'88 7.3 idi resurrection

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Sep 26, 2020
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F250 4x4. This truck sat unattended in a field for 19 years. Only 118 thousand kms on the clock. I hauled it to the infirmary and healed it. It actually started with little more than 2 fresh batteries and attention to fuel, but I digress...

No idea what sort of oil is in it but it's absolutely polluted, so it gets a flush change and filter x 2 (500 mile intervals) but here's my question:

My hope is to quickly restore better oil pressure and clean out goop using cheap 5w40 full synthetic (Klondike) then switch to either t6 or Mobil 5w40 after the inevitable discovery and repair of myriad oil leaks. With winter already banging on the door up here on the near-tundra, would I be mistaken to use 15w40 synthetic once the treatments end? Or heaven forbid straight 30, which I am told is available in synthetic? Have any of you guys running the older 7.3 idi's had significant issues using quality 5w40 syn year round? Other than leaks. That's too be expected.

And if I may stray off my own topic, is napa diesel antifreeze actually helpful in preventing potential cavitation? I've heard the napa stuff advised but only from folks who have no idea why.

Many thanks for your consideration.
 
I would not waste your money and time using cheap synthetic to rinse her out. Get the cheapest 15w40 diesel rated you can and do that. After a couple of those, again I would run some cheap Dino with a seal conditioner added. Never know what problems it will give you since it has been sitting so long so no need for expensive oil. Make sure the block heater works. If it gets through the winter, then consider a long term oil maintenance plan. I would start using Howe's diesel treat immediately. Hope this helps.
 
It does, thanks. Already on Howe's BTW. I have some 30 conventional and 15W40 on hand, but if I might expand my thinking a little... Synthetic is known for cleaning and that's my main objective here, regardless of grade and/or cost. Conventional will clean some but nothing like even an inexpensive synthetic. I have 20l of Klondike 5w40 sitting in my shop and just bought the small 7.3 idi filter. Way I look at it it's just the cost of the filter really. Oil's already paid for and the motor should Benefit.

The truck is kind of a time capsule, barely past break-in and a true diamond in the rough. (Pics as soon as I can post them) I plan to treat it like the magnificent machine it is. All mechanical! Nuts eh?

Cheers old bean.

Edit: I forgot to mention it's naturally aspirated. Stubby glow plugs and loads of room to work.
 
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I would not waste your money and time using cheap synthetic to rinse her out. Get the cheapest 15w40 diesel rated you can and do that. After a couple of those, again I would run some cheap Dino with a seal conditioner added. Never know what problems it will give you since it has been sitting so long so no need for expensive oil. Make sure the block heater works. If it gets through the winter, then consider a long term oil maintenance plan. I would start using Howe's diesel treat immediately. Hope this helps.
Valvoline makes a high milage 15w40 diesel oil. Would be very good in that application.
 
I've seen these engines with well north of 1 million miles with annual oil and filter. Sitting in a field for 2 decades is something less than care, but this one shrugged it off it seems. It gets only high quality synthetic now (if well tolerated). I had a buddy tell me he put a vintage 7.3 on synthetic and it wouldn't start after a couple days. Deeper issues no doubt. This one has excellent compression so I'm fairly confident it will thrive on synthetic. 5w40 going in today.

Now if I could only get the #1 injector cap loose without twisting the line off I'd be a happy camper!
 
It does, thanks. Already on Howe's BTW. I have some 30 conventional and 15W40 on hand, but if I might expand my thinking a little... Synthetic is known for cleaning and that's my main objective here, regardless of grade and/or cost. Conventional will clean some but nothing like even an inexpensive synthetic. I have 20l of Klondike 5w40 sitting in my shop and just bought the small 7.3 idi filter. Way I look at it it's just the cost of the filter really. Oil's already paid for and the motor should Benefit.

The truck is kind of a time capsule, barely past break-in and a true diamond in the rough. (Pics as soon as I can post them) I plan to treat it like the magnificent machine it is. All mechanical! Nuts eh?

Cheers old bean.

Edit: I forgot to mention it's naturally aspirated. Stubby glow plugs and loads of room to work.
Hey, if the oil is paid for, great. You do what is best for you. The reason I mentioned cheap Dino, is that, at least in the past, they had a slightly elevated additive pack verses its synthetic counterpart. The oil itself will do minimal cleaning, but keeping a few short interval changes would most likely clean it more than keeping any synthetic oil in for any extended period.
 
I have 3 words for you-GEAR REDUCTION STARTER!! The best money I ever spent on my '89 7.3 IDI, now it starts cold without needing plugged in! If you use 5W40 synthetic, be prepared to change every oil seal on it-RMS, oil cooler orings, everything. Depending on how cold you get up there, a Wolverine oil pan heater & even heated battery blankets, used along with the factory block heater, would allow you to run any HDEO you can get, up to & including SAE 30 dino.
 
Adding-my research indicated that the 6.9/7.3 IDI engines seem happiest on conventional green antifreeze, using SCAs, because there is an apparent compatibility problem with newer coolants & front cover seals. Roadrunner might be able to advise, he may be running a Deere coolant in his, but I've had old school green & DCA-2 (Napa Kool & coolant filters) on mine since I had the radiator boiled out when I bought it. Amazingly, virtually no coolant issues!
 
I've seen these engines with well north of 1 million miles with annual oil and filter. Sitting in a field for 2 decades is something less than care, but this one shrugged it off it seems. It gets only high quality synthetic now (if well tolerated). I had a buddy tell me he put a vintage 7.3 on synthetic and it wouldn't start after a couple days. Deeper issues no doubt. This one has excellent compression so I'm fairly confident it will thrive on synthetic. 5w40 going in today.

Now if I could only get the #1 injector cap loose without twisting the line off I'd be a happy camper!
They are pretty reliable, and slow, but at 30+ years old it'll be a miracle if it doesn't leak like the Exxon Valdez, even on dino (mine does)! Trust me, you NEED SCAs, or cavitation will perforate the cylinders in short order, the walls are too thin & vibrate when running.
 
Back when I was running my 6.9 year around it would get T6 in the winter and regular 15W40 in the summer. The only thing that ever leaked on mine was the valve cover gaskets and when I was running T6 they would actually dry up. As soon as I switched back to conventional within a week they would be seeping again. Completely opposite of what everyone says.

If non one has told you yet use only motorcraft glow plugs and thermostats. It will save you a lot of headaches with these things!
 
I have 3 words for you-GEAR REDUCTION STARTER!! The best money I ever spent on my '89 7.3 IDI, now it starts cold without needing plugged in! If you use 5W40 synthetic, be prepared to change every oil seal on it-RMS, oil cooler orings, everything. Depending on how cold you get up there, a Wolverine oil pan heater & even heated battery blankets, used along with the factory block heater, would allow you to run any HDEO you can get, up to & including SAE 30 dino.
Got a magnetic and a pad, plus the factory. A little kerosene and away she goes. Doing the manual glow plug tomorrow. BTW, the 5w40 synthetic has already paid spades. Pressure is up, so are revs. All good.
 
Adding-my research indicated that the 6.9/7.3 IDI engines seem happiest on conventional green antifreeze, using SCAs, because there is an apparent compatibility problem with newer coolants & front cover seals. Roadrunner might be able to advise, he may be running a Deere coolant in his, but I've had old school green & DCA-2 (Napa Kool & coolant filters) on mine since I had the radiator boiled out when I bought it. Amazingly, virtually no coolant issues!
Bought the napa cool with the coolant. I plan to change yearly so the rest is moot? Seals and gaskets are being stockpiled as we speak...
 
They are pretty reliable, and slow, but at 30+ years old it'll be a miracle if it doesn't leak like the Exxon Valdez, even on dino (mine does)! Trust me, you NEED SCAs, or cavitation will perforate the cylinders in short order, the walls are too thin & vibrate when running.
118k. Need I say more? Hardly run. And, I've hardly noticed the purported lack of power...
 
Adding-my research indicated that the 6.9/7.3 IDI engines seem happiest on conventional green antifreeze, using SCAs, because there is an apparent compatibility problem with newer coolants & front cover seals. Roadrunner might be able to advise, he may be running a Deere coolant in his, but I've had old school green & DCA-2 (Napa Kool & coolant filters) on mine since I had the radiator boiled out when I bought it. Amazingly, virtually no coolant issues!
Roger on the CoolGard/CoolGard II as its designed for use with all Deere legacy engines.
 
What do you guys reckon about running extended life diesel antifreeze with napa cool? (What I done did yesterday) I also have zero problem changing it out bi-anually. Not really all that keen to be adding filters etc, but if I must... I've seen it posted elsewhere that what I've done, plus changing it out every two three years - and testing the ph - gets around any possible issues. Is that just hot air?
 
Here we go. A pic of it in its field of grass. Sank darned near up to the axles.
20200918_133222.jpg
 
If you look closely you can see pools of diesel from the formerly badly leaking return lines.
20200922_123341.jpg
 
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