Lower timing chain noise

[Bob Falfa]

I have, what I believe to be, a noisy lower timing chain. The noise is only present with the engine at 1700 - 2200 revs, with the car stationary or on the move, and sounds like a grinding noise, rather than a rattle. A friend thought it was my brakes binding (they're definately not). I'm guessing that it is the lower chain rubbing on the guides.

I've been quoted ?1800 to replace the lower chain, and as this is an XJ6 engine, I'm not keen to spend that much money on it.

My questions are:

1) could it really be the lower timing chain? What else should I check?

2) is it possible for catastrophic damage to occur?

3) if I'm tonking on at motorway speeds and major failure does occur, am I likely to end up upside down or in a hedge?

4) how much for a new engine? And where to get one?

[christopher storey]

Noises are very difficult to diagnose. The first thing to do is to try and locate it with as much precision as you can - using a rubber tube stuck in your ear and held near various parts of the engine can be a useful tool. If this IS lower timing chain noise you should be able to locate it reasonably precisely to the front timing case below the water pump .

But it may well be something else. A few things to check :

An exhaust pipe , particularly the front downpipes , just barely touching the frames or body somewhere

The top timing chain tension

The distributor for a. side to side play in the shaft , and b. for the bob weights working properly

The alternator and alternator fan

The carburettors/linkages just touching the right hand frames

Something resonating at these speeds - e.g. heat shields, splash shields

Edit : I should also have said that even if it is timing chain noise, although it is a time consuming job to rectify,provided the rest of the engine ( particularly the various sprockets ) is in reasonable condition it is not that difficult to do on a DIY basis . It requires the cylinder head off , the front pulley and water pump off, preferably the sump off , and the timing case removing . The chain itself is easy to replace and although the fixed slipper type tensioner is a bit problematic in that in my experience modern replacements are not that accurately made, with patience it is a perfectly feasible job to do yourself

[1954Etype]

Take the fan belt off and run the engine. That will rule out the alternator, wster pump and tensioner.

[PeterCrespin]

1) could it really be the lower timing chain? What else should I check?

2) is it possible for catastrophic damage to occur?

3) if I'm tonking on at motorway speeds and major failure does occur, am I likely to end up upside down or in a hedge?

4) how much for a new engine? And where to get one?

Hello Bob, I knew your brother Al :-)

1) Yes, if the hydraulic slipper jams or even drops out with a very slack chain. Does your engine oil have fine particles in it? The diagnosis is easy enough with a solid rod rather than a tube. A mechanic's stethoscope or long rod/ultra-long screwdriver placed on the timing case each side and pressed against your ear will make the sound very easy to locate.

2) Depends what you mean by catastrophic. If the chain snaps it could bunch up and punch a hole somewhere but it's unlikely. The longer you leave it the more likely you are to embed hard particles in your bearing shells.

3) No. Even if the engine stopped or locked up you'd just dump the clutch and coast to an oily halt. But then it would be smart to avoid sustained hammering of a noisy engine...

4) Since it's an XJ engine you could do like for like replacement or rebuild for not too much. Scour eBay or the breakers.

The sump will have to come off to get the new chain over the crank nose unless you fit a jointed chain (not recommended). Since you will be basically down to a long block anyhow, I'd go the whole hog and give myself room to work by taking the engine out and fitting fresh rings/hone plus shells and clean the crank out, but you could just do the chain and tensioner I suppose. Make sure the chain dampers/guides are correctly adjusted so the tensioner doesn't have to take up too much slack as the new chain beds in.

Pete

[Durango2k]

When I took my engine apart, I found all ! the inner parts of the tensioner loose in the SUMP, so NO tension at all.

Yet I am sure it was DRIVEN with this condition for a longer time, because the metal mout of the tensioner, the "base" was still on the block.

The main chain has ground it down, and caused two "tram lines" on it.

So:

a) yes, you can continue even when it?s this bad

b) I would not recommend it.

c) it would be a good idea to remove the sump, clean it out, and see if you can judge on chain + tensioner.

Carsten

[abowie]

I've been thinking what I would do here.

To me the salient points are

(a) that the diagnosis of engine noises is as always an uncertain process and
(b) that the engine is already not the original one for the car.

With the caveat that you are confident that the noise really IS coming from within the engine, I think that probably the easiest and most cost effective approach would be to replace the whole short motor with a known good unit.

Your quoted budget of 1800 seems to me a lot to change a 6 cylinder timing chain, even allowing for 2 days to remove and replace the engine. If this then does not solve your problem, or fails to address other damage to your bottom end, you are still in trouble.

I would have thought that for around that money you could buy an XJ6 short motor, have it stripped honed and rebuilt and reinstall it into your car. This way you have an engine you can be confident in. If it were me I would replace the clutch at the same time.

[Bob Falfa]

Thanks for the advice. I'll keep you posted!

[pmansson]

I just read this thread twice, as I have the same issue on an XK140 with a rebuilt engine. Rattling noise between 1700-2200, whether driving or revving a parked car. No difference on hot or cold engine (perhaps less noise with cold engine).
I have tried locating the noise with my stetoscope. No immediate answer
How did the story end for the E-type?