Testing glow plugs....?

[diesel4me]

Been trying to check the glow plugs on my Burb's 6.2....I know you can test the glow plugs by using a test lamp from the positive battery terminal to the glow plug tab,but what if your trying to see if 12V is getting to each one when you activate the relay with the manual button?..

I tried putting the test lamp to ground and probing the glow plug wire while it was connected to it,and I get no light!--but if I unplug the wire,then I'll get the light to light up...is that normal??-- I cant see why I get no lamp when I try testing for voltage while the wire is still connected to the glow plug...some of the wires feel like they might be broken or corroded under the insulation,and I'd hate to bust my nuts changing the glow plugs (not to mention the expense! ) ,if they are OK and it is the wiring thats keeping the glow plugs from glowing!..

The truck appears to have had a Ford solenoid rigged to the firewall ,that has the original glow plug harness hooked to it,along with a manual push button to activate it...I haven't dug into the harness for the glow plugs yet,but the wires I can see attached to the solenoid,the two thick red ones,with fusible links in them,look to be in great shape...but I'm wondering if the green wires to the glow plugs are going bad--anyone ever replace them?..I assume all 8 of them meet at one big splice junction inside the engine harness somewhere?..

I've determined at least 5 glow plugs are working,I have not been able to unplug a few without risking breaking off the tabs where the wires go on,they are rusty--and the two glow plugs behind the A/C bocx?..I doubt I'll ever be able to reach those,or get them to come out if I did!--kind of doubt they were ever changed because of that,and I'm assuming they are probably dead..this thing just wont fire up without a snort of ether,even in 55 degree weather,and I fear I'll ruin the engine if I have to keep using starting fluid on it..

 

[tRustyK5]

The back two GP's on the passenger side are easier to get with the front tire removed on that side. Pretty much straight access from the wheelwell area.

Alligator clip to ground, probe to the spade when it's not connected to the GP, have someone push the button...or back probe the spade connector.

Ether is bad. Does the HPCA work on that truck? That makes a big difference on cold starts.

Rene

 

[diesel4me]

I beleive it is,because the fast idle works ,it idles higher for a good 5 minutes before it'll kick down,and while its idling high you can hear more diesel clatter,once it kicks out it quiets down a lot...

This truck has had some wiring "modified" and I have not yet dug too deeply into it yet..I see someone jumped a connector at the passenger side rear of the engine,I assume it might be the HPCA wires?...there appears to be some kind of tube that goes under the intake in the same area where the fuel line goes to the IP,it sure feels like a slight pressure it coming out of it..I have to pull the air cleaner off and see if I can get a better ook in there at it..dam leaves from a tree fell all over the engine while I was rigging up the plow pump last week and covered a lot of things up..

Whoever had this truck was gung-ho about converting it to a greasecar,among the modifications they did was cut an access hole in the floor to get at the fuel tank sending unit,and they put a universal electric fuel pump on the main fuel line--dummy's mounted it inches from the rear spring shackle where road spray can drown it,and they used a whole roll of 3/8" rubber fuel line from the pump to the Raycor fuel filter they put on the firewall...and they bypassed the original mechanical lift pump on the engine too...

I have pumped out about 3 gallons of fuel to see if it looked contaminated with water or possible "alternative" fuels,but it looked OK and I dumped it in my plow truck and it seems to run OK (though its had some issues with bogging out a few times,but its electric fuel pump might be failing,and the fuel filter is what came with the truck 7 years ago and hasn't been changed by me yet,so it could be that ,not the fuel itself--plus the truck sits forever and rarely has much fuel in it)...the Suburban had close to a full tank when I got it,and the former owner said he put about 6 gallons of kerosene in the tank the day before I bought it,in hopes that would make it easier to start...so far if anything I think it made it worse...

I guess I'll have to unplug all the glow plugs and test the wires to all of them--but I will not be able to tell if they are getting a full 12V with a test light,or enough "amps" thru them to power up the glow plugs sufficiently...some of the green wires to the glow plugs feel "mooshy" under the insulation ,but still light the test lamp,I suspect they might heat up and lose voltage or not pass ANY current to the glow plug(s) in some cylinders..I get plenty of white smoke from the passenger side tailpipe when I crank it over awhile,however the drivers side shows none,until it finally starts,then a plume comes out of that side..that makes me think some of the drivers side glow plugs aren't getting energized,once she runs it runs good ,so I dont think its anything to do with the injectors..

Sometimes I wish we could just screw spark plugs in these engines and get rid of the glow plugs..expensiive pain in the ass to change frigging things,I think they suck!....been tempted to go back to GAS engines ...

 

[brian wafer]

when i check my glow plugs, i use a wire with a female therminal hook on glow plug,and touch the positve therminal off battery with other end. if glow plug is dead there is no spark if its good you see a nice strong spark.

 

[diesel4me]

OIl leaking from HEAD GASKET...?

Anyone here who has had the cylinder heads off a 6.2 that can tell me if they have an OIL passage in the head and block ?....

Yesterday I had my '85 Suburban running (first day it started without "assistance" ,mostly because it was 60 degrees out),and after I had it running awile,I see smoke coming off the drivers side exhaust pipe...
I crawl under it and see oil drippng on it from the back of the engine..

I hoped it was just an oil cooler line that had a rot hole,but no--they looked OK after I sprayed brake cleaner on them--they had oil on them,but it dripped from above onto them...I started it back up,and watched the area ,and as far as I can tell,the oil is dripping out of the HEAD GASKET!..I cant see the oil sending unit,but it doesn't appear to be wet up where that is.. I looked at the 6.2 I have for parts sitting on an engine stand,and best that I can tell,it IS where the head meets the block,that the oil is coming out of...

I think I am DONE with this truck...I have had it--I wasted the past two weeks lying under it and bending over the engine compartment ,putting a Fisher plow frame ,pump,joystick,etc on the dam thing,and my back has killed me every step of the way..the truck still has issues with its 700R4 tranny,and I am sick of looking at it--I wont have the cash to put it on the road,and I certainly dont want to pull the heads,as every injector line will likely snap off due to rust,and the exhaust manifolds are so rotten I dont even want to touch the studs..this is probably the final nail in this things coffin....

I am tempted to just throw my pickups plate on it and drive it to the crusher 3 miles away,and get my 350 bucks for it in scrap now....too bad I'm into this POS for 700 bucks already!....

I'm fast becoming a NON fan of diesels...I think the six-point SPEW is the second largest turd GM ever made ,next to the 350 Olds diesel...

Right now I wish I had a couple of 250 or 292 straight sixes and SM465's to swap in place of the diesels,and the crapbox 700R4 ..I see no advantage to owning a diesel any more--fuel is much more costly,parts are expensive,and they SUCK to work on,for the average Joe who is used to gas engines.like me..I'd gladly take the slight loss in fuel mileage,I dont go anywhere anyway...I'm getting to the point I dont want to own ANY vehicles any more,I'm so sick of wasting my life and money trying to keep one running and "legal"...having problems like this on top of my sucky life situation is making me suicidal..

Anyone think some "Oil Stop-Leak" would help this problem?...I dont,but I'm willing to do anything but take the engine apart--if I was to fix it I'd probably just yank it right out--and if I do that,I might as well DITCH the diesel and put a gas engine in it..good luck finding a carbed engine here though,they are very scarce and people wont sell them cheap anymore thanks to that..

 

[tRustyK5]

I don't think there is any pressurized oil passages between the block and the heads...just drain passages. The only pressurized oil going up that high comes through the pushrods just like a gasser. I think you have a valve cover leak.

Why not find a TBI engine, and convert it to carb if your set on a gasser?

i know how frustrating a 6.2 can be when it's nearing the end of it's service life and has seen crappy maintenance. They're not bad engines, but they do need a bit more dedication than a gasser does. Your climate just makes it all a lot worse with the rusty parts...

I'm in kind of the same boat with my TBI 350. Exhaust manifolds are pretty crusty, had a horrible exhaust leak and saw the stud/spring/nut assembly is beyond any help. Spring is rotted, nut is 'round', stud looks fragile. I figured screw it...jacked the exhaust up against the donut and tack welded the whole thing in place.

My old 6.2 in my Black Jimmy had a leak I could never isolate and or fix. It was passenger side above the starter somewhere. The starter was always dripping oil.

Rene

 

[diesel4me]

WEll,I guess I'll have to get the truck up higher and look again,maybe it is the valve cover gasket or the oil pressure sending unit,but it sure looked to me like ir was oozing out of the area where the head meets the block...sucks,the engine does run swett ,(once you get the dam thing to start!)..I dont want to spend another penny on this until I am sure its not a head,head gasket or the block thats leaking!...I'm not about to waste 80 bucks and my time putting glow plugs in it if the motor needs to come out,or apart!..

This WOULD have to happen in November,with snow due here any day now....

 

[85-m1028]

I used to get bad oil leaks from the vaccum pump. It would fill the engine valley and run down the back of the block.. making it look like the head gasket was leaking..

As for the checking the plugs, I use an ohm meter. If they have infinite reading then they're gone.

A new fuel filter and some #1 diesel with some conditioner will help the cold starts. because of the very cold temps it will be very hard to start unless you have a block heater.

The smoke out the exhaust could just be some bad injectors or pump.

 

[DEMON44]

10-4

test glow plugs. isolate each one. Ohm them out. open is bad. to the stud and the head, they ground through the threads.

 

[kennyw]

The voltage drop from having the glow plugs still connected to the wiring could be enough to keep the test light from working at the glow plug terminal. Technically the bulb is still lighting, but just too dim to see.

 

[diesel4me]

Probably the truth!...I know when you test a bulb with a test lamp,both the bulb and test lamp light up, if the bulb is good ,but at a much dimmer glow than one bulb alone..

I've been tempted to just chop all the green wires going to the glow plugs and make a new harness of 8 wires to replace them,and wire them up to the two fusible links that the stock wiring goes too,that way I wont be dealing with old wiring thats corroded or half toasted under the insulation..in a way I dont see how those 14 ga wires pass enough amps to "glow" a glow plug to begin with,never mind after 25 years...if the truck still wont fire up after that,I guess I'll have to get 6 more new 60G AC glow plugs and pray to god the old ones can be unscrewed and come OUT..
first I'll have to find a way to scrape up that kind of $$$$$ though...

The Burb acts weird,if I go to start it cold ,I let the glow plugs heat up for 10 seconds and the engine sounds at first like it wants to fire right up--then it'll just crank over without any cylinders "firing",and it'll just crank and crank,only way to get it fired up is with ether..but once it does start it runs good,once the excess fuel gets cleared out...much like a gas engine acts if you flooded it,thats what led me to ask if a diesel can be "flooded: in my other post here..

My 82 K2500's 6.2 starts on the second or third revolution usually,despite its wiring being older and in no better shape,and at best it only has 7 working glow plugs (one dead one refuses to come out and I'm not gonna bust it off trying too!)...maybe that engine just has better compression,I dont know..the Burb engine does not seem as peppy and it does whip over pretty fast,but it also has a gear reduction starter in it too,the '82 has the "regular" version..I'm going to have to check the injector pump timing on the Burb,I think its a bit retarted and could stand some advance maybe--my brothers old Fordson Major diesel backhoe used to be a SOB to start,acted much the same as my Burb,he found the pump timing was way off,retarted,he put it back to the right spot and the thing fired up like new after that,and it never needed starting fluid again..the Burb might have a loose timing chain,its hard to tell because these engines sound like a stonecrusher even if they are in good condition!..