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1996 4.6 P38 - knocking sound on idle


argonaut
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As the title says, I have a strange knocking sound when the engine is idling, as soon as the revs climb over about 800rpm the sound disappears and is never evident when driving, only on idle.

I have had a look underneath the car when the engine is running thinking it might be a loose exhaust or bad engine mount but I can't find anything. The video is rubbish quality and there's nothing to see but the sound should give you an idea what I mean.

Anyone have any idea what this might be? The drive plate was (according to the previous owner) renewed a few months ago.

Cheers

http://s193.photobucket.com/albums/z314/mythonaut/Range%20Rover/?action=view&current=RangieKnockKnock001.flv

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  • 2 weeks later...

Sounds like hel£.

A couple of thoughts but it's not easy at distance.

1. Crankshaft damper, dont think so

2. Oil pressure problem or main bearing, dont think so as the noise has almost no rythm.but it could be.

3. Starter motor loose and colliding with drive plate, Possibly, does it work as it should without bad noise.

4. Drive plate or torque converter bolts loose, could well be does the noise stop or change when in gear.

5. It does sound something like my diesel which has a poorly dual mass flywheel and clatters at idle.

6. Someone has been left inside and want's out.

7. Loose alternator or tensioner but it does sound to be from the back of the

engine?

Watever it is it's a heavy sound and likley to do damage if you continue to use it.

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You have a loose catalytic converter.

Get underneath with the engine switched off and give them a bang with the side of a clenched fist- Do Not use a hammer (they are brittle/fragile) or you could damage an otherwise o.k. cat.

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You have a loose catalytic converter.

Get underneath with the engine switched off and give them a bang with the side of a clenched fist- Do Not use a hammer (they are brittle/fragile) or you could damage an otherwise o.k. cat.

I didnt think of as it sounded heavier but it would explain the lack of rythme, hope it is.

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slipped linner is a high pitch and can be heard constatly and does not go quite when the revs are applied trust me heard both noises before def flywheel or loose torque convertor

A slipped liner sounds exactly like a noisy lifter. The tell tail signs of a liner is that it does not make the noise when cold and lifters are usually their loudest when cold. A liner will also often quieten down as you lift the revs into the mid and high range.

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Chaps, many thanks for your replies - you've helped me put my mind at rest a little.

Now I have a new problem, the car died on me the other day, I pulled out of a junction, put my foot down a little to accelerate up to traffic speed when suddenly the car lost power completely, I pulled off to the side of the road where the engine coughed and spluttered a little and then died. After this it wouldn't restart. It would try to start, fire a few times but wouldn't run. A passing mechanic stopped to help me out, did some tests including squirting some sort of easy start stuff into the MAF intake - doing this it would fire more and seemed to try to run. Both of us felt that this could be a problem with the fuel pump. Anyway, I had to get the car towed to a BMW dealer (they used to be a Land Rover dealer and still have the LR testing equipment etc) - they phoned me this morning to say they believe that the engine is daffyied - based on the knocking noise that I posted in this thread at the beginning. I explained that in my view this isn't anything to do with the current problem (although granted I suppose it could be), I also wondered if the noise was due to a lose cat banging around, especially as the noise disappears when the engine is running above around 750rpm.

So, some questions:

1) is there a simple way to check the fuel pump? I thought about simply disconnecting the fuel outlet pipe and then when cranking the engine see if fuel is being pumped (would tell me much about what fuel pressure though)

2) My car is fitted with LPG. The LPG tank is almost empty - is there a simple and importantly safe way to remove the LPG system if I need to do this or is this something that a specialised workshop would have to do?

3) Long shot this one, does anyone know of someone here in Budapest that might be able to help?

Cheers

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Sorry, another daft question, I am considering getting my car transported back to my house to do this work myself but I would need to get it into my garage, I have found out that the P38 measures 2228mm wide with the wing mirrors and my garage entrance is 2218 wide - could some kind soul tell me how wide the car is with the mirrors folded in? Can't find that info anywhere.

Cheers

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Just measured my mirrors, they stick out 250mm when in their normal position and 110mm when folded in so you'll lose 140mm each side by folding them in, giving you a width of 1948mm if your figure above is correct.

Of course you still have to get out of the door once you've driven into the garage, can't help thinking of this...

http://www.youtube.com/watch?v=DTbOXL9F0uo

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slipped linner is a high pitch and can be heard constatly and does not go quite when the revs are applied trust me heard both noises before def flywheel or loose torque convertor

Cheers - that was one of my earlier ideas, good to have it confirmed as a cause (my car is an automatic)

Just measured my mirrors, they stick out 250mm when in their normal position and 110mm when folded in so you'll lose 140mm each side by folding them in, giving you a width of 1948mm if your figure above is correct.

Of course you still have to get out of the door once you've driven into the garage, can't help thinking of this...

http://www.youtube.com/watch?v=DTbOXL9F0uo

Excellent (good videa too) thanks for the information

When you disconnect the LPG it will seal itself off / shut down the flow. So no problem there.

Good news, cheers

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Chaps, many thanks for your replies - you've helped me put my mind at rest a little.

Now I have a new problem, the car died on me the other day, I pulled out of a junction, put my foot down a little to accelerate up to traffic speed when suddenly the car lost power completely, I pulled off to the side of the road where the engine coughed and spluttered a little and then died. After this it wouldn't restart. It would try to start, fire a few times but wouldn't run. A passing mechanic stopped to help me out, did some tests including squirting some sort of easy start stuff into the MAF intake - doing this it would fire more and seemed to try to run. Both of us felt that this could be a problem with the fuel pump. Anyway, I had to get the car towed to a BMW dealer (they used to be a Land Rover dealer and still have the LR testing equipment etc) - they phoned me this morning to say they believe that the engine is daffyied - based on the knocking noise that I posted in this thread at the beginning. I explained that in my view this isn't anything to do with the current problem (although granted I suppose it could be), I also wondered if the noise was due to a lose cat banging around, especially as the noise disappears when the engine is running above around 750rpm.

So, some questions:

1) is there a simple way to check the fuel pump? I thought about simply disconnecting the fuel outlet pipe and then when cranking the engine see if fuel is being pumped (would tell me much about what fuel pressure though)

2) My car is fitted with LPG. The LPG tank is almost empty - is there a simple and importantly safe way to remove the LPG system if I need to do this or is this something that a specialised workshop would have to do?

3) Long shot this one, does anyone know of someone here in Budapest that might be able to help?

Cheers

If it won't run on LPG or petrol, it is not likely to be the fuel pump.

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If it won't run on LPG or petrol, it is not likely to be the fuel pump.

Well, the engine was still cold when this happened and usually, it won't switch to LPG until the engine is at least partly warmed up. I do wonder though whether the loose drive plate / torque convertor problem may have resulted in damage to the reluctor which would in turn of course completely mess up ignition timing - what do you think? Is that a possibility?

Also, when disconeecting the LPG, where you recommend I disconnect it?

Thanks for your help

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Could easily be a developement of the original problem,

If the torque plate and and converter are loose it could have collided with the crankshaft sensor, the result could be lose of run signal.

If it wont start on lpg or petrol but will fire on easy-start it suggests that the engine isnt totally flubbered it might just need to te told where number one cylinder is through the crank sensor.

It would be normal for bad noise to be followed by component failure as previously mentioned.

By the way mine can fit into a starard garage door with the mirrors folded in but it's tight.

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Could easily be a developement of the original problem,

If the torque plate and and converter are loose it could have collided with the crankshaft sensor, the result could be lose of run signal.

If it wont start on lpg or petrol but will fire on easy-start it suggests that the engine isnt totally flubbered it might just need to te told where number one cylinder is through the crank sensor.

It would be normal for bad noise to be followed by component failure as previously mentioned.

By the way mine can fit into a starard garage door with the mirrors folded in but it's tight.

That's my thinking too - logic suggests that if you already have a problem and another comes along soon after then they may well be related. I read over on Rangerover.net about the issue with loose torque convertor eventually (possibly) causing problems with sensors which is why I was wondering if that's what's happened with my truck. I will be trying to get the car shifted back here over the weekend and then I can start having a poke about and see if I can find out what's wrong. Good to hear it will fit through a standard garage door opening, I was down in the garage with my tape measure earlier and I think it will fit but it will be a bit of a squeeze.

Thanks to everyone for their suggestions, I will report back with progress....

Cheers

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  • 1 month later...

Well, a short update, the garage have finally (after 5 weeks) found a little time to get my car up in the air and have a look. They reported back that they found the Crankshaft Position Sensor has been dislodged and damaged and that a "small piece of metal is missing from the flywheel". They were planning to weld this but have now told me they can't and that the car will need a replacement flywheel and a new CPS. They have quoted me over £450 for a new flywheel which I think is a little on the steep side - has anyone got a good tip of where to get one at a decent price? My car is a 4.6 HSE automatic, built Dec. 1996.

Cheers for any tips.

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You might find it help contacting Martin Toole who has stripped a number of P38s of the same vintage. He trades on eBay as r-r-parts-ltd. He's s good guy and very fair on pricing. Just because he isn't advertising the exact item doesn't mean he hasn't got it. Best of luck.

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guess what i was right! lol the flywhel is expensive unless you can find the correct year one on ebay second hand it will have tobe new

You were indeed right - it took a lot of arguing before the garage were convinved that they should check this first - they insisted it was a valve problem and I had to get quite shirty with them - thanks again for the tip.

@MartinM, thanks for the tip, I'll get in touch with the eBay chap

Cheers

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Yes that's for a auto. I dont understand a word of German but a picture is worth a thousand words!!

Thanks Paul, good to know because the price seems reasonable, I speak German so no problem for me, I'll try and get in touch with the seller tomorrow.

Cheers

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Well chaps, I know I'm making a little heavy weather of this but I don't want to buy a pig in a poke and then have to spend more money buying something else. I've found a replacement flywheel on the the German eBay site for a reasonable price and it "appears" to be in reasonable nick. I just want to check to see what else I will need - reluctor ring I think and am I correct in assuming that this is available seperately? (I don't want to buy a cheap flywheel and then a brand new expensive one to go with it). Here's a front and a back view picture, thanks for your help

post-21022-127545591533_thumb.jpgpost-21022-127545592775_thumb.jpg

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