P38A Rattle when in gear and foot on brake...(SOLVED)

Morning guys,

I have a new sound presenting over the weekend. There is a metallic rattle/vibratrion coming from under the car somewhere around the engine.

Seems to be worse when the car is cold. It comes in with gear selection. Either forward or reverse with my foot on the brake it will rattle, put it in neutral is stops. Take my foot off the brake it stops.

There is a slight delay between selecting drive and it starting so I think it might be gearbox or transfer case related.

It is also apparent when pulling away for for a very slight instant, but as soon as you're moving it stops.

Any ideas?

I assume it doesn't matter if you're holding it with the foot brake or the hand brake?
My guess it only occurs at a certain RPM which only happen under stationary idle under load.
In which case it could be any of the many brackets in the engine bay rattling around.

Can you hold it on the hand brake, with decent chocks and try and find it?

Check the vibration damper on the crank pulley.

I'll go and try it at lunchtime. It only occurs at tickover or just above. Once you get above that it all quietens down...

How do I check the vibration damper @Datatek ?

It's like once the slop in the drivetrain is taken up it stops.

MrGorsky said:

I'll go and try it at lunchtime. It only occurs at tickover or just above. Once you get above that it all quietens down...

How do I check the vibration damper @Datatek ?

It's like once the slop in the drivetrain is taken up it stops.

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The crank pulley is in 2 parts bonded together with rubber, when the rubber fails, the 2 parts oscillate producing a rattle.
Take the belt off and see if the pully can be rotated a little back and forth.

It's not the crank pulley. At least I can't feel any play in it.

Can't see anything loose in the engine bay, or anything that might knock together. With the door open it sounds like it's coming from under the drivers seat area.... I'll have to get someone to stand on the brake whilst I roll around on the floor looking. I don't think the handbrake is up to keeping it still!

Also, it seems intermittent. Sometimes I have to cycle from D to N to R to N to D again to make it rattle. Sometimes it does it straight away. I'll report back after I've had a chance to properly look at it underneath.

Might need to take the aux belt off to feel any play in the rubber.

Could it be the CAT's rattling ? Mine did a few years back, but eventually replaced.

I took the belt off and gave the pulley a good wrench from all sides. Seemed solid a rock to me. I think it might be the CATs. That's where it seems to be coming from. I'll get a helper to stop it rolling over me and I'll have a proper look this weekend with luck....

Perhaps it's a rattling heat shield .

2 noises of this type on my previous Rangie.
One was a failed exhaust gasket so you heard the pop-pop-pop (like a rattle) when stationary on the M25 (insert M-Way of your choice) and the solid concrete barrier between you and the other direction.
Second was rattling CAT bricks.

Try hitting the cat with a rubber mallet. Then if it doesn't claw you, go outside & do the one on the car !!

I can't hit her anywhere with a rubber mallet..... so much time and money spent, I don't want to break her any more!!!!!

Just remembered, Heat shields over the exhaust next to the gearbox do that.

If its from the bellhousing area it could be the flexi plate starting to go ....

If its from the bellhousing area it could be the flexi plate starting to go ....

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I wondered about the flex plate….. but it’s less than 2000 miles old. It was Britpart, but even they should be able to make a plate of steel last longer than that shouldn’t they!!!

I really don't want to have to get that out again....

Datatek said:

Just remembered, Heat shields over the exhaust next to the gearbox do that.

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Yes, I thought that too, but I don't think it sounds like that. It's a stronger more purposful rattle like something creaking or vibrating, rather than a flapping on rusted mounting kind of rattle if you see what I mean.

I checked those heat shields when I had the engine out, and replaced any corroded fastenings so I don't think it's that, but I'll double check it.

This weekend I'll get fully under her and have a listen.

Also check the rubber coupling on the back of the transfer box where it's connected to the prop

MrGorsky said:

I wondered about the flex plate….. but it’s less than 2000 miles old.

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If that was not long ago ,id be checking all the gearbox bolts ,studs ,in case the box is falling out ..

****ing rain all day here today so I doubt I'll get under it.

I can make it rattle on command now though. If I hold my foot on the brake and just get the revs above tickover I can hear it pretty clear. If I try and rev higher it goes away.

Feels like the exhuast just touching the chassis or something like that..... but I can't see where that's happening.

It also seems to be more present as you pull away now. It keeps going until the speed it increased, but again more so when cold. What does a stretched or failing morse chain sound like....?

MrGorsky said:

****ing rain all day here today so I doubt I'll get under it.

I can make it rattle on command now though. If I hold my foot on the brake and just get the revs above tickover I can hear it pretty clear. If I try and rev higher it goes away.

Feels like the exhuast just touching the chassis or something like that..... but I can't see where that's happening.

It also seems to be more present as you pull away now. It keeps going until the speed it increased, but again more so when cold. What does a stretched or failing morse chain sound like....?

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Not like that IMO