LD28 Glow plug information

Discuss (and cuss) the Nissan LD-series OHC Six diesel engine, popularly available in the US in 1981-83 Datsun/Nissan Maxima Sedans & Wagons.

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kassim503
Posts: 1027
Joined: 14 years ago
Location: Stony Brook, NY

#16

Post by kassim503 » 10 years ago

I know the 80's chevy CUCV trucks the military used has a big honkin resistor bank for the 24-12 drop for the glow plugs. There's one on ebay right now
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

rlaggren
Posts: 541
Joined: 12 years ago
Location: San Francisco

#17

Post by rlaggren » 10 years ago

Looks like an easy fix. If it's anything like the wire elements I've seen on heaters, though, you may want to tell the seller to pack it like it was fresh eggs or it might not be working when it gets to you.

Rufus
82 Maxima wagon

Dr. Jones
Posts: 125
Joined: 14 years ago
Location: Raleigh NC

Finding TDC of cyclinders other than #1

#18

Post by Dr. Jones » 10 years ago

Hi Guys,

I have been having troule starting on cold mornings and chased it down to the glow plugs. One came out (#5) and does nothing on when hookup up to the glow system and the continuity test shows it to be bad also. I have two others #2 and #6 that are stuck in the block. It is hard to believe that it has been starting as good as it has on 3 glow plugs.

What I need is a step by step of how to find TDC for these cylinders, any help is greatly appreciated.

I will post some pictures later in the week

Thanks

Note: all numbers are taken from from the fan end back (cylinder closes to fan #1 closest to tranny #6)
'82 Maxima Sedan x2
'92 Saab 9000 Griffin Edition Wrecked
'80 Ford E100(twisted tranny) SCRAPPED

diesel-man
Posts: 150
Joined: 14 years ago
Location: Elkton, MD

Re: Finding TDC of cyclinders other than #1

#19

Post by diesel-man » 10 years ago

Dr. Jones wrote:Hi Guys,

What I need is a step by step of how to find TDC for these cylinders, any help is greatly appreciated.

Note: all numbers are taken from from the fan end back (cylinder closes to fan #1 closest to tranny #6)
I believe the easiest way is to take the plug out of the sight hole on the front side of the bell housing. (there is a mark on the flywheel) This will line up your timing gears, injection pump, etc. But it could be 180 degrees of cam timing out, so you check the cam lobe position through the oil filler hole. (you should find this info in the FSM under replacing the injection pump belt...same procedure. Lastly you can triple check it with a glow plug out and stick in a piece of wire and turn the crank a little each way.

diesel-man
Posts: 150
Joined: 14 years ago
Location: Elkton, MD

Re: Finding TDC of cyclinders other than #1

#20

Post by diesel-man » 10 years ago

Dr. Jones wrote:Hi Guys,

What I need is a step by step of how to find TDC for these cylinders, any help is greatly appreciated.

Note: all numbers are taken from from the fan end back (cylinder closes to fan #1 closest to tranny #6)
I believe the easiest way is to take the plug out of the sight hole on the front side of the bell housing. (there is a mark on the flywheel) This will line up your timing gears, injection pump, etc. But it could be 180 degrees of cam timing out, so you check the cam lobe position through the oil filler hole. (you should find this info in the FSM under replacing the injection pump belt...same procedure. Lastly you can triple check it with a glow plug out and stick in a piece of wire and turn the crank a little each way.

Carimbo
Posts: 459
Joined: 14 years ago

Re: Finding TDC of cyclinders other than #1

#21

Post by Carimbo » 10 years ago

Dr. Jones wrote:Hi Guys,

I have been having troule starting on cold mornings and chased it down to the glow plugs. One came out (#5) and does nothing on when hookup up to the glow system and the continuity test shows it to be bad also. I have two others #2 and #6 that are stuck in the block.
"Stuck in the block" meaning they are turning but not coming out? Or stuck not even able to turn? These two, do they test bad?

Dr. Jones
Posts: 125
Joined: 14 years ago
Location: Raleigh NC

#22

Post by Dr. Jones » 10 years ago

I can't get at them to test them. They are 90% percent of the way out but have become hard to turn and I want to be sure I can get the pieces out in case they do break. Again it is the #2 and #6 cylinder (#1 being closest to fan and #6 being closest to transmission) that need to be brought to TDC.

A couple of other questions/concerns on different procedures to remove debris from combustion chamber:

1. The glow plug element is magnetic but not as magnetic as the threaded steel? , is it safe to assume I can just break the element off and then move the piston up until I can slide a magnet through the glow plug hole and retrieve the the piece? Does anyone see any potentail problems with this method(is it probable that the piece will lodge between the piston and wall)?

2. Al stated to to blow air into the glow plug hole and blow the remaining piece out of the the injector hole, does anyone know if he accounted for the combustion chamber to set in the head? When I started I assumed that the head was carved out to allow combustion within the head/cylinder, but there is a combustion chamber set into the head(picture on pg EM-27 ; FSM). Since this is the case do I need to bring the cylinder to TDC and if something does fall through the combustion chamber is the only way to retrieve it to pull the head? One last question is there any chance of dislodging the combustion chamber from the head with compressed air?

Sorry for the long post, but the old Blue Demon is my only ride at the moment. I will be checking back in periodically throughout the night so if I left something out please feel free to ask for it.

Thanks
Joe
'82 Maxima Sedan x2
'92 Saab 9000 Griffin Edition Wrecked
'80 Ford E100(twisted tranny) SCRAPPED

Carimbo
Posts: 459
Joined: 14 years ago

#23

Post by Carimbo » 10 years ago

Dr. Jones wrote:They are 90% percent of the way out but have become hard to turn and I want to be sure I can get the pieces out in case they do break. Again it is the #2 and #6 cylinder (#1 being closest to fan and #6 being closest to transmission) that need to be brought to TDC.

A couple of other questions/concerns on different procedures to remove debris from combustion chamber:

1. The glow plug element is magnetic but not as magnetic as the threaded steel? , is it safe to assume I can just break the element off and then move the piston up until I can slide a magnet through the glow plug hole and retrieve the the piece? Does anyone see any potentail problems with this method(is it probable that the piece will lodge between the piston and wall)?
Better to have that piston at TDC; the piston crown will be very close to the cylinder top, effectively closing off any avenue for the GP tip to fall into the cylinder. The combustion chamber (pre-combustion chamber?) is above the cylinder, in the head as you presumed. The injector tip and GP protrude into this pre-combustion chamber.

You want to avoid having anything fall into the cylinder.

Seems that if the GP is 90% out and becoming stubborn it either has a mushroomed tip, or carbon buildup. If carbon buildup you may be able to remove it easier by spraying some carbon solvent (carb cleaner?) on the portion still in the head thru the injector hole, then turning the GP in, then out slightly, working it back and forth a little more each time.

If mushroomed tip probably you will end up breaking it off removing it and resort to fishing it out or blowing it out w/ compressed air. One guy supposedly vacuumed it out (via the injector hole?) w/ a stepped-down hose on a big shop vac. Magnet? Don't know.
Dr. Jones wrote:When I started I assumed that the head was carved out to allow combustion within the head/cylinder, but there is a combustion chamber set into the head(picture on pg EM-27 ; FSM). Since this is the case do I need to bring the cylinder to TDC
Yes to close off the cylinder so nothing can fall into it. A better illustration to help you visualize it is on p. MA-28. You can see that what they called the combustion chamber is really a machined "cap" that covers the bottom of the formed open round pocket in the head, gives it some shape inside for swirl, and greatly necks down the opening into the cylinder to increase turbulence. Search around on this forum and you will see some pics of the underside of the head, also to help you visualize what you are dealing with. At TDC the top of the piston should be nearly touching the bottom of the head's "combustion chamber," sometimes referred to as precup.
Dr. Jones wrote:One last question is there any chance of dislodging the combustion chamber from the head with compressed air?
Probably not. It is frozen into the head, and further held in place by part of the headgasket/engine block. Where would it go?

NOTE: The injector holes are larger than the GP holes. Easier access for fishing expeditions. Remember to install new heat shields. Pretty mandatory.

Dr. Jones
Posts: 125
Joined: 14 years ago
Location: Raleigh NC

#24

Post by Dr. Jones » 10 years ago

Thanks that is very helpful. How do I locate TDC of the #2 and #6 cylinders and what are heat shields?
'82 Maxima Sedan x2
'92 Saab 9000 Griffin Edition Wrecked
'80 Ford E100(twisted tranny) SCRAPPED

Carimbo
Posts: 459
Joined: 14 years ago

#25

Post by Carimbo » 10 years ago

Dr. Jones wrote:Thanks that is very helpful. How do I locate TDC of the #2 and #6 cylinders and what are heat shields?
Easiest way I can think of now is to find TDC for #1:
Line up flywheel mark w/ mark on rear plate site hole just above the starter (See FSM, p. EM-37), and verify both cam lobes for #1 are pointing up away from the valves. Look thru the oil fill hole. Follow the firing order to find the others, You can probably verify close enough TDC for others by threading a piece of thin wire thru the respective injector hole until it contacts the piston top and observing its movement. Somebody may have an easier way by degreeing the crank pulley?

Heat shields are the wavy washers that seal the combustion chamber and conduct heat where the tips of the injector nozzles contact the head. See FSM p. EM-39, MA-28, among others. They have been discussed in these forums before.

Dr. Jones
Posts: 125
Joined: 14 years ago
Location: Raleigh NC

#26

Post by Dr. Jones » 10 years ago

I'm going to put this on hold until I have time to pull the head. When I do I was thinking of making some sort of template to identify all cylinder TDC's from the #1. I was thinking of marking the Harmonic balancer at the top when TDC for #1 occurred and then finding the others in relation to the original mark. What I envision ending up with is a circle with slits cut from it. This way if anyone needs to fish something out of the combustion chamber there won't have to be any second guessing if your at TDC for that cylinder or not. Any constructive input is appreciated.
'82 Maxima Sedan x2
'92 Saab 9000 Griffin Edition Wrecked
'80 Ford E100(twisted tranny) SCRAPPED

goglio704
Posts: 726
Joined: 14 years ago
Location: East Tennessee

#27

Post by goglio704 » 10 years ago

Don't pull the head unless you have all the gaskets in your possession first. The gaskets are getting scarce. I would only pull the head as a last resort if I lost a piece of glow plug and couldn't retrieve it.

My parts motor has the head off of it already. When the weather is better, I could investigate your idea, but there has to be a way to determine TDC for all the cylinders without removing the head.

The glowplug and injector ports both go into the prechamber, so you can't simply probe for the top of the piston. All you will find is the bottom of the prechamber.

A vacuum / pressure gauge might be a way to find TDC on an individual cylinder. After verifying that both valves for that cylinder are closed. Slow turning of the crank while watching for the transition from pressure to vacuum might be revealing.

Rather than worry about TDC, it might be easier to make sure the opening from the prechamber to the cylinder is on the uphill side by jacking up one side of the car or the other. If gravity is on your side, any pieces will tend to stay in the prechamber for easier removal. A vacuum cleaner hooked to the injector port might be safer than compressed air which could blow the piece out into the cylinder if the piston is not at TDC. I can check my spare cylinder head to find out which side has the prechamber opening.
Matt B.

83 Maxima Sedan, LD28, 5 speed, white, 130k miles. My original Maxima.
83 Maxima Sedan converted from gasser, LD28, 5 speed, 2 tone blue, 230k miles
82 Maxima Sedan, LD28, 3 speed auto, 2 tone Gray/Silver, 140k miles
81 810 Sedan, LD28, 3 speed auto, rust, rust, and more rust!

2005 Jeep Liberty CRD

Carimbo
Posts: 459
Joined: 14 years ago

#28

Post by Carimbo » 10 years ago

Dr. Jones you may be making this harder than it should be. Again, are the "stuck" GPs not turning at all or hard to remove after turning them out?

The injectors you removed-- do those correspond to the stuck GPs? If so, you should be able to see (by looking thru the injector holes) if the GP tips are mushroomed and going to give you trouble. If not, why remove the head?

Dr. Jones
Posts: 125
Joined: 14 years ago
Location: Raleigh NC

#29

Post by Dr. Jones » 10 years ago

Hi,

Thanks, these are all great suggestions. I thought of using the pressure differential in the cylinder to find tdc, but was absolutely convinced I like that idea, but is probably the way I will do it if I don't pull the head. My main worry of not pulling the head is what if the glow plug breaks into a few pieces and I neglect to retrieve one.

If you could pull your head out and take some pictures of the combustion chamber that would be great.

How can I tell which Head gasket is the one for my car without pulling the head (which of the 3 thicknesses)?

The plugs are threaded all the way out of the head and will not back out. The injectors were corresponding to the glow plugs and when I look at the glow plugs through the Injector hole they seemed to look "normal" but when I looked at them while twisting them out of the head there was a pronounced "wobble". So instead of "mushroomed" they are more "hooked".
'82 Maxima Sedan x2
'92 Saab 9000 Griffin Edition Wrecked
'80 Ford E100(twisted tranny) SCRAPPED

Carimbo
Posts: 459
Joined: 14 years ago

#30

Post by Carimbo » 10 years ago

And how were the injector tips? Clean or lots of carbon deposits?

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