View Full Version : 1.8T engine knocking noise
23-04-2012, 10:44 AM
Have a noise coming from the engine that sounds quite knocky. Itís very apparent at idle with the hood up.
In and around the same time as this started I had a low coolant alarm.
In the last week or 2 the noise has gotten louder and I now also have a bigger coolant leak somewhere in the engine.
Itís not the expansion bottle as checked that last night but I am loosing at least a litre a day now.
My gut is telling me the water pump has gone but it is only 35k since the belt was done and the pump was changed then too. I also believe it was the brass pump that was used and not the plastic one that gives trouble.
Anyone ideas anyone, as would hate to do the timing belt again unnecessarily.
Car is Audi below in signature.
23-04-2012, 01:28 PM
You meed to get an experienced ear to listen to it. My first worry with these engines is always oil pressure.
23-04-2012, 02:59 PM
Thanks for the reply Crasher.
A little bit of history.
I had an oil pressure issue with this engine about 35k ago which led to big end bearing replacement, strainer clean, engine flush with new oil x 2, sump and rocker cover wash.
There was no hydraulic lifter damage and in fairness it came back very strong from this work and I have not had a peep out of it since.
Oil is replaced with 10/40 magnatec every 6kish. I know it can run on 5/30 but didn’t want to change oil viscosity after 50k miles.
My initial thought was when I heard this noise was oil starvation to the lifters, but the simultaneous coolant fluid loss kind of turned my head a little.
I probably should look for the source of the coolant loss and will do. Just assuming the fluid loss is unrelated and it is the lifters making the noise, do you think if I removed the sump and done the strainer I should be back on track again or is there anything else you would recommend.
23-04-2012, 05:56 PM
Its very difficult to be accurate when I can't hear it but it comes over to me as noisy valve gear due to oil pressure problems.
23-04-2012, 08:12 PM
I think you are right and it was my initial thought as its that low dull kind of diesel knocking sound. If I give her a good revving it goes away and slowly creeps back in when idling. Sort of like a partial blockage and the extra pressure of revving the car gets the oil up to the top for a bit.
One other thing i noticed is I'm spraying a bit of oil out the side of my rocker cover gasket when I was revving it earlier. I would drop abt a litre every 3k so I dont know if this would have any impact unless a pressure drop up there could cause an issue.
Was thinking of giving it an engine flush and see how I get on. Was gonna use that stuff you put in, drive for a mile or so and dump it. (would you recommend this)
Will also do the rocker cover gasket and give it a clean in and around there.
Hopefully I might get away with just doing that.
23-04-2012, 09:53 PM
If I give her a good revving it goes away and slowly creeps back in when idling
Classic 1.8T loss of oil pressure symptom due to bearing wear.
24-04-2012, 10:48 AM
<REMOVED> anyway... will have to get that looked at
Do you mean (lower) crankshaft bearing wear or (upper) camshaft bearing wear.
24-04-2012, 01:00 PM
It will be crank bearing wear hopefully, the cams run in the head material and have no bearings.
26-04-2012, 07:29 PM
Loosing a load of coolant now so lifted her up and the fluid is dripping from the pulley the V belt tensioner is attached to. My understanding is the water pump is directly above this pulley. If this is correct it can only be the water pump now, right???
Can timing-belt tools 3387 (2 hole pin wrench) and T10008 (locking plate) be picked up easily, and are they expensive?
Also bought an OEM cylinder head cover gasket as it need replacing. According to elsawin is requires some sealant also. Is this correct and what sealant should I use?
On the knocking noise im 99% sure its only coming from the cylinder head, i.e. valve gear. Im just gonna engine flush x2 here and pray for now.
This is getting expensive now.....
Appreciate all help here..
27-04-2012, 12:56 PM
Yes that will be the water pump.
27-04-2012, 06:28 PM
OK, timing belt and pump renewal inevitable. doing it Monday.
Hooked up oil pressure gauge to engine and am getting
Idle = 2.5 bar
2000 RPM = 4.25 bar
3500 RPM = 4.65 bar
Elsa win states a minimum of 1.3 bar at 2000 RPM and 3.5-4.5 bar at 3500 RPM.
Are these figures very good, good, average? I guess its telling me the engine has good oil pressure.
I read the noise could be coming from the hydraulic cam chain tensioner. Going to add (Liqui Moly pro-line) engine flush anyway, do rocker seal and remeasure pressures as a precaution.
Could the noise also be coming from the oil dampened tensioner on the timing belt arrangement, Could the water pump leak have damaged this?
Would appreciate your opinion here Crasher or anyone else who has experience in this.
27-04-2012, 11:59 PM
What is the oil pressure at a hot idle?
28-04-2012, 12:07 AM
just finished completing flush and seal change.
Idle was 4 bar after start up (cold). Let her warm fully up, gave her some welly and she never dropped below 2.5 bar when fully hot (idle)
Just a note:
I didnt see any sludge build up on rocker cover whan I had it off, looked very clean to be honest, oil was p.issing into spark plugs sockets though. Gasket(s) were rock hard.
28-04-2012, 08:25 PM
That a very high hot idle pressure even for a new engine but your cold with some revs ( I presume) pressure is a good bar lower than I would expect.
04-05-2012, 10:01 PM
Just to close out the thread. The noise was coming from the oil dampened tensioner on the timing belt arrangement. It practically fell apart when belt was changed. Tks to crasher for the replies and at least I know my oil pressure is good and I don't have a sludged engine.
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