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Discussion Starter · #1 ·
Hi all,
Later this week I will be pulling the engine from my truck and replacing it with a used engine pulled from a used truck, and I would like some suggestions as far as what work to do on the engine while I have it out, I have considered everything from a complete overhaul of the engine to simply putting the new engine in as is. Tell me your opinion and why.
Here is some background. The truck is a 94 K3500 NV4500. Mostly stock except for 2/0 battery cables, a high idle switch, glowplug controller w/ duraterms upgrade lights, upgraded speakers, and heated seats front and back. Used as a farm truck/ daily driver/ adventure rig w/ cab over camper.
I don't put many miles on the truck as I don't commute for work (camp job) but I do want it to be reliable as Im driving the kids to hockey with it or for when we take the camper out of town.
The current engine runs strong, no real complaints there, but the edge of the block is broken off where the rear starter bolt mounts. I've known about this problem for about 8 months, but I suspect it may have been like that for at least the 3 years I've had the truck. Still starts, I'm still driving the truck. However after reading into the issue on this site I've decided it's worth swapping the block for peace of mind. I've taken to parking on a hill when I'm far from home or deep in the woods out of cell range.

The new engine comes from a 96 c2500 with an auto has been parked several years. New batteries and a little rigging of the fuel system and it fires right up. 135000 miles.

Both engines are F code.
New engine is obdII I plan to use all electronics off of the old engine.
Turbos are not the same any thoughts on which is better?
Accessory positions are different, and I'm considering running a dual alternator set up and ditching the vac system for the turbo.

I plan to continue driving the truck for at least ten years. Budget for this project is somewhat flexible, but I drive a quarter century old truck because I'm frugal ( and let's be honest these trucks look way better than anything new on the market)
So fire away with your thoughts, opinions tips or tricks.
Thanks in advance.
 

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Ronald Reagan fan
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If the replacement engine runs great then I’d probably leave things as is.On the other hand replace the glow plugs if condition is unknown so you won’t struggle trying to start it afterwards during frigid temperature.

How does the oil pan look?
 

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1994 k3500 CCLB, NV4500
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Discussion Starter · #3 ·
I will probably be swapping the glow plugs as the ones in the old motor are relativelyi new duraterms and I have been very happy with how they work.
You don't think it's worth replacing the rear main seal or head gasket preemptively while the engine is out and on a stand?
What do you mean about the oil pan? It doesn't appear like it's been damaged or are you suggesting I pull it and look for debris or signs of wear inside?
 

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I'd check the rear main seal, oil pan, water pump, Harmonic Balancer and Pulley, change out the valve cover gaskets, Fresh OPS, replace all rubber fuel lines and fuel return lines.
Pop test the Injectors, and replace those glow plugs as you mentioned
 

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Ronald Reagan fan
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I will probably be swapping the glow plugs as the ones in the old motor are relativelyi new duraterms and I have been very happy with how they work.
You don't think it's worth replacing the rear main seal or head gasket preemptively while the engine is out and on a stand?
What do you mean about the oil pan? It doesn't appear like it's been damaged or are you suggesting I pull it and look for debris or signs of wear inside?
When I mentioned oil pan I was referring to a lot of rust/flaky appearance.Wouldnt want to see it spring a oil leak if the metal is thin.Well if you are putting the engine on a stand,new head gaskets and bolts are a good thing to do.It beats leaning over the fenders trying to do it in the truck that’s for sure.
 

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Discussion Starter · #6 ·
Yes engine will be on a stand, I am pulling it and everything else useful off the donor then moving the donor out to make room in the shop then bringing my truck in to do the swap. I'd like to take my time and cover all my bases while I have the chance.
Haven't spent a lot of time with the new engine, but I know the oil pan on the old engine is solid so if need be I will swap them.
 

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Ok.Sounds good.
 

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Discussion Starter · #8 ·
OKDually, you mention pop testing the injectors, and I seem to remember reading on hear how to make a pop tester with a hydraulic bottle jack. I couldn't find it on here though. Can you send me the link to that if you know where it is? Thanks.
 

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OKDually, you mention pop testing the injectors, and I seem to remember reading on hear how to make a pop tester with a hydraulic bottle jack. I couldn't find it on here though. Can you send me the link to that if you know where it is? Thanks.
There are video links on Youtube like this example:
 

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Before installing. I would run a compression check on the donor engine. To verify it is in good shape with no blown head gasket or cracks. Lot easier to fix these when engine is out of the truck.
Might also want to pop the oil pan and inspect for cracks in the main webs.
Also beings your truck is a 94 1 ton. It most likely has the oddball injection pump only used in 1994 HD 6.5 trucks. The IP out of the 96 will not work with your PCM unless the model numbers match
 
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I do head gaskets, ARP head studs and new injectors. But 1st, pull pan to check for main web cracks . I check the heads and block deck to be sure nothing is warped. Heads are checked for cracks also. I also put new umbrella style valve stem seals in.
The 96 turbo would be a upgrade.
 
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Discussion Starter · #13 ·
Thanks for all the responses. I will be sure to check the IP to see if they are the same. A couple more questions: first all the gasket sets seem to come with oil pan and valve cover gaskets. Are these gaskets any good or should I just stick with the black gasket maker? Seems like there are only a handful of gaskets on these engines from the factory. Maybe this is a dumb question but do these need an exhaust manifold gasket? As far as I can tell there is no trace of gasket on the exhaust manifold.
Second: the 94 runs green coolant and the 96 orange does it matter what I put in the 96 engine? The gaskets I ordered as well as the whole rest of the cooling system will be from the 94.
 

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I would use a tube of Permatex " The right stuff" on the valve covers.

If your 96' has DexCool and you want to change it then you need to do a complete flush of the system.
If you mix other coolants with DexCool it will gum up your coolant system.
Other wise, just stick with the Dexcool
 

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Discussion Starter · #15 ·
Ok that's good to know, how through does the flush need to be? The block (with the dexcool) is drained, if I hook it up to my old cooling system and fill it with regular antifreeze could the little bit of residual in the system cause issues?
 

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Ok that's good to know, how through does the flush need to be? The block (with the dexcool) is drained, if I hook it up to my old cooling system and fill it with regular antifreeze could the little bit of residual in the system cause issues?
If you flush you need to get rid of all of the Dexcool. Any remaining that mixes with the other coolant will sludge up the system.
You will need to flush the block and system really well
 
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I like putting a T fitting in the heater hose and connect a garden hose to the fitting.It’s a good way to get most of the gunk out of the system.
 
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