View Full Version : Knocking noise
HELLO FOLKS,
Wonder if anyone can help me. I started my Discovery this afternoon, after driving it all day around town, only to hear a knocking noise. It is knocking at idle, regardles of whether I'm moving or not, dipping the clutch or not. The knocking goes after 1100 RPM, any ideas please?
Paul.
Jon v8
7th Dec 2005, 20:10
What year/engine type is it ? How many miles? Have you managed to identify whereabouts on the engine the noise comes from? please give us a bit more to go on !!:)
It's a 95 300 Tdi, with 90,000. The noise seems low down to me in the engine:(
bilge rat
7th Dec 2005, 21:50
cam pulley come loose, just a thought . alan.........
TEMPL4R
7th Dec 2005, 21:52
cam pulley come loose, just a thought . alan.........
Crank pulley
Thanks,
Am I safe to drive it for a short while?
I'm no mechanic, could I get to it myself, do I need special tools?
TEMPL4R
7th Dec 2005, 21:59
Feel inside the pulley at the bottom of the fan belt and see if the washer is loose.You might be able to move the pulley by hand.
If you have air con, turn it on full and put all the lights on. Start the engine, If it is the pulley loose, the drag on the belt should alter the noise.
bilge rat
7th Dec 2005, 22:00
personally iff its a heavy knock i wouldn't drive it iff its timing pulley related could be nasty ,bent pushrods broken rockers etc. really difficult to diagnose fault like that without hearing it . alan.........
At the start of the week, there was a constant squealy noise, not fan belt slipping, like alternator? squealing, the type of noise I've come across on many a Transit van. This stopped yesterday. The knocking started this afternoon.
personally iff its a heavy knock i wouldn't drive it iff its timing pulley related could be nasty ,bent pushrods broken rockers etc. really difficult to diagnose fault like that without hearing it . alan.........
It's a light knocking in time with the engine at tick-over, then up the revs slightly to just over 1000 and all goes quiet and smooth again:rolleyes:
I don't have any air-con.
TEMPL4R
7th Dec 2005, 22:10
Alan is perfectly correct, it is difficult without hearing the noise.
Have you checked the oil level?
A heavy knock could be crank pulley, big end
A light knock could be little end, or piston problem.
If it goes away it could be timing belt tensioner slipped and a slck belt.
If your not certain, call a mechanic.
TEMPL4R
7th Dec 2005, 22:13
water pump and alternator are high up and to the right.
Fan bearings can fail with a squeak, squeal or knocking. Give that a good push and pull.
take the fan belt off and see if it's still there.
Alan is perfectly correct, it is difficult without hearing the noise.
Have you checked the oil level?
A heavy knock could be crank pulley, big end
A light knock could be little end, or piston problem.
If it goes away it could be timing belt tensioner slipped and a slck belt.
If your not certain, call a mechanic.
I checked the oil last week-end and it was just under MAX. I let a mechanic look at it late this afternoon, who said he couldn't see anything wrong, didn't like the sound of it, but was not experienced with Discoveries.
TEMPL4R
7th Dec 2005, 22:19
Take the fan belt off and try it.
We get a lot of trouble with BMW tensioners and idlers making strange noises.
Thanks for all your help, I appreciate it:)
Jon v8
7th Dec 2005, 22:24
It's a light knocking in time with the engine at tick-over, then up the revs slightly to just over 1000 and all goes quiet and smooth again:rolleyes:
I don't have any air-con.This rules out the brake vac pump-these knock all the way up the rev range. But you need to find out what this is-as everyone else is saying,it could be anything. Templ4r is on it I think with a loose crank pulley -not unknown on tdi motors. I wouldnt carry on driving it till its sorted.I gave an invoice to a customer many years ago for fitting a replacement crank in a 2.5 td 90 - he wasnt happy,(Loose bolt, worn crank/woodruff key):eek:
Took it to the 4x4 centre. They are baffled. All pulleys tight, got to go in next Tuesday to be stripped:(
Took your advice this afternoon, put a spanner on the tensioner, lifted it to release tension, noise lessened. And? 1/2 inch of play in the water pump pulley! New water pump going on tomorrow, hoping that this IS the problem........:shhhh:
TEMPL4R
9th Dec 2005, 18:07
Is the garage doing the water pump, or are you?
The bottom bolts are long and go through to the block. The gasket there leaks some times when you change the pump. Ask them if they are changing that gasket or taking the chance it won't. We explain this to customers as it takes about an hour longer. If they don't want it doing properly, any leak from there will be their responsibility.
Chris
Roger Whittle
9th Dec 2005, 20:45
Is the garage doing the water pump, or are you?
The bottom bolts are long and go through to the block. The gasket there leaks some times when you change the pump. Ask them if they are changing that gasket or taking the chance it won't. We explain this to customers as it takes about an hour longer. If they don't want it doing properly, any leak from there will be their responsibility.
Chris
You are a swift and dangerous man Chris, but honest - and that'll do nicely.
Roger.
Yep, I agree with the sqeeling noise coming possibly from the automatic belt tensioner. These things are known for the bearing inside to fail.
As for the knocking sound under 1000rpm, my guess is a big-end bearing failing. The pulley coming loose is very unlikely because of the high torque and loctite with which it is fastened. (but check never the less)
One other thing is maybe that the noise could be clutch-related.
Get the Disco checked ASAP.
Greetz,
Wim
TEMPL4R
9th Dec 2005, 21:21
You are a swift and dangerous man Chris, but honest - and that'll do nicely.
Roger.
We got caught out on a 300 a while ago, the young "Technician" did the job. Just changed the pump. Came back a few days later and we had to take it off with the housing and do the gasket.
It takes about 45 minutes to change the pump and bleed the system. Take the housing off and it adds another £37 to the bill.
I tell them I'm doing the gasket, unless I get a signature on the job sheet that they don't want it done. If it leaks ( which it does most times) they pay for it all again.
Chris
Roger Whittle
10th Dec 2005, 20:05
I tell them I'm doing the gasket, unless I get a signature on the job sheet that they don't want it done. If it leaks ( which it does most times) they pay for it all again.
Chris
Presented with the facts thusly, you'd be mad not to opt for another thirty-seven squid.
Roger.
TEMPL4R
10th Dec 2005, 20:17
Yes Roger, that's a problem with dealing with paying customers. They always want the cheapest option, but soon come back and start squealing when it goes wrong.
I just explain, "That's how I do it" if we don't agree, I don't do it.... simple.
Chris
The pump got changed, but no improvement, it's off into the garage in the morning to have some spanners on it:( :Countdown
(A mate of mine changed the pump)
Jon v8
13th Dec 2005, 20:50
Broken Crank :(You are joking ? Never seen that on a tdi before.:eek:
Roger Whittle
14th Dec 2005, 01:12
Broken Crank :(
Ooooooo nasty! The crank on my old series lla scabbed, but broke is rare a rocking horse poo.
Roger.
You are joking ? Never seen that on a tdi before.:eek:
I can't get my head round the fact that it is as serious as this, but runs like a bird when the revs go over 1100 RPM. The lad said when the motor was up on the ramps, and he got under the sump with it running, it was horrendous:(
TEMPL4R
14th Dec 2005, 21:31
Strange that is. When ever I've had a crank go it's either a 3 Bearing ( common) or a vibration damper problem on a straight six.
If they break across the web at an angle, you can feel it when you press the clutch. The pulley moves back and forth as well.
Every time I've heard that noise, it's a loose pulley. I'd get a second opinion.
Every time I've heard that noise, it's a loose pulley. I'd get a second opinion.
Took your advice, and had it in to the engine centre, where they are convinced that it's crank bearing. They've said 'go quietly' till Monday and they'll have the sump off and do the job. I'll have the belt changed and the gasket below the thermostat done while it's in bits.
The sump came off, crank and bearings checked.....nothing wrong. They took the front end off, and found a floating bolt near the timing belt, it had shredded and grooved the belt but not broken it! Had a new belt and kit fitted, along with some seals. Lucky I think:o
pheel steel
23rd Dec 2005, 22:03
Glad to hear that's all it was Pig. I just couldn't see any way it was a broken crank. Crank bearing, maybe!
Good luck with it and have a good un
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