Looking for advice.
Truck is new to me - 2002 with 195k miles on it. I’ll be doing a lot of routine PM on it including pulling valve covers for 50 cent mods and re-torquing critical bolts. I’ve got posts saved on both of those.
What about glow plugs? Routine change out or leave them alone since they work fine? The truck came from the Deep South, doubt they were ever used much by previous owner.

 

If they're working I wouldn't change them but that's just me. You can ohm them out at the UVCH connection, the two outer pins on both ends of both connectors are them. I can never remember the acceptable ohm range but someone will be along with it.

 

I can tell you for a fact that just because the truck came from the south does not mean that the glow plugs were never used. I live in GA and my glow plugs come on for just about every cold engine start. By cold engine, I mean sitting overnight or more, even in August or July. That is the way the system is designed. They may only come on for a short time, but they almost always come on during a "cold" start.

As Mark said, ohm test them and go from there. The procedure (and much more information) can be found in the 7.3L PSD Tech Folder which is a sticky thread at the top of this sub-forum.

Last December I was installing a Borg Warner SXE turbo and decided to check my GP's and UVCH's. I told myself if I had 3 or more GP's out, then I would change them all. Well, I had 3 that were not working. I ended up changing the GP's with Motorcraft (NEVER USE AUTOLITE GP's) and International UVCH's and gaskets. Somewhere during the previous life of the truck someone had used a Dorman UVCH on the driver side and I was not satisfied with the condition or the projected lifespan of the wires. So, I spent a bit extra and those parts are well matched against the upgraded charging/starting wires, Denso starter, AGM batteries, etc...

So, test the GP's and make an informed decision from there. Let us know what happens.

 

Your bigger issue would be the Glow Plug Relay wearing out, than the Glow Plugs themselves.
The Glow Plug Relay will come on... Your Glow Plugs will come on for a time.
Are the Glow Plugs wore out and need changing. Not likely, ohm them out.
imo Leave your Glow Plugs alone and put on a new Glow Plug Relay.

 

Do a glow plug LED mod and it will confirm what Sous has said. You will be stunned to find out just how often and for how long the glow plugs are energized even on mild days.

 

You know, this is exactly why I did the GP LED mod and I was a bit surprised (maybe more informed is the right term?) as to how often the GP's do fire, even in GA on a hot summer day...

GP LED mod background information...

 

I do not believe that the LED glow plug mod tells you enough information about some of your systems.
I prefer to use a voltage meter that plugs into the cigarette lighter. power port.
By knowing your true (or as close to true as possible) voltage output put you will know.
1) your starting voltage of your batteries (key off)
2) voltage number when your GPR comes on (key on, wait to start)
3) your voltage drop when cranking to start (key on and cranking)
4) voltage of batteries, truck running, GPR goes off.
5) voltage will slowly rise when GPR goes off and will after about a minute settle to the point of Alternator output.

No need for a LED light and a massive amount of visual information.

• 

 

Brother Les is also right!

Just to close the loop on my end, I had installed a Tekonsha P3 which has a "diagnostic" section and can display the voltage in the system.

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1



Because I was not quite satisfied with having to push 3 buttons in order to get to the voltage reading, I purchased and installed a 12v voltmeter with dual USB ports into the cigarette lighter spot for my truck. I put it on a switch so that it is not always on. There are some with switches built into them, but I opted for one like this one.

This is not the exact one I purchased, but it is a close representation.

https://smile.amazon.com/Charger-CHG...xpY2s9dHJ1ZQ==

 

I'm far from an expert but I'll throw in my opinion. My 99.5 came to me in July with 240k and no maintenance records. If I were to go to the trouble of removing the valve covers for whatever reason, I would replace the glow plugs just for my own peace of mind. They're not that expensive.

 

I installed an underdash voltmeter years ago, and I can watch the big voltage drop when the glow plugs kick in. I like to see the drop, as it tells me the whole system is working all the way through the relay to the plugs themselves. I can also watch battery voltage under other conditions.

 

Thanks all,
I found a write up on ohm’ing them out. I had forgotten they run for a little while warming up.
I’ll pull the valve cover connectors when I take the IC pipes off for some other maintenance soon and if they don’t all ohm good, I’ll order 8 new ones and replace them all. Glow plug relay looks pretty new, probably a recent replacement.
Sucked a little not getting any maintenance history, I have to presume the worst.

 

Is your labor to do them later a big deal? Do you have $50-75 to toss in now so you don’t have to go back?

I have dozens of GP’s that all test good, but were changed as PM. There is no sense in installing new injectors and dropping old GP’s in when the ONLY cost is the cost of the part.

But, if I was broke or just cheap (I’m probably both...), I would ohm them out and change as needed. The good ones could last another 100k miles.

on edit: I will reiterate what Sous said, only use Motorcraft glow plugs. You can shop around and find them cheaper.

 

No, do not presume the worst. It does have 195,000 miles on it. So it had to have some maintenance.
I have driven 7.3 vans that had over 600,000 miles on them. It is a good engine that will take a lot.
We will love to give you suggestions on how to spend your money (on blings and things), but we do not just throw money at changing parts for no reason.

Ask us anything and as a herd we will head in the right direction.

 

Be sure if you go under the valve covers, do a compression check. You will have a baseline for the future & help with other problems as they pop up.
Good luck.

Edit

 

Thanks all. Motor is strong, runs great, mileage is decent (16.3 at 75 down the expressways bringing it home). Yeah it has some new parts, turbo, water pump and GPR all look recent. Only meant the worst as far as PM being due or overdue on everything. So all new fluids, hoses, belts, lubes, IC boots, rebuild fuel bowl, clean exhaust tube, tstat and housing, etc.

OK Planned Mods. I’ve already put in an AIS in since the air filter was shot. Zoodad going in. HPX crossover. Picked up a Racor CCV filter at a great price. Hutch and harpoon mods. Stock exhaust is in great shape so I plan to take out the OEM muffler and replace with an Aeroturbine for flow. AIH delete. Gauges and a PHP Hydra with smaller tow tunes after I upgrade the tranny and cooler. New shocks and air bags. Plan to pull a lighter fifth wheel. The one I’m eyeballing is 9800lbs max loaded weight. Got a great deal on an ATS turbo housing so that too. That’s the list, everything else is bling...