Strange Sound

[quadzilla]

Hi All - when I accelerate under load (e.g., taking off at a green light) I have a high pitched rattle - kind of like dragging a chain - sounds like it is coming from the rear of the van near the exhaust. I can't reproduce the sound when I rev the engine from an idle in the driveway - only when I am driving. I have a manual, and I hear this sound when accelerating through all gears. Nothing appears to be amiss otherwise - no loss of power, no reduction of fuel economy, no loss of oil, not over-heating, and I can hit the regular rpms and top speeds through each gear. This is not a throw-bearing issue and the clutch is in good shape.

Any suggestions?

[mararmeisto]

Could be your muffler banging against the side of the van - this is a common issue. The muffler hanger bends out after a while and it starts to rattle.

The sound doesn't happen when you sit in your driveway because the back end doesn't twist and squat like it does when you are gaining momentum. Try to do it when you're at speed and you'll see the same thing: no rattle.

[robinimpey]

If it is only under load the first place I would look is your u-joints. If you have one that is dry they can make the sound you're describing. A bit of grease in each one will let you know if this the the problem.

Let us know what you discover.

[quadzilla]

Thanks for the replies - it is not the exhaust - the system is in good shape and relatively new (4 months). The u-joints look drier than a cracker fart, so I will give that a go.

What kind of grease should I use?

[Golf Cart]

Any multi purpose grease will do.

I bought one of thoses little mini grease guns from Canadian Tire just for U-joints. The grease that they sell is good for that application

[jessef]

Replace the old ujoints with good quality spicer or like one's.

They've probably never been replaced in Japan.

I would not trust ujoints from there.

I've seen them blow apart and cause drive shafts to shoot out. Not pretty.

[quadzilla]

Question: if the u-joints are dry, wouldn't they make that sound all the time? The sound is only there when I am accelerating -when driving without accelerating, the sound goes away.

[marsgal42]

Question: if the u-joints are dry, wouldn't they make that sound all the time? The sound is only there when I am accelerating -when driving without accelerating, the sound goes away.

The engine moves on its mounts, the rear axle winds up, angles change. Start the engine with the hatch up, blip the accelerator, watch how much the engine moves. The driveline must be flexible to accommodate this.

...laura

[robinimpey]

Question: if the u-joints are dry, wouldn't they make that sound all the time? The sound is only there when I am accelerating -when driving without accelerating, the sound goes away.

Nope. It is the extra torque of acceleration that makes the u-joint make that noise............if that's what it is.

[quadzilla]

That makes sense re: the shifting of the engine and the noise. But, old grease out, new grease in and no change in 'the noise', but I now know how easy it is to grease my u-joints

So if the sound is only there on acceleration, and greasing the u-joints didn't do anything, then it must be something else related to the movement / non-movement of the engine and various other parts under load. Any other suggestions?

[konadog]

Maybe new motor and tranny mounts...

[quadzilla]

UPDATE - the strange sound is my turbo.

[Erebus]

But, old grease out, new grease in and no change in 'the noise', but I now know how easy it is to grease my u-joints

There are eleven grease fittings on a Delica:
3 on each front suspension
3 on the rear driveshaft (2 U-joints plus the slipjoint)
2 on the front driveshaft (one is a bolt, not a nipple)

So the slipjoint could have caused it, except I see you're blaming the turbo.

[quadzilla]

Hey Erebus - not me blaming the turbo -this was Glen at Coombs Country making the call. I am not that mechanically savvy, so appreciate the suggestions put forth and when I head back to CCA I will definitely discuss the other possibilities.

Happy Trails!

[coaxial]

So the turbo was the cause? any details would be helpful as I suspect I have the same noise happening - high pitched rattle under load.

I'll be greasing all my points, checking u-joints, exhaust, and cv-joints tonight.