aviationstation
NAXJA Forum User
- Location
- Peoples Republic of Kahlifornya
Just thought I'd give my 2 cents with respect to rebuilding your XJ 4.0 mill.
If your rebuilding your Jeep, make sure that you check the following before you button everything up! For more details, read the PROBLEMS section below.
1. CHECK YOUR WIRES FOR THE CORRECT FIRING ORDER
2. TURN ON THE KEY, LET THE FUEL PUMP PRESSURIZE THE FUEL RAIL, THEN BLEED THE AIR OUT OF THE FUEL RAIL USING THE SCHRADER VALVE! REPEAT THIS STEP A FEW TIMES (say, 2 or 3).
3. USE A PRESSURE TESTER TO CHARGE THE COOLING SYSTEM BEFORE YOU START THE ENGINE. A COOLANT LEAK WHILE YOUR FAST IDLING A NEW ENGINE COULD REQUIRE A SHUTDOWN, WHICH IS NOT THE BEST WAY TO BREAK IN A NEW CAM (AND RINGS).
COST: The cost is very close to our target of $1,200, but with a longer materials list... (which is good).
1. Engine Kit: EngineTech 4.0 Kit $390.00*
* Price matched by Auto Power Machining, Oceanside, CA
2. Machining: Approx $575.00**. Included:
- Polish & Chamfer Crank
- Resize Rods
- Press on new pistons
- Bore .030" (or $20 bucks a hole)
- Hot tank, flush & paint block and head
- Install cam bearings & freeze plugs
- NDT (non-destructive test block, crank, head)
- Surface check head, new EXH valves & EXH seats
- Grind INT valves & seats, lap all valves
- Install Stem/Guide Seals
** Work performed by Auto Power Machining, Oceanside, CA
3. We also replaced the following items: ($198.00)
- Trans input shaft/pump seal
- Trans filter & fluid
- Water pump, T-Stat (185) & all hoses and clamps
- Heater control unit
- All heater hoses
- Serpentine Belt
- Battery
- Air Filter
- Oil Pressure Sending Unit (very fragile)
- Temp Sending Unit (back of head)
- Engine mounts
- R&R diff fluid
- Misc: 4 New shocks and the rear u-joint
The PROBLEMS: The first start went a little awry. I'm a small block chevy guy and I thought this 4.0 would be a breeze, but a XXXXy misstep on my part made a 1 hour event into an all day problem. The engine would turn over but it was popping back through the intake. My first thought was the nightmare of the timing chain being off a tooth! But, after I pulled my head out (and after I threw my new Snap-On extension about 50 yards), I realized the distributor was off 180 degrees. I opted to pull the dist & reinstall it rather than re-arrange the wires.
Then, it started! But...it had an intermittend miss and would not idle. Using .040 safety wire, I wired the throttle open so that it would maintain around 2,200 rpm. I left it there for a good 20 minutes to get the cam well broke in. During this time the temps were a little out of whack, but after filling the last quart or so of coolant it settled at around 210. This seemed high with a 185 t-stat, but I fugured that there would likely be a higher than normal amount of friction as the rings seated, etc.
With the miss still a problem, I decided to pull the plugs. This is a lot of fun on a new engine that is breaking in! The plugs will likely to be hot enough to completely remove any fingerprints that you may have, so all you mechanices on the lamb should consider doing this!
Anyway, to my dismay the #3 plug electrode was nearly closed (this is why I don't work on the space shuttle). To be sure, I regapped all the plugs and then fired it up. It was still having a hard time starting, but once running it seemed to idle out ok. I then took it on a test drive and was lucky to get up the small hill by my house. At WFO it would barely accelerate or would simply hold its current RPM. Temps were still in the 210-220 range as well.
All was not going good!
I got back home & decided to act on a hunch and bleed the fuel rail line. It's hard to say how much air came out (because its accompanied by fuel) but after doing that, the car not only starts great, but runs good as new. Power is great (for a little 4.0), and the temps are now in the 185-190 range.
Hope this helps those considering a rebuild.
M Randolph
If your rebuilding your Jeep, make sure that you check the following before you button everything up! For more details, read the PROBLEMS section below.
1. CHECK YOUR WIRES FOR THE CORRECT FIRING ORDER
2. TURN ON THE KEY, LET THE FUEL PUMP PRESSURIZE THE FUEL RAIL, THEN BLEED THE AIR OUT OF THE FUEL RAIL USING THE SCHRADER VALVE! REPEAT THIS STEP A FEW TIMES (say, 2 or 3).
3. USE A PRESSURE TESTER TO CHARGE THE COOLING SYSTEM BEFORE YOU START THE ENGINE. A COOLANT LEAK WHILE YOUR FAST IDLING A NEW ENGINE COULD REQUIRE A SHUTDOWN, WHICH IS NOT THE BEST WAY TO BREAK IN A NEW CAM (AND RINGS).
COST: The cost is very close to our target of $1,200, but with a longer materials list... (which is good).
1. Engine Kit: EngineTech 4.0 Kit $390.00*
* Price matched by Auto Power Machining, Oceanside, CA
2. Machining: Approx $575.00**. Included:
- Polish & Chamfer Crank
- Resize Rods
- Press on new pistons
- Bore .030" (or $20 bucks a hole)
- Hot tank, flush & paint block and head
- Install cam bearings & freeze plugs
- NDT (non-destructive test block, crank, head)
- Surface check head, new EXH valves & EXH seats
- Grind INT valves & seats, lap all valves
- Install Stem/Guide Seals
** Work performed by Auto Power Machining, Oceanside, CA
3. We also replaced the following items: ($198.00)
- Trans input shaft/pump seal
- Trans filter & fluid
- Water pump, T-Stat (185) & all hoses and clamps
- Heater control unit
- All heater hoses
- Serpentine Belt
- Battery
- Air Filter
- Oil Pressure Sending Unit (very fragile)
- Temp Sending Unit (back of head)
- Engine mounts
- R&R diff fluid
- Misc: 4 New shocks and the rear u-joint
The PROBLEMS: The first start went a little awry. I'm a small block chevy guy and I thought this 4.0 would be a breeze, but a XXXXy misstep on my part made a 1 hour event into an all day problem. The engine would turn over but it was popping back through the intake. My first thought was the nightmare of the timing chain being off a tooth! But, after I pulled my head out (and after I threw my new Snap-On extension about 50 yards), I realized the distributor was off 180 degrees. I opted to pull the dist & reinstall it rather than re-arrange the wires.
Then, it started! But...it had an intermittend miss and would not idle. Using .040 safety wire, I wired the throttle open so that it would maintain around 2,200 rpm. I left it there for a good 20 minutes to get the cam well broke in. During this time the temps were a little out of whack, but after filling the last quart or so of coolant it settled at around 210. This seemed high with a 185 t-stat, but I fugured that there would likely be a higher than normal amount of friction as the rings seated, etc.
With the miss still a problem, I decided to pull the plugs. This is a lot of fun on a new engine that is breaking in! The plugs will likely to be hot enough to completely remove any fingerprints that you may have, so all you mechanices on the lamb should consider doing this!
Anyway, to my dismay the #3 plug electrode was nearly closed (this is why I don't work on the space shuttle). To be sure, I regapped all the plugs and then fired it up. It was still having a hard time starting, but once running it seemed to idle out ok. I then took it on a test drive and was lucky to get up the small hill by my house. At WFO it would barely accelerate or would simply hold its current RPM. Temps were still in the 210-220 range as well.
All was not going good!
I got back home & decided to act on a hunch and bleed the fuel rail line. It's hard to say how much air came out (because its accompanied by fuel) but after doing that, the car not only starts great, but runs good as new. Power is great (for a little 4.0), and the temps are now in the 185-190 range.
Hope this helps those considering a rebuild.
M Randolph
