'89 R3500 Crew Cab 2wd to 4wd conversion & beyond

[mrk5]

I wanted to have AN lines for the oil cooler so I don't have to mess with the factory style clips. Not that I have any experience with them, but the cooler I'll use will likely have AN fittings and I don't want to have to adapt the factory hoses to work with that. The catch is one of the factory fittings has a special piece on the end that's needed in order to direct flow to the cooler. Scoggin Dickey used to make an adapter with the AN fitting but it's not longer available. The fittings are steel so I bought weld-on AN male adapters. I cut the end off the factory fitting where it's slotted for the clip.




Stacked them up in a vice clamp to weld together.




Had to do a little grinding to keep the flats available for a wrench.




Here it is fully assembled with the plastic do-dad on the end.




If it wasn't for the plastic do-dad, these would be straight forward adapters, -10AN to 3/8 NPT. Since the weld-on AN adapters came in a 2 pack, I made the other fitting the same way.






The other thing I did with the oiling system was to change the bypasses, there are 2. Factory units are 10psi but there are also GM Parts versions that are 30psi. Some people also just remove the bypasses. The purpose of them is to bypass the filter and cooler if there is a differential pressure greater than 10 or 30 psi depending which version you use. If you remove the bypasses, all oil is directed to the filter and cooler. The issue becomes if the filter or cooler get plugged up, the engine could be oil starved. The downside to the low 10psi versions is that some filters are restrictive enough oil ends up bypassing the filters instead of getting cleaned up. I decided I'd rather have dirty oil than no oil in the case of a filter issue. Plus I change the oil yearly with 3000 miles on it tops so it shouldn't be too dirty.

Bypass part number:

GM Genuine Parts 25161284: 30psi bypass​

GM Genuine Parts 25013759: 10psi bypass​

The 2 bypasses can be seen below. The shiny round pieces, one in the center of the filter area and the other around the perimeter.



I used a screw driver to pry out the outer bypass. You can thread a 3/8" bolt into the center bypass to pry it out since it's way down in the hole.

I thought I was in a pickle because I don't have an allen wrench big enough to get the filter adapter screwed out. Luckily I had a punch that fit perfectly. Just used a big adjustable wrench to turn it.

 

[ktmoutfront]

Part numbers for the 30psi bypasses?

 

[sweetk30]

just a fyi : 8.1L dont need a fancy adapter . straight pipe thread . and if pulling cooler just pull pressure valve units and go .

good thinking outside the box tho and got it done . and NOT melting the plastic .

 

[nvrenuf]

I put a Fram filter on my fresh 454 while it was on the engine stand and installing it in my Blazer…. I didn’t want to chance bumping / denting a good Wix 2 qt filter.

 

[mrk5]

Part numbers for the 30psi bypasses?

Bypass part number:

GM Genuine Parts 25161284: 30psi bypass​

GM Genuine Parts 25013759: 10psi bypass​

​

They are less than $10.

 

[mrk5]

just a fyi : 8.1L dont need a fancy adapter . straight pipe thread . and if pulling cooler just pull pressure valve units and go .

good thinking outside the box tho and got it done . and NOT melting the plastic .

The plastic piece popped off. Wasn't too bad getting off, but I thought I was going to break it popping it back on. Managed to get it back on without damage. I had ordered a new replacement fitting in case I did break it.

 

[ashman]

I don't know why you didn't want the factory clip style. When have you ever seen those fail?

 

[mrk5]

I don't know why you didn't want the factory clip style. When have you ever seen those fail?

Haha, and create a murder scene on the Rubicon Trail?

 

[folkenheath]

The other thing I did with the oiling system was to change the bypasses, there are 2. Factory units are 10psi but there are also GM Parts versions that are 30psi. Some people also just remove the bypasses. The purpose of them is to bypass the filter and cooler if there is a differential pressure greater than 10 or 30 psi depending which version you use. If you remove the bypasses, all oil is directed to the filter and cooler. The issue becomes if the filter or cooler get plugged up, the engine could be oil starved. The downside to the low 10psi versions is that some filters are restrictive enough oil ends up bypassing the filters instead of getting cleaned up. I decided I'd rather have dirty oil than no oil in the case of a filter issue. Plus I change the oil yearly with 3000 miles on it tops so it shouldn't be too dirty.

Bypass part number:

GM Genuine Parts 25161284: 30psi bypass​

GM Genuine Parts 25013759: 10psi bypass​

The 2 bypasses can be seen below. The shiny round pieces, one in the center of the filter area and the other around the perimeter.

Great work Scott!

That is a decent compromise, I would like to point out that oil can bypass the filter on both versions, 10 psi and 30 psi, you just reduce the chance it will bypass. This may sound obvious, but let me explain.

Some filters are so junky with the fibrous filter media they literally don't allow any oil through from when they are brand new. If you block off the bypass completely, you will see this immediately because you will have no oil pressure. We have seen this on the dyno where a brand new filter (bypass plugged in the block) had no oil pressure! Changed the filter, problem solved. However, whether your bypass is 10 or 30, you wouldn't even know this, you would just be supplying 100% unfiltered oil for that entire oil change interval.

If you use quality filters, this is less likely. And if you change your oil and filter often, clogging is unlikely. So I think those two things are the most crucial, whether you plug the bypass or not.

In almost 2 decades of running with the bypass blocked (in 2 vehicles), using quality filters, and changing it frequently, I have yet to have an oil pressure issue because of the blocked bypasses, and I know 100% of my oil is filtered, all the time, because if it wasn't, I would of lost oil pressure.

I do carry a spare filter, and I have both a gauge and a warning light, just in case. You can take it a step further, and have the engine shut off, or reduce power(timing), if oil pressure is below a certain point. One downfall to that, if there is some super rare occasion where you lose oil pressure, right at the exact moment you need power to get out of say, a life threating situation that will be over in seconds, you may rather risk engine damage than be injured/killed. That's why I use the idiot light and the gauge, I should see it right away, but its 100% up to me to shut it down. If it's just a gauge and you see it even only 30 seconds later, it may be too late.

Now, when it comes to the oil cooler bypass, that one makes sense. You may also consider combining a thermostat with the bypass. No sense in having the oil cooled when it's below 200 degrees, too cold of oil will build up condensation in the oil. Of course just having an oil temp gauge would tell you whether this system is functioning correctly or not. Your climate may dictate whether you add an oil cooler or thermostat with it.

 

[mrk5]

Great work Scott!

That is a good compromise, I would like to point out that oil can bypass the filter on both versions, 10 psi and 30 psi, you just reduce the chance it will bypass. This may sound obvious, but let me explain.

Some filters are so junky with the fibrous filter media they literally don't allow any oil through from when they are brand new. If you block off the bypass completely, you will see this immediately because you will have no oil pressure. We have seen this on the dyno where a brand new filter (bypass plugged in the block) had no oil pressure! Changed the filter, problem solved. However, whether your bypass is 10 or 30, you wouldn't even know this, you would just be supplying 100% unfiltered oil for that entire oil change interval.

If you use quality filters, this is less likely. And if you change your oil and filter often, clogging is unlikely. So I think those two things are the most crucial, whether you plug the bypass or not.

In almost 2 decades of running with the bypass blocked (in 2 vehicles), using quality filters, and changing it frequently, I have yet to have an oil pressure issue because of the blocked bypasses, and I know 100% of my oil is filtered, all the time, because if it wasn't, I would of lost oil pressure.

I do carry a spare filter, and I have both a gauge and a warning light, just in case. You can take it a step further, and have the engine shut off, or reduce power(timing), if oil pressure is below a certain point. One downfall to that, if there is some super rare occasion where you lose oil pressure, right at the exact moment you need power to get out of say, a life threating situation that will be over in seconds, you may rather risk engine damage than be injured/killed. That's why I use the idiot light and the gauge, I should see it right away, but its 100% up to me to shut it down. If it's just a gauge and you see it even only 30 seconds later, it may be too late.

Now, when it comes to the oil cooler bypass, that one makes sense. You may also consider combining a thermostat with the bypass. No sense in having the oil cooled when it's below 200 degrees, too cold of oil will build up condensation in the oil. Of course just having an oil temp gauge would tell you whether this system is functioning correctly or not. Your climate may dictate whether you add an oil cooler or thermostat with it.

That's a much better explanation than I gave. I had forgotten about the oil cooler thermostat idea. I was wondering if it's possible for the bypass to open when the oil is really cold.

Another surprise project I've been working on while the engine is out of the crew cab. Be prepared to be shocked.




I will keep the regular headlight set up and make the grill narrower. My biggest obstacle is the radiator. I have the diesel size radiator that is 6" wider than a typical radiator. When I narrowed the driver side, the cut line landed in the radiator area. After drawing a lot of cut lines and doing some thinking, I landed on a plan. I sectioned the headlight buckets out of the core support. I cut an additional 5-1/4" off each side and welded the headlight buckets back in. Then I cut the ends off the core support. This way the radiator mounting provisions are unchanged. A little bit of the radiator will be behind the headlight on the driver side.











Here you can see the piece I cut out.



Once the engine is ready I'm going to get it back in the truck and then get to work finishing up the front clip. I wanted to have the core support ready so I can install the radiator and be able to run the engine. Which also makes it easier to move the truck in and out of the shop to work on it.

 

[nvrenuf]

Are the fenders turned in at the cab or mid way?

 

[mrk5]

Are the fenders turned in at the cab or mid way?

I'm planning to angle them from the cab. Since the inner structure is already half tore out, it won't be hard to finish cutting it out.

 

[Fastereddie]

Oh snapThat's a much better explanation than I gave. I had forgotten about the oil cooler thermostat idea. I was wondering if it's possible for the bypass to open when the oil is really cold.

Another surprise project I've been working on while the engine is out of the crew cab. Be prepared to be shocked.

View attachment 466650


I will keep the regular headlight set up and make the grill narrower. My biggest obstacle is the radiator. I have the diesel size radiator that is 6" wider than a typical radiator. When I narrowed the driver side, the cut line landed in the radiator area. After drawing a lot of cut lines and doing some thinking, I landed on a plan. I sectioned the headlight buckets out of the core support. I cut an additional 5-1/4" off each side and welded the headlight buckets back in. Then I cut the ends off the core support. This way the radiator mounting provisions are unchanged. A little bit of the radiator will be behind the headlight on the driver side.

View attachment 466654

View attachment 466653

View attachment 466652


View attachment 466651


Here you can see the piece I cut out.

View attachment 466655

Once the engine is ready I'm going to get it back in the truck and then get to work finishing up the front clip. I wanted to have the core support ready so I can install the radiator and be able to run the engine. Which also makes it easier to move the truck in and out of the shop to work on it.

 

[mrk5]

I've been searching to figure out how I could cap the fitting that connects the EGR to the exhaust. I can't believe how many forum posts I found with the wrong information until I finally got the right one. Honestly some of the problem is figuring out the best search term because these last 454's can be referred to by several terms; GenVI, Vortec 454, 7.4L, 7.4L Vortec, 7400 Vortec, and L29. Anyway, I finally found the correct thread info and found the perfect plug on Amazon. The thread was "7.4L EGR" in reference to my comment about all the different search options.

I had mic'd the threads on the male part of the fitting and they measured 1-1/16" diameter on the threads and that actually helped me find the correct answer. The fitting is a male -14 JIC to male 3/4" ORB (O-Ring Boss). The 3/4" ORB equates to a 1-1/16"-12 thread size into the intake manifold. It would be relatively easy to find a -14 cap but I really didn't what that big fitting poking out there. This is the plug I found: https://www.amazon.com/gp/product/B00CCXZMYM/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Before:


After:


Making a plate to cover the EGR valve area will be pretty easy. I don't know why the original fitting is so beat up on mine. It came out pretty easy with a big socket and the impact. I had some big deep metric socket for a sensor I don't remember now what it was from that got the job done.

Incidentally, the factory fitting is steel so a fella could just weld a cap onto it if they didn't want to spend $6 for the fitting I found.

 

[rderosier]

That's a much better explanation than I gave. I had forgotten about the oil cooler thermostat idea. I was wondering if it's possible for the bypass to open when the oil is really cold.

Another surprise project I've been working on while the engine is out of the crew cab. Be prepared to be shocked.

View attachment 466650


I will keep the regular headlight set up and make the grill narrower. My biggest obstacle is the radiator. I have the diesel size radiator that is 6" wider than a typical radiator. When I narrowed the driver side, the cut line landed in the radiator area. After drawing a lot of cut lines and doing some thinking, I landed on a plan. I sectioned the headlight buckets out of the core support. I cut an additional 5-1/4" off each side and welded the headlight buckets back in. Then I cut the ends off the core support. This way the radiator mounting provisions are unchanged. A little bit of the radiator will be behind the headlight on the driver side.

View attachment 466654

View attachment 466653

View attachment 466652


View attachment 466651


Here you can see the piece I cut out.

View attachment 466655

Once the engine is ready I'm going to get it back in the truck and then get to work finishing up the front clip. I wanted to have the core support ready so I can install the radiator and be able to run the engine. Which also makes it easier to move the truck in and out of the shop to work on it.

Ohh man, awesome.
Now do a demo on how to do the 90 headlights narrowed, thx.

 

[mrk5]

I feel like I neutered my poor big block. Went from tall and proud to a little stubby.





Yes, I lopped off a big chunk of the oil fill tube. I tried driving the tube out but my first attempts weren't getting any where and it seemed like it was going to be a struggle.

 

[kgblazerfive]

I like the front end.

I am going to add some to mine once I get working on the cab swap. I really like how sloped mine is so going to take some work to get it to all fit and work and stuff.

 

[82355]

You should get a tunnel ram!

Martin

 

[Tnsejed]

I missed alot over the last few weeks. Looking good Scott. Dovenose is nice!

 

[mrk5]

You should get a tunnel ram!

Martin

Honestly, I would like to just for the fun and ridiculousness of it. I was just commenting to Nate about it when we were walking around the swap meet. If I ever stumble onto a good deal, I might just do it. Tunnel ram with multiport injection would be awesome.