Knocking from engine...what a plonker
Discussion
Got the car back after a bit of work here and there at my local garage.
I notice the engine is still knocking after she ran out of oil when I took her out on my last drive...pitiful I just didn't check the pressure gauge when I took her out that sunny December afternoon. Knocking increases tempo with revs, it's very noticable and annoying.
After sticking some random thick oil me and the old man found in the shed, we started her up again that day and the tapping disappeared.
Pleased to know the sump has now been welded and other jobs done...the bonnet brackets at the front have been strengthened with new bolts and locknuts, red vinal is now on the bottom dash bit (he hasn't had time to do the main bit - sigh - guess I'll give it a go), a fuel line fixed up, the sender unit had been corroding, now cleaned up apparently and it actually works now, exhaust manifold welded again...oh yeah and there was a bit of the chassis needing a bit of attention which he welded up for me.
We get her back now, and the tapping is there only when you depress the gas a little and she begins to rev. It's been sitting there with no oil in the engine for about a month, so I'm thinking it may settle down. Where can I go with this to diagnose this further? Compression test? Change the oil?
Your thoughts please chaps
Can you tell where abouts it's coming from? A blowing exhaust manifold can give a very mechanical sounding tap that gets louder with the throttle.
If you suspect bearing problems then look at the oil pressure. Low oil pressure is a sign that the bearing clearances are too high and/or a worn pump. Bearing clearances can be checked by dropping the sump and taking the caps off, this lets you do a surface inspection and check for roundness, if it looks OK you can use plastigauge to measure the actual clearances. Less easy to measure the little end clearances, but while you have the big end off you can rattle the conrod around and see what's happening.
Could also be valve clearances out, before you go too far down this route you need to know whether you have solid or hydraulic lifters.
Finally it could be a worn cam but you'd be likely to notice that in driving too.
If you suspect bearing problems then look at the oil pressure. Low oil pressure is a sign that the bearing clearances are too high and/or a worn pump. Bearing clearances can be checked by dropping the sump and taking the caps off, this lets you do a surface inspection and check for roundness, if it looks OK you can use plastigauge to measure the actual clearances. Less easy to measure the little end clearances, but while you have the big end off you can rattle the conrod around and see what's happening.
Could also be valve clearances out, before you go too far down this route you need to know whether you have solid or hydraulic lifters.
Finally it could be a worn cam but you'd be likely to notice that in driving too.
GreenV8S said:
Can you tell where abouts it's coming from? A blowing exhaust manifold can give a very mechanical sounding tap that gets louder with the throttle.
If you suspect bearing problems then look at the oil pressure. Low oil pressure is a sign that the bearing clearances are too high and/or a worn pump. Bearing clearances can be checked by dropping the sump and taking the caps off, this lets you do a surface inspection and check for roundness, if it looks OK you can use plastigauge to measure the actual clearances. Less easy to measure the little end clearances, but while you have the big end off you can rattle the conrod around and see what's happening.
Could also be valve clearances out, before you go too far down this route you need to know whether you have solid or hydraulic lifters.
Finally it could be a worn cam but you'd be likely to notice that in driving too.
It sounds to me from the passenger side...not sure whether its more of the front or the back. I reckoned front, my mate reckons back. I could get a video if you so wish.If you suspect bearing problems then look at the oil pressure. Low oil pressure is a sign that the bearing clearances are too high and/or a worn pump. Bearing clearances can be checked by dropping the sump and taking the caps off, this lets you do a surface inspection and check for roundness, if it looks OK you can use plastigauge to measure the actual clearances. Less easy to measure the little end clearances, but while you have the big end off you can rattle the conrod around and see what's happening.
Could also be valve clearances out, before you go too far down this route you need to know whether you have solid or hydraulic lifters.
Finally it could be a worn cam but you'd be likely to notice that in driving too.
She idles fine. Just at a particular rev range under medium throttle. But it's a deep sound, sounds far away, a 'knock', not a high pitched 'tap. Oil pressure seems okay.
Whats the oil pressure doing at idle when its hot?
It does sound like the engine has suffered - don't panic it will keep going for ages, though it may stop at some point in fairly spectacular fashion if something lets go.
Remember that Topgear episode when Clarkson was driving that Maserati that went bang!!??
It does sound like the engine has suffered - don't panic it will keep going for ages, though it may stop at some point in fairly spectacular fashion if something lets go.
Remember that Topgear episode when Clarkson was driving that Maserati that went bang!!??
Soddit. Definatly an engine swap then! i should have taken the 3.6 cologne 12v tuned engine chaps details before it ended early for whatever reason. Good excuse for a 24v too.
I don't think its as low as big ends though. Sounds more like small ends. But you're right, engine won't heal itself. What a pain in the a$$
The Lukas said:
i should have taken the 3.6 cologne 12v tuned engine chaps details before it ended early for whatever reason.
IIRC their id was tooveyengines and they were in Crannock, and a quick google shows a John Toovey Road and Race there.How do you run out of oil though? If it is using oil that quick then the engine is knackered anyway.
When my 2.8 had oil starvation (caused by track day with too little oil, I was told), it caused the big end bearings to seize and then move about. The engine ran with a similar sounding knocking, but it then began to overheat after 10-15miles or so. How's the temperature of yours?
I ended up having a full rebuild, sorry!
Regards,
Shentodj
I ended up having a full rebuild, sorry!
Regards,
Shentodj
Just tried phoning that company. Erm, temperature is fine to be honest...but I've only driven her home about 5 miles so not allot really.
Ah engine rebuild that sounds expensive. I want to make full use of this though, if there is a time a squeeze more power out the S3, now is the time!
Ah engine rebuild that sounds expensive. I want to make full use of this though, if there is a time a squeeze more power out the S3, now is the time!
Or did the oil really run that low? 
Hey Lukas you have eliminated the possibility that the noise is from outside the engine havent you ? It couldnt be a lack of clearance somewhere caused by soggy engine mounts.. maybe the ARB touching the sump ? or the zorst touching the chassis ?
just a thought before you go stripping anything...
K
just a thought before you go stripping anything...
K
Edited by ketvrin on Friday 27th February 14:30
Lukas try to get a decent second hand engine, your engine will cost way more that its worth to have rebuilt.
I had a 2.3 V6 granada (more or less the same engine) and had the same problem you describe - at a particular constant level of revs you could hear the bearings clanking away - it had zero oil pressure at idle and I drove it permanently 'with enthusiasm'. It never went bang. I even towed a caravan with it.
I wouldn't worry too much for now, make sure your breakdown cover is up to date and continue to enjoy the car, and check the oil!
Keep an eye on the oil pressure - when it really starts to drop particularly at idle its getting worse.
Some really cheap 20/50 motor oil will help keep the pressure up a bit (its thicker).
I had a 2.3 V6 granada (more or less the same engine) and had the same problem you describe - at a particular constant level of revs you could hear the bearings clanking away - it had zero oil pressure at idle and I drove it permanently 'with enthusiasm'. It never went bang. I even towed a caravan with it.
I wouldn't worry too much for now, make sure your breakdown cover is up to date and continue to enjoy the car, and check the oil!
Keep an eye on the oil pressure - when it really starts to drop particularly at idle its getting worse.
Some really cheap 20/50 motor oil will help keep the pressure up a bit (its thicker).
If you want to try some good oil the Millers CFS 10/60 is excellent; I use it in the S and it comes to pressure quickly even when very cold and holds the pressure very well when hot so could be worth a try? If the engine is on the way out it won't solve the problem but may give you some longer life to get a replacement sorted.
I do however agree with the comment above about checking other possible causes so make sure its not the exhaust banging somewhere or a faulty engine mount - I remember a friend with an S2 who did a track day and thought he'd done his big ends - after replacing the engine found the mounts were the problem! (no it wasn't me!!)
Jim
I do however agree with the comment above about checking other possible causes so make sure its not the exhaust banging somewhere or a faulty engine mount - I remember a friend with an S2 who did a track day and thought he'd done his big ends - after replacing the engine found the mounts were the problem! (no it wasn't me!!)
Jim
Jed-S said:
The Lukas said:
i should have taken the 3.6 cologne 12v tuned engine chaps details before it ended early for whatever reason.
IIRC their id was tooveyengines and they were in Crannock, and a quick google shows a John Toovey Road and Race there.How do you run out of oil though? If it is using oil that quick then the engine is knackered anyway.
Russ35 said:
Jed-S said:
The Lukas said:
i should have taken the 3.6 cologne 12v tuned engine chaps details before it ended early for whatever reason.
IIRC their id was tooveyengines and they were in Crannock, and a quick google shows a John Toovey Road and Race there.How do you run out of oil though? If it is using oil that quick then the engine is knackered anyway.
Take a lot of advice before you go mad with the cam - what you find with the big power gain claims for a cam is that it shifts the power up the rev range so you have to cane it all the time to get the performance - and there's poor performance lower down the rev range where the real world driving is.
The V6 is not very highly tuned - the result is you get a fat lazy torque curve that accelerates pretty much in any gear - once you go down the tuning path that characteristic may be lost.
you know you really want a V8
The V6 is not very highly tuned - the result is you get a fat lazy torque curve that accelerates pretty much in any gear - once you go down the tuning path that characteristic may be lost.
you know you really want a V8
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