Hi, this is some info for anyone looking to swap out the MR18DE with its bigger sibbling the MR20DE.
Whats Prompted This
I did this because my MR18 started to fail at about 70K miles (only 2 years old). At first it sounded like a diesel at startup, but after about another 5K miles it sounded that all the time. It would die if I came to a normal stop so I would have to come to a "slow" stop until I felt the transmission disengage or if I was forced to stop quickly I usually popped it into neutral. What made me know that it was something outside of normal piston slap or valve clearance was the extremely excessive oil consumption I was seeing as noted in this thread
. I changed the oil maybe every 7-10K miles which is not bad for modern oils, plus I use the car to commute so its almost all highway mileage at cruising speed. The engine was not abused.
Of course Nissans warranty on the car is quite pathetic for a modern car. 36,000 miles or 3 years normal and 65K miles on the drivetrain. And in fact they no longer offer the MR18 as an option so that made me wonder if they know something is wrong with the engine.
After takeing my old engine out I was able to get a better look at it. I haven't taken the engine apart but it is very obvious that cylinder 3 is the failed cylinder. I'm referencing cylinder 3 from the timing chain end:
Passanger side [Timing Chain 1 2 3 4] [transmission] Driver side
Most the of failure reports I've seen have been cylinder 3 and I would assume this is the same one.
Heres what the spark plugs and exhaust valves look like.
Why the MR20
Well obviously the 0.2 liters increase in displacement is a nice feature. And the fact that people have reported that the 1.8L Versa ECU is able to run it without issue. But the other thing I was thinking about was that the Sentra was simply a more expensive car then the Versa. So maybe some of that money went into a better built engine. Just from looking at the two engines side by side I could see some little things here and there where the MR20 had a little bit better parts quality. So if there are tell tell signs on the outside I'm hoping there are some on the inside as well
. While I have heard about several Versa's with the MR18 going bad I really haven't seen much about the MR20. But remember the MR18 was an upgrade so many of the Versa's out there don't have this engine where as the MR20 was the base engine so alot of Sentra's have this engine. The engine is bigger, but only about 10% bigger. So realistically, the gains of a stock MR20, your looking at maybe the gains that an MR18 would see with intake/header/exhaust (and obviosuly an MR20 with those same upgrades would be more). So its not like your sticking a V6 in there so don't have those expecatations.
I used Car-Part.com--Used Auto Parts Market
to source the engine (and later the transmission). For the engine search for 2009 Nissan Sentra "Engine" and then obviously the 2.0L MR20DE as the variation.
------------------ Swap Info ------------------
I would rate the experience level as moderate. The engine and transmission are pretty straight forward and simple. The service manuals are easily available online
and provide most of the information you will need. I have done engine swaps before and I have done major upgrades on cars before, so my experience level is pretty high. Just set aside plenty of time and don't feel rushed. If you only have 2 days to get it done I wouldn't recommend it. I took 3 days at about 12 hours a day. I had a person help me with engine hoist maneuvers and some of the bigger stuff like CV joints, but I did all the hoses and wiring and general disassembly/assembly (dressing the engine).
Day 1 - Undress the original engine down to just the engine mounts holding the engine
Day 2 - remove old engine and get new engine in place and engine mounts secure
Day 3 - Redress new engine
You will want a good selection of metric wrenches and socket wrenches. Make sure you have a variety of 1/4", 3/8" & 1/2" sockets and extensions. I used no air tools on this project (as I prefer hand tools). I do have a 2 foot 1/2" socket breaker bar that comes in very handy as well as other pieces of metal tubing to slip over normal socket wrenches to give them more leverage.
You'll need the obvious sizes:
But there are also some oddballs on this car.
30mm (for the CV joint hub nuts)
When doing this project I realized I had zero 16mm 1/2" sockets. Never needed them before this car and they aren't always common with socket sets. If you need individual sockets I recommend either Harbor Freight or Northern Tools. They both have a good selection of individual sockets and the prices are good.
Buy a box of snack size and sandwhich size ziplock bags and a sharpie marker. Put every bolt you take off in a baggie and label it. It will seem like a hassle at first but when you start putting stuff together you will thank your lucky stars. Plus you will be so happy when you get to the last baggy
As your taking stuff off the car take pictures with a digital camera. Not your cell phone. Something you can actually see good detail on. Take pictures from different angles from different distances. I probably took 50 pictures of the engine bay. It came in very handy when I was needing to reroute the wire harness or put brackets back on.
Put labels on anything you may be confused by. Label each fuel injector clip. Label each ignition coil harness. Label the O2 wires, the MAF sensor, etc. A roll of blue 1" painter tape is good for this. This will also help you lay the wiring harness down as you will know where each branch generally needs to go towards. Label the rubber hoses and which end goes where.
Preprint Service Manual
You don't need to print all of them, but here are some of the key pages I used from the service manual
I have a computer in the garage for full access to information, but these I printed out so they could be near the car ready to get dirty. Also a good idea to print these out and go over them so you get an idea of what you'll see.
EM (Engine Maintenance)
FAX (Front Axle)
CVT (if you have the CVT obviously)
When looking at the service manual note the little wrench symbol next to each component. For example on EM-14 (EM is the PDF and 14 is the page, this is the style used in the service manual) you see the spark plug and coil. Notice the spark plug has a white wrench with black background while the coil has a black wrench with white background. This particular image has a key in the bottom left that explains what they mean, but most of the images do not. The spark plug is listed as "19.6 (2.0,14)". These are the same values given in 3 different measurment standards. The last one, 14, is the foot pounds and is what most of us would be familiar with. Note that the coil boot is listed as "7.0 (0.71,62)", but that this time the 62 refers to inch pounds, which you would need to divide by twelve to get the foot pounds. Just use some common sense on stuff like this. A coil boot would not need 62 foot pounds of torque on the tiny little 8 or 10mm screw. For the most part the stuff you will be dealing with will be in foot pounds on the illustrations or you will simply tighten by hand (who uses a torque wrench on a coil boot??)
Part Differences Between MR18DE and MR20DE
Heres the things you need to note on the MR20 or transfer over from the MR18.
1. Fuel and Evap bracket under throttle body (Use MR18)
2. Bracket for Main engine and transmission wire harness loom on front of engine above engine id stamp (use MR18)
3. carrier loop for intermediate shaft on back of block (Use MR18)
4. Oil sender on front of block under intake manifold (Use MR18)
5. Water manifold on engine block above where transmission mates up (1 extra 0.5" pipe on MR20) (Use MR18 or cap MR20)
6. MR20 has extra 0.5" pipe in block above water pump, cap off.
7. MR20DE has an extra sensor on back of block. Keep it in place, though it will not be used.
Pretty much everything else can stay on the MR20. I did use the intake manifold and throttle body from the MR18 but only because mine was cleaner. The MR20 version did look the same. I used the exhaust manifold from the MR20, it mated fine to the Versa catalytic convertor. Fuel injectors are same between the two, so don't mess with the fuel rail. You can order an accessory belt just as you normally would for a Versa (1.8L with or without A/C depending if you have it).
For the extra water pipe in the block on the MR20 (above the water pump) either go to a auto parts store and buy a "bypass cap" or be ghetto and get a piece of 0.5" fuel/radiator rubber hose and stick one end to the pipe and shove a bolt in the other end of the tube and use clamps on both ends. I used the bypass cap method which are very heavy duty rubber caps. I bought a kit of assorted sizes and had to use a smaller thin one to first go over the tube then the 1/2" cap fit very snug over it, otherwise the 0.5" cap was a little loose. I then used a hose clamp on the cap. Worked fine so far.
-- Fuel Line --
For the fuel line, use the little plastic circles that come in the kits. Its a royal pain in the butt, but just keep spinning the circle thing around under the fuel line and wiggle the fuel line back and forth and keep trying to pull up. It will eventually go.
-- CV Joint --
For the CV joints. First drain the transmission, the CVT has about 10 quarts of liquid in it. Pop out the driver side CV joint. Stick a crowbar on both sides of the CV joint at the transmission and pry on both at the same time. The CV joint will eventually pop out. Have a towel ready, transmission fluid will come dripping or pouring out. To remove the CV joint don't do what the service manual recommends by taking off the bottom of the suspension, its impossible. Simply unbolt the hub nut (30mm) and remove the two bolts that hold the hub to the strut. Once you do that the hub can be moved out of the way. Watch the tension on the brake lines. Use Zip ties through the bolt holes you just removed to keep the hub safe. The passanger side is the same, but you don't need to pry anything. Loosen the CV joint hub nut and then detach from the strut and you can just pull on the strut till it pops out from the transmission. The passanger side CV joint is about twice as long and is one peice.
-- Wire Harness --
Fully remove the wire loom from the engine and tranmission. You need to unplug only 2 of the 3 ECU connectors. I think orange and blue, don't unplug the harness thats closest to the cowl. To release the ECU harness there is a tab on the top of the plug that keeps the big latch from swinging. Release the tab and the latch can then rotate.
There is a sensor on the accessory belt side of the engine that is very hard to get to. I used 2 screwdrivers. One to push the release tab and one to push the harness down off the sensor.
-- Removing Engine --
Remove both the engine and the transmission together as one piece. It will make it easier to put them back together.
If your going to remove from the top, which most people probably will, the hood definently needs to come off. I would highly recommend removing the front radiator support as well as the cowl. We were able get the engine out with those things attached by we tore up or bent them. We removed it and going in was so much easier.
The brake booster (I think??) attached the bulkhead above the transmission does not need to be removed. It will be damn tight, but we were able to clear the CVT around it with some maneuvering. We did take off the cap just for that extra 5mm
This is another reason why taking off the radiator support and cowl is a wise idea.
Take the water pump off the engine prior to lifting. The pulley on the pump will cause clearance issues with the frame and air conditioner lines.
The exhaust manifold needs to come off as well for clearance issues. Its easy to get to from above the engine. I was actually surprised by how much room was back there. You could easily stick a smallish turbo on a MR20DE in this car
-- Mating Engine & Transmission --
This was a big gotcha for me. Once you unbolt the two they come apart relatively easy. Putting them back together is the same way. The dowels will align them and they should slide together flush. DO NOT USE THE BOLTS TO BRING THEM TOGETHER. If they are not coming together correctly its not the dowels, its the alignment of the torque convertor or the clutch. I did not realize this and on the 3rd time of using the bolts to draw them together we heard a large bang which sounded it came from inside the transmission. Because I didn't want to chance having to do all this work again I went ahead and bought another transmission ($850 used).
(CVT specific, but probably applies in some parts to the other transmissions)
We then came up with a much better process. Put both the engine and transmission upright on the ground. Turn the engine crankshaft until one of the holes on the flywheel lines up with the cutout for the starter(remember only turn the engine clockwise when looking at it from the crankshaft pulley side, if you miss a bolt, just keep turning until it comes around again). Put the torque converter inside the transmission and try putting it on the shaft. Very important to note the cutouts at the back of the shaft that match the shape of the tabs on the torque converter. You should be able to push the torque convertor all the way back to the point that you can't stick your finger behind the torque converter. Once the converters in place, rotate it until one of the 4 studs lines up with the hole in the flywheel you can see through the starter cutout. Then slowly bring the engine and transmission together. Let the 2 dowels line them up, and make sure the torque converter slides through the hole. Then the engine and trans should be able to be pushed flush against each other by hand. At this point the torque converter will probably be a little too far back to get a nut on the stud. You can reach in with your finger and pull it forward against the flywheel. Then start putting nuts on. I used some locktite as I put them on. You need to put the nuts nearly all the way on the thread, don't make them tight just yet, but if you don't put the nut all the way down they will rub against the engine block as you rotate the flywheel to get to the next studs.
Since I replaced the transmission the service manual says several times not to drive the car until its been hooked up to Nissans CONSULT III diagnostic system so that some memory can be cleared. The car has about 150 miles on it so far and the transmission behaves fine and theres no warning light or anything present, so I don't think that part is necassary.
-- CVT Fluid Refill --
The service manual says the let the transmission cooler hose on the drivers side of the radiator to hang down and fill the tranny with fluid until it pours out of that tube. I bought 10 quarts of Nissan NS-2 CVT fluid (@ $20 a pop!) and I *think* the fluid was just starting to come out with all 10 quarts. I'll check the level again next week to see where its at. But ya its going to take ALOT of fluid the first time.
-- Accessory Belt --
You will need to remove/install the belt while in the engine bay. Use a 14mm wrench and rotate the tensioner towards back of the car. Then, due to clearance, stick the short end of an allen wrench inside the slot. The water pulley is the best bet for the last pulley. Slip the belt over all the ribbed pulley and then the belt should slide over the smooth water pulley with little effort. Then release the tensioner and it should be perfect.
-- Alternator --
To remove the alternator there are 2 bolts. One on top and one on bottom. They are the same design. The bracket has a cut out about halfway that lets you pull the bolts about halfway out. Then you can wiggle the alternator loose from the bracket. It will probably be a tight fit on the top. You won't be able to back out the bolts all the way due to the frame.
-- Air Conditioner Compressor --
To remove the wire harness from the A/C compressor wedge a screwdrive between the harness bracket and the compressor. You should then be able to grab the harness to release it. Just one wire here so dont pull on the wire.
You do not need to pull the compressor out of the car. Unbolt it from engine and pull it back up into the cavity between the chassis and the air conditioner radiator. Use zip ties to secure it. This will save you money and time from getting the A/C system recharged.
I added 3 quarts of oil to get me started. Let it settle for 30 minutes or so while you do other stuff. Then check the level.
For the coolant I connected the lower radiator hose and then stuck a plastic tube into the taller (rear) heater core pipe. Then just slowly filled with coolant until it came out of the other heater core tube. There was no particular reason to do it this way, I just wanted to have a visual reference of the coolant. Once that was full, I connected the heater core hoses and connected the upper radiator hose. Then I continued filling the coolant through the radiator cap until it overflowed into the bottle. Once you get it full be sure to give the upper radiator hose a couple light squeezes to get any air bubbles out of it.
As your filling everything make sure nothing is dripping or leaking. Its a good idea before hand to dry up any liquids from the engine or floor just so you know whats new. Make sure you tightend the oil drain, the radiator drain, transmission drain, and the oil filter.