4.0 to 4.7 HO drivetrain swap - JeepForum.com
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Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > WJ Grand Cherokee Forum > 4.0 to 4.7 HO drivetrain swap

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Unread 07-16-2013, 10:16 PM   #1
CopperDeer
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4.0 to 4.7 HO drivetrain swap

Alright well in my searches I didn't find many cases of swapping from 4.0 to 4.7 and just a couple vice versa. Seems to have some controversy / stigma attached to it??? My 99 4.0L Quadra-trac has 175k and is quite worn out. Problems with head gasket, rear axle is bent, rear differential is noisy, front diff or DS problems, etc. I found a smashed up 04 with the high output V8 and Quadra-drive with less than 100k mi at an insurance auction I frequent. I can do all the labor myself and will have a helper most the time in a pretty well equipped shop I've generously been allowed to use for a week or so. If I can get it for a reasonable enough price (~$1000?) and hope to recoup much or all of that cost selling spare parts from the swap / donor... what case do the naysayers have? I'm under the impression everything bolts up and is identical on either chassis.

I plan to swap the following from the donor vehicle to my Jeep:
Complete engine w/ all accessories
Transmission
Transfer case
Engine harness
PCM & TCM
Motor mounts, brackets, crossmember, etc
Immobilizer module with key taped to it, eventually hoping to get a key programmed to it's SKIM and cut for my ignition
Instrument cluster, don't believe it's req'd but I like the updated gauges
Both axles and driveshafts, not req'd for swap but a good opportunity
Our A/C is already non-functional so I'll consider what's necessary to adapt there later, if ever

The only thing I am under the impression that I would have to buy is a new radiator compatible with the 4.7 since it was destroyed in the donor car's accident. And of course all new fluids and a tune-up while everything's out.

Any input, advice, encouragement, trolling, etc would be much appreciated!!!


Last edited by CopperDeer; 07-16-2013 at 10:40 PM..
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Unread 07-16-2013, 10:29 PM   #2
rm2001wj
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The 4.7 HO came with a hydraulically driven radiator fan operated by the PCM. Replacing that can be very expensive, close to what you want to pay for HO itself. Try to find a junk yard fan from any 01 or later 4.7 before you commit to this project.
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Unread 07-16-2013, 10:44 PM   #3
CopperDeer
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Thank you! This is EXACTLY the kind of info I was looking for, I didn't know about this. Must have skimmed it over in the FSM, found it now, I see it's tied into the P/S system. Obviously I don't want to risk overheating the sensitive 4.7. Hopefully the P/S lines are salvageable on the donor vehicle and I'll just need the fan. Took a pretty hard hit to the front. I may not be able to source the parts in time but I can get them from a junkyard at a reasonable cost eventually, even if some lines need replacing too it shouldn't exceed ~$100 at the local yard.

Would it be too risky to drive the Jeep a few hours on the highway at night from the shop back home without the cooling fan / power steering system functional? Can't imagine the fans make a difference at low load / high speed / fair ambient temp. Maybe I'll even rig up an electrical fan temporarily. Thanks again for the critical info.

Last edited by CopperDeer; 07-16-2013 at 11:07 PM..
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Unread 07-16-2013, 11:19 PM   #4
pinky2252s
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Quote:
Originally Posted by CopperDeer View Post
Thank you! This is EXACTLY the kind of info I was looking for, I didn't know about this. Must have skimmed it over in the FSM, found it now, I see it's tied into the P/S system. Obviously I don't want to risk overheating the sensitive 4.7. Hopefully the P/S lines are salvageable on the donor vehicle and I'll just need the fan. Took a pretty hard hit to the front. I may not be able to source the parts in time but I can get them from a junkyard at a reasonable cost eventually, even if some lines need replacing too it shouldn't exceed ~$100 at the local yard.

Would it be too risky to drive the Jeep a few hours on the highway at night from the shop back home without the cooling fan / power steering system functional? Can't imagine the fans make a difference at low load / high speed / fair ambient temp. Maybe I'll even rig up an electrical fan temporarily. Thanks again for the critical info.
I wouldnt risk it. I would rig up an electric fan.

Couldnt you just swap the PCM from the donor too...?
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Unread 07-16-2013, 11:39 PM   #5
Redneck92
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Fix/replace the 4.0L with a new 4.0L I'd avoid the 4.7 v8 like the plague. Pain to work on(mainly just because it's a wj), not really the most reliable only good think is they have plenty of power.
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Unread 07-16-2013, 11:57 PM   #6
CopperDeer
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Originally Posted by pinky2252s View Post
I wouldnt risk it. I would rig up an electric fan.

Couldnt you just swap the PCM from the donor too...?
I mentioned I will be swapping the PCM but what does that have to do with the fan? I'm going to try to get all the parts for it before all this goes down but it might not pan out. I'm not sure what I'm going to do about it but it's not enough to scare me from the swap. Worst case I will retain my old P/S setup and use an electric fan. Since we don't have working A/C and I won't be towing anything I don't see why this would be a problem.
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Unread 07-17-2013, 12:00 AM   #7
CopperDeer
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Originally Posted by Redneck92 View Post
Fix/replace the 4.0L with a new 4.0L I'd avoid the 4.7 v8 like the plague. Pain to work on(mainly just because it's a wj), not really the most reliable only good think is they have plenty of power.
Since I need other major parts, I'm pretty set on getting a donor vehicle either way but I could easily get another 4.0L and drop it in. I have a lot of experience with this motor and have done several head gaskets. But if I'm geting a donor vehicle I figure I might as well upgrade. I understand the reliability concerns and it may require some work down the road but it's worth it to me to upgrade to a modern drivetrain design and gain some much needed horsepower and coolness factor
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Unread 07-17-2013, 12:30 AM   #8
Jer-Bear
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The power steering pump makes an awful noise if it isn't turning the fan. Don't risk warped heads, load it on a trailer or pull it.
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Unread 07-17-2013, 12:46 AM   #9
CopperDeer
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I see that there is a flow control valve in the hydraulic fan which would be catastrophic to bypass. I've found a couple threads on deleting the hydraulic fan due to it's high replacement cost. Although there doesn't seem to be an easy fix, I should be able to rig up my 4.0L's power steering pump (internal flow control) onto the 4.7L's bracket and make it work without the hydraulic fan.
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Unread 07-17-2013, 12:56 AM   #10
Jer-Bear
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Well, I've come to learn that the hydraulic is better than electric or mechanical when it works. If the solenoid does in fact go out, there are ways of tracking down the solenoids. I'd keep it if I were you.
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Unread 07-17-2013, 01:04 AM   #11
CopperDeer
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Oh no doubt I agree it's superior. I would love to have it. But it sounds like it will be quite costly and potentially time consuming to repair / straighten out when I already may be pressed for time on this project. I will keep all the 4.7L P/S lines and pump and hopefully can get this fan later down the line and reinstall the 4.7L P/S system with the hydraulic fan. In the meantime the electric fan from my 4.0L should be adequate for our needs. Like I said, it won't face any A/C use, towing, racing, excessive idling / stop&go traffic or ambient temps over 90*F.
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Unread 07-17-2013, 07:36 AM   #12
rm2001wj
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With the 4.7 HO PCM, you can expect the MIL to turn on, at least intermittently, with the code P1499, if the hydraulic fan solenoid is not working or missing.
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Unread 07-17-2013, 10:35 AM   #13
CopperDeer
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What if the solenoid is wired up but not doing anything? I'm sure I can trick the computer into thinking it's operating a fan. Went to the junkyard today and luckily found a 4.7L WJ, but it was a 99, so it used a mechanical fan. Considering converting to use that fan with the electric condenser/aux fan (the setup my 4.0 has now). Ideally would love to have the hydraulic fan someday, though.

Despite the controversy, I'm going to run a 180*F thermostat in this motor too as some added insurance.
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Unread 07-17-2013, 10:42 AM   #14
jserna
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I would get a 4.7stroker I6 if you want the extra power, to avoid the hassle of a swap.
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Unread 07-17-2013, 03:53 PM   #15
CopperDeer
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Honestly for me and the skills and tools I have, a swap is going to be easier than rebuilding an engine. I'm just under the belief the 4.0 is too outdated of a motor nowadays and want a modern drivetrain. Our Jeep needs so much work it just seems to make sense to get a donor and get it all over with at once. I really think I'll end up breaking even on the money too, between a rebuildable 4.0, a great 42RE, NV247, rebuildable axles, and and all spare parts from the donor...
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