Tis' the Season... Hard Starts Cold

[STR8-6]

OK guys, the season is here, the trucks have been running good all year and now as the temperature is begining to drop our 7.3's are acting grumpy. I want to take you through some steps (easiest and least expensive to the worst) These are things we see every year at our shop.

General Info: I was once guilty of this and have had to fight hard to move my focus and start thinking beyond so listen up and I will hopefully save some of you some headaches:

"Your glow plug system has ALOT LESS to do with cold weather starting than you think it does!"

The idea that glow plugs are essential to starting understandably carries over from the preceeding IDI models where is was in fact critical, however, with the powerstroke the injection timing is more precise and the fuel is better atomized due to much higher pressures. If you have a hard start cold condition, more often than not it is a tired injector issue and not your glow plug system<--- that being said the glow plugs (although not essential) do assist in cold weather starting so here are the stepd that I will go through when we get a truck in for this complaint:

1: glow plug relay (commonly mis-stated as a solenoid but this is in fact a relay) the two small wires are pointless to test unless you are diagnosing a PCM issue as they are not a simple ground vs. switched hot scenario... one of these is key-on hot and the other is grounded via the PCM. In very rare cases the PCM will fail for this circuit but like I said... rarely.

Working with the large terminals, take a test light and ground the clip to the negative of the battery and probe the booted side of the terminals, this should be 12v. Now clip the clamp side of the test light to the other large terminal and stab the handle end into the negative post of the battery (make sure its a good connection) jump in the truck and turn the key to the run position, the test light should illuminate (special note: the ambiant air temp needs to be cold enough generally for the PCM to activate the relay, if this test fails, unplug the Oil Temp Sensor and repeat the test) in addition to the test light you may want to feel the relay and insure a mechanical "click" takes place. If either of these tests fail, replace the relay (replace with the apropriate relay, a common ford starter relay WILL NOT work the same)

2: Make yourself a test lead of some kind that has an alligator clip on one end of about 4' of medium guage wire and a semi-rigid "probe" or "poker" on the other end. Clip the alligator to the positive terminal of the battery. Disconnect the UVCH connectors and brush the probe against the 4 outermost tabs (these are the larger terminals, two on each end). You should get a very slight spark or light blue arc, this indicates a good glow plug. In most cases a bad glow plig will present with no spark at all, in rare cases a larger arc may occur but this also indicates a shorted plug.

If all but two or three of your glow plugs test good (assuming the relay test passed) you may have injector issues.

3: This is going to be the removal of the valve covers and inspecting connections but be sure to do step #4 before this (this is #3 because it is cheaper than #4)

4: Obtain a scan tool!, at this point you will need to do an injector buzz test when the engine is cold, in most cases the bad injectors will present with a "lazy" or "tired" buzz. Its time to pull them and have them tested and replaced as needed.

From experience, if you have a hard start cold and when it starts the engine "lopes" and/or "chugs" for a bit after starting, glow plugs WILL NOT fix this issue, you have injector problems. The good news is you can limp it by, you will just have to get up a little earlier and let the truck warm up before it will go anywhere.

Final Note: I am from Michigan and these are conditions typical to this and similar climates. If you are from Juno, Alaska install 4 additional batteries- leave the truck plugged in and underground out of the wind and start a fire under the engine 1 hour before cranking. Better yet just leave it running ALL the time and wire the PTO driven generator to your house A little humor there but the info above is apropriate for the northern/lower 48 on most days of the year, I do agree that a truck sitting outside in single digit temps and below can really benefit from a proper working glow plug system but not as much as plugging her in.

In closing: while using a block heater in combination with good injectors, the ONLY thing your glow plug system does is reduce smoke during start-up. All of this has been laid out to help some of you look beyond the glow plugs for hard starting as I was once so guilty of myself. Remember, all the dodge guys like to delete their grid heaters and they dont have plugs at all to begin with, lots of them running around here with no cold start issues all year.

Thanks for reading and hope it helps!

Cheers

[chvyrkr]

My old engine had no GPR installed, and started at 0* temps.

It was a little cranky and white smoked, but it started.

Just to illustrate that if the injection side of the house is in good shape, you don't need those glow plugs.


Another note, the "buzz test" only tests the injector solenoids, UVCH's, and PCM/IDM.

You're not testing the mechanical side of the injector, which is usually the culprit when HEUI trucks start havin fits about starting in cold temps.

Specifically the upper half of the injector. The poppet valve to poppet seat wears over time, and cold oil plays hell with that. If that poppet can't make a good seat, that cold thick oil is gonna punch it right out of the way instead of pushing the intensifier piston in the injector down and forcing the fuel to inject and atomize.

Use that scanner to watch ICP while cranking. If you're seeing over 500 psi and it's still choking on start up, chances are the injectors are worn.

5-40 weight oil is a decent bandaid for this for those that can't swing an injector R&R before winter.

[huntere7.3]

Originally Posted by chvyrkr

My old engine had no GPR installed, and started at 0* temps.

It was a little cranky and white smoked, but it started.

Just to illustrate that if the injection side of the house is in good shape, you don't need those glow plugs.


Another note, the "buzz test" only tests the injector solenoids, UVCH's, and PCM/IDM.

You're not testing the mechanical side of the injector, which is usually the culprit when HEUI trucks start havin fits about starting in cold temps.

Specifically the upper half of the injector. The poppet valve to poppet seat wears over time, and cold oil plays hell with that. If that poppet can't make a good seat, that cold thick oil is gonna punch it right out of the way instead of pushing the intensifier piston in the injector down and forcing the fuel to inject and atomize.

Use that scanner to watch ICP while cranking. If you're seeing over 500 psi and it's still choking on start up, chances are the injectors are worn.

5-40 weight oil is a decent bandaid for this for those that can't swing an injector R&R before winter.

-Im having cold start issues and by no means have the cash for new injectorswhen you say 5-40 oil is a bandaid ill definitely change the engine oil to 5-40 but are you also saying do an injector oil change to 5-40 as well? i know it can take quite a while for the injector oil to mix with the engine oil.my buddy showed me a trick how to change the injector oil with a pump cap for a bottle good info too man.thanks a ton!!

[chvyrkr]

Injector oil, or the oil trapped by the high pressure oil system, gets changed by starting the engine.

Actually pulling the oil out of the res yourself when you change the engine oil is a snake oil trick.

Seriously, let the truck idle for 10 minutes after you change the oil and every drop in the HPOS will be brand new oil from the pan.

I forget the exact flow numbers for the HPOP, and the exact consumption rate of the injectors, but having seen the numbers before I can promise you it takes no time at all for the small volume trapped in the HPOS to be refreshed as the engine runs.

[rebelduty66]

Originally Posted by chvyrkr

Injector oil, or the oil trapped by the high pressure oil system, gets changed by starting the engine.

Actually pulling the oil out of the res yourself when you change the engine oil is a snake oil trick.

Seriously, let the truck idle for 10 minutes after you change the oil and every drop in the HPOS will be brand new oil from the pan.

I forget the exact flow numbers for the HPOP, and the exact consumption rate of the injectors, but having seen the numbers before I can promise you it takes no time at all for the small volume trapped in the HPOS to be refreshed as the engine runs.

im also having hard start problems in flagstaff az got the truck from phx its a 2000 and has been there its whole life replaced the realy. helped a little but still white cloud of smoke and doesnt start imidiatly will try plugging it in and see if it helps any tips would be greatly appreciated

[benzo]

I bet it will start after being plugged up 30 min.I am going to 5-40 instead of the 15-40 rotella and see what happens.

[cap20]

That is an excellent step by step tip , thanks !

[Fordman247365]

I will jump in with my exp. also and agree, yes the injectors directly affect cold starting. Before my new injectors truck had to be plugged in under 20*, thats with a Stancor and new GP's. After the new injectors I dont ever plug it in unless it is going to be under -15* with no problems starting with 15 w40.

[Creative]

My truck (1997) has just recently gotten to where it is slow to start, turns over about 3-5 seconds before it cranks. I have not noticed any white smoke at start up but it has been between 45-70 when I have tried to start. I tested the relay and it is good. Tested plugs and found 3 bad ones all on one side. Should I check on the injectors or go ahead and replace the glow plugs first?