The curious case of the increase in engine noise

Hi all, bit of a mystery today, hopefully you can throw some suggestions at it. 1985 90" with a Disco 200tdi conversion. Driving on an A road around 55mph when the engine noise suddenly became much louder/more tappety. Not a wierd noise, just the usual TDi clatter, but I'd say the volume went up by 20 or 30%. No warning lights. Pulled onto the hard shoulder - no leaks, nothing odd looking and sounded OK at idle. Pulled away again gently, as soon as I used much accelerator the noise returned, with light throttle all sounded normal. No sign of power loss. We were a few miles outside the nearest town, so I decided to gently drive into the town in case we were left stranded out in the country. About 1/2 mile down the road at close to 50mph, the noise suddenly disappeared, the engine was a quiet as it has ever been. It remained like this for the rest of the 40miles back home. I'm thinking maybe a blocked oilway that cleared itsself, but I'm pretty baffled how this would happen with fresh oil - I changed the oil and filer around 1000 mile ago. I'll change the oil again tomorrow and look for any particles. Could it have thrown a valve cap which caused a blockage?

If your motor had thrown a valve cap I do not think the noise would have gone away,but worth a check anyway.

Bit or carp in the fuel, or more likely a sticky injector or pumping unit.

lynall said:

Bit or carp in the fuel, or more likely a sticky injector or pumping unit.

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I hope you're right - I'll change the fuel fiter as well. I always add a bit of millers to my fuel, in the hope that it helps keeps the pump in good order. The noise happened about 30 miles after I had filled up.

What has been said already is good ..

If it still doesn't work I'd check the fuel pickup in the tank .. messy job but if there's cack in there it might be worth it!

Paul D said:

What has been said already is good ..

If it still doesn't work I'd check the fuel pickup in the tank .. messy job but if there's cack in there it might be worth it!

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Thanks Paul - I'll have a look at the fuel filter this afternoon, it should show me if there's any crud in the fuel. Any tips for getting the fuel pickup/sender out? - I looked at it last year, but it wasn't budging much and I didn't want to break it while it was still working.

zeaphod said:

Thanks Paul - I'll have a look at the fuel filter this afternoon, it should show me if there's any crud in the fuel. Any tips for getting the fuel pickup/sender out? - I looked at it last year, but it wasn't budging much and I didn't want to break it while it was still working.

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Im not sure what is on the defender pick up, but on the early series there was a small gauze filter on the bottom of the stack pipe that can and does block up.

zeaphod said:

Thanks Paul - I'll have a look at the fuel filter this afternoon, it should show me if there's any crud in the fuel. Any tips for getting the fuel pickup/sender out? - I looked at it last year, but it wasn't budging much and I didn't want to break it while it was still working.

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Buy a new lid/seal first ... Last time I did one the original broke .. and no stock at local parts man ...

I tried spraying brake cleaner to clean it up a lot, then Plusgas to free it or lubricate it, but it still jammed and broke so I just hoicked it out with a chisel and a touch of brute force.

It might be worth, before trying to remove the cap, especially if there's already notalotta fuel in the tank, to empty it through the drain plug into a clear container and check the state of the fuel. When it gets to the bottom you might be surprised to see what's in there! I did this, then filtered the lumps out with some cooking filters, maybe coffee can't remember, then re-used the fuel a few times, shaking the tank as best I could and emptying/filtering it a few times. Worked wonders for cleanliness of the tank.

Well all valve caps were in place, nothing found with a magnet in either the contents of the fuel filter or engine oil. Maybe must some bad fuel.

Out of curiosity which named station did the fuel come from?

It was a local chain - Maxol. I haven't had any problems with their fuel before.

Just wondered as there was that fiasco with Tesco a few years back.
Maybe their tanks were low and you just picked up some crud?

Quite possibly. I've driven her a bit since and am now paranoid about engine noise - not good in a 200tdi!

Mine was also making a noise recently. When I put my foot down there was a slight rattling/grinding sound along with a whine (sounded like a distant police siren)..........new turbo......ouch!!!

This was not a slight noise - and the turbo sounds and operates normally - get thee behind me Satan, I've enough to worry about with a 1000 mile camping trip coming up! I'll pack the AA card

Anywhere nice?
I'm also in the (long) process of getting ready for my winter camping. I usually run with a Berghaus Air 6 but going to change over to a roof tent, I'll see how it goes, either way they'll be a Berghaus tent or a roof tent plus bars for sale in February!.
Its Scotland in December/January for us!!!
Good luck with your search of the noise and hope its not as expensive as mine.

jathca said:

Anywhere nice?
I'm also in the (long) process of getting ready for my winter camping. I usually run with a Berghaus Air 6 but going to change over to a roof tent, I'll see how it goes, either way they'll be a Berghaus tent or a roof tent plus bars for sale in February!.
Its Scotland in December/January for us!!!
Good luck with your search of the noise and hope its not as expensive as mine.

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We're off to Wales/Scotland - reliving our early years camping out of a 109 from John O'Groats to Devon. I've winter camped a bit in Scotland - make sure you have a good sleeping bag! The campsite in Glenmore is open year round and has good showers - very nice after a hard day in the hills.