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24V Timing Belt Questions

41K views 113 replies 18 participants last post by  Alfisto Steve  
#1 ·
Group,
Well, I need only for the timing belt itself to arrive and I will have the necessary things to tackle the timing belt on the 94 LS. I spent the weekend reading the Cardisc and the TSBs. I have a couple of questions, though:

1. I have read that a good substite for the tensioner locking pin is a 'Welding Rod'. What kind of welding rod? Where do I get them?
2. Many thanks to Alfisto Steve for lending me the cam locks. My question is: once the timing belt covers are off and the engine is moved to TDC, should I then lock the cams, knowing that the rear exhaust cam has slipped? Or should I simply set the engine at TDC, remove the belt, and then lock the cams?
3. Is there another source for a 41MM socket to turn the crank?
4. Why does the manual forbid the use of a ratchet when setting the engine on TDC?
5. Is the belt tension set with the cam locks on or off?

Based on my (limited) understanding of the process, here is how I think I should approach it:

  • Gain access to the timing belt (Remove serp belt, H2O pump, covers, crank sensor, etc.)
  • Remove the induction stuff and cam covers.
  • Bring the engine to top-dead center (TDC).
  • Remove the timing belt.
  • Install the cam locks.
  • Put on the new belt.
  • Set the tensioner, as described in the TSBs.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Take a Valium.
  • Rotate the engine and check the timing.
  • Reassemble.

Is this the correct approach?
 
#3 ·
John hold those thoughts but let me get you the procedure to make it easy on you. Do not take time belt off yet believe me it is better to set up engine at TDC with sparkplugs out and try to install timing dies so you know how many cams are in time with belt still on. I am overcome by events today so can't detail it out have a scotch and relax right now.
 
#5 ·
The Players are all here.

I now have all the parts on site to replace the timing belt. The only additional pieces that I might need are idlers, and I will assess them once the old belts are off. Again, here is my proposed approach:

  • Gain access to the timing belt (Remove serp belt, H2O pump, covers, crank sensor, etc.)
  • Remove the induction stuff and cam covers.
  • Bring the engine to top-dead center (TDC).
  • Remove the timing belt.
  • Install the cam locks.
  • Put on the new belt.
  • Set the tensioner, as described in the TSBs.
  • Remove the cam locks.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Reassemble.

Are there any alternative sources for the 41 mm socket? I can get a 1 5/8 most anywhere, however finding a thin wall is a challenge....
 
#6 ·
Reply To Your 24v Tb Steps

REPLY TO YOUR 24V TB STEPS
john.harrill said:
I now have all the parts on site to replace the timing belt. The only additional pieces that I might need are idlers, and I will assess them once the old belts are off. Again, here is my proposed approach:


  • DISABLE ALARM AND DISCONNECT BATTERY
  • Gain access to the timing belt (Remove serp belt BUT FIRST HAVE DRIFT PIN RIG TO FIT SERP BELT TENSIONER, LOOSEN BOLTS IN POWER STEERING AND WATER PUMP PULLEYS WITH BELT STILL TENSIONED, LOOSEN SERP BELT TENSIONER COMPRESS TENSIONER AND HOLD IT AS YOU REMOVE SERP BELT THEN INSERT RIG PIN IN TENSION TO HOLD LOCKED, REMOVE POWER STEERING PULLEY, REMOVE TENSIONER AND BRACKET TO GAIN ACCESSS TO TIMING BELT TENSIONER. H2O pump, covers, crank sensor, etc.) REMOVE TOP DOG BONE ENGINE MOUNT, REMOVE LEFT INNER FENDER LINER, SUPPORT TRANNY ON JACK REMOVE TRANNY MOUNT AND LOWER TRANNY ONTO SUBFRAME TO GET MORE CLEARANCE TO WORK ON REMOVING TIMING BELT COVERS (THIS DROPS ENGINE AWAY FROM CHASSIS SO YOU CAN REMOVE TIMING BELT COVERS AND GET TO CAM PULLEYS ETC EASIER.
  • Remove the induction stuff and cam covers. COLOR CODE/TAG ALL SENSOR CONNECTORS BOTH SIDES BEFORE DISCONNECTING. IF 95 REMOVE EGR TUBE BAJO FITTING AT EXHAUST MANIFOLD AND EGR VALVE ATTACHING NUTS AT INTAKE. WATCH HOW BRAKE BOOSTER BANJO FITTING IS ASSEMBLED (MANY CRUSH WASHERS.
  • Bring the engine to top-dead center (TDC). REMOVE SPARK PLUGS
  • DO NOT Remove the timing belt YET.
  • Install the cam locks. IF THEY ALL WON'T FIT HOLD CAM PULLEY THAT IS OUT OF TIME WITH SPANNER AND LOOSEN NUT AND KNOCK PULLEY OFF TAPER WITH BRASS MALLET AND HAVE WRENCH ON FLAT SPOT ON MIS TIMED CAM TO HOLD IT/TURN IT SO CAM TIMING DIE WILL FIT.
    NOW CHECK TENSIONER AND SEE IS IT IS IN PROPER POSITION TO INSERT 1/16" "WELDING ROD/DRILL ROD" IF SO INSERT ROD THROUGH TENSIONER AND PISTON RIG PIN HOLES. YOU NEED TO HAVE WEIGHTED TENSIONING TOOL PINS IN TENSIONER ECCENTRIC TO LIFT TENSIONER AS YOU LOOSEN HOLD DOWN NUT SO IF YOU NEED TO SLOWLY COMPRESS TENSIONER TO GET RIG PIN IN YOU CAN. iF YOU CAN'T YOU WILL NEED TO REMOVE TENSIONER FROM ENGINE AND COMPRESS IT IN A VISE TO GET RIG PIN (DRILL ROD INSTALLED.
  • Put on the new belt.
  • Set the tensioner, as described in the TSBs.
  • Remove the cam locks.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Rotate the engine and check the timing.
  • Reassemble.

Are there any alternative sources for the 41 mm socket? I can get a 1 5/8 most anywhere, however finding a thin wall is a challenge....
 
#8 ·
Excellent!

Great!
Thanks for the description. I'll begin in the next couple of days. I have budgeted around 2 weeks for the job. I want to take the necessary time to get it right.

I plan the take notes and photos to chronicle the job.:D
 
#9 ·
I have 24v TB process notes in my steno book and pictures but no time to really write it up correctly. My wife says I try to spend to much time tech writing and not enough enjoying the family so I am writing this while playing Mr. Mom. Have a couple free hours now as I let my daughter go to movie matinee today. Summer vacation is going to cramp my style but family has to come first.
 
#10 ·
Family

I understand completely.

The reason I am waiting for a couple of days to start is that I have to provide transportation for my daughters (dance class) until Friday.
I can't be without a car that carries more that two people until then......

I think I have enough to get started.
 
#16 ·
A proiductive evening..,

I had toyed with the idea of leaving the 164 in the driveway, freeing the garage for the wife's '88 spider. But I decided against it. The skies opened up at around 6:00, validating my decision.

I was able to get alot done while the rain fell:

Drained the coolant.
Disconnected the battery and temp sensor wires
Removed:
  • wheels and fender liners.
  • passenger-side strut.
  • induction
  • coil packs.
  • Thermostat
  • Dog bone and gearbox mount.
  • Serpentine belt
  • Water pump pulley
  • Rear timing belt cover
  • Lower serpentine pulley

Tomorrow I plan to remove the front timing belt cover, and cam covers. Next, before removing the timing belt, I'll bring the engine to TDC and check the tension.
 
#17 ·
How are you going to measure TDC? Do you have a way of using a dial indicator in the #1 spark plug hole?
I was reading the tech article on how to do the TDC on a 24v and it says to watch the dial indicator for TDC. Just as it comes up to TDC and not after, is where you stop and set the timing. Evidently if you go past the first part of TDC you have mistimed the valves. From what I know of timing Alfa's there is a spot where the crank can go a couple of degrees while the rod/piston is at TDC before going on down after. So what I am reading is that you have to stop just as it first peaks.
Correct me or rewrite what I just wrote if I am out of line here.
Thank you
 
#18 ·
You can get a cigar without dial indicator by slowly rotating crank with plugs out and watch as notch on face of front pulley comes up to triangled cast pointer on front cover. Also use a 12" 3/8" drive extension or long screwdriver in #1 plug hole (closest one to dog bone engine mount point on rear head).

Watch as extension/screwdriver rises and then stops rising that should also have pointer and pulley aligned. You can tweak crank pulley slightly back and forth slightly to get TDC exact without compromising cam timing.
 
#19 ·
Measuring TDC

Steve's approach was the one I had planned on using, as I have used it with good results in the past on 4-cylinder Alfas.

I usually put a socket extension in the No1 spark plug hole, after marking it with a Sharpie. The marks on the extension need not be precise, as they only serve to help your eye see the movement.

Question:
On the two short hoses that connect the heads and the thermostat, are there 2 clamps per hose? Or just one?
 
#20 ·
I am following this discussion with avid interest as I am going to have to do my timing belt on my Q sometime in the future. I have used the screw driver approach on any number of occasions, where as I have also used the dial indicator. My preference now is to use the dial indicator as it is more precise. My question about this as related to the cam timing is just how precise does the timing have to be, so that valves don't get bent on a 24v engine? The cam locks I would imagine help with alignment/show misalignment of the cams as related to TDC. Correct?
Just how precise does this have to be? As I mentioned in a previous post, there is a neutral spot on the crank at TDC that is a couple degrees of crank rotation.
Just as a side bar to this, I have the V6 timing tool and the Alfa dial indicator that goes with it. I used this tool on a 2 liter motor a few months back. That extra length of the V6 tool made timing that engine a breeze. Before I had a real difficult time screwing the timing holder into the spark plug valley.
 
#21 ·
Update

Four things to report:
1. The serpentine belt tensioner 'shock absorber' is cracked at the upper boss. It will have to be replaced.

2. I can see the timing marks on the cams from the last time the belt was changed. The front head's mark line up adjacent to each other, but the rear head's do not. The rear exhaust cam has slipped at least two teeth.

3. I'm having a hard time seeing the TDC pointer on the engine. Where is it on the block?

4. The two pin holes that the tension tool fits into are rotated to almost the top of the tensioner wheel. The tool cannot be assembled in such a way as to have the arm parallel to the ground. Also, where is the hole for the rig pin?
 
#22 · (Edited)
john.harrill said:
Four things to report:
1. The serpentine belt tensioner 'shock absorber' is cracked at the upper boss. It will have to be replaced.

2. I can see the timing marks on the cams from the last time the belt was changed. The front head's mark line up adjacent to each other, but the rear head's do not. The rear exhaust cam has slipped at least two teeth.

3. I'm having a hard time seeing the TDC pointer on the engine. Where is it on the block?

4. The two pin holes that the tension tool fits into are rotated to almost the top of the tensioner wheel. The tool cannot be assembled in such a way as to have the arm parallel to the ground. Also, where is the hole for the rig pin?
1. If you get a new one it hopefully will come retracted with rig pin holding it compressed. Leave it compressed when you install it.

2. Then three of the foor timing dies should fit and crank pulley shold be at TDC.

3. It is not actually on block but front cover about 11:00 position. As I said it looks like a triangle pointer and at TDC notch on face of crank pulley splits between two teeth and you want that pointer to split teeth and match line in pulley.

4. Maybe try rotating adapter with two pins in it 180 degrees to get pins on top or loosen bolts holding adapter to weighted arm as arm at adapter attach point has half moon slots to raise or lower arm on adapter to make weighted arm parallel.

Rin pin holes for 1/16" drill rod are in tensioner piston housing and small chrome pistion not in tensioner eccentric arm or tensioner pulley that weighted tool pins go into. You have to remove PS pump pulley, PS pump bracket that goes to accessory belt tensioner bracket and then remove accessory belt tensioner and bracket assembly to really see TB tensioner with its rig pin holes (tensioner looks like a lower case letter t and is about diameter of a cigar).

If air gap between tensioner housing face end that piston sticks out of and face of eccentric arm is not 1/8" and if 1/16" drill rod rig pin does not insert freely into tensioner housing go through hole in piston and out the back side of tensioner housing then timing belt is not tensioned correctly.

On Myrons 24v I found rig pin hole way off (piston extended to far) and air gap about 1/4" and eccentric arm almost frozen to pivot pin so there was not real tensioner movment keeping belt in proper tension as engine expanded and contracted when going from hot to cold or cold to hot.

I had to remove tensioner put it in vise and very very slowly compress piston so I could insert 1/16" rig pin. Then I had to remove snap ring and fight to get tensioner eccentric arm off stud on front of block. Then I had to use a gun barrel brass cleaning brush to ream out crud so it would move freely after I also polished stud.

I also had to hold cam pulley of cam that was out of time, loosen nut, knock pulley loose off cam end, rotate cam to get fouth timing die on.

Then I found I had to leave that pulley loose to get new timing belt on all 5 cogged pulleys, two ilder pulleys , cranks shaft cog pulley and tensioner pulley before I could set belt tension by rotating eccentric to get that 1/8" air gap with 1/16" rig pin still in tensioner piston. This is where properly set weighted arm comes into play.

Hope this is not overload but until you have worked through the rigging/tensioning process and gotten correct air gap with rig pin still in piston it isn't correct.

Once you have it and all four cams still locked down then hold loosen cam pulley and retighten nut to lock pulley to taper on cam.

Then you are ready to hold weighted arm and torque down nut holding tensioner pulley to eccentric arm and prceed to recheck 1/8" arm gap. If OK you can carefully remove 1/16" rig pin from tensioner by raising or lowering weighted arm very slightly so rig pin slips out. Then rotate engine with plugs out using socket on crank and see that tensioner air gap remains correct and you can slip in and out 1/16" rig pin easily in tensioner.

It was hard for me to visualize this the first time and I had to tweak it a couple time to get it correct.
 
#23 ·
Yesterday's Findings

After studying the belt in place, I decided to remove it, as the goal of this operation was to replace the belt and re-tme the engine. What I found was an epiphany.

A few weeks ago, I had a mystery rattle coming from, what I thought was the top of the engine. Just as it had appeared, it vanished. Good news, right?

Wrong. Looking at the timing belt idler on the front of the engine, I could see the ball bearings inside of it. The seal on the idler wheel was missing and the idler had seized. The earlier noise was the bearing in it's last days, and when it seized, the noise went away. The jumping of one of the cams last week was probably brought on by the seized idler.

The timing belt showed signs of heat-induced degradation. I think that I may have been only a few days away from a complete belt failure. :eek:

Where I am now:
  • I have located the holes in timing belt tensioner and the chrome piston. By applying very slow pressure, I can get it to move into the cylinder. I just need to find a suitable rig pin.
  • The eccentric wheel bracket pivots freely, and so does the wheel itself.
  • The cams are locked down. So I don't think it will be necessary to loosen the cam wheel. (By the way, the cam had jumped 2 teeth.)
  • The reason I am having difficulty with the tensioner tool is that the hub is for the serpentine belt tensioner, (1820275000) not the timing belt tensioner hub (1820274000).

Does anyone know a source for the correct hub? Also, a source for the serpentine belt 'shock absorber'?
 
#24 · (Edited)
I think I may have the correct hub in a shipment of tools I got from Difatta Friday evening but we were leaving town Saturday morning and all I had time to do was retrieve the UPS box from front porch and stash, so stay tuned.

We get back home tonight and I hope to get to open my surprise tool shipment from Italia that giovanni@difatta.com had back ordered for me.

I am so glad you opened your patient before you have a valve bending experience.

Here is a parts list of nice to change items when doing Timing Belt Change:

Duh! belt 60561244
two top idler pulley assemblies 60561649
one tensioner idler pulley assembly 60580235

Usually reuseable tensioner 60584475

As for accessory drive the tensioner cylinder assy is 60561380 "shock cylinder"
Accessory tensioner idler pulley assy 60561614
Two accessory belt idlers 60561615

Accessory belt 60618584 has a superceding part number as per a factory bulletin I think but don't have number handy now.

Hope your vendors have parts you need to order.
 
#25 · (Edited)
As for some earlier questions I missed. The closer TDC is the better and with the timing dies holding all four cams in time you may find it neccessary to knock loose a cam pulley or two loose to get belt on all cogged pulleys.

And since cam pulleys are not keyed to cams like 12v engines you can fine tune (time) crank to perfect TDC.

I had to loosen rear head intake pulley on Myron's 95LS to even be able to get timing belt on all cogs without moving crank so expect to knock a pulley loose to get belt on. I hope 24v cam pulley wrench is one of my backordered tools in surprise shipment.

His car now starts with touch of key and idles almost water glass on head smooth but not quite as smooth as a 1927 1.5L Bugatti my friend's father in law' in JAX has but super smooth for a production line engine.