engine rattle in 5th and 6th

[Maccad40]

hi all

Was wondering if anyone eles has got a rattle/vibration happening under heavy acceleration in 5th and 6th.
sounds like it is coming under the drivers side floor.
thought it might be a guard vibrating or is it something in the manifold

cheers

 

[Old.Tony]

Welcome to the forum!

We have an auto so heavy top-gear acceleration is accompanied by a kick-down and a thrust in the back, but there have been a few reports of manuals with loose-ish hydraulic lines on the firewall that cause rattles. Nissan were replacing the lines (they were probably manufactured too short) but others have solved the problem by putting packing foam under the hydraulic piping.

It must be loud to be heard in 5th/6th gear though - at the normal speed for those gears (60km/h+) you'd think road noise would also be quite loud. If you're getting the noise at a lower speed than that, is yours a petrol? It could be 'pinking' from a lower octane fuel. My Yamaha FJ1200 used to do that when pulling out of a corner at 1500rpm until I changed to high octane fuel.

 

[10navst]

I've heard that rattle also. But only two or three times I've had the car so it was hard to pinpoint the problem. What you've suggested old.tony about the hydro lines could be it cause that is where the sound is. To me it sounds like when you get a playing card and gently hold it against fan blades.

 

[Maccad40]

Nah I've got a diesel old tony and it sounds like a tin flap of some sort. so 10navst is right it sort of sounds like that.
but it only happens at certain rev point

 

[Old.Tony]

There have been a couple of reports of radiator fan blades cracking. Is it possible that as you rev the car, the fan is flexing more than it normally would and making contact with the shroud/radiator? I'd be checking that fairly quickly and hoping it's not the case.

Even the diesel manuals had the hydraulic pipe issue. I asked about petrol because of the fuel octane issue, but both petrol and diesels have hydraulic lines running down the firewall.

 

[Maccad40]

thanks tony. i checked the fan blades they are all good .
These hydraulic lines your talking about on the fire wall where abouts are they and how the easiest way to get to them

 

[Mrluver22]

I've also experienced the rattling and yes Old.Tony hit the target with the hydraulic lines as the culprit. Think those lines are the clutch lines.

 

[Maccad40]

what is the easiest way to get to these lines

 

[Maccad40]

would you be able to put up a pic of what you've done tony to stop the rattle

 

[Old.Tony]

Mine's an auto, so I haven't done anything. However, a few people have put packing foam under the hydraulic lines. The clutch pedal pushes a lever which pumps hydraulic fluid from the clutch reservoir down the pipes into the clutch housing. It'll be similar to brake lines (same principle too). They should be on the back of the engine bay up against the wall running from the clutch fluid reservoir down and under to the bell housing. You should be able to spot where it sits close to the metal wall - just whack some packing foam in there and see how it goes.

 

[Brownie82]

Mines does it in 5th only. When i 1st heard it i put my foot slighty on the clutch pedal (only enough to take the slack out of it). Or if that doesnt work, put your foot behind it and pull back. See if that stops, have read that the clutch springs get loose. I think its a 5 minute job. Mine isnt there all the time and i forget about it, so i havnt done anything.

Cheers.

 

[big zetor]

does the same noise happen going over corragation's or rough road, because I had an air con pipe just touching the firewall behind the brake booster.

 

[Chris C]

Check the AC pipes along the fire wall, they will rattle and sound like the dash behind the stereo is falling out, mine were not even pushed into the white plastic clips, they were just sitting there flopping about.

The other noise under load almost made me sell my car, it was doing my head in.

It turned out being the steel pressure line from the clutch slave cylinder coming into contact with the brake booster, it does a Loop or 2 behind the booster to act as a dampner, it would touch the booster and resonate through the cab, it sounded like a bit of sheet metal flapping about under the dash.

The noise come into the cab through the brake pedal box and uses the brake pedal as sound generator, I found mine by drivng up long hills in 6th, loading it up, and pushing the brake pedal to the side, this made the noise go away, then Iwent hunting.

The line can be bent away, gentley, so it has 10-12mm clearance, you will never hear it again.

It was one of the greatest days of my life when I shut it up, the Dash rattles in this car were driving me insane, I had a HDJ79R cruiser with 300,000 km in a coal mine, with less dash rattles. I very nearly sold the car due to the rattles.

The only rattle I get now is if I have the A/C on 16deg on windscreen, after 10-15 minutes, the vents get too cold and start to rattle under engine load, if I turn of the windscreen and use face vents, the noise goes in about 5 minutes.