Very loud knocking and rattling noise
 

Hi
Yesterday after an hour or so of 70 to 80 miles per hour steady autoroute driving my Euro 1983 3.0 SC suddenly lost some power on an incline and a persistent just hear- able clicking rapidly became very noticeable clattering as I tried to keep to about 60 or 70 MPH
Oil and temp gages stayed good and no leaks
Parked for a few hours and still some clatter but a little better so started to drive slowly home
By the time I got back the noise was unbelievably loud
Idle sound was still more or less same as usual maybe a little more noise but hard to tell as now completely freaked
Spent the night trawling here and trying to compare with some recorded sounds for suspected Chain tensioner(s) chain guides etc . - Maybe all in my mind but think mine sounded much worse with some loud knocking added to the rattling noise!
Turned the ignition (nervously) this morning and all is back to the usual ticking and slight mechanical noises at high revs which I¬m told are pretty normal /good for the mileage (125K)
Is that “reasonably quiet when cold very noisy when hot” thing typical of chain tensioner(s) (albeit hydraulic fitted by PO) failing and how do I check them - or should I check something else first ?
Please help as cant even demonstrate the noise at a garage now unless I drive till the noise reoccurs and really not keen to do that
Thanks
Ian

You might have already jumped time because then you get real noise and the engine will still get you home on 3 cylinders.
Pull the valve cover because usually you break rockers and bend valves. Broken rockers are easy to see...
Bruce

Loud knocking could be the Chain tensioners but you say the PO did the upgrade to Hydraulic tensioners. To be honest I´d get the car to the workshop and let a pro look at it before speculating on what it might be

I know that for a fact didn't want to run very well but it got me home. I would get it to a mechanic ASAP and not drive it any more knocking could also be a rod failing but the fact that it is almost non-existant cold then the viscosity of the cold oil could be keeping an otherwise failed tensioner up.

http://forums.pelicanparts.com/uploa...1283429534.jpg

The hydraulic tensioners can fail too. Hopefully the PO modified the tensioners by adding stops.

Cold oil is thicker - so if you have a tensioner that is very close to failing, it might work OK cold, and then collapse at high temp. Nothing to play around with. I wouldn't drive it or even start it until you know what's wrong.

Thanks guys
Think this looks beyond my skills and think I need a pro on it as suggested by twistoffat
Bruce wouldn`t it run really badly (if at all) even while cold if had broken rockers and or bent valves?
Ian

Have it towed because you don't want the chain to break a ramp which can cause all sorts of grief.

Decided to have a look myself
 

Hi
Not sure what I`m looking for but felt I needed to get some courage together and "have a go "
Have Waynes101 book and the Haynes manual in hand - just hope you guys will bear with me as I try to start learning.
Please forgive what are likely to be some pretty dumb questions as this progresses and please do not hesitate to state anything you may feel is obvious
So far -
Set up at TDC for 1 and have got the valve and chain covers off
Can see nothing that looks obviously out of place loose or broken anywhere.
Oil looked good and no bits of anything in the sump or elsewhere.
Can you guys see anything wrong on the attached pictures?
What sort of things should I be looking for?
The right hand tensioner squelched a little (very little) when pressed hard and there is a very small amount of play in the right hand idler pulley (back and forward maybe a mm over the tensioner end) but needed quite a firm hand to move it and chain still seems tight all over
Chain ramps look OK
If have done some damage to valves etc is it likely to be subtle or obvious? They all look pretty much per pictures have seen in various books
Thanks
Ian http://forums.pelicanparts.com/uploa...1284288315.jpg
http://forums.pelicanparts.com/uploa...1284288412.jpg

Ian now you have it open have you tested the chain for slack. There should be none

Hi Ian,

I notice some wear on the cam gear. The top part looks a bit more shinny. I just took out mine looks like yours! I have done 200,000 km on my car already. but the whole problem is is all ok when cold. I could reev the engine when cold without noise last month. I got worst after fuel disrtributor/wur replacement, my injector is going to be replaced, doing my valve spring all at once. i wondering if the wear shown as your picture requires a cam gear replacement. i think it does not but i hope i have the words of the people on this forum.

i dont know how it looks when hot. all i know when hot and under load the sounds comes. Maybe you got to remove the valve covers as well as the valves are also due for adjustment.

I hope you give it a try.

Hi
Wow - Quick responses - thanks.
Twistoffat
Chain is really quite tight both sides - can move it slightly with enough effort but not slack

Peter
Hope the shinny bit is just lighting - Symptoms sound same as yours - Was noisy when hot quite when cold - Im puzzled - Have also taken off valve covers and will try to adjust valves but when this problem out of way as do not think particularly bad or connected (think noise was pretty much from chain area)

Attaching two more photos of tensioners from above in case any help http://forums.pelicanparts.com/uploa...1284293996.jpg
http://forums.pelicanparts.com/uploa...1284294109.jpg

Take a pic straight on. Can't see the piston in the tensioners at those angles. Well, just the left side is hard to see.

Might want to put it in neutral and turn the engine over by hand just to see if anything weird jumps out.

Ian,

I see your problem - there's a wooden clothes pin stuck in the side of the chain. J/K

Seriously, it looks from the camera angle that the engine is still in the car. As mentioned above, try to get some pictures of the tensioners from straight on, and the chain ramps. You say all looks good, and that may be. If it were mine, here's what I would do at this point:
1.) Remove and rebuild the tensioners.
2.) Do the Jerry Woods modification to the tensioners http://forums.pelicanparts.com/porsche-911-technical-forum/199819-shops-dont-recommend-carrera-tensioner-update-3.html
Go to page 3 for details of the Jerry Woods modification.
3.) Reinstall tensioners and check the cam timing to ensure the timing has not changed either before or after you removed the tensioners.
4.) Do a thorough valve adjustment
5.) Button it up and try it again. If it still makes the sound, it might be coming from elsewhere.

What I recommend above may sound difficult for a novice, but nothing above is really all that difficult. Mostly it's just getting to know and understand what you doing, and very little actual mechanical ability. This board will help you through any rough spots.

Hi MCA
Thanks for your reply
3 more Photos attached
Cranked round and back to TDC 1 by hand nothing strange or untoward noticed
Ian

http://forums.pelicanparts.com/uploa...1284299475.jpg
http://forums.pelicanparts.com/uploa...1284301089.jpghttp://forums.pelicanparts.com/uploa...1284301556.jpg

Hi Rex
Posted my last before seeing yours - Yep kicked myself for not taking out the clothes peg on that photo - it was there to remind me to tie off the chains etc before eventually removing a tensioner if needed to try to avoid loosing the cam timing --knew I would pay for it as soon as I saw my post

The engine is still in the car

Outboard ramp photos attached - Thinking of replaceing outboard ramps anyway and inboards if all else fails (and maybe just for good form anyway) but no evidence in sump or elsewhere that they have broken and understand inboards not so easy and need to support engine and remove frame to access some bolts.

Will that tube modification fix the tensioner or just be there as a temporary backstop if they fail?

Think the cam timing is beyond me but was hoping that as it ran normal and quietly when cold the morning after the noise (although not tested under load) and if no damage to valves when driving home (How do I really check that ?) I could assume that the cam timing was still OK and so long as took care with the tying off bit could avoid re doing that - what do you think?

Thanks
Ian


http://forums.pelicanparts.com/uploa...1284304126.jpg
http://forums.pelicanparts.com/uploa...1284304220.jpg

Just a backstop in case they loose tension - makes it easier to sleep at night.

Not true. You only need to remove the upper valve covers on each side, then it takes less than 10 minutes to do. I've done it in less time. As I said before, it sounds hard, but it isn't. It only takes a few minutes to understand the theory, then the actual test is really easy. This board is great at helping overcome your hesitation.

Might as well pull the valve covers and take a look before doing anything else.

Have you removed all 4 valve covers yet?
There is alot of dirty oil staining and the oil looks dirty so you may have one or more clogged oil holes in the cam spray bars.

This is a big maybe but if that happened then some of the rocker arms and cam lobes have not gotten any oil to cool and lubricate them for a while.

Driving it like that they grind and score each other up rapidly from the lack of oil and the intense extremely hot friction.
Then the clearances between all moving valvetrain parts increase and make alot of noise especially when hot and driven some more until there is sticktion and binding between the rocker arm bushing and rocker shaft as they run with no oil to lubricate and cool them.
A rocker arm being forced to pivot but sticking on a dry overheated and scored rocker arm shaft as the valve closes and seats can make a hammering knocking noise.

I've seen rocker arms that got so hot from being run with clogged cam spray bars that they turned blue where they ride on the cam lobes. That means they got red hot there from the lack of oil and intense continuous friction while the motor was running.

Once cold again a scored and extremely overheated rocker arm bushing and shaft contracts and clearance increases so there is less friction and the rocker arm pivots on the shaft easier and a little quieter at idle speed even though there is still no lubricating oil there.

In your pics it looks like the driver side chain and sprockets are somewhat worn because the tensioner piston has extened around 1/4" compared to where it would be with new chains and sprockets. Passenger side tensioner is not extended quite as far but there is dirty oil staining everywhere in there. I've seen them worn more than yours and still run ok but not great.
Cam timing retards gradually as the chains and sprockets wear.

What kind and grade of oil have you been using.. it looks like it should be changed more often.

Looks like you have broken teeth on your chain wheel.

JFairman, yes the timing retards your dead right, Ian and I and have the same problems now.

I tested my timing every month and it is retarding more and more.... so it adjusted the distributor to the max.

I am still thinking if i should buy the carrea complete upgrade kit including the timing chain,sproketsand all.

At same time i wonder if i should rebuild by mechanical tensioners. I cant seem to find a rebuild kit, and what goes into the rebuild?