glow plug issue

[mustangwally]

i have a 85 sd25, and have noticed it is hard to start when cold. there are new glow plugs and a new battery in the truck. voltage output is about 10V to the glow plugs when the key is turn on, but the light on the dash does not stay on for very long(3-6 secs). as the weather gets colder up north here i think i could be running into problem getting the truck to start

any suggestions on what the problem could be???


thanks in advance!

[asavage]

I 'm not sure about your Type II glow system, but other Nissan glow systems with which I'm familiar (720 Type I, Maxima, Sentra) all have the dash light lit by the controller, and not by the bus. On ALL of my Nissan diesels, I ignore the dash light, and listen for the GP relay dropping out (typically you can hear the relay "clunk" when it turns off) and I begin cranking after I hear the "clunk".

On my Sentra diesel, I put a separate dash light that's connected to the No. 1 GP, so I know when the voltage goes from full to afterglow (the light dims). The early 720 (with the older Type I system) do not have afterglow, but the Type II that you have, all Maximas, and all Sentras do.

10v is a bit on the low side. Is your battery undersized? On the older 720s, the GP system has a fusible link that is very prone to corrosion where it connect from the battery harness to the main wiring harness, and also another large spade connector near the firewall (GP relay to engine harness) whose connector also corrodes. These are VERY common failure points on the Type I system. Perhaps your system has the same issues.

We do not have a lot of experience with the later Type II systems, with only about four members here having them.

HTH

[Nissan_Ranger]

The 10 volt reading could be a voltage drop caused at a number of places by poor connection. Battery cables; connections at terminal ends, terminal to block grounding, undersized cables. The relay terminals could be poor as could the relay itself be internally. If you can get someone to turn on the key for you and get the glow circuit working you can sometimes find a bad connection by the warmth present at that bad connection; bad connections heat up under heavy electrical loads. Literally anywhere there is a connection from one conductor to another should be suspect and especially if the vehicle has been exposed to road salt. Keep us posted

N_R

[davehoos]

check for water temp sencor/dirty wiring.
not much else in the system other than the timer.
water temp sencors are not a forever item-these can also have wild calibration issues often needing a few to obtain the needed signal.

you could bridge the plug with a resister to test the time.variable resister.
had a quick look at a manual-it shows bellow 50C up to 4 seconds of glow warning lighttypeI-[20C type II 2 seconds]-
4-10 seconds of glow plug depending on water temp and 4-16 seconds of after glow if bellow 50C.

this dont make sence to me,another part of the manual shows no glow plugs untill below 25C.

my issue with the early timer was that it didnt work untill the water was near freezing.

just check along the wiring for the volt drop-if 10 at pulgs-and 12 ish at battery,i like to have a second battery or car conected to hold maximum volts when testing.might be the new plugs are pulling more current than the genuine plugs.common issue with voltage control plug systems.

[plenzen]

I put a meter on my SD25 yesterday and got a reading of 10.56V when the glow plugs come on at "pre glow". Once they go to "after glow" the voltage drops to 6.0 V. The GP light on the dash board goes out quite quickly on mine as well and the owner’s manual suggests that you start cranking at that moment. I assume this is to crank the engine while the plugs are still in their "pre glow" cycle and still glowing red with full power to them. I have installed a seperate light on the dash for when they are actually on and ignore the OE dash light. The light that I put in will also glow dimmer during the “after glow” cycle as well. I have also installed an air heater under the throttle body and it is explained in the posting under "user’s rigs, Retired Pauly's 1987 D21". ( would use the link to "see this thread" but am really computer stupid and although Al has spent much effort and patience trying to explain it to me I just cant seem to make it work ) I have also installed Delphi HDS283 glow plugs that I got from GCL fuel systems in Calgary ( http://www.gclfuelsystems.com ) and I keep the NGK Y-11R2S1's as spares. The Delphi plugs are rated at 11V and have a different tip on them. They are more pointed than the NGK's and look similar to a sharpened crayon. FWIW the old service manager at Nissan told me that hard starting was a big problem with the SD25 and at -10C "It Wont Go!”. He said that the SD22 was bad enough but that the 25 was harder to start than it was. The biggest improvement that I made was the air heater and the different glow plugs. I have had success in starting in -22C after 12 -14 hrs on the 3rd or 4th crank. The first couple it will fire and stop and fire and stop and once there is enough heat in the cylinders and cycle the GPs and the heater again it will go. It does not like it, but it goes.

FWIW


Paul
Edit: Just FYI the truck is equipped with two batteries and both are in good condition.

[davehoos]

hard to start was also a big complaint with SD25/TD25.its not all that cold here.less trouble with the van-may also be an ip adjustment had to send a few away to be recalibrated when new.

D21 SD25 mostly sold here as 4X4 to farmers/fishermen that use alsorts of fuel brew and big jump start batteries.these tend to be driven into the ground.
many have said to me that it takes that short roll on the driveway to spin the engine quick enough and the tractor is a shore thing.

TD27 dont have as much drama.and the import TD27T start very easily.