4.6 / 4.0 swap

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SMLE

Well-known member
Aug 21, 2014
107
2
GA
4.6 / 4.0 swap ---SUCCESS---- !!

My 2003 Discovery II engine failed some time ago. Looks like a sleeve problem.


I also have a 1996 Discovery I, manual transmission. I am in the midst of swapping the 4.0 out of it for a Chevy 350. The 4.0 was running when I pulled it and is just sitting on a stand in the back of the shop. I am wondering if I could just slip the 4.0 into the 2003 without too much trouble, just to get it back on the road for a while... Will it bolt up to the '03 transmission?
 
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S

SMLE

Well-known member
Aug 21, 2014
107
2
GA
Yep, the 2003 has the secondary air...


So, it sounds like installing the '03 heads from the 4.6 onto the '96 4.0 lower end should work, with some modifications to the crank sensor bracket.


Should I think about swapping the front covers, or are they not compatible with one another?


The 4.6 is a Bosch engine, but the 4.0 is a GEMS.


Starting to sound like for the cost of a gasket set, head bolts and some minor parts I may be getting the '03 back on the road soon.
 
squirt

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
Just curious, how did the 4.6 failure manifest? Is it just ticking/tapping when it's warm, like most "slipped liners"?

If so, I wonder whether it might be worth the effort to try to pin the sleeves to solve the issue. Not much to lose, and might be easier than retro-fitting the older block.
 
S

SMLE

Well-known member
Aug 21, 2014
107
2
GA
squirt said:
Just curious, how did the 4.6 failure manifest? Is it just ticking/tapping when it's warm, like most "slipped liners"?

If so, I wonder whether it might be worth the effort to try to pin the sleeves to solve the issue. Not much to lose, and might be easier than retro-fitting the older block.
Click to expand...



Bought the vehicle at around 110,000 miles . Was not ticking the whole time we looked and test drove. Started ticking within a couple days of purchase. Continued ticking till around 124,000 miles at which point it started overheating by pushing the coolant out the overflow after a few minutes of running. Never allowed to severely overheat...


Pulled the motor, disassembled the motor and found cylinder number five to be "steam cleaned". Head gasket was good. Motor appeared to have been rebuilt at some point as I found 40 over pistons...


Pressure tested the block up to 80 pounds and found no leaks. In the process of pulling the sleeve on #5 and re-pressure test.


Using the 4.0 sitting idley in the shop idea came to me a couple days ago and decided to ask questions here about...


Thanks!
 
jymmiejamz

jymmiejamz

Well-known member
Dec 5, 2004
6,008
361
35
Los Angeles, Ca
SMLE said:
Pulled the motor, disassembled the motor and found cylinder number five to be "steam cleaned". Head gasket was good. Motor appeared to have been rebuilt at some point as I found 40 over pistons...


Pressure tested the block up to 80 pounds and found no leaks. In the process of pulling the sleeve on #5 and re-pressure test.
Click to expand...

You will almost certainly find a small crack behind the liner. There are no cooling ports on cylinder five, so a head gasket leak would not cause that. Its possible that the head is cracked, but highly unlikely. FWIW I have had two different machine shops tell me that you can just put a new liner in without actually fixing the crack, but I've never tried that. You can have the crack welded and then have a new liner put or just go with another block.
 
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discostew

Well-known member
Sep 14, 2010
7,733
1,024
Northern Illinois
jymmiejamz said:
You will almost certainly find a small crack behind the liner. There are no cooling ports on cylinder five, so a head gasket leak would not cause that. Its possible that the head is cracked, but highly unlikely. FWIW I have had two different machine shops tell me that you can just put a new liner in without actually fixing the crack, but I've never tried that. You can have the crack welded and then have a new liner put or just go with another block.
Click to expand...

I totally agree with Jymmie on this.
 
KyleT

KyleT

Well-known member
Mar 28, 2007
6,059
8
39
Fort Worth, TEXAS
Fwiw I've seen 40 over Pistons from the factory.

Also the front cover will need to be swapped over as the 03/04 doesn't have An oil cooler.


Also swap the rods and crank into the gems block using the 4.0 Pistons.
 
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