First Timing Chain Replacement

[Sculthorpe]

The car that I purchased 18 months ago has about 42,000 miles on it and I believe that the engine still has the original chains etc. It came with some spares which included tensioners, guides, and "German" chains. As a precaution I have decided to renew the timing components. I have purchased genuine JWIS chains that I have sourced here in the USA, and the sprockets, seals, and related hardware are from JDPart. Those components are proudly marked as "Made in England." I feel good that at least the hardware is up to the task.

This will be my first time replacing timing chains on any vehicle, so hopefully the labor side of the equation is also up to the task. I have studied the ROM as well as the Rimmer video and I feel confident to proceed. The ROM states that the bonnet should be removed. Is this really necessary?

Also, is there is anything not mentioned in the ROM that I should be aware of before I dig in?

Thanks!
Mel

[sujitroy]

Mel, There is an engine service manual somewhere on this site in the technical sections. Download that. It's not really needed during disassembly, but useful on reassembly. If you can't find it, I have a copy and can email it to you. my email is sujitroy@yahoo.com. I'm in California. Removing the bonnet helps. It at least helped me. You can face the timing cover and bits head on. You may want to get a new oil pan gasket just in case you damage the one on the car.

Sujit

[wilf]

+1 on removing the bonnet - it does indeed help, as you will spend a lot of time leaning over the front edge of the car to get at the front of the engine.

[DJT]

Removing the radiator grille also helps.

[Mark S]

Remove the bonnet - it's three studs each side into captive floating retaining plates and a pin through the retainer. Ten minute job to re-fit and align.

Obviously you need the front grill off and radiator out, power steering pump off, alternator off. Segregate all the bolts removed in separate plastic bags taking careful note of the length of all the timing cover bolts and exactly where they all fit.

Stuff a rag in a plastic bag under the crank so that you don't drop anything into the open sump pan.

The oil sump pan is a rave to remove (I've done it in the past), needing the crossmember dropping. When I did the chains, I couldn't get the timing cover back on without damaging the soft pan gasket (but I didn't have any really thin "shim" to protect it). If you have shim, the front of the pan may just "spring" down enough to slide in. It's a tight fit between sump and the two head gaskets and you can only get at the next two bolts back on the sump so couldn't drop it a bit either. I really didn't want to damage the head gaskets, so ended up cutting off the front of the sump gasket and using silicone. The water pump cover also hampers a parallel install of the timing cover. If it leaks, you have lost nothing and just drop the crossmember/sump and fit a new gasket afterwards.

If your front pulley is grooved where the seal runs, use a speedy sleeve/oversized seal, or find a disc around 2mm thick and install the new oil seal in the cover 2mm further back.

Keep everything as clean as possible!

Enjoy the satisfaction that you have done the job yourself.

[jbuckl]

Bonnet off, grill off.
none are strictly necessary. But will help to see & locate everything.
familiarise yourself with the tensioners ratchet mechanism & it’s resetting & initialisation.
I use the red plastic setting spacers , but don’t use the feeler gauge between the slipper & chain.
ensure that the chain slack is removed on the tight side & taken up by the guides on the slack side.
the system must not be too tight or it will over load bearings & guides causing wear.

[wilf]

I just cannot see how you would easily get the crank pulley off without removing the radiator. It is so easy to get the rad out anyway.

[jbuckl]

I just cannot see how you would easily get the crank pulley off without removing the radiator. It is so easy to get the rad out anyway.

Of course!
edited.

[Sculthorpe]

Thank you all for the suggestions. I will take your advice and remove the bonnet and grill. Sujit: I have the Engine Service Training file and will review it.

I'm looking forward to exploring the upper rev range of this great sounding engine after the job is complete. Up to this moment I have kept it below 4k rpm due to concerns with the original chains.

Mel

[sujitroy]

You may need am impact wrench to remove the crankshaft pulley bolt. If the car is a manual, leave it in neutral, just in case you live in an earth quake zone and the car decides to move.
Sujit

[Sculthorpe]

IMG_0007.jpeg Well, the disassembly has gone well so far. My next question is the position of the jackshaft sprocket. According to the ROM and to the Rimmer video, the scribe line should be just below 3 o'clock but mine is sitting at around 5 o'clock. I aligned the pulley at zero degrees and both cams are likewise positioned where the timing grooves are aligned with the marks on the bearing caps. The rotor arm is also pointing toward number 2 cylinder of the cap. I believe that the engine is at TDC. Am I mistaken? What now? Reassemble with the existing positioning, or set the jackshaft according to the ROM and then re-set the distributor gear to get the rotor timing back in synch?

Mel

[wilf]

I set the jackshaft pulley according to the ROM, then retimed the distributor from scratch. So long as you are happy doing the latter, you could, in theory, set the jackshaft sprocket almost anywhere! But for the sake of future owners probably best to go by the book.

[sujitroy]

The reason that the ROM mentions the slight incline is so that the distributor gears mesh with the jack shaft gear and you are able to time the car and c/amp the distributor down. (if not you may have a tough time getting the timing right or you wont be able to clamp the dizzy down. ) I was told that this was critical for the TR7 but not so critical to the Stag. However, I did follow the ROM and have a slight incline, but not as much as shown in the photo. Is your photo showing the new chains installed? If so the tensioner is extended and should not be.


Sujit

[Sculthorpe]

Wilf: I was thinking the same as you, that the orientation is not critical as long as the distributor is set accordingly. As an aside, I need to reset the distributor anyway because I am only able to achieve a maximum advance of 4 degrees before running out of adjustment at the pedestal. I was a bit concerned to see the position of the scribe marks since this is my first time with this procedure.

Sujit: These are still the original chains and the tensioner extension is why I am in the process of replacing everything. I was able to see them before teardown by using a borescope with WiFi connection to my iPhone. A fun little tool for only about USD35.

[sujitroy]

Please share details of your borescope. I bought a cheap 10$ camera for my phone put it rather useless for anything on the car.
Keep the stuff you remove. If the tensioners are original I would consider reusing them.
Sujit