Humming noise at 40mph

[NMM]

Hello.

I have a Mk4 Seat Ibiza with the 100bhp 1.9TDi engine. Recently my car has started to make a very loud humming noise whenever I am doing about 40 mph. The noise sounds like it is coming from the front of the car. It happens regardless of the gear I am in at the time. If I slow down or speed up by 3 or 4 miles an hour the noise goes away. There is no noticable difference in the way the car drives or accellerates at 40.

A friend thinks it might be a turbo problem. When I bought the car, I got a diesel because I was doing a 40 mile each way motorway commute. Last year I got a new job nearer home and my commute is now only 5 miles each way on low speed roads. My friend says that mainly doing short low speed journeys is bad for turbo diesels and that is why this might be a turbo problem. What puzzles me about this theory though is that the noise occurs in 5th gear. I was under the impression the turbo doesn't kick in until about 1500 revs. At 40 in 5th the car is only doing 11 or 1200 revs.

Is my friend right as this sounds expensive? If so how much is it likely to cost?

 

[Torquemonster]

It's true,td's don't like short journeys and not getting warmed up properly.I doubt very much it's anything to do with your turbo.What are your tyres like?.Might just be a characteristic of them?.

 

[RUM4MO]

Hub bearings? Strange you only hear it in fifth gear though if it was hub bearings.

 

[NMM]

Thank you for the replies

RUM4NO, It happens in all gears so that might be a reason.

Tyres could be a possibility too. They have done about 30k miles so they could be wearing.

 

[Nath.]

boost pipe rattling against the fuel line ???

very common problem, a bit of foam stuck in the gap and it should sort it out

 

[RUM4MO]

Thank you for the replies

RUM4NO, It happens in all gears so that might be a reason.

Tyres could be a possibility too. They have done about 30k miles so they could be wearing.

Ah, all gears, then it sounds like hub bearings - if so I'd change both sides as this is a known weak point on these cars. I crapped it when my Passat 4Motion started doing that - I left it for about 6 months - but it didn't go away, I was convinced it was a transmission problem which with a 4Motion equates to BIG MONEY. I swopped back to original wheels (with less off-set) and it was a bit better, so I plucked up enough courage to hand it to the dealer who found it was hub bearings - so I got both sides changed. If you check for slackness on the assembly or roughness you will probably find nothing obviously wrong though.

Phone your local VAG dealer for a price - parts are the bulk of the cost, ie hub assembly complete with bearing, hub nut - I think if you have ABS a special tool is needed to prevent damage to the wheel sensor - so doing it yourself and needing to replace the sensor might make taking it to the dealer cheaper!

BTW, fitting wider wheels with increased off-set will increase the loading on these assemblies.

 

[NMM]

My car has been in the garage today. The problem was a wheel bearing.

There must have been a noise at all speeds (just that it was most pronounced at 40) and it had been gradually building up as my car is now much quieter then I remember it.

 

[RUM4MO]

Out of interest, what was the damage (£££) as I'm sure this will need doing to my wife's Polo 9N at some inconvenient point in time. The noise will manifest itself more at certain road speeds due in part to the human ear not having a very flat response - and lower frequencies get lost a bit in the background "noise". Did you get both sides changed or just the one that was currently noisy?

 

[NMM]

It was actually done under warranty so I don't know what it cost.

My car is 2 and a half years old but I wasn't sure if it would still be under warranty or not. The third year of the warranty is worded very strange. I am not the first owner of the car, I did not buy it from a Seat dealership, it has never been serviced at a Seat dealer and the garage I took it to is not the one that originally supplied it. I expected there to be something amongst that lot that would fall foul of the terms and conditions of the warranty, but as there is a Seat garage within walking distance of work I thought I would give it a go on the off chance.

I was pleasantly suprised when they phoned me up to tell me it has been fixed and it was done under warranty.

I only had the one side done. They wouldn't do the other under warranty as it isn't causing a problem. I didn't bother getting it done. If it does go in the next 6 months I know it is still under warranty. If it goes after that a local garage will be cheaper.

 

[RUM4MO]

It was actually done under warranty so I don't know what it cost.

My car is 2 and a half years old but I wasn't sure if it would still be under warranty or not. The third year of the warranty is worded very strange. I am not the first owner of the car, I did not buy it from a Seat dealership, it has never been serviced at a Seat dealer and the garage I took it to is not the one that originally supplied it. I expected there to be something amongst that lot that would fall foul of the terms and conditions of the warranty, but as there is a Seat garage within walking distance of work I thought I would give it a go on the off chance.

I was pleasantly suprised when they phoned me up to tell me it has been fixed and it was done under warranty.

I only had the one side done. They wouldn't do the other under warranty as it isn't causing a problem. I didn't bother getting it done. If it does go in the next 6 months I know it is still under warranty. If it goes after that a local garage will be cheaper.

That's fair enough, and a good result that has boosted your confidence in VAG (a bit).