I've been through about 4 TCT to date and the current one is sounding like a tractor again.

I've read loads of posts about these and possible causes e.g. sticky worm gears, incompatible oil, weak springs etc...

My local Honda garage is convinced the chain is stretched and say Honda won't chage it under warrranty (parts) again. Therefore, it's a 5 hour labour job plus chain. The head has to come off.

My problem with the stretched diagnosis is:

1) Countless owners have this reoccuring problem which is solved by TCT replacement
2) Noise only appears when the engine is hot. Surely a stretched chain would be noisy hot or cold?
3) Problem tends to happen when engine oil level is allowed to get low. After filling up, noise stays. Sounds like some sort of oil lock occurs when level is low?


So, this weekend I'm going to take the TCT off the car, take it to bits and clean it up.

Is there anything I need to be carefull of? I.e. is there any seals that, once the TCT is removed, need replacing (the TCT is about 6 months old).

Hope this works

 

if its stretched you should be able to check by just removing the rocker cover
the timing marks wont line up if the chains stretched

 

Thanks for the tip

Though I don't what the timing marks look like or what they should line up with

On removing the TCT, the workshop manual says to use a 5 x 0.8mm bolt at least 40mm long. Is that like an M8 bolt from B&Q I don't have anything like that lying around.

 

My TCT fell apart when I took it off on my engine swap ..

A bit of swearing, a paperclip and a lot more swearing got it re-compressed and back in the new engine.

Parts are the housing, a spring, a hollow screw (that the spring fits in) and then the piston with internal screw (that the hollow screw fits in). Then the piston slides into the housing.

 

Couple of things.
Have the TCT been replaced under warranty previously? If they have then the problem can be classed as an ongoing issue (i.e. one that's reported before the warranty period expired but still causing problems afterwards). Therefore you could try pushing the dealer/HUK to replace the chain as still under warranty or at least some form of Good Will Gesture.

Be aware they could well fight like cat and dog not to do it. So far if it was done in the regular warranty system they'll have been able to charge all the work back to Honda Japan and make a healthy profit at the same time. If it's done now chances are either HUK will pay for it (GWG) or the dealer will pay (failure to Fix It Right) hence they'll feel the pain.

Regarding your comments about the stretched diagnosis (and I've ZERO confidence in Dealers to have the foggiest how an engine works, even the good ones, so I'm not saying they're right)
Point 2 - The tensioner is hydraulically applying pressure to the chain. When the engine is cold the oil is more viscous and hence the the oil pressure in the engine tends to be higher (less able to flow through the pressure relief valve that limits the pressure)
Point 3 - Since the system is hydraulically powered it needs oil in the system. It's possible the engine is picking up airated oil. Oil in the pan kind of looks like a pint of guiness. You want the nice black stuff at the bottom. On top of that is a creamy head. If you try to sup on that you get a lot of slurping. If it's doing that, again there may be a lack of hydraulic pressure.

I don't have a personal theory as to why they make noise since I've never had a chance to strip one appart and measure it with the drawings to compare wear level of check the oil gallerys for blockages etc.

 

From what you have said Fluffy, it is an oil pressure issue and not a chain issue?

Is it possible that when cold, there is just enough pressure to press on the stretched chain (hence no noise) but when hot, there is just not enough pressure to deal with the stretched chain (hence the noise).

OR

A stretched chain would be noisy cold or hot.


P.S.

During last service, garage added 0w 40 oil.

I might drain and refill with 5w 40 (the TD stuff from Castrol) tho only done 3000 miles since oil change.

 

It is both an oil issue and a chain issue.

Think of it like this:

Ideally, you would have no slack in the chain at all. This would be pretty bad in terms of bearing wear on the crank and cam shafts, as you are applying a lateral load.

Therefore, there must be SOME slack in the chain. In order to ensure the correct tension in the chain, a timing chain tensioner is used.

In an ideal world, the engine components would never wear and the TCT could apply a constant tension to the chain by sitting in a fixed position.

Engine components do wear though, hence requiring different TCT positions for a constant tension to be experienced by the chain. Also, stretching of the chain will mean that the TCT needs to be adjusted further to keep the correct tension in the chain.

Accepting that chain tension is directly proportional to the force with which the TCT is pressed against the chain, it is therefore feasible to use a constant pressure fluid (engine oil) to push a piston (TCT) onto the chain to maintain a constant pressure. As we know, engine oil pressure is not constant, but in fact proportional to engine speed, hence the requirement for a pressure relief arrangement.

Therefore, changes in viscosity and/or density, as identified by Fluffy, will change the pressure experienced by the TCT piston and therefore the tension in the chain.

Hence: Yes, the temperature, level and type of oil WILL affect the rattling noise.

The TCT piston will have a limited travel. If the chain is significantly stretched, the TCT will need to travel to or past its limit in order to achieve the required tension in the chain. For whatever reason (wear? bedding in?) you may find that a new TCT has slightly further reach at the limit of travel than one which is (say) 6 months old.

It is therefore feasible that changing a TCT will temporarily mask, but not cure the underlying issue of a stretched timing chain.

That said, the advice given is based on theory and engineering principles. It may well be that I have overlooked something.

As mentioned above, you may be able to check alignment marks to determine whether or not stretch has occurred. Alternatively, there may be a go/no go stretch gauge available.

 

Take a look at:

https://www.s2ki.com/forums/index.ph...=320897&st=500

(take it out, dismantle, sand blast the thread, refit - couple of hours work and probably cost you a tenner).

 

So I took apart the TCT at the weekend, short story is the noise has gone

First off, I took out the air box.

Then proceeded to take out the TCT.

Once out, the ram poped out and springs everywhere The M5 screw I bought from B&Q wasn't big enough, or so I though!

After that initial mishap, took it all inside and had a good look over it. I noticed a couple wear marks on some of the faces on the worm and on the housing for the ram. They looked like the had been highly polished, most likely due to constant, heavy rubbing.

With it apart, I cleaned and flushed everything then oiled it back up with engine oil.

Using the same B&Q screw, I realised that it fit into the end of the worm and that's how you lock it down. Note, the nuts that come in the pack are slightly too small and you should get a washer to stop the nut going into the threaded hole.

With the ram fully retracted and locked in place with the nut I reinstalled the TCT and went for a short drive. Noise totally gone!

I've been driving about all weekend and into work this morning. No noise!

So looks like this has fixed things for now, maybe a job for the future when the noise comes back. I'm sure it will

 

Still doing well, think it's good for few thousand more miles!