[Labs_4_Sale]

I tried searching but haven't found any addressing this issue, hope someone can straighten me out.
Experiencing hard cold starts (temps in mid 30's) and white smoke at start up.
The Glow Plug Relay showed voltage across the big posts same as batteries (12.5V) with the key on, the small post nearest to the firewall only reading .5V the other reading 12.5V
Replaced the relay (with a cheapie) and it tested @ battery voltage with the key on, all good, started the truck but it was already warm.
I then replaced the batteries cause they were old and due.
Tried to start the next morning, same hard start. I tested the relay and the rear small post is showing .5V again with the key on, 12.5V across the large posts.
Before I go any farther looking for some input on whether the cheap relay could be my issue in combination with the old batteries (thought I read that somewhere but can't find the post now), or if there may be glow plug issues causing the relay to fail.
Merry Christmas All!

 

[klhansen]

Check the Hard/No Start link in my signature. If I'm interpreting your latest test results correctly, your new GPR was DOA.
Follow the test procedure in the thread and also check your glow plugs themselves (they may all be bad if you have 12V between the two large posts).

 

[Labs_4_Sale]

So what should I be showing for voltage on the smaller pins with the key on. the new relay was working when i first installed it I believe, I had 12V on both of the small pins with the key on, now I only show .5V on the rear and 12V on the front.
Thanks for your help

 

[bugman]

With the key on what you are seeing is correct. That is until the relay shuts off then you should see the 12.5 volts or whatever battery voltage is present on both post. You will see this because of the coil winding in the relay. When the PCM sends the switched ground to the relay it will be active and you will only see the higher voltage on one of the small lugs.

Now after saying that it looks like you need to test the glow plugs and see what their resistance reading are. It appears that you may have a few dead ones.

 

[ArcticDriver]

A reminder to test the GPR voltages when engine is cold.

It doesn't matter the engine temp when you test the resistance (Ohms) of the GPs.

When you get a chance you might want to fill in your forum signature with your location and info about your truck.

Merry Christmas !

 

[Labs_4_Sale]

Good info guy's, thanks for the help.
It looks like I will be testing glow plugs on Saturday and will post results.
Any thoughts for replacements if needed, it's for a '99 7.3L

 

[bugman]

For glow plugs Motorcraft/Beau ZD-11's only no others.

 

[klhansen]

For glow plugs Motorcraft/Beau ZD-11's only no others.

It's spelled Beru (the GP manufacturer for Ford and International.)
Like bugman said, either Motorcraft ZD-11 (Ford PN F4TZ-12A342-BA or International PN 1820497C2

 

[Labs_4_Sale]

So it looks like it's time to learn how to replace glow plugs. the best readings I got was 2.9 ohms on 3 of them.
I addition to the glow plugs you mentioned with 177,000 miles I assume it would be wise to plan on replacing valve cover gaskets and the internal wiring harnesses, if so do you have any recommendations/part numbers and suppliers?
Thanks again.

 

[ArcticDriver]

So 2.9 ohms is higher than mine read new! How many read "0" ?

VC Gaskets are re-usable but I think most guys replace the UVCH. There is a design flaw in the originals that allows the plug connection to loosen just enough to lose connection. I didn't know at the time I replaced my GPs so I can't offer details.

Cheers

 

[Maryland dieselnick]

Ok a good plug will be between .2-2.0 ohms.


Temperature absolutely makes a difference when measuring a glow plug.

Glow plug bridges if equipped on a particular engine ( Diesel engines in general) to isolate the glow plugs and testing ideally should be tested somewhere around room temperature.

 

[Maryland dieselnick]

And RxDiesel glow plugs are great and do not swell but most here do Motorcraft.

 

[bugman]

The reading for a good glow plug from a factory manual are a resistance between 0.6 and 2 ohms. While temperature should be taken into consideration it usually isn't a factor when testing on a cold engine with cold plugs.

With 177k miles on the engine I think that I would just replace the valve cover gaskets and the under valve cover harness. They have been working for a long time and the extra cost isn't that bad unless you are strapped for money. I know that when I plan on doing mine that I'll replace everything, but then the OBS trucks have a few problems with the harnesses and gaskets that the Super Duties don't.

As for where to get them, there are a number of suppliers out there. RiffRaft Diesel is one of them that sells factory parts and have all that you would need.

 

[Labs_4_Sale]

yeah, I had 3 dead ones