Head/timing chain

Cathode

Active Member
How noisy should a timing chain be? As some of you may know, I've rebuilt my engine and I started it a few times. Yesterday and today, it started first time quite well, seems to tick over ok and doesn't hunt. When I rev it a bit, the timing chain does sound a little noisy. Rachety sought of noise. Like it's too loose, which it's not, if anything it could be too tight but, it's a bit louder than it was before I built it.

Does anyone have any interesting points on this? Any advice or how it should sound. I know it's impossible for me to determine what "noisy" is in a post but I would expect it to be less noticeable if that helps.

Any thoughts would be appreciated .
 

Eng1

Member
As a guess , it’s probably the tensioner not moving with oil pressure build up , so a bit of slack causing chain to touch the guides
Pull it out and give a good clean and soak in ATF and pop it back in and try
Was the engine rebuilt ?
 

Eng1

Member
Could easy be a sticky tensioner which hasn’t moved in a long time .
The reason for the question on rebuild or not - sometimes oil ways get a bit gummed up and blocks not chem cleaned when rebuilt
If so you can flush oilways out :
Dump oil and refill with cheapo oil ,add a bit of derv (about 1/2 litre) and atf about 1 litre) , slightly overfill
Run at idle for 15 mins -DO NOT REV it !!!
Then dump the oil and refill,with a new filter
The ATF has a very high detergent level , it has to in order to keep gearbox oilways spotless as they have very narrow bores and cannot clog .
This cleans the whole engine oil system and cures things like sticky hydraulic tappets (not Gtir) and oil squirters
Long term cleaning can be done by just adding a bit of ATF prior to an oil change
Sounds mad but works !!
it’s a bit like using running in oil , I’ve done it many times and you can often hear the difference on turbo bearing by the sound change , never had an issue on any car with this flush method .
The oil is unbelievably clean after flushing for ages
 

Cathode

Active Member
Thanks for this Eng, I appreciate you taking the time to give your thoughts.

I’ll give this a try if my fiddling doesn’t have any consequences.
 

Eng1

Member
There is nothing wrong with home built engines , but it’s just most people don’t have an ultrasonic hot tank in the shed .
It’s another day trip or two to take the block and head to get chem cleaned and collect Again and it might be a long way away , so it doesn’t happen .
Using synthetic oil during running in is shit , flushing works but the generic flush stuff is not very strong (it’s mostly ATF) hence a bit of derv
If the engine is a high miler /few oil changes or has never been revved hard (old lady driver ) flushing can work against you as it’s only the carbon making a seal and once cleared all sorts of issues happen ( the engine is knackered by now )
If you flush it’s interesting to put the old oil into a bottle or pint glass and inspect it , you would be surprised what it looks like after 15 mins !!
 

Cathode

Active Member
Today I checked and rechecked the valve timing. I have read the manual, watched videos and looked at pictures. From what I can tell the valve time is spot on no mistake. The chain is tight but I think that’s just how it is and the rachety sound I’m getting could be coming from the metal timing chain slipper guides that I installed as an upgrade over the original plastic ones.

I’ve checked the injectors, plugs and leads and they’re all good and working as they should. The distributor on the other hand could be providing a problem but more on that later because I discovered today that, it runs and idles better without the MAF plugged in! So, I can only think that the AFM is possibly knackered.

The distributor isn’t making very good contact which I imagine is not helping issues but combined with a dodgy AFM, it’s gonna run lumpy. When it runs and I put my foot down it wants to die. I can nurse it to rev but it still isn’t smooth.

Anyone have any thoughts?
 
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Eng1

Member
Testing is the way forward , testing gives data and you eliminate possible things
Fuel
Air
Spark

air leaks check hoses and pipes one by one ,clip by clip , fuel from tank to injector , spark /electrics by voltage checks , item by item , the LT , coil , resistors,o2 sensor , knock sensor ,transistor, MAF output , position sensors , make a list of all possible items and tick them off one by one ,once tested
You could have two or three things that are marginal and combine to give the problem
What is the ECU ? Stock or aftermarket? Any fault codes ?
For sure it’s a pain in the arse , but knowing every part is good is future proofing the car ,and many parts cheap to replace.
I’ve just been through a similar thing on one of my cars , 2 weeks testing everything , every single signal to the ECU , eventually found a crankshaft sensor wire screen damaged and picking up interference from HT at revs causing misfire , found a couple of minor things whilst testing but got it in the end - test the shit out of it !!!
always test voltages and do not rely on resistance alone , that can lie to you due being off load .
Start with Air , leaks and soft hoses and clips then gasket faces - soapy water or leak detector spray or easy start and the good old eyeball check with a wiggle .
Test !!! Then you don’t guess it’s ok ,you know it’s ok !!!!!!
 

Cathode

Active Member
Eng, you’ve got vision. Sometimes I just don’t know where to start. I’ll get testing and start with electrics.

Thanks for this
 

Eng1

Member
Ok , start with the LT (low tension) you need your battery voltage as a reference (ignition on)
Measure at each point (connector) in the LT .
Some parts are 12v and some 5-6 volt - the transistor is used as a switch to switch 12v to the coil .
Between components is simply wire and connector pins /sockets , these are very very low resistance and you should only ever get a minimal voltage drop .
Say supply is 12,2v , you should read around 12.15 as a minimum , if you read 12.1 or less = you have a problem , there is a high resistance somewhere
Air leaks are straight forward- the engine at idle is under vacuum , sucking in air . A quick spray at joints with easy start and any leaks suck in easy start - you will hear the engine react .
At the same time you are checking all the pipes , there are quite a few and easy to miss one ! Plus the plenum - once done you now know the engine pipework is leak free , a good place to be .
The HT can be done in the dark , you can’t meter it as it’s 20000volts , but you can visually check each plug laid on the head - a fat blue spark ,tic tic tic regular as clockwork every time
The MAF has a voltage output (low at idle ,say 1 volt) this you can measure , the ECU has a default setting if the MAF is disconnected, if it runs better without MAF in default , maybe you have a leak sucking in air (bypassing the MAF ) so it is unmeasured and the ECU is fuelling wrongly.
Eventually you will find the issue by elimination (issues) with data to use as your aid
Fuel problems are usually pronounced with revs and power or load but can be at idle too , you can measure pressure , but it’s flow that is important, you can pump into a glass to see flow .
(Ie you can have a blocked filter /line and still have pressure but much reduced flow) , I have even had water in a line trapped as it is a U bend , the water is heavier than fuel and won’t pump out but reduces the fuel flow as it moves back and forwards in the U
 
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