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Delco-Moraine ABS nitrogen accumulator removal (very tight!?) - Suspension/Brakes/Wheels/Hubs/Steering/Geo - The Lotus Forums Jump to content


Delco-Moraine ABS nitrogen accumulator removal (very tight!?)


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Hello Everyone,

Yesterday I wanted to have a look at my DM nitrogen accumulator so I depressurised the system and then tried to remove it from the ABS pump. I thought it would be a 3 seconds job but it didn't move at all. And as the whole pump/sphere assembly is mounted on silent-blocs and then screwed in the GRP body that looks quite a bit scary to apply any more torque than I have already done: Is it known to be a bit hard to unscrew?! I hope it's not galvanic corrosion between the accumulator and the pump aluminium body ... :/

I may try to fabricate a bar to hold the aluminium pump body but it's a bit scary, really. And I don't really enjoy the idea of removing the whole pump body first (I could do it obviously, but I just wanted to insert the pressure gauge in between the body and the accumulator to check the system, so it's not very clever if I have to remove the pump first ... :D

Any thought? Is the accumulator known to be hard to remove?

Thanks in advance!

Edited by Giniw
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If it's that hard to remove, and it's just for checking the pressure, I'd leave it well alone rather than risk damaging something. You could fit a pressure gauge elsewhere as well, for example wh

I replaced my accumulator back in 2017 (I've replaced it twice - 2003 &  2017).  Thought it was the switch this time, but was the accumulator again.  No issues getting mine off.  In fact I remembe

Have you performed the easy test? Let the pump run to build pressure, wait a bit and see how many times you can pump the brakes before the pump starts again. You should be able to apply the brakes 3 o

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If it's that hard to remove, and it's just for checking the pressure, I'd leave it well alone rather than risk damaging something.

You could fit a pressure gauge elsewhere as well, for example where the pressure switch sits. Maybe that's easier to remove. You would need to add a 'T' to mount the switch again and run the pump.

Filip

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I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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Posted (edited)
8 hours ago, Escape said:

If it's that hard to remove, and it's just for checking the pressure, I'd leave it well alone rather than risk damaging something.

Actually I am pretty sure the accumulator is shot but I do like to test and understand before starting to changes random parts.
Which is why I bought a nice original Kent Moore gauge from the USA (along with a bleeding tool that goes into the DOT 4 reservoir, but that is another story! ^^), so your suggestion to test the pressure through the contact switch hole is pretty good but a bit disappointing since I would prefer to use my fancy new (for me) "special tool" gauge :D

I sprayed it with a bit of penetrating oil and had to leave for the week anyway, with a bit of luck the next weekend it will be easier ...

Edited by Giniw
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I replaced my accumulator back in 2017 (I've replaced it twice - 2003 &  2017).  Thought it was the switch this time, but was the accumulator again.  No issues getting mine off.  In fact I remember it being really easy to unscrew, compared to other parts on the car.   

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Simon  (94 S4)      My Esprit will be for sale in late 2017

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Have you performed the easy test? Let the pump run to build pressure, wait a bit and see how many times you can pump the brakes before the pump starts again. You should be able to apply the brakes 3 or more times with a good accumulator. If the pump runs after each press of the pedal, the accumulator is probably not accumulating pressure. Could also be the pressure switch or internal leaks, but the accumulator is a known wear item, so logical to start there. And usually not too hard to take off and replace.

Filip 

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I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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9 hours ago, s4simon said:

I replaced my accumulator back in 2017 (I've replaced it twice - 2003 &  2017).  Thought it was the switch this time, but was the accumulator again.  No issues getting mine off.  In fact I remember it being really easy to unscrew, compared to other parts on the car.   

Thanks! I wonder why mine is so hard to remove (when I say hard to remove it's partly because the whole is mounted on silent blocs and then in the GRP, if it were mounted on a sturdier thing I could apply more torque without worrying that much)

6 hours ago, Escape said:

Have you performed the easy test? Let the pump run to build pressure, wait a bit and see how many times you can pump the brakes before the pump starts again. You should be able to apply the brakes 3 or more times with a good accumulator. If the pump runs after each press of the pedal, the accumulator is probably not accumulating pressure.

Yes that is why I suspect it's shot, the pump is switching on each time. But as you say it could be the pressure switch so that's why I would prefer testing it before I order any part. And if it's the accumulator (which is probable indeed) I will need to remove it anyway %)

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I've got the whole pump/accumulator off my car at the moment and while its out I was planning to replace the rather rusty looking accumulator.

I had a quick look at it this evening having read this thread and it's not wanting to budge willingly. Will have a proper go at it over the weekend.

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With a 17mm socket on a normal 1/2" ratchet I couldn't get the accumulator to budge. I got mine off by flipping the whole assembly over and slotting a pry bar between the pump and the pressure switch neck (I was a little apprehensive about doing this) and then using a breaker bar it loosened with barely any force required.

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You could always try an impact gun, if you don't want to take out the pump. It has a better chance of breaking the threads lose without damaging the mountings.

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I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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You can also test with a multi-meter on the pressure switch (wires disconnected).  If black-brown make on the first press of the brakes, then you have no volume in the accumulator (or a ton of air in the brake lines!).  If they don't make, then you have a corroded or weak set of contacts in the pressure switch.  As discussed, it should take several presses of the brakes to get black-brown to make (turn on pump) and then several more to get black-white to un-make (activate anti-lock light and get ABS computer to run the pump every time you hit the brakes).     

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Posted (edited)

@tomcattom > Thank you very much for the follow up! Was it corroded inside or just overtightened?
As for me I had not the occasion to go any further as I am helping someone on his car so I don't have time to do anything on the Esprit at the moment unfortunately (thank goodness the M100 is running well ^^)

As @Escape said I will have to try gently with my impact wrench on a low setting to see whether it helps (and I think I will remove the mounting from the GRP first as I really don't want any stress on it)

@Richard123 > Thanks a lot, this is quite interesting to know this procedure too! :)

Edited by Giniw
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The threads themselves weren't corroded that I recall, the underside of the accumulator body was riddled with corrosion however.

I don't know how tight it's supposed to be done up so I can't say if it was overtighten or not, I'd have to see what the manual says to make a call on that. Bear in mind there is a rubber o-ring on the thread which may well cause some additional resistance, especially of it's hardened over time, mine seemed okay in that regard though.

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