Desert Rat

...nothing. Well, the crank was turning, but none of the cylinders were lighting off. To make it worse, after a couple seconds of turning, it abruptly ended with a loud "crack" and a strange smell (almost smells electrical?). I tried the same thing a little later, and ended up with the same result (just wanted to see if it was repeatable). Frustrating to say the least because I followed the FSM and Chiltons meticulously through the rebuild.

I'm tempted to think I have a timing issue, but I'm positive I had the cams and crank aligned correctly for the timing belt, then again when installing the distributor. The thought of tearing this down again definitely doesn't appeal, but before I do (or have a tow truck pull up in my driveway), any thoughts on what direction to take or where to start looking? I'm at a loss.

BTW, 91 3VZE 4Runner. TIA - this forum has been amazingly helpful.

FastCat

A "crack" sound and "electrical smell"?

Sounds like an electrical short to ground happening somewhere.

It could be anywhere from the starter motor circuit, to the ignition circuit. Have you checked for any blown fuses? That would certainly narrow things down to follow a blown fuse.

eric-the-red

First thing I'd check is that you don't have the distributor 180 degrees off. It's easy to accidently get it firing on the exhaust stroke, instead of the compression stroke.

Rusty Davis

I 2nd that

Even good mechanics make this mistake from time to time. Checking the timing marks on the cams and crank wouldn't hurt, but I don't know how this could cause the loud noise you're hearing.

Toysrme

Realign everything, and have someone else crank the engine while you watch it. Make damn sure there are NO electrical problems.
Normally what happened is the cams, or the distributor are 180* off - doesn't matter which.

Fuel doesn't combust because spark happens during the opposite stroke.
If it's the distributor, it'll be a little poof as the spark ignites fuel in the combustion chamber, the intake valve opens & the flame travels into the intake manifold where raw fuel is at. No real harm done.

Now the fun begins when you watch someone with the CAMS off 180*!
The engine intakes air via the exhuast, compresses it which heats it. While this has happened, fuel is pooling in the intake manifold & heads.
After a few revolutions there is A LOT of fuel piled up on the intake valves, they open, the fuel dumps in the combustion chamber right when the spark ignites, and basically you get an explotion from the combustion cahmber going into the intake manifold - where it ignites all fuel in it & goes BOOOOM.

AKA the worst back-fire you've ever heard when a car is cranking. That is not a good condition. It'll slam the AFM flap shut & the only escape is the AFM's idle by-pass. It can damage the AFM, and split / blow off about any intake hose.

Desert Rat

Thanks, all. Here's a run down of what I did putting it back together:
1) Cam matchmarks at 12 o'clock, aligned with crank per FSM. Installed timing belt.
2) When it came time to install the distributor, pulled spark plug from #1 cylinder. Manually turned crank until I felt puffs of air coming out of cylinder due to compression. I tried using a compression gauge, but couldn't get anything to register, so I defaulted to "feel." Aligned crank pulley mark with "0" on cover when I was convinced it was on the compression stroke.
3) When installing the distributor, aligned mark on driven gear to the mark on the distributor housing. Rotor was positioned to fire on #1 cylinder. Installed distributor, aligning marks on the distributor with the mark on the camshaft bearing.

Then I started it up and voila, here I am. Sound like I did anything way off base?

Regarding the "crack" sound and electrical smell, a short is quite possible. I looked at my fuses and didn't see anything, BUT...there is one ground wire that I'm questioning whether I have it in the right place. It attaches to the LH fender well, immediately next to the igniter - the question is where the other end goes? I currently have it screwed into the LH head, pretty much next to the engine lift bracket. I'm at work now and don't have access to my camera, otherwise I'd post a pic. Anyone know which ground wire I'm talking about?

callmej75

Your ground wire you are referring to is in the right place. As far as timing goes, I'd take out plug #1, put a screwdriver down in the hole, turn the crank til the piston comes up and check to make sure your timing mark is on 0* when it reaches full compression stroke. Pull your distributor out gently. Now look at your rotor and see if its pointing towards #1.

When my timing was off it made some nice little pops and cracks when I tried starting it.

My question is:
After you put the timing belt on, did you rotate the crank pulley two times and look at the cam marks and see if they were still aligned at 12 o'clock position in conjunction with your timing mark at 0*? There is a possibility of being off one tooth on the timing belt when they are aligned with the cams. One way I was able to tell that the belt was aligned properly was when I put the tensioner pulley spring on, it was hella tight from the recoil and belt was tight, thus making it hard for the spring to stretch.

Pull the dist. first and check to see if the rotor is at #1 when at 0* on compression stroke.

eric-the-red

One other thing to check, make sure you've got the plug wires in the correct order.

callmej75

yep

Desert Rat

Plug wires are where they should be - but good suggestion. Thanks for the confirmation on the ground wire, I'll check that off my list.

Regarding lining up the cams and crank for the TB: I tried installing the TB two different ways. The FSM says to not use the cam match pins when lining everything up. I installed the TB using the match pins and not. When I didn't use the pins, the cam pulleys would invariably rotate counterclockwise (say, to 11 o'clock) once I applied the tension spring. I eventually got it so that they didn't move, meaning everything was in alignment when I got the new belt on. However, I did have to ever-so-slightly turn one of the pulleys (with the TB on) in order to get the matchpin back in. I turned the crank twice to make sure everything still aligned, and it came up fine. The TB is new, so there are no alignment marks on the belt (not even from the factory). It's simply a matter of putting it on and making sure the cams and crank are aligned correctly, right? How would you know if you're one tooth off in this case?

How far over should the idler pulley be once the tension spring is on? All the way to the left when finally tightened down? I'm positive it's not there - perhaps 3/4 of the way over.

I'll try the screwdriver trick in #1 to confirm I'm doing this on the right stroke.

snap-on

that pic was after i fired it up to verify that it was correct.

Desert Rat

Thanks for the help all. I tore down the front end this morning and found that the TB was exactly one tooth off - and the distributor was 180 degrees off. Fixed both of those, turned the key and...

It kinda runs. It'll actually run for a couple seconds and die. I'm thinking not every plug is firing. Does this seem to make sense, or is there somewhere else I should be looking? I was going to mess with the timing a bit once I hooked the timing gun up, but can't keep the truck running long enough to use it. Thoughts?

snap-on

double and tripple check the belt timeing, it took me forever my first time to get it right. it took a good hr of trying to get everything to line up just right. invarrably id have everything right except be one tooth off on a cam.

dstrick32

Is the air intake system hooked up, it will not run without it. Just start and shut down if there are any air leaks in it!!

Manson

Did you have the valves ground or did you just replace the gaskets. If the valves were ground they need to be shimmed correctly or you may have low or no compression on some cyls.

leebee

im surprised that a factory tb has no marks on it. mine came with alignment marks and it took a bit of fussing to get things lined up but it worked and my rig fired up immediately.

lee

Rockford Fosgate

I'm no Toyota guru, just a regular guru of all things mechanical and lactating.....but my gear,,,, and every year on the net is flipped over.....obvious timing malfunction,,,,possibly.

millball

I reckon that the OP got it running sometime in the past ten years, but you are right about the sprocket.