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post #57 of (permalink) Old 03-22-2018, 09:06 AM Thread Starter
MRDANGERUS
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Join Date: Aug 2010
Location: N-East Central USA
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Timing Belt - Remove & Replace Procedure, part I

Installed the Blue Timing Belt and replaced the tensioner bearing. Tim's procedure was very helpful.

Here is the Tim Engle's timing belt doc from the Yahoo group Turbo Esprit.

Timing Belt - Remove & Replace Procedure.doc (126.5 KB, 193 views)

When working from the topside of the engine, do NOT brace yourself against, or lay upon the intake manifold or the plenum/ air box.

If you do, at a minimum, you may flex a joint and create an air leak that will drive you nuts trying to diagnose later.

Worst case, the fuel injection intake manifolds (later Esprits) are known to crack. Replacements are out of production/ out of inventory, and if you do find a used one, they are very expensive.

Esprit owners could pull the engine, but that's a ton more work. If you have to ask how to replace the timing belt, then youíre not prepared for removing and replacing the engine and transmission. If you read this document, and replacing the belt with the engine in the car begins to sound to you like a lot of work, then brace yourself, because removing and replacing the engine is going to be more work. I recommend doing the job with the engine in place.

Bolts & bits you remove should be put in plastic bags, which are then marked with from where the contents came. Take lots of before photos... with a digital camera, you can't take too many. Never trust your memory.

Planning Ahead Ė Auxiliary Pulley Timing

For engines equipped with distributors, the auxiliary pulleyís position is critical to ignition timing. Change how the pulley is indexed on the timing belt, and you change the ignition timing. For later 910ís with crank triggered ignition, this is a non-issueÖ skip over this section.

The Auxiliary pulley has a timing dot on its rim thatís used for indexing the auxiliary pulley (in addition to the dots used for timing the cams). The standard procedure is for that dot to be facing forward, and the pulley turned so the dot is at about the five oíclock position and lies on the centerline between the Auxiliary Shaft and the Crankshaft. Given the distance between those two shafts, and the other bits between them, it can be difficult to accurately index the Aux pulley. In an Esprit, working between the engine and the firewall, the degree of difficulty goes up another notch.

DORMAN Pan 264431

The following alternative method requires that you place some paint marks on the Intake Cam Pulley and Auxiliary Pulley before starting to dismantle things. The downside is that later it will only replicate the current setting. If the timing is off now, it will be off later when you get it all back together. Check the ignition timing before starting. If you like where it is, then proceed with the following. If the timing is wrong now by more than can be adjusted at the distributor (i.e., the pulley needs to be indexed on the belt), then itís best that you abandon this method before you start, and plan on following the book method later.

Set the crank to TDC with the cam pulley timing dots properly aligned and on the centerline between the cams. Then put a paint mark on one of the teeth on the intake cam pulley where itís easily visible. On the mid-engine Esprit, thatís on the back side, toward the top of the pulley. Do the same on the aux pulley. It's not important which two teeth, just as long as each is in the area where the belt is in full contact with the pulley and not lifting away from the tangent point. I choose teeth as close together as possible while still in full contact with the pulley.

Now, count the number of belt teeth between the intake paint mark to the auxiliary paint mark, and write it down the number where you won't lose it. It's good to take a digital photo of the paint marks for future reference, and write on a print.

*~*~*~*
Caution, most cleaners/ degreasers will quickly remove a paint mark. If you're going to clean the pulleys, then don't wipe off your paint marks, or the factory painted timing dimples.

*~*~*~*
Later, when you install the timing belt, confirm the crank is at TDC and get the belt started on the Int &Exh cam pulleys with the dots aligned on the centerline. Then, count belt teeth from your paint mark on the Intake cam over to the painted tooth on the aux pulley, and slip the belt onto the pulley in that position.

Dis-Assembly:

On Esprit Turbos, remove the fiberglass under tray from the bottom of the engine bay.

Working from the top side, remove the thermostat housing and the hose that runs across the top-front of the engine bay above the alternator.

Disconnect the battery (+) cable. Remove the alternator and its triangular support bracket. Earlier engines, like the 907, donít have the triangle bracket, but all 910 Turbo engines do. The V-belt definitely has to go, but removing the alternator itself is just a matter of making work room. Removing and replacing it donít take long, and subsequent steps are easier with it gone.

In the Bosch fuel injected 910 models, remove the black plastic fuel injection hoses that run across the front of the engine bay. Thatís optional to a degree, but they are really in the way and vulnerable to damage. It takes less time to remove them than it does to talk you into doing it.

The Bosch fuel lines are pressurized to 95 psi and the accumulator bleeds down slowly after the engine is switched off, so presume the lines are fully pressurized. Wrap a rag around a fitting while you slowly crack it loose. Allow the pressure to vent slowly before just spinning the bolt out. Each banjo bolt fitting has a small aluminum crush washer for sealing. Be sure to pick them off as well. Order replacement crush washersÖ avoid re-using the old ones.

Remove the V-belt from the vacuum and water pumps. The vacuum pump tensioning bolts are difficult to access. For them, buy a regular "L" shaped Allen wrench plus a GearWrench of the same size (Sears sells GearWrench brand). I think it's 8mm for the adjuster... ?? Measure first. Using a hacksaw, cut off of a stub of Allen wrench about 5/8" to 3/4" long and stick it into the cap screw head, turning it into a male Allen drive. Then put the GearWrench on the Allen stub. That way you can access it from the side instead of head-on, and the GearWrench's ratchet action avoids the need to re-position the wrench one flat at a time.

Sears usually stocks a variety of GearWrench styles in each size: stubby, regular, long, flex-head, etc. Buy the longest one you can get. Those cap screws are usually pretty darned tight, and a standard 8mm wrench is too short to give you much leverage. Buy a long one.

Loosen the A/C belt tensionerís pinch bolt and pivot bolt. Remove the V-belt. That can be easier said than done. Itís easier if the tensioner is completely removed. Then pull the bottom run of belt forward, hooking it on the outer edge of the compressorís pulley. Force it as far as you can. A screw driver between the belt and pulley rim can be used as a lever. When it wonít go any further, put a 19mm (3/4Ē), half inch drive ratchet on the crank pulley bolt, and manually turn the engine over, walking the belt off the AC pulley.

V-belts are cheap. As long as you're going to remove them anyway, plan to install new ones later. In that case, removing the old ones goes much faster if you use a utility knife. It's a good idea to have the new belts on hand before cutting the old ones.

Remove the V-belt pulley from the front of the crankshaft. Have a helper put the transmission is 5th gear, release the clutch and stand on the brakes while you loosen the bolt.

Try to pull the pulley off by hand. If itís stuck, try tapping it forward with a plastic or rubber mallet. The pulley is aluminum, so donít go after it with a big steel hammer. Thereís some room to pry at it, but nothing really solid to pry against if real brute force is required. Donít go breaking other expensive bits. Patience, penetrating oil (Kroil is the best), and heat may be required.

If you do use heat, be careful not to direct it behind the pulley where it may damage the front main seal. For the same reason, donít get the overall mass too hot. Use heat on the pulley only, and in moderation.

If the pulley is well and truly corroded onto the front of the crank, this could be the nastiest part of the whole job. Especially since most 9XX installations donít have enough room in front of the engine to permit the use of a large 3-jaw puller.

Make a note for laterÖ always install the front crank pulleys, both the V-belt pulley and the small toothed timing belt pulley, with a liberal application of Anti-Seize.

On the up side, more often than not, the pulley comes off without much fuss.

Removing the Timing Belt:

If the belt is to be replaced with a new one, then the simple expedient to removal is to cut it with a utility knife. Same could be done with the V-belts. However, itís best to have the replacements on hand before cutting.

If the belt is to be re-installed, then draw an arrow on it indicating itís present direction of operation. The cord body takes a set during use. Once run in, the beltís direction of operation should never be changed. If it is to be re-installed, then take pains to install it the same way it was before it was removed. If you forget to do that, then buy a new belt rather than gamble on getting it wrong.

Set the crank to TDC with the cam pulley timing dots adjacent and aligned on the centerline between the cams. If the dots end up on far opposite sides of the cam pulleys, then turn the crank through one more full revolution and back to TDC (i.e., the cams turn as 1/2 revolution for each crank revolution).

Always turn the crank in its normal operating direction, clockwise. Never go backwards. Thereís no direct timing risk related to going backwards, but there are a variety of secondary ills that can occur. There are different ills for different iterations of the 9XX engine. Rather than getting into each condition, Iíll just say that always turning the crank in the normal operating direction is a safe habit to practice.

If the engine is equipped with an eccentric timing belt tensioner, then loosen the pinch bolt (17mm offset ring wrench) and then turn the eccentric (19mm offset ring erwnch), to the maximum loose position, giving you the most belt slack possible with which to work (itís still not much).

If the engine is equipped with the spring loaded, semi-automatic timing belt tensioner, the piston must be retracted and pinned prior to removing the belt.

Back out the tension adjusting screw until there is approximately 12mm of exposed thread. Donít go too far or the threads will disengage and the internal springs will shoot it out. Do not have your head down in the line of fire, and good luck finding the adjuster later. Thereís a 4mm hole in the front side of the tensioner, either above or below the piston bore. A locking pin is inserted through the hole to engage a groove cut around the piston, locking the piston in place. The holeís location changed through the years. It may be above or below the piston bore, it may be exposed and to the right of the lower mounting bolt, or it may be hidden under one of the mounting bolt washers. If itís under a washer, more often than not itís under the lower washerÖ but not always. With the other bolt torqued tightly enough to hold the tensioner in position, remove the bolt and washer that hide the locking pin hole. Start a 4mm pin in the hole (I use a snug fit drill bit shank), wiggling it along with an inward pressure. Place one hand on the timing belt mid-way between the intake and auxiliary pulley and push down firmly. The additional pressure on the belt will retract the tensionerís piston into the bore. When the pistonís groove aligns with the hole, the pin should drop inÖ with some effort and wiggling. Make certain the pin is fully engaged, then release the hand pressure on the timing belt.

Last edited by MRDANGERUS; 03-22-2018 at 05:12 PM.
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