I posted earlier about how the timing chain in my 73 Toyota snapped.
The following is what I did and should have done and will do next.

Hopefully others will learn from my experience, and others will input their thoughts.
It's all a learning experience....

What I Did:

Removed the radiator shroud.
Removed the radiator.
( This allowed easier access to the engine.)

Removed the timing chain cover bolts.
( I kept them separated in a jar. )

Removed the drive pulley.

Removed the water pump.
( Easier to work on the timing area )

Used smaller bolts through the two pulley holes.
( I couldn't find the correct bolts -- 11 MM??? -- at the hardware store. )

What I Should have done:

Power washed the engine.
( Grime does make anything easier)

Removed the grill.
( It's better to go straight in rather than having to work down at an angle in the engine compartment. )

Made a cardboard replica/outline of the timing chain cover and put the bolts into this replica after removal.
( This way the bolts go back into their specific area. A dump of bolts into a jar doesn't allow this type of exact replacement.)

Put A little WD-40/Liquid Wrench on the shaft of the cam pulley as it was coming out.
( I finally got the pulley off with a harmonic balancer. But it was more difficult than it should have been. Lubrication would have helped. Neighbor got it off with a few taps of a hammer. )

Use the correct bolts and attached to the pulley directly rather than using smaller bolts through the pulley.
( Going through rather than attaching to the pulley itself made the pulley come off at a slight angle. This made it more difficult to get off. )

What Comes Next:

Clean the timing chain cover.
( Dirty with crud. )

Remove the grill
( Straight in is easier! )

Fix the Timing cover with KB Weld.
( The chain gouged into the soft aluminum, leaving a slight cut through to the other side of the cover. )

New seal on the cover.

New gaskets for timing cover and water pump.

POSSIBLY:

Put on a new gear.
( The tips are slightly missing on the current gear. I'm told this will cause the chain to slip eventually, and the engine will have another timing/timing chain issue again, and I'm back at square one again fixing instead of driving. )

New tensioner.
( I don't know... is this necessary? )

New chain guide.
( The old one was worn by the now-snapped chain to the point it crumpled upon removal of the timing cover. )

Rust-O-Leium the water fittings.
( Can I scrape away the rust and spray Rust-O-Leium one these fitting areas? I'm told this stuff binds to rust and inhibits further rusting. True? Okay to do? )

I was also told paint the parts you've worked on.
( This way you know at a quick glance what areas you've done and inspected.)

What I learned:

Take your time and do it right.
( Quick is not always easier. See pulley bolts for example.)

Little by little, it gets done.
( Don't have to do it all at once. Don't get frustrated. Do a little at a time. Take a rest. Then go at it again. )

I really appreciate having a truck.
( Not having a drivable truck is so disheartening. I've taken for granted how many things I haul around in it. I just want it to run again.... )




Thought and opinions please.
Pics of the area thus far attached.

 

What I Did Today:

Remove the UPPER Tensioner:

This piece was ripped up! Couldn't see it from down into the head when the valve cover was off nor from the front angle when the timing chain cover was removed. The head obscured a full view.

But after going in with a 14 MM box ratchet, the tensioner came out rather easily. But as the pictures attest, the guides were cracked and chipped away.
So this one part definitely will be replaced.

I also removed the LOWER side chain guide. In the Hanyes Guide it's called a "Chain Slipper" for whatever reason. In my situation, the entire wall was gone - missing. The only piece left was the side that attached with two bolts. So I will replace that chain guide - chain slippper.

Since these parts are racked and or missing, I'm told I should drop the oil pan ( In the Haynes Manual the oil pan is called a "sump" - fyi ) as the missing parts are probably swimming around there in the oil and could cause more problems in the future.

So that means dropping the pan, cleaning out the sump, putting on a new oil pan gasket. ---> Your thoughts?

Also : Do I need to set the timing to top dead center ( TDC ) before putting on a new UPPER timing chain?

If so, both the crank shaft and the cam shaft? Or just one of the two?

 

The timing cover had a crack in it.

Plus the timing chain cover had a gash in it. Created by the upper timing chain that was too close to the cover and gouged out onto the cover.

Turned out there was suppose to be a timing cover shim between the timing cover and the engine block front. Whenever this truck had the engine rebuilt, that shim was removed or missing or something. That small space would have kept the upper timing chain from touching the timing cover.
The price for a this shim from the dealer: $65.

I JB Welded the crack on the outside of the timing cover. Brought it to the local Toyota dealership, and they said since the cover was aluminum, a weld might just burn through the metal and make a bigger hole. Hence the JB Weld option.

Put the timing cover gasket on the cover with a bit of high temp red gasket seal. Found a dealer who had two 18 R gasket kits still in stock! $15 bucks! Lucky!

 

Lost,
Just my thoughts about all this, and they aren't worth much, but I would certainly pull the pan and ensure there is no foreign objects in there. Is it necessary? Well, its probably arguable, but I am a nit noid kinda mech when it comes to my toyotas and if it aint supposed to be there, then remove it. As far as the timing chain question and TDC, don't move a single thing unless you want to have some realy advanced trouble shooting when you get it all back together... I am not familiar with the 18 series engine but the concepts are all the same. Looking back, probably should have placed the #1 cylinder TDC before anything else to remove a potential guessing game later. In any event, I will be watching this post so let us kow what happens when you get it all back together. Did you have to pull the head? Again, I am not sure about the 18 series, just trying to help out...

cheers!

 

NavyMC-

Major thanks for the thoughts and perspectivs. I'm doing these post as I do the work so anyone who may be doing their own timing chain -- 18rc or whatever -- can read what I did, did incorectly, and not make the same errors. That's the intent.

And I just gotback from Pick-N-Pull. 1978 Hilux in yard. Perfect condition. As of this morning, it had undented front fenders, pristine grill, doors, dash, bumper ... and the differential was still there!

 

So here's the latest:

I went out and removed the upper timing chain ... again. It turns out that chain was stretched. It came out of a 20 R I disassembled. In this set of photos, the new chain is on the left, the old chain on the right. (Other photos in more detail show the stretching in another post on toyotaminis.com for reference.)

What I Did: Installed a used timing chain.

What I Should Have Done: Spent $11 and installed a new timing chain.

I also removed the crank shaft timing pulley/cam. It used two number 7MM w/1.25 pitch bolts on a harmonic balancer-puller to remove. These 7 MM are a bit difficult to find, so if you have an 18R and see these 7MM bolts, spend that $1 ahead of time.

What I Should have Done: Marked the gears, pulleys, et al with a marker/Liquid Paper or such when I put the engine to TDC. A visual line is a good secondary guide.

 

So I'm doing the shade tree mechanic gig until it gets too hot today.

What I Did:

I compressed the tensioner arm with painter's tape. I slithered a snake of tape with the adhesive side out and around and taped it to itself. This compressed the tensioner so that it won't expand while the timing chain is going on the two gears/sprockets. Adhesive side out so not to stick to the tensioner.. Later I'll cut this tape, and the tensioner arm will expand as I remove the tape.

What I Should Have Done:

I should have doubled the tape. I used one strip.

While this one strip held as I was put the timing chain through the channel in the tensioner and placed the chain through the head and engine block, the tape snapped as I was adjusting the tensioner. So if you see two different colored tapes in the pics, that's why. Also don't put the painter's tape above-n-around the tensioner channel. The timing chain won't be able to go through ....

Use two pieces of painter's tape, back-to- back.

What I Did:

I pulled the transmission fluid line off when removing the radiator.

What I Should Have Done:

Wrapped the unconnected line with plastic wrap. Tranny fluid was spilling on the ground. Oil and asphalt don't mix.

What I Did:

Put the sprocket on backwards.

What I Should Have Done:

Put the sprocket "protrusion" in towards the engine.

Look at the pic. See the sprocket/gear part that looks like a flattened-out volcano? That side goes in towards the engine block. The flat side faces outward towards the timing cover, radiator, grill, et al.

I originally put it in backwards, and after getting the tensioner mounted, the cam gear gear wouldn't mount since the lower gear was creating an off angle for the timing chain.

Helpful Hindsight Hints:

A) Mark the parts/items for alignment and easy replacement.
B) Take pictures/video BEFORE removing gears, chains, etc.
C) Put the volcano side of the sprocket inward towards the engine.

Learn from my mistakes and folly.

 

So my next step was to - once again -- put the sprockets/gears back onto their respective spindles with a NEW upper timing chain.

Some wrench-heads were telling me that the best method is to put the both upper and lower gear onto to the timing chain and then install both gears onto their spindles simultaneously.

What I Did:

The first thing I did was to get a boot shoelace and tie it to the upper timing chain. I threaded the laced between the chain's dual link set-up. Why? Because if I simply tied the lace around the entire side of chain, there would not have been enough space/tolerance to maneuver the chain in the gap at the upper head area.

I then dropped the chain through the timing chain gap in the head via the boot-lace and placed the both the sprocket and the cam gear into the chain as well as threading the tensioner into the middle with the guide to the right ( driver's side ) and the tensioner arm to the left ( passenger's side ).

See first picture for a visual....

I tried to pull the whole attachment up thru the head with the boot lace. It didn't work. The gears kept falling off the chain, and the painter's tape wrapped around the tensioner snapped after a few tries.

What I Should Have Done:

After re-taping the tensioner, I dropped the upper timing chain down through the head. Removing the cam bolt-plug on the head made this easier. I then threaded the tensioner through the guide on the right side of the tensioner. I had difficulty getting the tensioner into its proper placement until I finally found the best method.

I took the chain threaded tensioner and shifted it so that the tensioner arm was facing downward toward the ground ( South ) and the now threaded guide-side was facing upward ( North ). I then moved the entire piece into the head area. Once inside, the piece easily shifted horizontally and oriented into it's proper side-to-side position ( Moved from South to West and North to East, so to speak ).

I put the bolt through the holes in the tensioner and hand tightened it all in to place. Easy this time!

I then pulled the chain upward through the head and placed the cam sprocket into the upper timing chain. I approximated where the teeth should go when I would ultimately place the cam sprocket on to the cam, but I didn't attach it yet.....

Instead, I carefully placed the cam sprocket/upper timing chain down through the head again, and placed the bundle in the gap between the cam shaft and the head where the now-removed plug is located.

This drop left enough slack at the bottom of the timing chain that I was able to thread the chain easily onto the teeth of the lower sprocket. I then pulled the cam sprocket/timing chain bundle upward again. A tight pull and the whole bundle almost fit onto the cam!

I was off a couple of teeth on where the sprocket was suppose to be positioned onto to the guide peg located on the end of the cam shaft. It was tricky to keep the bundle and bootlace taut and still move the cam sprocket one tooth at a time. After a couple of these moves, the cam sprocket was in position and went onto the peg.

The upper timing chain was finally on and tight as it should be!

I screwed in the bolts to secure the cam sprocket in place, and then tightened all the other bolts in the timing chain. HUGE difference in the chain tension!

A neighbor checked my work and said it looked okay. I then removed the bootlace. I was wedged into the chain in the the teeth and sprocket. I got it out by cracking the bottom bolt counter-clockwise. Once it cleared the cam sprocket, it wqs easy to untie and remove.

 

Here are the before and after photos of the used-vs.-new timing chain.

Note the difference in tightness and slack.

Who knew a chain could stretch that much???

Also a picture of how I threaded the chain with a boot shoelace for reference....