Ford F350 7.3 PS Turbo Diesel Cold Weather Starting Issues

. This link should help you test your glow plugs:

Free Advice for Diesel Owners.

. Use synthetic heavy duty diesel engine oil; e.g., Mobil 1 Delvac:

Mobil Delvac 1 5W-40

If you install an additional by-pass oil filter, and perform regular Used Oil Analysis (UOA) and change the by-pass filter annually, you could easily keep the oil in for 50,000+ miles. This makes it very cost effective and has been done regularly for years in diesel rigs. There are many other benefits, as well.

. Block heater.

. Clean battery terminals and connections.

. Ensure both batteries are fully charged, after checking fluid levels.

. Purge water from fuel system and change fuel filter.

Colder temps require more to start most motors.
Diesel's will often need just a little more help cold!

Why? The crankcase oil is cold and stiff. And the fuel is cold and stiff.

If the engine and crankcase oil isn't warm, it takes a strong battery to crank it, and if the fuel is cold, it takes healthy glow plugs to start the combustion.

Glow plugs warm the fuel, etc, but the block heater warms the larger machine. Change the glow plugs, and plug in the block heater. If you don't know where on the engine these belong, no offense, but I would recommend you find someone who will be doing this for you.

You won't regret either repair. Both will benefit you.

Diesels do require good strong battery systems for proper starting especially in cold weather.so checking them and assuring this part of your starting sysems is in good operating condition is primary. Your trouble starting coinciding with the cold weather most indicates faulty glow plug system. The glow plugs acually cause combustion of the fuel on start up when the engine is cold. A sensing system determines a cold engine by measuring the temp of the coolant (antifreeze) in the engine. Then the glow plug control circuit is energized sending electrical current to the glow plugs which are located in the engine block extending into the combustion chamber. These plugs cause the fuel/air mixture to burn/explode in the engine. Once the engine heats up, about a minute, the heat generated by the high compression in the engine coupled with the heat already produced by the glow plugs and the engine firing will produce combustion without the operation of the glow plugs. In warm weather these glow plugs operate either not at all or very little and engine startup is easy. Cold weather complicates this as explained above. The glow plugs should be checked individually since they don't usually all fail at once. They are available at auto parts stores as well as auto dealerships, cheaper at auto parts stores. If glow plugs check out ok glow plugs circuit components are the next suspects. Small garage mechanics with a reasonable knowledge of diesel operation can handle these checkout pocedures and they cost less. Hope this helps.

All, thank you very much for responding to my diesel engine cold weather starting issues. I plan to visit a few mechanics today to find out when I can get the truck in to have the glow plugs checked, etc., etc. I did notice it has 2 batteries and now have a better idea why.

For what it is worth, it is true that I probably shouldn't be messing around with this stuff myself as I don't have the knowledge or the tools to do the job; however, thanks to all of you, I can now talk to a mechanic with more knowledge at my finger tips.

I am a computer person by trade so if you have any issues with your laptops or desktop operating systems or applications, please let me return the favor and get you some tips on how to fix your system.

I'll keep all of you posted on my truck repair process. BTW: I did like the idea about the extra oil filter and the thought of replacing the fuel filter as well. I may have to become a grease monkey myself .

Sounds like your glow plug relay needs to be checked first. There are instructions on 7.3 Cold Starts on Hard/No Start? Check here first. - TheDieselStop.Com Forums


Here they are:
How to check Glow Plug System

To check the Glow Plug Relay (GPR)

A Ford Dealership Diesel Mechanic replaced the Glow Plug Relay Switch. Then tested that electrical connection as you described. It seemed to have passed. We will see what happens when the outside temps drop again. If I continue to have issues then the glow plugs will be checked next. If it isn't too much trouble and I can find the tools, I wouldn't mind testing the glow plugs as you described. Thanks for the mechanical education. I could save myself a ton of money if I could do some of these repairs myself. The relay seemed like an easy item to replace. Do you have any tips on replacing some of the small hoses such as the power steering hose? It appears that a lot of the hoses are getting hard, dry and brittle. I guess it would be best to get bulk hoses; then, I can just cut the lengths off a role. Additionally, I don't want to lose a bunch of fluid. Again, Thanks.

I have found that for P.S. Hoses as well as rubber brake lines, it's sometimes easier (and the most economical) to buy replacement hoses. These hoses have special ends/fittings that are best left to the professionals to put together. This website TheDieselStop.Com Forums - Powered by UBB.threads is FULL of people who have many years experience working on their 7.3 Fords.
-Nivrat

This has happened to me many times with my 1990 7.3 idi I had to change the glow plugs once a year. And I also changed the harness and relay because they were the original ones. That's were I would start.

I just replaced the Under Valve Cover harness on the drivers side due to loss of power. It fixed my problem! I also bought a second harness (they fit either side!) so when the passenger side acts up I will have it on hand.