and use my test light? Connect to ground and see if there is power at the glow plug? Going to start troubleshooting on the no start issue. I would like to start there that way if I need to replace then I will have a full working set to start with. And how loud is the glow plug relay/solenoid/controller on the inside fender supposed to be. It buzzes a couple of times when keyed on. __________________ Roy 85 Short Bed Silverado- Work in progress. http://67-72chevytrucks.com/vboard/s...d.php?t=564818 1987 R10 shortie

10-30-2013, 10:13 AM	#2
Corts60 Just here to tinker Join Date: Jun 2008 Location: Holland, MI Posts: 3,697	Re: How do I check glowplugs on a 6.2? I would start at that relay. If it is buzzing, the contacts have more than likely failed. It should only click once when you turn the key on. __________________ 78 C10 SWB Diesel #1 (wrecked)http://67-72chevytrucks.com/vboard/s...1978+silverado 78 C10 SWB Diesel #2 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=650751 60 GMC Suburban (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=445526 60 GMC 1000 (sold)http://67-72chevytrucks.com/vboard/showthread.php?t=298235 67 GMC 1500 (sold) http://67-72chevytrucks.com/vboard/s...d.php?t=803695 73 Chevy C20(Daily)http://67-72chevytrucks.com/vboard/s...d.php?t=852767 86 Suburban(summer unit) http://67-72chevytrucks.com/vboard/s...d.php?t=810697 88 Suburban 4x4(sold)

10-30-2013, 10:22 AM	#5
57ToyBox Registered User Join Date: Apr 2007 Location: Callander Ont. Posts: 387	Re: How do I check glowplugs on a 6.2? A good glow plug will produce a small amount of resistance. Disconnect the wire and do a continuity test. High resistance indicates a bad glow plug __________________ --Glenn-- http://67-72chevytrucks.com/vboard/s...d.php?t=345975 http://67-72chevytrucks.com/vboard/s...d.php?t=564403

10-30-2013, 11:43 AM	#6
D13 Registered User Join Date: Feb 2007 Location: Memphis MI Posts: 1,851	Re: How do I check glowplugs on a 6.2? You will have power on the far side of therealy (to the glows) for 10-15 seconds after key on, with the engine cold. Best thing I ever did for the 6.2 was put a manual override in parallel. When I turn the key the old realy clicks on, I hit the override, and hold it an extra 10-15 seconds afte the relay kicks out. never had a start issue when I have fuel (next - spin on Racor filters with air bleeds and an electric fuel pump). Best way to test glows is to pull them and activate them and look for the tip to get hot. Absolute best thing to do is pull them and replace them with 60G's, self limiting so the tips don't burn and swell (common failure on the 9G's), then add the override and give it the extra time and it'll be happy. __________________ 1987 2 ton 1982 250/TH350 beater in progress Dad's 1981 3/4 L6 3 on tree posi and no options, awaiting restoration or scrapping Plus a mess o' tractors

10-30-2013, 07:04 PM	#7
chengny Registered User Join Date: May 2007 Location: New Hampshire Posts: 349	Re: How do I check glowplugs on a 6.2? These might help. Glow plug trouble shooting guide - from the military's CUCV manuals:

10-31-2013, 12:57 PM	#8
crashz Registered User Join Date: Jul 2012 Location: MA Posts: 207	Re: How do I check glowplugs on a 6.2? D13 nailed it. Couldn't be said better. His comments on filters and fuel pump are on as well. Got my e-pump and will be installing spin on Mack filters (primary and secondary as I have a full set) for the 87. __________________ 2012 Chevy 2500HD, 6.0L, 6spd auto, 4x4, ECSB 1987 GMC V3500 Dump, 6.2L diesel, TH400 1983 GMC K2500 - awaiting its restoration and Cummins swap.

10-31-2013, 01:02 PM	#9
crashz Registered User Join Date: Jul 2012 Location: MA Posts: 207	Re: How do I check glowplugs on a 6.2? BTW - if you pull/replace the glow plugs, remember they can swell and will pack with carbon. Take you time with them and do not break off the ceramic tip inside the head. Mine came out hard on the 87 but plenty of penetrating oil disolved the carbon and allowed them to slide out. They were getting stuck well past the threads, so I was able to unthread and pullout a 1/4" before getting stuck. Pull very gently! __________________ 2012 Chevy 2500HD, 6.0L, 6spd auto, 4x4, ECSB 1987 GMC V3500 Dump, 6.2L diesel, TH400 1983 GMC K2500 - awaiting its restoration and Cummins swap.



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