Damper oil

[MollyOwner]

Hi everyone,
I have a recent intermittent "clonking" from my nearside, forward of the passenger seat. It is not road speed related and quite random. Have checked everything that could possibly "clonk" and nothing raising its head, so now am wondering if the damper oil is low, very old - or absent. She did pass an MOT four months ago, performed by an MOT tester who is familiar with Minors, having just restored one.

Am somewhat confused by the various suggestions for replacement oil, ranging from sae20 to sae 40 or even 50. I realise that engine oil is not totally suitable. My plan is to use sae20 unless folk really do think a slightly heavier oil is better.

Also, rather than disturb the bottom washer seal and valve assembly, has anyone had success in withdrawing the old oil with tubing and a syringe via the filler plug, or is it better to actually drain it all from the bottom and clean the valve?

Thanks in advance!

[RobThomas]

If I were a betting man I'd say that the exhaust is whacking the crossmember or the damper drop link.

With regards to your specific question, it is advised in the manual to remove the damper completely via a pair of bolts holding it to the thick steel bracket. Usually these bolts are tight and rusty, so, not always easy. Using a syringe will not get more than maybe 50% of the oil out and that'll be the 50% with the least grot in it since grot sinks. I would persevere with getting the damper off to drain it all out and then cycle the arm ina vice to ensure it travels without clonks and that the air is purged. 20 weight might be thinner than you'd need, hence the suggestions for 30 weight (lawnmower oil) or 40 weight (Ebay?) to thicken it up a bit.

If you just drain it via the bottom valve then you might struggle to purge to air out.

Best of luck!

Oh, and maybe take some photos to post up on here??

EDIT: Doh, front damper? Slightly easier to extract it from the car.

[Sleeper]

Just as an aside ( I'm about to do the same job myself ) , what is the standard spec of oil for the front dampers ? and why us heavier/lighter oil than standard..
I take it will be lighter to give a smoother ride ?

Thanks
John

[Trickydicky]

The only way to successfully remove all the oil is with the drain plug removed, the interior of the dampers are two pistons. Because of this you can only drain them fully by exercising the full travel of the damper arm.
You can do this by removing the drain plug and rocking the car on the suspension.
If you wish you can disconnect the damper arm from the top link but you may not be able to do this as the taper pin may be stuck which means removing the pin via the top trunnion.
I have had best results with sae 40 oil, in my opinion (and that of the great man) is the best viscosity.
If you have a steering clonk and you are certain it is the damper with little or no oil in it, remove the top plate of the damper and check the connecting rod of the pistons has not sheared and the damper is only working on 1 piston. The oil in the damper also serves to lubricate the internals and if they run dry it can seize and break the connecting rod.
If it is intact, check there is no more than 3mm of play in the damper arm at the connecting pin end of the suspension (it will need disconnecting from the trunnion to check this) again wear in the damper is due to it running dry. This can also be a source of a clonking noise.

[MollyOwner]

Thank you for the advice.
I've had fun!
Some black, but also streaked with cleaner oil, dribbled out the drain plug. Refilled at the top but, despite vigorous rocking, nothing is coming through to the drain. Took the six screws out and removed top cover. The top of the assembly is moving freely from side to side when car rocked. Filled it right up and rocked but still nothing coming out the bottom.
I'm not the worlds best engineer I confess but do like to have a go at my own repairs, generally successfully but this has me fixed!!

I should add that I am trying the job in situ but may need to heed Rob's advice and remove the damper.

Any suggestions gratefully received!

[Trickydicky]

Replace the drain plug as this is a pressure valve across the two cylinders. Rock the car and the damper (with any oil in it) will stiffen up and it will move the bottom of the damper.
Then remove the drain plug and pump the oil out by rocking the suspension up and down. Do this until there is no more oil pumped out.
If you have no success then your only option is to remove the damper arm from the top trunnion and remove the damper and do the same with the damper off the car.
If you do this, dont clamp it directly in a vice as you may damage the casting, bolt it to a stout piece of wood and then mount it in the vice to pump the arm.
Be aware that the front dampers when filled with oil, the arm is quite difficult to pump due to resistance.
Good Luck!

[MollyOwner]

Thank you Richard

[Sleeper]

MollyOwner
You have my sympathy as I have just been through the same routine with mine....removed the valve ( and hidden spring/tiny washer ) and no amount of rocking up and down would persuade the oil out ( apart from the original 10ml when the valve was removed ).
After taking the tops off found one damper full of nice clean oil , the other full of black sludge ( looks like the DPO had changed one damper ).
After much head scratching decided the only way was pressure ......so adapted a spare damper lid with a silver-soldered in tyre valve , re-fitted and a quick blast with the air-line pumped the old oil out....then flushed with new oil ...then topped up with new 30 oil.
Will leave it overnight for the new oil to settle then check the 10mm below the top level.

2017_1110damper0001.JPG (285.96 KiB) Viewed 1734 times

shown on a spare damper in the vice

John

P.S. An Asda ( other supermarkets are available ) medium tie handle freezer bag is just the right size to hang round the back of the damper to catch the old oil...