Advice wanted: knock from front of car under load, inefficient brakes & oil leak

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Advice wanted: knock from front of car under load, inefficient brakes & oil leak

Post by David »

Hi all,

As the title states, I'd like a bit of advice on my BX.

After driving it around for the last month and clocking up around 700 miles, there are some annoying issues that I'd like some advice on.

Firstly, there is a knock from the front of the car, it normally appears when you put a load on the engine, or when engine braking going down a hill, you'll hear a knock from the front. It sounds like it's from the drivers (RH) side, somewhere, but I have no idea what it could be.

I've had the car on a lift, and had various iron bars in all the suspension components & engine mounting areas, but I can't find it. All 3 of the engine mounts have been replaced since May this year. I can't get any movement from anything, so I don't know what it can be. There's no abnormal play in the drive shafts either. It was there before the engine mounts were replaced, but as they were old and perished, I replaced them all for good measure.

Could it be the transfer box? There's no play in the drive shafts, and as it doesn't sound noisy (like a bearing has gone) when driving along, I don't think that it's likely, but I don't know what it's capable of.

Or, could it be a small bush on the subframe, where the engine mount bracket bolts to the subframe itself? There doesn't seem to be any play in this either when I had an iron bar in it, but this is the only part that I haven't replaced.

The subframe itself is tight, and I've checked all the bolts that hold it to the car. They're all fine. Any thoughts?

Secondly, the brakes don’t seem to be *that* good. Sure, they work, but I've read that the brakes on a BX are supposed to be exceptional, but in reality, they seem better on my Ford. I went down a very steep hill the other day, and resorted to putting the A/C on for better engine braking.

The brake pads & disks are still like new, but they're around 15 years old, so could this have anything to do with it?

There's no air in the system, as I bled it all out when I had the engine out & changed the LHM last year. The car doesn't have ABS; it's just a conventional system. Any thoughts?

Thirdly, there's an oil leak from underneath. This might be a difficult one to address, as I believe that it's down to the 4x4 system, but here goes...
It's running down the L/H side of the gearbox. I've not investigated this one yet, as I've only just noticed it, but I don't know if it's coming out of the gearbox, between the gearbox seal & the outside of the 4x4 drive cog/ splines, OR if it's coming from the transfer box & running between the drive shaft & inside the 4x4 drive cog/ splines.

If it's the former, then It should be easy enough to fix with a new seal, HOWEVER, if it's the latter, then I imagine that it'll be difficult, as the seal around the driveshaft is comparable to an elastic band! I've never seen a replacement seal the same for sale.

When I put the car together, I replaced the gearbox seal, and it didn't surface when I've been off road with the car, it's only appeared when I've had the car up to 70mph. I also put a lot of grease around the drive shaft inside the transfer box, so maybe this might have something to do with it?

Any advice on the above points would be greatly appreciated.
1992 Citroën BX 1.9 Diesel Meteor 4x4 - The Project.

1992 Citroën BX 1.9 TXD (with GTI engine; Mulleys old car) - Parts car.

2004 Citroën Xsara Desire. (Now gone).

2016 Ford Focus Zetec - Daily Driver. (Absolute bone shaker).

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Re: Advice wanted: knock from front of car under load, inefficient brakes & oil leak

Post by Defender110 »

I know you siad you've checked the subframe but when my TZD did this it was the front subframe moving, it appeared tight but i noticed a clean mark around one of the subframe bolts showing the subframe had been moving. I undid and retightened the bolts which sorted it.
1997 Mercedes C230 W202
2003 Land Rover Discovery Series 2 Facelift TD5 - Daily driver / hobby days and camping.
1993 Land Rover Discovery 200tdi Series 1 3 door - in need of TLC
2020 Fiat Panda 4x4 Cross Twin Air.