Engine removal factory service supplement

[Jonny]

Or... useful things for a first-timer to know which the FSM doesn't mention.

A few days ago I removed the engine/tranny assembly for the purpose of a clutch and head gasket job. It was a very stressful few days which had me wondering which of the several removal methods to use, how high do you need the van, how heavy is the beast, where is its center of gravity, jeez there are a lot of tubes and wires and where ARE all those sensors located anyway, and generally losing sleep about the million ways I could screw up, break stuff or squash myself under the darn thing.

So, the following series of post are a record of the things I ended up answering for myself one way or another (sometimes from other posts here on TVT) and comments/photos which, when used with the FSM, give a more detailed picture of what you're meant to be doing.

The FSM uses the support from below method of removal. Samay / Previa Legend also uses this method on his Youtube videos and makes it look so easy (it isn't, of course). The FSM also disconnects the wiring harness from the components and leaves it attached to the engine. You can also disconnect the harness from the engine/components and leave it attached to the body. There appear to be pros and cons both ways, but since this is a FSM supplement I'm describing the process with the harness coming out with the engine as per the FSM.

[Jonny]

Equipment I used for this.

*A space which allows the vehicle to be raised 18" from its normal resting height. The lower edge of the door sill starts at approx 10" and needs to go to approx 28" to get the engine out with the equipment I used below.
*Pittsburgh 2000lbs low profile transmission jack from Harbor Freight. Strength rating and lifting range (~7.5" - ~30") is ample for this job.
*1/8" mild steel sheet 16" x 36" to mount to the jack as a support platform. If I was doing this again I would use 16" x 32" because mine seemed a little longer than necessary and slightly got in the way of working on the front engine mounts.
*Four scissor jacks.
*Two or four 6 ton jack stands.
*Lots of blocks.

I mounted the 1/8" platform to the jack's table so that the center of the platform was offset 2" rearwards (towards the jack handles) from the center of the jack's table. This worked well, supported the engine and tranny adequately and gave plenty of room to strap the transmission down when it became time to remove the engine mounts.

[Jonny]

OK, time to get down to the removal details. I am referencing my 1991 FSM. I'm assuming all future years are similar. Some of the steps are very straightforward and obvious, so I'll concentrate on the ones which seemed to lack detail.

Oh, before you start, read through this whole thread with your wd40 in hand. You'll want to go squirt a bunch of the bolts and nuts before you start, preferably 2 or 3 times with a day between each. I'll mention the potential rusted bolts/nuts in the relevant sections. Breaking rusted bolts is REALLY annoying, particularly when they go into the engine block.

Disconnect battery, remove under covers (*spray any rusted nuts which are accessible), drain coolant from radiator and block, drain engine oil (and tranny and transfer oil depending on job), OK next....

Aha, SADS. Now it get's interesting.
You do not have to remove the alternator and A/C belts. Just loosening the pivot bolts, adjuster lock nuts and giving the belts some slack is adequate.
At the engine end of the SADS make sure you remove the bolts per the FSM (just the ones with the oval washers). I saw on youtube a guy removed the other ones and this does not help at all.
At the front end of the SADS, do not remove the 3 bolts. The upper ones are hard enough just to get the end of a wrench to. You do not want to fiddle around trying to get them back in. Loosen the bolts so that they're about 3/8" out...

previa sads front.jpg

Rig up some sort of support wire for the end of the SADS at the engine (SADS does not like to dangle) and pry it away carefully frontwards with a crow bar. This is how the SADS separates from the engine...

previa sads rear.jpg

The next steps in FSM have a diagram, which is nice (hoses in water pump vicinity), or are straightforward (accelerator cable). Even though you've already drained the fluids, whenever a hose is disconnected there is inevitably a river of the stuff waiting to hit you in the eye, so be prepared with some catch pans.

On to the next post/FSM step and a bit of a doozy it is....

[Jonny]

There's a nice sketch of the ECU connectors, but where TF are they? I crawled around all under the van looking for them and eventually did a web search. They're under the driver's seat. Seat needs to comes off, two bolts at back.

There are 7 connectors here to undo...
Diagnostic, 3 ECU, 1 Igniter and 2 harness-harness.

previa ecu.jpg

I had to take the bracket off and pry around on the back to avoid breaking the diagnostic connector. There's probably an easy way if you know in advance how the bugger is designed.

previa diagnostic.jpg

I recall that disconnecting the three ecu connectors was intuitive, then you can get that main bracket and the ecu unbolted and out of the way so you can get at the igniter and the two little effers at the bottom. The 2 little effers at the bottom have a tab underneath which you pinch and the connectors separate. At least that's the theory. One was a total struggle and I had to cut the carpet so I could get at it better. I think these plastic housings are designed by sadists.

Then everything pushes out through this hole into the engine bay...

previa ecu harness hole.jpg

Time for some dinner.
OK, I need to take some more pics, so this will continue tomorrow sometime...

[Jonny]

This post should have been earlier in the thread. This is how I jacked and supported the car while feeling safe working underneath. It is completely overkill, but it sure felt comfortable being underneath with all those different systems which would have to fail for there to be an accident.
I would pump the floor jack 1/2" at a time, tensioning up the scissor jacks on the wheel jacking points each round, and adjusting the jack stands/sliding in another paver under the wheels whenever there became room to do so. I'd alternate between front and back 2 or 3 inches at a time. It took a while but I always felt safe.

previa jack support.jpg

You only have to go high enough for comfortable working at this point. My theory was that the higher you had the van when you got to the point of actually removing the engine, the more unstable the engine would be on the extended tranny jack. Once the engine is lowered you can continue raising the van just enough to wheel it out.

[Jonny]

Back to the FSM steps.

"water by-pass hose from floor pipe"
"brake booster hose from floor pipe"
No diagram here, unfortunately.
This description sure implied that the "floor pipe" was a single entity and I should be looking for some pipe with 2 hoses splitting from it somewhere. Not the case. I eventually deduced that "floor pipe" is a pipe attached to the floor of the van and there are several of them. These are the two hoses you're looking for, on the left side of the engine. The left one in the photo is a vacuum hose connecting from the intake manifold to the brake booster in the front accessory compartment of the van, while the right hose connects circuitously from the engine water jacket to the coolant reservoir.

previa floor pipe hoses.jpg

Onward...
"Remove the two bolts and disconnect wires and hoses from floor panel".
No diagram.
WTF are they talking about? There are bolts and hoses and wires all over the place attached to the floor.
It must be these two (one in the shadow).... accessible from the driver's side... and get your wd40 out.
The contraption which is held by that obvious bolt is the VSV for the fuel pressure regulator.

previa floor panel bracket.jpg

There are a couple of clips securing the harness where it goes around the access hole. Pull out on the little tab and the clips slide off...

previa harness clip.jpg

"two hoses from union on intake manifold". This union is on the bottom left side of the manifold, seen here from below, with the hoses already removed. There is a pipe coming straight down and one heading horizontally forward...

previa intake manifold hose union.jpg

It's time for me to get some work done again on this thing and separate the tranny from the engine so I'll try to finish this thread early next week.

[Jonny]

The air intake removal section actually has a nice diagram. Woo hoo. Basically you're disconnecting everything from the large intake duct.... the hose next to the oil cap at the top of the duct and the 3 hoses from the common union at the bottom of the duct.

Next... more hose disconnections with no diagram.
Here is the fuel pressure vsv which you disconnected from the floor via the driver's access hole in post #6

previa fuel pressure vsv.jpg

Since the whole assembly is now disconnected from the body and the only other connections are to the engine you don't have to disconnect anything. It all comes out with the engine and harness. Even the disconnected labelled hose in the pic can be left attached to the intake manifold if you wish, I disconnected it merely because I was going through the learning process with barely adequate instruction.

I believe these are the two pipes receiving the distributer ventilation hoses (wrapped in plastic to protect ingress of stuff). You just disconnected one to remove the intake duct. Disconnect the other now.

previa distributor vent pipes.jpg

The charcoal canister hose attaches here to the intake manifold vacuum pipes (upper one). The other which has been disconnected (lower one) is from the fuel pressure vsv.

previa canister and fuel vsv pipes.jpg

[Jonny]

Electrical connectors from driver's access hole....

previa driver's side connectors.jpg

Upper right... cold start injector (black, 2 prong)
Upper left with pink paint... throttle position sensor
Lower left... idle air/speed control valve
Lower right... exhaust gas recycle system temp sensor (CA only).
Fuel inlet and outlet hoses are the ones wrapped in plastic in the upper part of the pic.

I am baffled by the A/C vsv connector reference in the FSM. I don't think this connector attaches to the engine wiring harness. I ignored it and as far as I can tell it is not part of my engine wiring harness.

In the FSM there follows another wiring harness disconnect step, but unless I am mistaken this is a duplicate of the one described in post #6 where we disconnected the fuel pressure vsv and harness clips (clamps?).

[Jonny]

Disconnect both oxygen sensors connectors and get the harness off the body.

Good luck getting that middle exhaust pipe section off. WD40, heat, impact, whatever other tricks there are. Several years ago I removed it for another job and had to cut/drill all the bolts out. Everything was just shapeless blobs of rust. The rear bracket bolts I replaced with two stainless through bolt/nut combos, and drilled/retapped the front ones and used stainless bolts there, too. Happy to say it all came apart with no problems.
The FSM doesn't have you remove the exhaust manifold at this time, and it doesn't get in the way during engine removal, but the bolts are perhaps just as accessible now with the engine solidly in the van. I think I'd do it at this point in the process if I was doing it all over again.

One more set of connectors to deal with underneath the van on the passenger side. Pic taken after engine removed.
Coil on left, tranny ground bracket upper right, condenser lower right. See that bracket. It didn't originally look twisted like that. Get the WD out.
Also, do yourself a BIG FAVOR and completely remove the coil from the van. You will appreciate the extra room. WD40 here too.

previa coil etc.jpg

Mine's a manual transmission and disconnecting the stuff per FSM is pretty straightforward. With respect to the shift linkages, there's a small flat machined onto the post above the link, so you can hold it with another wrench (I think it's a 9mm - maybe the only 9mm thing on the van?) while taking off the nut. Thankfully they disconnected easily.

Rear prop shaft off and now the engine is ready to be removed.

[Jonny]

If you decide to leave the harness attached to the body as opposed to the engine, here are the differences...

Leave the oxygen sensor part of the harness on the body (disconnect the sensors of course).

I'd still remove the coil for space reasons.

Photo after engine removed. Disconnect the distributor connector with clamp...

previa distributor connection.jpg

Access through passenger floor access. Photo taken after removal of engine.
Disconnect 4 injectors, 4 harness bolts, vsv hose to pressure regulator (top right of engine) the water temperature sensor connectors (there are three on my '91) on the engine front right and the knock sensor connector... hidden on top of the engine behind the injectors. The knock sensor might have to be accessed after the engine has been lowered a bit. There may also be a crankshaft position sensor on later models.

previa injector knock sensor.jpg

Photo taken after removal. Remove 2 harness bracket bolts (broken brackets on my harness) and harness ground on top of engine in front of intake manifold after lowering engine a bit. These seem quite inaccessible otherwise.

previa engine ground.jpg

Even though the fuel pressure vsv stays with the body it would seem wise to disconnect it and the nearby harness clips so that there is some play in the harness system while lowering the engine until all the engine disconnections have been made.
The vsv vacuum hose to the intake manifold needs to come off, though.

Disconnect the oil level sensor connector from the oil pan left side and the oil pressure sensor connector from the bottom of the engine.

Leave all that ECU stuff under the driver's seat untouched.

I think that's it.

[Jonny]

OK, now the engine comes out.
Get some WD40 on all the mount nuts and bolts.

This is the transmission jack with the 1/8" plate. It is 16" x 36". 16" x 32" would be better. Memorize which way to turn the knobs to adjust the table angle. Once the weight is on the table they are kind of hard to turn and the movement isn't obvious right away because of the slop in the table. It's annoying to have to turn it back again if you go the wrong direction.

previa jack setup.jpg

Get the jack up under the engine. It's hard to see here, but the center of the jack plate (the one which comes with the jack) where the arm of the jack is pushing is positioned below the junction of the engine and transmission. It is too far back - the assembly was still considerably front-heavy. I'd guess the center should be somewhere near where you see the contact with the oil pan in the photo. Adjust the table angle, strap the tranny down and lift the engine until you see a little movement.

previa jack position.jpg

There's a bit of flex in the plate, but that's ok and I even used it to advantage with my overkill scissor jacks setup. I've got one pair working the back and one pair working the front adding reassuring stability and allowing small changes in height and angle with the scissor jacks before significant adjustments were made with the tranny jack table.

previa tranny jack scissors.jpg

Take out the rear mount frame bolts and the lower nut on the bracket. This is one place where I could fine-tune the load on the bracket with the scissor jacks and get the bracket off easily. It will just fall down out of the way.

Previa transmission mount 1.jpg

With the front engine mounts, take the two lower bolts/nuts off, and the one nut on top so that the mount is loose.

previa front engine mount.jpg

Adjust the table angle to lower the rear end a few inches. (This is about the angle you want - here's a photo of the engine coming out, so this angle works. The table only has about 5 degrees of backward tilt, the rest comes from the taper of the engine/tranny assembly. This is a manual transmission so with an automatic things may be a bit different with the table angle.) Then lift the front of the engine up about an inch until there is enough room to remove the front mounts. Some people will remove the whole cast iron bracket assembly which mounts to the block for even more room.

previa engine angle.jpg

At this point you're ready to maneuver the thing out. You're basically moving it back and down, back and down, until it's free of all possible obstructions. Go literally 1/2 an inch at a time at first, each time thoroughly checking all around the engine (and the top through the floor access holes) to make sure you haven't left anything attached and you're not going to break off any pipes and sensors.
There is no mention of taking the oil filter off, but I couldn't see how it comes out with it on, so it got removed. You did remove the coil from the body right? Other items I found myself in danger of hitting were the sensors on the left side of the engine, the oil filter mount, the water sensor engine top right, the distributor and this little pipe by the front engine mount.

previa pipe careful.jpg

After the jack was fully lowered I had to raise the van by another 4 - 6 inches to get the whole mass out. This was a great feeling though....

previa engine removal anglej.peg.jpg

This was rather long and detailed, perhaps unnecessarily so in places, but it provides a recipe to follow for someone who is inexperienced, like I am, with engine removal. Knowing that a noob actually did it a certain way, with most of the steps outlined, might help someone in the future. I know I wouldn't have been able to do half the stuff I have on my Previous without a number of sources. The manual and TVT are always my first references and as far as I'm concerned regarding car repairs there's no such thing as too much information.