large vehicle hinges

The hinges for the back doors of my Merc 709D are incredibly stiff. If unbolted from the door it's hard to move them by hand. These are very big heavy doors by the way. The hinges are external; surface mounted. The pin in the hinges has domes caps with a blind hole at each end. Presumably they are meant to be thief proof.
I feel that I ought to free the hinges. But how do I do this? WD40 has failed. And is it possible that the hinges are meant to be very stiff, to control the door?
Bill
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On Sun, 10 Jun 2018 21:11:42 +0100, Bill Wright
I got a panicky call from a mate one Sunday morning when the rear door fell off his Shogun. He too had noticed it becoming stiff but had done nothing about it. ;-(

Sounds familiar.

Possibly.

Yes you should, before it's too late! ;-(

I'd say you have to get some lubrication in there.

I would always start such experiments with a REAL penetrating oil, not WD40.

I can't see how they could if it's *just* a steel pin in a cast housing (as most of them are)?
In the case of my mates I took the hinges off, used heat and penetrating oil to allow me to remove the broken off section and the fixed bit from the other side and turned him a couple of new pins and sent him on his way (to the airport as it happened)!
Cheers, T i m
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On Sunday, 10 June 2018 21:22:03 UTC+1, T i m wrote:

Regualr lube might improve it some but that's probably all. Try ATF, that can free up even seized things. You might need to dilute it with acetone, white spirit etc to get it to run in.
NT
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Fark, that would have to be the ugliest thing I have seen in a long time.

Have they always been that stiff from new or can you ask someone who got theirs new about that if you bought yours used.
The bonnet hinges of my Hyundai Getz did get very stiff over the 12 years I have had it now. Never did get around to doing anything about it because while stiff, it was still possible to open the bonnet.
Then during the last of our equivalents of your MOT, the fella who did it asked me if I wanted him to fix it on the spot and since he was less likely to find something to quibble over I just said 'sure'
He did use WD40 and an air hose and it took quite a while to free it up.
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On Sunday, 10 June 2018 21:11:39 UTC+1, Bill Wright wrote:

Can you form a reservoir around the top of the hinge with plasticene (or similar) and fill it with lubricating oil to dribble down inside?
Owain
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On 10/06/2018 22:29, snipped-for-privacy@gowanhill.com wrote:

Or drill out the blind hole in the top dome, fill with oil, and then plug with epoxy or similar after getting it free? Option which removes need to take them off.
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On Sun, 10 Jun 2018 23:56:13 +0100, newshound

I like that solution. ;-)
(Assuming they aren't nylon lined then a Teflon lube might be better ...), I'd start off with a real penetrating oil and hinge movement between applications and once an improvement is detected, follow up with some heavier oil.
The penetrating oil seems to create a 'path' and the heavier oil then follows that.
Cheers, T i m
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Is there any likelihood of Nylon being used as a bearing sleeve?
The stuff absorbs water and swells.

--
Tim Lamb

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On Mon, 11 Jun 2018 08:54:21 +0100, Tim Lamb

Well, I have seen nylon (or a 'plastic' at least) lined hinges, pivots and bushes and was going along with the thought that it may have been ok for some time and then slowly got tighter?

I wonder what the rowlocks and crutches are made of on all our boats? They look like a form of nylon and some places only say they are 'plastic' and others actually state 'nylon'?
https://www.sheridanmarine.com/product/rwo-nylon-rowlocks
In fact, aren't most of the plastic bits on boats Nylon and you couldn't get much more exposed to water than on a boat! ;-)
I've just had the bushes break on a cycle brake lever (I was trying to bend the ally lever straight) and they too feel like nylon. Nylon has give whilst being pretty tough and wear resistant?
Cheers, T i m
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On 11/06/2018 02:09, T i m wrote:

I think they are unlikely to be nylon lined as the loads are fairly high, and even filled nylon is likely to creep and extrude at modest stresses.
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On 10/06/2018 21:11, Bill Wright wrote:

Car hinges are normally roll pins. In your van, they might be solid. As others have said, your problem is (lack of) lubrication. The clearance has become blocked by corrosion products and/or fretting wear debris. Because of the geometry, just spraying WD40 or even something better at the "joints" may well not work. If it is possible, I would start by unbolting them completely and soaking in the recipe of your choice for at least a couple of days. "Recipe" could be Plus Gas, ATF + acetone, diesel, or even for that matter WD40. After soaking for a while, apply exercise until you notice an improvement. Then carry on soaking. Seek on Mercedes forums whether (and if so how) the pins are removable; you could be right, they may not be without using an angle grinder.
I've replaced roll pins a few times on older cars when they have become sloppy enough to wear through a significant proportion of the material (remember that the roll pin wall thickness is only a couple of millimetres). The risk of one being significantly worn if you can't move it is small. However there is a possible risk of fatigue in ones that are stiff.
On my Renault Master, "door control" for the back doors is provided by a separate strap (which can be disengaged to allow opening beyond 90 degrees). There's usually enough friction even in well lubricated doors to prevent them from flapping about.
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On Sunday, 10 June 2018 23:32:01 UTC+1, newshound wrote:

I would not remove the entire hinges. This will break the paint finish, lea ding to need for remedial work or to corrosion.
I would not use wd40 as a soak. WD-40 is not successful at this, and if you wanted to use it, just buying white spirit & adding a drop of oil is many times cheaper than buying it branded as WD40. If you look at tests of penet rating oils you'll see WD40 at the bottom of the league, with outcomes norm ally being failure. Why people keep recomending this junk I don't know.
NT
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On 11/06/2018 10:24, snipped-for-privacy@gmail.com wrote:

On one of my vehicles the tailgate hinges unbolt from the body but were integral with the door. So by taking the door off, you could actually soak both hinges completely in small pots of oil.

Because a lot of people have it to hand, and the aerosol applicator is convenient for many things. I agree, you could "make your own" from white spirit and some gear oil. And I agree that Plus Gas and other custom penetrating oils are better (although they are arguably not so good for other jobs). But it is still the case that WD40 will often free up something which is not too badly stuck.
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On 11/06/2018 15:24, newshound wrote:

WD40 MAY well be OK for YOU, but it is a water displacer NOT a lubricant (penetrating or otherwise). Some people regard it as a go-to lubricant but just because you have it/it is readily available, does NOT mean it is the best stuff to use.
It is relatively expensive and not that brilliant but even 3-in-1 is preferable as a penetrating oil.
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On Monday, 11 June 2018 17:04:53 UTC+1, soup wrote:

e

As a lubricant, WD-40 is the worst thing going. It's nearly 100% not lubric ant. As a penetrating oil, it simply isn't. Tests comparing pen oil formulae con sistently show it's the worst, and does not do the job. So... what use is it? Seems to me the mfrs have done a very good marketing job on what is basically white spirit with huge markup. White spirit is at least as widely available as WD. And most of us have some sort of oil at le ast, all of which are more effective than WD.
NT
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snipped-for-privacy@gmail.com writes

Marketing:-)
Does work well protecting metal surfaces from condensation/corrosion and where the aerosol action may reach inaccessible areas.
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On Tuesday, 12 June 2018 08:19:03 UTC+1, Tim Lamb wrote:

sure, the result is the same as using any type of oil only less effective. A superthin film of oil is what it delivers once the spirit has evaporated.

Aerosol can be useful sometimes, but I can't remember when I last needed to aerosol spray a very very thin mix of oil anywhere.
It's nothing but marketing bs.
NT
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On 10/06/2018 21:11, Bill Wright wrote:

I asked James at the garage. He said, take them off, soak them in diesel for a few days, work them. Repeat. If this fails get them very very hot then work them, then whilst still hot chuck them in the diesel.
Bill
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On 12/06/2018 03:38, Bill Wright wrote:

Oxy-acetylene is the standards garage cop-out.
I had a Peugeot 305 estate a few years ago that needed new rear brake pipes. The ones on the trailing suspension arms. Rather than fiddle about they removed the trailing arms just to make it easier for themselves.
This is no mean feat on an aging Pug 305, where the coil springs are horizontal, with very thick coils and need a special spring compressor. The knuckle joint at the bearing end of the swinging arm is invariably rusted so they used the oxy trick and that boiled all the grease out of the radius bearings which then started knocking a couple of years later.
They were a Pug main agent too.
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On Sunday, 10 June 2018 21:11:39 UTC+1, Bill Wright wrote:

They probably have a weather seal to keep the rain out (and WD40) Can you not drill holes in the caps and put WD40 in that way? The hole would need to be blocked off afterwards with some sort og jollop.
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