Land Rover FAQ, Part IV, Timing Chain

I. Accessing the front cover, or getting to the bit to be worked on:

Getting to the timing chain to replace it and its related sprockets is no easy task. To do so, a significant portion of the front of the car needs to be removed, as well as the oil and coolant in the engine. It is not a difficult procedure, but is laborious and time-consuming.

A few caveats, before we dive into the engine.

This is a job best planned, if possible, for when the engine is already in need of an oil change. When removing the front cover, coolant from the passages will run down into the oil pan, ruining the oil in the pan. Thankfully, I had stock on hand...oops.

Also, it's a good time to change the coolant and hoses if it's been a while. Considering they've got to come out, why put old parts back? Plan ahead if you can, and do a bit of preventive maintenance at the same time as the repair.

Now, to work.

First off, remove the tire from your bonnet, and the bonnet itself. This is fairly necessary, as good light and access to the engine bay is needed for this job. Now, drain the coolant from the engine and radiator, following whatever procedure is necessary on your car.

After draining the coolant, remove the grille, and then remove the radiator from the front panel of the car, to obtain an unobstructed access way to the front of the engine.

Here is where the manual and I differ. The manual clearly calls for the entire front panel with the radiator to be removed, but I found it easier and cleaner to remove only the radiator and access the front of the engine through the resulting opening. It's not quite as easy, but it's a lot less work, especially considering the age of the wiring and the auxiliary things like winches that get in the way.

Now, with the radiator out, loosen the dynamo or alternator and remove the fan belt, then remove the fan and its pulley. These don't really have to come off, but for only 4 bolts it makes life much easier.

With this done, the crankshaft pulley and the starter dog have to go. With a cat's paw or a screwdriver, bend back the locking tabs on the washer, then shock the starter dog loose by applying your wrench to it and hitting it with a hammer. Don't be shy with it - shock is the only way to get these loose - pulling on the wrench is NOT going to do it.

With the starter dog removed, slide out the crankshaft pulley. This may or may not come easily, as the pulley can and does rust to the crankshaft due to water getting past the dog in wading situations. If yours is reluctant, some penetrating oil and a 3-jaw puller may be in order, but it will come off. With that finally off, you're now ready to remove the cover.

II. Removing the front cover:

The cover is held on by bolts along the outside left and right edges, as well as a stud underneath the dynamo tensioning arm and 3 bolts in a triangular pattern at the top right on the water intake port. These, along with 3 bolts at the front of the oil pan hold the cover in place. You do not need to remove the water pump, as none of its hardware fouls the cover removal.

Along with these fasteners you'll need to remove the coolant hose stub running between the water pump and the thermostat housing. In my case, rather than removing and possibly damaging the hose, I removed the 2 bolts holding the right-angle thermostat bypass casting to the side of the thermostat housing and took it with the cover. I gave me a chance to replace that gasket, which had been weeping anyway. Choose whatever method works for you.

Be very careful removing the cover, as you don't want to tear the oil pan gasket if at all possible. It seals the front cover to the oil pan, and if it's been Hylomared to the block it may well tear. If it does, think of it as an opportunity to inspect the inside of the pan for metal shavings and clean out the sludge, and replace the pan gasket. As you've already got the oil out, it won't take but an extra 10 or 20 minutes. This time, Hylomar it to the pan and not the block so that you won't have this problem again.

III. Now I'm in there, what do I do?

Once the cover is removed, you're ready to start replacing parts. I'm not going to go through the alignment and setup procedures for the timing chain here, as the variations are more than I can deal with in a small article. Follow the manual procedures for your engine and you can't go wrong. I'm just going to hit a few high points here that I found difficult and feel it could help you in your repair.

First off, do yourself a favor and replace the front pulley seal. This gets done by prying out the old one, coating the new one with Hylomar and drifting it into place gently with a block of wood and a mallet. If the cover hasn't been off for a while I will guarantee it's ready to leak - do it now and save the effort.

Carefully inspect the timing chain tensioning mechanism while you have it off the engine block. When I removed mine, I found that the tab that engaged the block and held the aluminum gear had cracked and was in imminent danger of failure. Problems like this are not unusual with cast-aluminum components, so make sure all is OK.

During this inspection, make sure that all of the oil passages in the tensioner are clear, and aren't clogged with shavings or gunk. This can be done by blowing parts cleaner through them, or compressed air works too. Inspect the bearing point where the aluminum tensioning gear rides for excessive wear - if you can't see the machining marks on one side, it's worn and you may want to replace the tensioner.

In any case, after the inspection, replace the aluminum tensioner sprocket. They wear out right along with the chain and it's unlikely yours will be reusable. Coat the inside of the tensioner sprocket bushing with a good coat of high-quality assembly lube or 90-weight, to give it a good start-off till the oil gets to it.

While you're in there, inspect the sprockets on the cam and crankshafts. If the teeth are worn to points or the metal is mushroomed along the gullets, replace them with new. A good chain and bad sprockets will turn into a bad chain and bad sprockets faster than you care to deal with. The sprockets will oftentimes be reusable (mine were) so don't replace them unless they're showing definite signs of wear.

As a note on replacing these sprockets, be careful to make sure you get the crank sprocket on properly, by noting the way the old one is on before you remove it. The crank sprocket isn't symmetrical, and getting it on backwards will wear the teeth away quickly leading to premature failure.

If you're lucky, your chain won't have slipped and everything will still be in alignment. If not, be careful which alignment procedure you follow in the manual for synchronizing the camshaft and crankshaft. There's one for older engines with the timing mark on the flywheel, and one for newer engines with the marks on the front cover. Make sure you use the right one, and spin the engine several ties after installation and check it again t ensure you haven't gotten the silly thing 180 out.

On the subject of camshaft setup, if you've got an older petrol engine without external timing marks or a Diesel, a good substitute for the dial indicator called for in the chain alignment procedure is a piece of card and a well-sharpened pencil. Tape/fasten the pencil to the top of the rocker arm and place it so it draws a vertical line on the card, which is taped to or held under a bolt on the block. Rotate the engine through one full cycle of the #1 valve, then get your maximum opening by turning the camshaft until the pencil points at the bottom of the mark that it made previously. Simple and direct, and easier to find than a dial indicator.

Once the new chain is in place and you're reinstalling the tensioner, clean all of the bolt threads with solvent and install the bolts and nuts with blue Loctite threadlocker. This is especially important on the bolt that holds the tensioner ratchet pawl, as it has no lock washer and the consequences of it vibrating out are very bad.

Don't remove the old anti-slap pad until the new chain is in place. It acts as an extra hand till you get everybody lined up and tensioned properly. Once the chain's in place and the tensioner's tight, then remove the old bolt locks and replace the anti-slap pad, setting the new one .010 from the chain - it should not touch. Use new bolt lockers - they're cheap, and this is another component you don't want coming loose.

NOTE: DON'T USE RED LOCTITE HERE!! Red Loctite is for assemblies that will NEVER come apart again without heat or air tools - bad for stuff that's going to be renewed every few years...

Last tip: Check, double-check, and triple-check the cam to crankshaft alignment once you get the tensioner back in and button everything up. If it's wrong, you need to do this all over again, and we don't want that...

VERY last tip: Don't be tempted to tension the chain manually by pushing out on the sprocket till the teeth on the ratchet engage. Doing this will put an undue strain on the chain and gears, and you'll end up opening the case again to fix it because of the awful whirring noises it'll make. I didn't do this, but a friend of mine did - and blew an extra day doing the assembly and reassembly again...

IV. Assembly is the reverse of disassembly....

From here, with the new parts in place, it's just a matter of sealing all the bits up again. Start by wiping down the gasket sealing surfaces with solvent, to remove old sealer residues and prepare for new gaskets. Scrape off old gaskets as necessary, but be careful not to scratch the surfaces!

I personally use Loctite 2A when I install gaskets - it's a thick, non-hardening sealer that helps take up some of the irregularities of the old covers on these beasts. Do whatever works for you, but do it to one side only so the gaskets don't tear if you need to remove them for any reason.

Pay particular attention to the sealing surfaces of the water inlet (the triangular gasket) and the right-angle thermostat bypass. As these are coolant areas, they tend to rust a bit more than the other areas. A bit of extra scraping and cleaning now means a better seal both now and later. Also, coat the bolts holding the front cover in place with Anti-Sieze or some equivalent - they tend to corrode in place, especially the ones in the water passage areas.

With the gaskets in place on the cover, bid a fond farewell to the chain for the next 100,000 miles and put the cover back in place, being careful not to pinch or distort the oil pan gasket. Tighten the bolts evenly, crossing the cover starting at the center to avoid undue strain. Don't forget the bolts up from below! Also, don't forget to put a new gasket in the thermostat bypass and bolt it back on, if you removed it as I did.

Coat the inside of the crankshaft pulley with Anti-Seize (to avoid fights on removal in the future), and coat the outside with 90-weight t ease the new seal into operation. Slide it back onto the crankshaft, install a new locking tab, and reinstall the starter dog. Put the gearbox in first and lock the handbrake, then tighten the dog to the proper torque and set the locking tabs. Replace the oil in the engine, and , if you wish, you're ready for a test run of a second or two.

Here, I started my engine just to make sure I'd gotten the timing right. I only ran it for a few seconds, but hearing it kick over was a good sign of success, and meant that there was little to remove again had it been wrong.

NOTE, IF YOU ARE DOING THIS ON A DIESEL, DO NOT START YOUR ENGINE WITHOUT COOLANT IN THE SYSTEM!!! Petrol engines are much more tolerant of this and can survive a few seconds without water - Diesels cannot! Please don't burn up your engine...

At this stage in the game, just reassemble all the bits you took off, replacing expendable parts as you see fit. Replace the coolant in your engine, leaving off the front heater hose to vent the air from the system - it's easier than messing with that silly little petcock on the side of the block.

With all back in place, start and run the engine, but don't drive it till you've warmed it up properly, then stopped it to check for leaks. Also, once it's warm, retime it and reset the point gap on a petrol engine - you'll find that the timing has slewed about considerably if the chain was appreciably worn. Diesels, I can imagine, would also benefit from a bit of pump re timing, but having not done it personally, I can't say.

V. Conclusion:

In hindsight, I realized that the wear in the timing chain was eating a lot of my engine's performance and economy. With the chain replaced, off-the -line acceleration improved, as did my fuel mileage. The engine's also running smoother, as is to be expected when the valve timing is now back where it ought to be.

The downside of this is that there were other problems, like wear in the distributor, that were masked by the wear in the chain. Don't be surprised if you find things like this - cleaning up slop in one part of a system usually shines a bright, glaring light on problems elsewhere.

All in all, though, it's a worthwhile repair that is not hard, but is labor-intensive. Enjoy working on your aluminum mate - the more you know, the better off you are.