1981 5.7 diesel DX rebuild

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Old Oct 25, 2025 | 10:58 AM
  #121  
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Here are a few more pictures from today.A new battery cable was installed across the top of the radiator and I decided to mount a coolant container from a 88-98 gm truck on the firewall on an angle to clear the heater hoses underneath it.I still need to stabilize the container a little more but it’s getting close to being started for the first time in a long time.

I placed a couple relays and bus bars on the driver side inner fender.One relay will control the electric lift pump on the chassis and the other will assist the stanadyne fuel heater.I’m hoping by Tuesday I’ll have it up and running.Once it’s running okay I’ll remove the grill and start installing the external oil cooler and oil cooler hoses.

I also want to put the original jack,etc on the passenger inner fenderwell.I still have the jack,etc from my grandfathers 1980 C20.Thats another reason why I put the coolant container on the firewall.












Last edited by dieselolds81; Oct 25, 2025 at 11:39 AM.
Old Oct 26, 2025 | 06:30 PM
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Nice job!
Old Oct 27, 2025 | 02:50 PM
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Originally Posted by dc2x4drvr
Nice job!
Thank you👍
Old Oct 27, 2025 | 02:54 PM
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Getting closer to start up time at this point.Just a few more wires to put in place and then it should be ready.The coolant is poured down through the thermostat area so the block could be filled completely.I just put the acdelco 6.5 thermostat and water outlet in place.I just need to install the top radiator hose.The Power steering pump is filled.All looks good.I should have this engine running tomorrow if all goes well.




Old Oct 27, 2025 | 03:31 PM
  #125  
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Tick Tock 😀
Old Oct 28, 2025 | 05:08 AM
  #126  
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I'm so ready to hear this thing rattle to life!
Old Oct 28, 2025 | 05:30 PM
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Originally Posted by dc2x4drvr
tick tock 😀
😂
Old Oct 28, 2025 | 05:31 PM
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Originally Posted by KCTexan
I'm so ready to hear this thing rattle to life!
As of now the engine is running.It has a rough idle but it’s not overly bad.I had a problem with injector #3 on the driver side.I installed 3 new gm injectors and went through all of them before I managed to find a good one.Its now working better with a reman injector in place.

All the injectors I have for the most part are in gm boxes from 1979 and most of them never did work perfect out of the box.Maybe stuck internally from sitting on the shelf?Who knows for sure.

I still have another 11 reman injectors I can use if I run into trouble.I might just install another set of 8 reman and see how it runs then.I do find the reman pencil injectors work better than gm nos units.

Aside of the rough idle it runs well.Oil pressure is around 70psi when first started cold.When it heats up the pressure is still well above specification.I had a couple small fuel leaks at first but nothing major but it has no oil leaks or any coolant leaks either.When the oil fill cap is removed there is zero crankcase vapours.Nothing at all.I’m pretty happy with it overall.Just a few kinks to work out is all.

I just need to bleed the brake system and put the hood back on.One other thing I need to do is install the oil cooler lines and mount the new oil cooler.I just might get a start on that tomorrow.More pictures are on the way.I’ll upload a video soon of how it runs as well.
Old Oct 29, 2025 | 04:31 AM
  #129  
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EXCELLENT! 👍

Good to hear that you got her started. Also, it's good to know that you have plenty of spare injectors.

In the future you might consider disassembling the injectors you have to put together a set of 8 at the proper pop-pressure. What that spec is; I don't know, but here's a tool that I bought to rebuild some of the injectors I got for my 86 Ford diesel truck.

BTW, here's a thread with links about rebuilding the IDI injectors for my Ford diesel truck. I know, I know... not the same beast. But maybe it will help someone.

https://www.ford-trucks.com/forums/1...formation.html

Last edited by Olds64; Oct 29, 2025 at 04:39 AM.
Old Oct 29, 2025 | 08:55 AM
  #130  
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You can use an IR thermometer to see which cylinder(s) are lame. It'll save you some time
Old Oct 29, 2025 | 02:11 PM
  #131  
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Originally Posted by Olds64
EXCELLENT! 👍

Good to hear that you got her started. Also, it's good to know that you have plenty of spare injectors.

In the future you might consider disassembling the injectors you have to put together a set of 8 at the proper pop-pressure. What that spec is; I don't know, but here's a tool that I bought to rebuild some of the injectors I got for my 86 Ford diesel truck.

BTW, here's a thread with links about rebuilding the IDI injectors for my Ford diesel truck. I know, I know... not the same beast. But maybe it will help someone.

https://www.ford-trucks.com/forums/1...formation.html
I appreciate the responses everyone.Thank you.I’ll probably run it for awhile at just above fast idle to ensure all the air is purged out and see how it behaves after that.The pencil injectors aren’t too plentiful nowadays.Tougher to find as the years go by.I have quite a few reman injectors though.Maybe around 11 I think.

Last edited by dieselolds81; Oct 29, 2025 at 02:20 PM.
Old Oct 29, 2025 | 02:14 PM
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Originally Posted by 66_Jetstar
You can use an IR thermometer to see which cylinder(s) are lame. It'll save you some time
Yes that is true.I do have a fluke thermometer that I’ll try and see if I can narrow it down.Cylinder 3 was causing me grief but it’s running much better since replacing the new injector with a reman.I’ll keep everyone updated on how things go.

Today I did get the oil cooler installed.Tomorrow I hope to get the moroso oil filter adapter in place with the oil cooler hoses.







Last edited by dieselolds81; Oct 29, 2025 at 02:17 PM.
Old Oct 31, 2025 | 12:15 PM
  #133  
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The Moroso oil filter adapter is in place at this point but I don’t really trust the ptfe hose I got from eBay a couple years ago.Its not really the hose I’m concerned about but the way the fittings attach to the hose.Those little ferrules make me cringe to be honest.

Tomorrow I’m going to the hydraulic shop to get two hoses made and at least then I can put my mind at ease when I’m driving the truck around not having to worry bout a hose been blown off and pumping oil everywhere.Its just too risky not to use hydraulic hose.More pictures on the way tomorrow.

I did decide to use a slightly different oil filter.Its a 1258 Napa gold which is supposed to be a higher capacity filter.Thats what I read anyway.More pictures on the way tomorrow.


Old Oct 31, 2025 | 07:58 PM
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Tonight I mounted the electric cooling fan in regards to the oil cooler.I have a tiny thermostatic switch that threads into the AN fitting leading to the cooler so it can engage the fan when the temperature climbs up.

It’s coming together anyway.Heading to the hydraulic shop in the morning to get the cooler hoses made up.







Old Nov 1, 2025 | 03:37 AM
  #135  
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I've been following- coming along great!
Old Nov 1, 2025 | 06:09 AM
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Originally Posted by Greg Rogers
I've been following- coming along great!
Thank you Greg 👍

I now have the hydraulic hoses made up.Cost a cool $300 but I’d rather pay that or lose what I’ve invested into this project.Getting ready shortly to install the hoses.I’m waiting on the AN fittings that accepts the thermostatic switch that won’t be here for another few days but I’ll still bring the wiring out to the fan and install a relay,etc.More pictures on the way.
Old Nov 1, 2025 | 09:11 AM
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Here are some pictures of how things currently look.No leaks anyplace.Its coming together gradually.I’ll probably install the wiring and relay for the cooling fan next.










Old Nov 1, 2025 | 06:57 PM
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Here are a few more pictures to add from tonight.I had a couple decals reproduced and they look real good.I asked the decal company to change the air filter part number on the small decal to another part number I gave them but they didn’t change it.But that’s okay.Its only there for looks anyway.

The vehicle emission control decal was tough to find.It took me quite awhile to find one like the original.

The cooling fan wiring is 90% complete.I just need to run the wire from pin 86 on the relay to a switched 12v source and that’ll take care of that until the AN fitting arrives from Amazon so I can attach the thermostatic switch upon the oil line.

I made a little bracket from some aluminum flat bar to keep the intake hose from drooping downward also.





Old Nov 2, 2025 | 04:33 AM
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I still have a few more things to do with it.I have a new transmission dipstick tube to install.Put some new vacuum hose in place from the vacuum pump to the injection pump vrv and install the hood.The brakes still need to be bled also.

I’m also going to send off a set of used pencil injectors I have that I’ve never used before to be rebuilt at a shop in Ontario,Canada that I’ve done business with in the past.I just want to get them gone through,etc in case I have issues down the road.

More pictures on the way…

Last edited by dieselolds81; Nov 2, 2025 at 04:36 AM.
Old Nov 2, 2025 | 07:57 AM
  #140  
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Very nice work. Following along.
Old Nov 2, 2025 | 05:12 PM
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Originally Posted by 67OAI
Very nice work. Following along.
Thank you.👍More pictures,etc on the way.
Old Nov 3, 2025 | 07:15 AM
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I found some paint on Amazon that’s pretty darn close to what the 5.7 diesels came with when brand new from the factory.


Old Nov 3, 2025 | 11:45 AM
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Hi this is a color i fond for these engines, it correspond to a Volvo of the 90' i will send you the cross reference in the next days
Old Nov 3, 2025 | 11:46 AM
  #144  
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Why i coul not post a picture
Old Nov 3, 2025 | 03:46 PM
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Originally Posted by Breakus



Hi this is a color i fond for these engines, it correspond to a Volvo of the 90' i will send you the cross reference in the next days
Nice job on your engine 👌Is it running now or still in the process of putting it back into a vehicle?

Today I made an attempt to install the new transmission dipstick and tube.The old tube was rusted in half.The tube right now is down in place but I need to install a small spacer between the transmission and mounting bracket.Seems the adapter plate that’s bolted to the engine is causing a little interference against the new tube.More pictures to be uploaded when I return home from work.
Old Nov 4, 2025 | 09:55 AM
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Originally Posted by dieselolds81
Nice job on your engine 👌Is it running now or still in the process of putting it back into a vehicle?

Today I made an attempt to install the new transmission dipstick and tube.The old tube was rusted in half.The tube right now is down in place but I need to install a small spacer between the transmission and mounting bracket.Seems the adapter plate that’s bolted to the engine is causing a little interference against the new tube.More pictures to be uploaded when I return home from work.
The engine ran for a little over 30,000 km and broke down again. The bearings on connecting rod number 6 went on vacation. I had already had a problem with this number 6 cylinder before, but it was the bronze connecting piston pin bearing... However, the connecting rod was no longer the same, but that's life! I had the block and cylinder heads resurfaced and installed +.10" cylinder head gaskets to calm things down. My problem is that the engine was compressing at 32 bar (470 psi), which is obviously a bit too much. Now I need to find cylinder head gaskets that are +.20“ thick and... +.20” in diameter, because I installed brand new oversized pistons. Suffice to say that the quest for the Holy Grail seems easy in comparison.
Concerning your transmission dipstick It's already complicated when you stick with the original because of the thickness of the sound insulation. I would say to put it in place at the top with the bracket that secures the motor to the gearbox and then take care of putting it in place on the gearbox side because it seems to me that there is a little more space there.

Old Nov 4, 2025 | 04:27 PM
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Originally Posted by Breakus
The engine ran for a little over 30,000 km and broke down again. The bearings on connecting rod number 6 went on vacation. I had already had a problem with this number 6 cylinder before, but it was the bronze connecting piston pin bearing... However, the connecting rod was no longer the same, but that's life! I had the block and cylinder heads resurfaced and installed +.10" cylinder head gaskets to calm things down. My problem is that the engine was compressing at 32 bar (470 psi), which is obviously a bit too much. Now I need to find cylinder head gaskets that are +.20“ thick and... +.20” in diameter, because I installed brand new oversized pistons. Suffice to say that the quest for the Holy Grail seems easy in comparison.
Concerning your transmission dipstick It's already complicated when you stick with the original because of the thickness of the sound insulation. I would say to put it in place at the top with the bracket that secures the motor to the gearbox and then take care of putting it in place on the gearbox side because it seems to me that there is a little more space there.
If I ever need head gaskets in the future I’ll contact cometic.They can make any gasket you need.Right now I have the victor reinz part number 3736 which I found were the best for this engine.They are discontinued now and have been for quite awhile.I’ve never had any good luck with the felpro head gaskets on this type of engine in the past.

Last edited by dieselolds81; Nov 5, 2025 at 04:31 AM.
Old Nov 17, 2025 | 01:44 PM
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Heading home tomorrow night so I’m hoping to get back at this project when I get there.
Old Nov 21, 2025 | 01:20 AM
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I added a maxifuse to make things a little safer heading to the busbar.The temp switch has been added to the oil line.And I added a few decals along the way.Hoping to get the hood mounted and grille back into place as well very soon.I just need to take the wire from pin 86 of the fan relay for the oil cooler to a switched 12v source and that’ll be good to go.








Last edited by dieselolds81; Nov 21, 2025 at 01:22 AM.
Old Nov 22, 2025 | 04:08 PM
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The engine is running much better now after adding a bottle of liquimoly diesel injector cleaner with 5 gallons of diesel fuel on top of that.A couple weeks ago I added a bottle of stanadyne performance formula with 10 gallons of fuel so the double dose of cleaner probably helped things tonight in making it run smoother.The injectors that I’m using have been tested before with a clean bill of health but have been laying in the box for a couple years.It had a bit of a rough idle but it is getting much better now.I think all it needs is a ride on the highway to wake it up a little.

I did purchase a set of reman injectors a few days ago because parts aren’t exactly plentiful for this type of engine and in another couple of years you probably won’t even find the injectors when you need them.Heres a bottle of the additive I used tonight.



Last edited by dieselolds81; Nov 22, 2025 at 04:17 PM.
Old Nov 23, 2025 | 05:11 AM
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The transmission dipstick tube is now in place as of a couple days ago.It was a bear to get bolted up to the bellhousing.I used a small 3/8” spacer to go between the dipstick tube mounting tab and transmission housing.The tube was hitting the adapter plate so that’s the reason for the spacer.

Tomorrow I’d like to get the brakes bled and go from there.
Old Nov 24, 2025 | 03:06 PM
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I’m heading to a local machine shop tomorrow to get an alignment collar made with a built in lip to be sure the 302 mustang crank pulley stays centered within the olds harmonic balancer.The mustang pulley has a larger hole than what the olds pulley had so I dont want the pulley to slip and go off center.

Last edited by dieselolds81; Nov 25, 2025 at 07:55 AM.
Old Nov 25, 2025 | 07:55 AM
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The pulley and balancer are now at the shop.I was quoted about $250 to make the collar.I told him to go ahead and do whatever needs to be done.Hoping to have it back sometime soon.
Old Nov 25, 2025 | 04:00 PM
  #154  
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Good job, why not use the GM balancer?
Old Nov 25, 2025 | 05:18 PM
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Originally Posted by dc2x4drvr
Good job, why not use the GM balancer?
Thank you.I’m still using the current 5.7 diesel balancer.Its just that the Ford mustang pulley is not snug upon the balancer.Its slightly larger on that inside diameter hole and therefore that’s the reason for that collar I need to get made in order to keep the pulley centered.
Old Nov 26, 2025 | 09:25 AM
  #156  
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Here’s a video of how it sounds.Basically two videos in one.I have the idle speed turned up a little but it’s running a little smoother.Just needs to be driven.

Old Nov 26, 2025 | 07:08 PM
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I have always wanted to build a 5.7 or 4.3 olds diesel. Where on earth did you find a set of NOS pistons? I guess nowadays just about anyone can make a custom set. But the lack of parts availability always kinda turned me off on these, of course I say that and i have 3 6.5 diesels laying around, so maybe I am being too critical... I
f you just fired that up and it had not ran for long in the video, you most likely still have air in the tubes damping the pulse in the lines. On a 6.5 which has a similar fuel system, I usually have to run them up and down the highway for a bit to get them to smooth out.
Nice job
Old Nov 26, 2025 | 07:12 PM
  #158  
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Oh I also forgot to mention that the engines are rare as hens teeth all the way out west where I am. I had a 350dx about a hundred years ago. Sold it to a guy in canada, found it about 10 minutes from my house so at the time, didnt think anything of it. Honestly havent seen any for sale since. I know they are out there, but they always seem to be back east somewhere.
Old Nov 27, 2025 | 03:58 AM
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Originally Posted by The_Jeremiah
I have always wanted to build a 5.7 or 4.3 olds diesel. Where on earth did you find a set of NOS pistons? I guess nowadays just about anyone can make a custom set. But the lack of parts availability always kinda turned me off on these, of course I say that and i have 3 6.5 diesels laying around, so maybe I am being too critical... I
f you just fired that up and it had not ran for long in the video, you most likely still have air in the tubes damping the pulse in the lines. On a 6.5 which has a similar fuel system, I usually have to run them up and down the highway for a bit to get them to smooth out.
Nice job
Thank you.

The pistons I have found in the past on previous 5.7 engines I rebuilt were on eBay but this last set of zollner pistons I bought off a guy in Wisconsin.He was a member on Delphi forums that I used to visit a lot and I remembered him talking about a few sets he had.They weren’t cheap though.By the time I received them from ups it was about a grand or so in total.
Old Nov 27, 2025 | 04:07 AM
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Originally Posted by The_Jeremiah
Oh I also forgot to mention that the engines are rare as hens teeth all the way out west where I am. I had a 350dx about a hundred years ago. Sold it to a guy in canada, found it about 10 minutes from my house so at the time, didnt think anything of it. Honestly havent seen any for sale since. I know they are out there, but they always seem to be back east somewhere.
I had a few of those engines in the past.I’m down to two now.I still have a 1978 D block engine complete that I rebuilt back in 2007.New pencil injectors and nos injection pump.Arp,the full shot.I’ve had a few D blocks that ran wonderful.Absolutely zero issues.I also had a DX engine from a Cadillac Seville but it had a crack in the main web area so it was junk.I tossed it.This current DX engine I just rebuilt came from a Cadillac Fleetwood.The car had all the doors removed.The engine had one cylinder head off.Rain on top of it.I was lucky to have saved it.The .030 overbore cleaned everything up and decked .007 fixed the issue.



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