Morning all.
Pulled the delay timer last night and measured the distances to begin tracking down why the compressor keeps cutting in and out.
FL 515mm
FR 515mm
RL 510mm
RR 525mm
This morning they are
FL 515mm
FR 485mm
RL 500mm
RR 480mm
Clearly I'm losing air from 3 corners. Am I unlucky enough to have 3 bust bags or where else on the circuit might I start looking?
Unless you know the bags have been replaced fairly recently with genuine Dunlops, you could be looking at a full set. Otherwise, it's the valve block. Time for the Fairy Liquid.
As the EAS SID says....
"The vehicle should not drop more than 15mm (0.6 in.) per day due to leakage", so, assuming a LR day is 24 hours and your overnight was 8 hours....
Your FL bag is great :)
If it's your bags, may as well fit a complete set. Currently £225 from Island inc vat and delivery
http://www.island-4x4.co.uk/springs-dunlop-isl004-p-629.html
Dunno when or if bags were done.
I'll do another measure tonight.
I'll assume that it can't be the block if 1 corner is good?
I rebuilt the block a couple of months back. I'm confident there's no leaks from the lines. If there was an internal leak, it would drop all 4 corners?
If you don't know when the bags were last changed, change them. Even if they were changed shortly before you got the car, you don't know what was fitted, the Britpart ones only had one O ring so hardly ever sealed properly. When you do change them, make sure you trim a couple of mm off the end of the pipe and chamfer it with a pencil sharpener, then the groove made by the old O ring won't stop the new ones from leaking as they'll be bearing on a clean piece of pipe.
It could still be the block as you won't be able to tell where the leak is. If it is after the solenoids, it could affect individual corners.
Is there anything relatively cheap that can be put inline on the airlines to the bags to isolate them from the block once they're up to pressure? At least then I'd be able to tell if it's bags or block side
You could fit a set of these http://www.ebay.co.uk/itm/P38-RANGE-ROVER-AIR-SUSPENSION-SYSTEM-EAS-EMERGENCY-VALVES-SET-/272726482487, pump each corner up and see if they still drop. That will tell you if it is the bags and not the block that is leaking. I've got a set that I keep in the car just in case I get a terminal fault that the Nano can't deal with when I'm hundreds of miles from home, so worth having anyway.
I thought more of an inline isolation valve like you'd put on a tap or shower.
Are these just a push fit with a Schrader valve on the other end?
And probably most importantly, what pressure is meant to be in a bag?
The O ring seals are lifed components and only last so long before flexibility drops off allowing them to leak. Used similar pipe and seals on the floating optical tables in the lab back at RARDE / DERA / DRA / QuinetiQ and these were only reckoned to be good for 5 to 10 years even in a benign air conditioned environment. Rather lower pressures tho' so inherently more leak prone. Having the compressor cut in half way through certain experiments could ruin your whole day! Do-overs on tricky 11 hour test runs I could definitely do without. No overtime for salaried staff. Unavoidable requirement for 3 + hours unpaid slavery not being calculated to improve the bunny happiness quotient at the best of times.
Clive
blueplasticsoulman wrote:
I thought more of an inline isolation valve like you'd put on a tap or shower.
So then you are adding 2 more connections and potential leaks, at least using these there's only one additional potential leak point. It would probably be more expensive to buy 4 inline valves than a set of these too.
blueplasticsoulman wrote:
Are these just a push fit with a Schrader valve on the other end?
Yes.
blueplasticsoulman wrote:
And probably most importantly, what pressure is meant to be in a bag?
Whatever pressure is needed to lift the car. The system cuts out at 10 bar, roughly 150 psi, which is obviously adequate to overcome the weight of the car, but it is volume of air rather than pressure that dictates how high the car sits.
About 55 psi is normal ride height according to a quick Google.
Probably but it will depend on the amount of weight in the car. Think about it, if you put 55 psi in the rear bags and it sits at normal height, as soon as you put some weight in it, it will sag so need more air which will raise the pressure.
Yeah I get that. Just need a starting point though. No good flinging a load of air in and popping the bag. That'd ruin yer day!
Valve set purchased as per Gilbert's suggestion.
Update whilst im waiting for the manual valve set I ordered to arrive.
Measured heights again overnight. This time it appears all 4 corners have dropped whereas last time only 3 did.
Bit of a nuisance being intermittent as surely if it's leaking, it's leaking which is why I haven't been entirely convinced in the past that it was.
Although I don't know when the bags were last replaced, they all look to be in good, clean condition. No cracking around the bottom.
I guess it would be unusual for all 4 bags to spring a leak at the same time? I'll know for sure when I get them valves but I would summise that i'd be looking at the block for the leak based on what I've found so far?
Although it had dropped by about 30-40mm per corner, when I started it up, it rose instantly so there was still air in the reservoir so it can't be between that and the block. I'm positive it's not leaking from the airlines out of the block.
There must be 1 source with a slow leak that causes the whole car to lose air consistently at each corner but slow enough that it doesn't drop much. It's never on bump stops.
blueplasticsoulman wrote:
I guess it would be unusual for all 4 bags to spring a leak at the same time?
Not really, they will all be the same age and all done the same mileage so why wouldn't they all age at the same rate? In saying that, rears almost always start to leak before the fronts.
Based on that logic, I best keep an eye on the radiators in my house. There's 17!
blueplasticsoulman wrote:
Based on that logic, I best keep an eye on the radiators in my house. There's 17!
Not really - your radiators probabbly aren't made of rubber, nor do they significently expand, or are expected to deal with sudden shock loads whilst being filled with air.
Richard did say further back that the britpart ones (as opposed to the dunlop ones in britpart boxes) didn't have as good a seal, it might be worth looking at that with the soapy water test, though the leak rate is so slow you might not be able to detect it anyway.
Was pointing to the highly unlikelihood of 4 (or more) of the same component breaking down at the exact same time.
I've done the soapy water test all over. I did this dance a couple of months ago and rebuilt the block. (possibly to no avail it would seem) Could still hear the compressor cutting in and out and in the absence of any visible leaks and through discussing it on here, the opinion was offered that my compressor operation is probably normal and that I can either just hear it or feel it. I never measured the distance from arch to centre wheel as I hadn't noticed a drop in height. It never sags at one particular corner. Always looks even. My road also has cambers at the curbs which perhaps hasn't helped as the delay timer corrects the height too thus never really drawing my attention to it other than as I said, I can hear the compressor from time to time. The leak is slow as it's never been down to bump stops and judging by the measurements I've recently taken, the drop is relatively even all around, except for the first night I measured when only 3 corners had moved. I measured this morning and 4 corners had moved.
Above, I was asking if there is one particular airline that if a leak occurred, it would drop the whole car evenly? If only the rear right bag had a hole in it, I would expect only the rear right corner to drop. Is that correct?
It would be ideal if all 4 bags are leaking. Easy fix. You know where the fault is. If it's in the block and soapy water shows nothing, it's gonna be more trial and error. Can't see inside the block when it's got air in it and stripping it down may not turn up any visible signs of the fault.
If the diaphragm controls the direction of air, could a diaphragm not closing all the way or with a nick in the rubber or something be allowing the air in the system to flow back out?
Or
The exhaust valve solenoid is sticking open a bit?