85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Well this has been on My Wish List for a long time and I think I’ve finally geared up the courage or as my son would say “at least 95%”, to pull the trigger and go forth with it. I must say that my major hesitation to start on this has been due to my lack of knowledge on a lot of engine/electrical related stuff, but from all the reading/research and with your help I feel like I can pull it off. So, bear with me and with all the questions that I will more than likely be asking as I go through with this project. This will be my first major engine related project, so please take it easy on me with your advice and criticism, but it’s all welcomed non the less…
My current plan is what might seem like a head scratcher but oh well…plan, well I am thinking about “robbing Peter to Pay Paul” Peter being my 01 Suburban and Paul my 85 C10 SWB.

My Sub has served me well since 2001 (155K miles) and now 16 later it’s hardly being used, if any at all and thus the sacrificial one…my 85 on the other hand is my daily driver, but with the 305/TH350 it leaves me with a lot to be desired for and I mean, c’mon, which would be more enjoyable to drive, big ole 01 Sub or an 85 C10 with the 5.3…or at least that’s just my way of justifying my plan to my boss…lol
What say you?
What besides the Engine/Trans/ECU/Harness (which I might just buy one) can I use from the donor?
I don’t plan on a complete tear down of the engine or trans at this point except for some seals and gaskets that are necessary. well thanks in advance for the advice and fingers crossed I don't throw in the towel. more to come.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Sounds like a plan to me!

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

You wont regret it! Plus you have the assurance of knowing that the donor engine is good since you've owned it so long. :metal:

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Sounds like a fun swap, will be tagging along.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

I'm not sure if yours is dbw or dbc...if dbw then you'll need the gas pedal
some people use the LS intake and filter box....gives it a factory look..
with the a/c on your 85 you may want to relocate the compressor. .if not you'll have to wack a notch in the frame...

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

After a long 6 month hold on the project due to unforeseen circumstances, engine rebuild on the Stang, I can say that the project has officially begun. So over the past two weeks I have been working slowly on the disassembly to prep the engine for removal.
I started by draining the coolant, oil and trans fluids. Then removing all of the front stuff to make a hole for the engine and transmission to come out easier when it is time for it. The core support is still in but its loosely held by the two top nuts on the fenders. Although I am doing this in my driveway, I still want to keep the dismantling mayhem to a minimum and not be a nuisance to the neighbors.

Then I moved on to disconnecting and labeling all the plugs from all around the engine. Removed the intake, coils, and loosened the manifolds. I also removed all the A/C related lines, drier to make more room for me. Not planning on using any of this just for room.
Next I moved to the tranny part. Removed the crossmember, removed all the O2 sensors and removed the exhaust from the manifolds. Disconnected the shift linkage. Don’t know if there is anything else I need to remove from the tranny before I take it out.
Started to loosen the wire harness by removing all the plugs at the fuse block. Tons of questions on this part…

This weekend I decided to work on the inside stuff. I am going to try to see if I use the seats and adapt them into the truck and so I removed these. The hard part was getting to the nuts when there is no longer any power to the seats…lol. I guess I should have started there before removing the battery.
So I had to find the power wires to the motors and de-pin the plug since I did not want to just cut the wires. Then I used my battery jumper pack and was able to get the seats moving so I could get to the nuts. Also removed the rear view mirror and harness for it, Idea from LS1 Nova.

So this is where I am at for now. More to come including all the questions.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Question regarding all this, do i keep all this blocks intact? or was i supposed to keep them all plugged in to the block? also the big harness going into the truck, does that get cut or do i have to pull it out with out cutting it?

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

are you gonna redo your harness or buy one ready to go?.....if your gonna buy a harness then I wouldn't worry bout the wiring as that'll all be new wire and plugs....
if your gonna redo your harness then you don't want to cut any wiring...yet...

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Plan A is to rework the harness my self but I am keeping plan B as an option if it becomes too much for me so that's why i decided to stop before cutting anything at this point.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Just finished up my 85 and it was not as bad as I thought.

Check out http://lt1swap.com/

Read every link and you can do it. He ever reflashed my PCM.

Good luck!

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Jay,

What did he charge you for the re flash? And what all did you have done? As far as any engine tune is concerned?

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

That's the site I will be mainly going to be using for this but since in my case I am the one removing the harness from the donor truck, I was wondering what bundles and plugs I needed to keep from all the stuff that was plugged into the fuse block. for example:
the Pic from LT1swap has the all 4 connectors, C100, C152, C2 and C153, which I have identified in mine (on pic 2) and they all merge with the engine harness and the computer wires (pic 3) so I will be keeping all these.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

but what about the other connections, if any, do I need to keep or remove from the vehicle. I have these other connections: this bundle goes into the cabin so do I need any from this bundle or just leave it here?

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

then I have this bundle that goes straight under the truck to the back? are there any from here that I need to keep? this contains the other end of the c100 and the c152 so do I need to keep these other ends of each of those, will I bee needing them?

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

I do not remember the exact price but I think it was under $100.

This was my request:
• Remove VATS
• Remove Emissions: EVAP, EGR, AIR, Rear O2, etc. if applicable
• Remove A/C controls
• Remove Flex Fuel ability
• Retain MLPS
• Retain MAF – 5 wires
• Retain VSS – use 1985 stock rear axle ratio and tire size for now
• Retain 2003 PS pump with 1985 steering box
• Enable electric speedometer - please calibrate for stock 1991 Suburban speedometer
• Enable cooling fans at stock temps - will use clutch fan for now but may switch over in future
• Enable DBW Cruise Control capabilities, if needed


I included as much info as I had on both my truck and the donor Tahoe. VIN, Gear Ratios, etc. I did not ask for any tuning as I wanted to get it in and running reliably before I started "tweaking" anything.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Once I remove the engine and the transmission, the Suburban will be going away to scrap soon after so :

Maybe dumb questions, but can I use any of the following:

fuel system items i.e. pump, lines...?

What about drive shaft (with some mods)?

anything, anything else?

I have removed and am keeping the front seats, the center console, the hitch (with the wiring harness, which I don't even know if it will fit one the truck but if not I can sell it).

with the exception of the harness that goes under and in between the dash, I have removed the entire wire harness that ran all the way to the back on the celling and floor which control the seats and all the dome lights.
interior harness was removed mainly because I wanted the wire part for the rear view mirror and then I just kept going so.

so I will keep plugging away for now but thanks for any info and helpful info you can provide

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

I did not remove my motor and trans so I'm not sure. The yard I bought from did the removal.

I asked that they include the fuse box but anything that did not go to the underhood fuse block or engine harness was cut. So I had ALOT of bare wires!

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Can i ask a quick question for you lost81c10? that last pic you posted, with the red plastic cover and bracket for the battery terminal / cables....

can you get a pic or describe where the ground for that goes to ? If I recall the big red cable goes to positive on the battery, and one up to the alt.
But where to the others go? I have that same assembly right now in my truck and wondering where to run them. Don't have a donor to look at. I'm thinking the ground runs to the frame somewhere ?

I have the big black cable going to the starter, that hugs around the oil pan....


thanks

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

my .02:

I would probably keep the driveshaft, it can likely be shortened to work for you.
cheaper than buying a new one

fuel system, most likely your lines are rusted / about shot. The pump assembly in the tank is not known as the most reliable piece....but you can possibly re-use that bucket assembly depending on what tank setup you have planned.

radiator and shroud assembly could work, if you don't mind cutting up your support. The LS one is quite a bit wider

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Hope i am understanding your question.
the ground from the red cable that goes to the + on the battery which has the ground coming out of it goes to the fuse block as pictured below.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

I guess i can included but i think you got where they plug into the starter but just in case and if you didn't need it then its all good.
Cable A is the Positive connection from the battery and into the Red plastic box you mentioned. Cable B comes from the harness and routed the same way as cable A. Cable B has 2 connections that branch off of it right as it gets to the starter.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

If you're going to be modding your own harness, then you really only need the harness on the engine. The big old fuse box will most likely not be used. You can use it, but I prefer the cleaner look of a much smaller fuse box dedicated to just the engine. It looks like its DBC so all you should need from inside the truck is the ALDL connector under the dash. Might keep the cruise control module in case you decide to add that later on too.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Thanks for the info. Ok so I will just take the engine harness (going all the way back to the rear, tranny, fuel pump..) which goes to the computer and to the three connector C100, C152 and C2 all the rest I will just leave in the truck.

What is the ALDL? I had not hear of that one. Now I have removed the OBD (I think that is what is called) connection with the wires from under the dash, driver side and Also the rear view mirror with the wires. By the way, what else besides the wires going to the mirror do I need to make it work like you did in your truck? do I need the little red looking light from the middle of the dash close to the windshield? I have it and the wires that were going to it but don't know if I need it at all as part of the mirror.

for cruise control, I did want to adapt it but from what I had read I thought it was impossible for a DBC body. so where is the module for it? is it this box in the pic? if it is I will remove it along with the cable to the TB and the wire connection which seems to be going into the cab, so just cut the wires close to the grommet or trace them all the way to the inside?

looking at the pic reminded me that I wanted to keep the hood light too.

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Cool. Thanks man!

Re: 85 C10 "Rob Peter to Pay Paul" 5.3 Swap
 

Assembly Line Diagnostic Link or ALDL is a proprietary on-board diagnostics system developed by General Motors prior to the standardization of OBD-2.

This is the underdash plug for the OBD system. you will need this.