My diesel starts fine when it is plugged in all night. However, when I drive to work and shut it off and come out 9 hours later (in 30-40 degree weather) it takes forever for the truck to get going. Does this sound like a solenoid problem or glow plugs? Or both?

Thanks in advance!!

 

I am not familiar with diesels but in general...

30-40 degree weather isn't usually enough to cause starting problems for an engine and electrical system in good shape.

The colder it gets the less power the battery makes and the harder the engine turns due to oil that becomes very thick. And Diesels need a bit more time for the plugs to come up to temp.

But like I said 30-40 isn't that bad. More likely in my experience is that you have dirty electrical connections. I would check the battery posts and clamps. They must be shiney metal where they connect. If they are grey or dark, you may not have a good connection. Does the engine turn slowly or what?

A quickie trick to try is to wedge(just a little) a screwdriver blade or flat knife blade between the gap of the battery post and cable clamp. Give it a bit of twist between the gap. Don't snap off the blade, the intent is to scrape a clean shiney metal circle in the gap. Sometimes this is enough to get an engine to turn faster. If this is the case then you probably DO have dirty terminals. Saved me more than once when I thought my battery was dead.

How old is the battery and how old the engine? Check both batteries, maybe the one driving the glow plugs isn't getting them hot enough? Or the one driving the starter isn't tuning fast enough? What weight oil do you use?

If the battery is old, winter brings out the worst in a battery on it's last legs. If the engine is old, I would suspect poor spark, intake mix or low compression, but yours is diesel so forget spark, but might be glow plugs.

If the battery terminals are clean and the engine turns slowly I would then move on to either dirty connections on the starter, solenoid or maybe a cable that is corroded inside the jacket. Or your oil might be thick. I think the diesel guys use 10W 40 or thinner for winter. On a gasser, if you were using 20W50 say, the oil will be like fudge when temps are below 30 and the engine will crank slowly.

Good Luck,

Jim Henderson

 

Maybe glowplugs. From your descritpion I assume it takes a while for the light to go out?

 

Thread moved to 7.3L PSD section.

 

Your truck is not sufficiently heating its fuel before you go to start it cold.

Its either your glow plugs, glow plug relay, or bad batteries. If your relay is not working sufficiently, your glow plugs arent getting any power and aren't heating the fuel inside the cylinder. If your batteries are bad, you wont have enough power to start the truck and heat the plugs at the same time.

 

I would say that the light stays on for approximately 10-12 seconds. I had the batteries tested and one of them was somewhat weak, but they were both charging. However, the battery cables were somewhat loose on the battery terminals. We tightened them down. The batteries are junk though. Whoever had the truck before me put some autocraft junk in there. I need to change the batteries anyways. Maybe I should go ahead and replace the batteries and glowplugs?

 

Don't change it if it isn't broke!

I agree it sounds like the glow plug relay! Research this forum glow plug relay lots of information I had to replace mine after the test. Easy test look at the relay, just behind and to the passenger side of the fuel filter. Two small termials in the center, two large terminals, one left, one right. The large on the left are 12volt allway's, the termial next to it(small) will get 12volts when the key is turned on which should trigger the relay and close the circuit and put power to the large terminal on the right.

 

I would think you have a glow plug system problem. The purpose of the glow plugs is to provide additional heating of the compressed air in the cylinder so that when the fuel is injected, a more complete combustion occurs.

The engine block heater warms the entire engine block, which also provides warmer air temperatures inside the cylinders. This inturn helps to provide a more complete combustion process.

I would say testing the Glow Plug Relay first, checking for little voltage drop across the main terminals, when energized. If you're not familiar with electrical testing, you can simply use a large screwdriver (insulated handle for heat protection) and connect the two large terminals of the glow plug relay for 20-30 seconds, while the key is in the "Run" position (not cranking). Then, advance the key to attempt a start. If the engine starts much better, then it is likely the relay. If not, it is likely the glow plugs or wiring harness under the valve cover.

Check the resistance of each glow plug by removing the electrical harness at the valve cover connection, probing each of the 4 "larger" contacts on the valve cover connector. Measure resistance (Ohms ) from the large contact to battery ground, using a DMM (digital multimeter). I believe that 2.0 Ohms is the maximum limit. If over this value, then need replaced. Check all 8 glow plugs, 4 each side of engine.

 

Well my truck would not start this morning. cranked just fine, and sometimes it would start (barely) but would not stay running. took over 45 min this morning. Granite it was -6 this morning, but I have a buddy with old 6.9 with out plugging in and it started just fine. Just had two new injectors installed, and they said the Glow plugs and relay test ok. so the WTF over comes to mind.
I did have it plugged in, but I think my timer might have been off time or some thing.
well see at lunch since its warmed up to around Zero deg with NEG 20-30 wind chill factor if the beast will start.

 

Id bet money its your glow plug relay. If it wont start at lunch, jump the large terminals with a screw driver. If it starts, bingo.

 

started fine. but buying one after work and changing it anyway.