P38A Isolating a leak.

pwood999 · Sep 2, 2023

It could be airline collets & seals, airline pinhole, leaky airbags or leaky valve in the block.

Soapy water test all the air lines at bags & block. Also do the airbags themselves at all heights. They generally either leak around the airline collets, or where the airbag folds over & cracks.

Valve block is more challenging because you cannot check to two bottom valves without removing the block. If left rear drops lowest it easy to access. because it's on top of the valve block next to diaphragm valve.. First use soapy water around the solenoid base. Then unscrew the RL solenoid and squirt around the valve itself.

It's also possible the valves are leaking internally & out the exhaust. This generally requires a bench test, but for a quick overnight check there's the balloon method !!

Get it pumped up, and remove the delay relay to prevent self levelling. Then put a balloon over the exhaust silencer, and check again in the morning. If the valves are leaking internally, the balloon will inflate !!

marjon · Sep 2, 2023

Flossie said:
Less than 24hrs later the left rear is flatter than a witches tit. Right rear isn't far behind. Thought they looked a bit iffy when I first got her 2 yrs ago. Those of you who have done the job.....is it worth getting her over the pit? I ask because I'll have to move stuff around to get her in and if it's no real help then I'll do it on the drive.

I did rears on a paddock, also front discs.

No need for a pit the work is in the wheel arch.

J

marjon · Sep 2, 2023

pwood999 said:
It could be airline collets & seals, airline pinhole, leaky airbags or leaky valve in the block.

Soapy water test all the air lines at bags & block. Also do the airbags themselves at all heights. They generally either leak around the airline collets, or where the airbag folds over & cracks.

Valve block is more challenging because you cannot check to two bottom valves without removing the block. If left rear drops lowest it easy to access. because it's on top of the valve block next to diaphragm valve.. First use soapy water around the solenoid base. Then unscrew the RL solenoid and squirt around the valve itself.

It's also possible the valves are leaking internally & out the exhaust. This generally requires a bench test, but for a quick overnight check there's the balloon method !!

Get it pumped up, and remove the delay relay to prevent self levelling. Then put a balloon over the exhaust silencer, and check again in the morning. If the valves are leaking internally, the balloon will inflate !!

Sounds like hes on independent valves.

J

pwood999 · Sep 2, 2023

If the airlines have valve on the block end, then the same applies. Soapy water on all joints & the valves. Then all over the bags at all heights !!

Flossie · Sep 2, 2023

pwood999 said:
If the airlines have valve on the block end, then the same applies. Soapy water on all joints & the valves. Then all over the bags at all heights !!

I'll definitely do that first just to confirm and yes, just on valves to test.

Datatek · Sep 2, 2023

Flossie said:
Less than 24hrs later the left rear is flatter than a witches tit. Right rear isn't far behind. Thought they looked a bit iffy when I first got her 2 yrs ago. Those of you who have done the job.....is it worth getting her over the pit? I ask because I'll have to move stuff around to get her in and if it's no real help then I'll do it on the drive.

Easy enough on the drive IMO. Getting the pins out can be a bitch. Follow the airbag replacement guide in the tech archive.
Whatever you do, don't lower the car with no air in the bag.

Flossie · Sep 2, 2023

Datatek said:
Easy enough on the drive IMO. Getting the pins out can be a bitch. Follow the airbag replacement guide in the tech archive.
Whatever you do, don't lower the car with no air in the bag.

What happens if I do?

Datatek · Sep 2, 2023

Flossie said:
What happens if I do?

You can knacker the bag, it may fold in a manner not intended. Follow my guide on how to change the airbags..

Flossie · Sep 2, 2023

Looked at that now ta.

Rubberknees · Sep 2, 2023

Flossie said:
Less than 24hrs later the left rear is flatter than a witches tit. Right rear isn't far behind. Thought they looked a bit iffy when I first got her 2 yrs ago. Those of you who have done the job.....is it worth getting her over the pit? I ask because I'll have to move stuff around to get her in and if it's no real help then I'll do it on the drive.

Did both my rears on drive way no problem

Grrrrrr · Sep 3, 2023

Flossie said:
Less than 24hrs later the left rear is flatter than a witches tit. Right rear isn't far behind. Thought they looked a bit iffy when I first got her 2 yrs ago. Those of you who have done the job.....is it worth getting her over the pit? I ask because I'll have to move stuff around to get her in and if it's no real help then I'll do it on the drive.

The bag replacement? Do it on the drive.

romanrob · Sep 3, 2023

Datatek said:
With the EAS relay removed there is no 12 volt supply to the EAS ECU so disconnecting the battery is no different. With no power to the EAS ECU the EAS is completely disabled.

Well fine, if the relay is completely removed... I had assumed we were talking about removing the EAS relay and replacing it with a yellow one...but clearly I was mis-interpreting

Flossie · Sep 3, 2023

romanrob said:
Well fine, if the relay is completely removed... I had assumed we were talking about removing the EAS relay and replacing it with a yellow one...but clearly I was mis-interpreting

That's got me thinking...I believe the eas special ,hard to buy new, relay is only necessary when running diagnostics? If that relay is replaced with a normal one would the eas still operate correctly? Just stick the special one back in if you need to run diagnostics and thus the special one gets an easy life and thus less likely to wear out.
I think alot :vb-weyes:

Datatek · Sep 3, 2023

Flossie said:
That's got me thinking...I believe the eas special ,hard to buy new, relay is only necessary when running diagnostics? If that relay is replaced with a normal one would the eas still operate correctly? Just stick the special one back in if you need to run diagnostics and thus the special one gets an easy life and thus less likely to wear out.
I think alot

You think too much. The EAS will work with a normal relay but will not self level when parked, nor will you be able to just plug in diagnostics in the event of it dropping to the bump stops en-route without faffing about. Also, the EAS relay is not a simple relay, it contains electronic components which deteriorate when unused.

Flossie · Sep 3, 2023

T'was just a thought, I'll leave be then.

romanrob · Sep 3, 2023

Henry_b said:
Pulling the relay is the easiest way to isolate IMO.

My old duchess has 11yr old dunlops under her and they haven't dropped an inch in the 3 months she's been sat.

or just pull fuse 44...if we really want the easiest way - but it's just shades of grey, at the end of the day

romanrob · Sep 3, 2023

Datatek said:
You think too much. The EAS will work with a normal relay but will not self level when parked, nor will you be able to just plug in diagnostics in the event of it dropping to the bump stops en-route without faffing about. Also, the EAS relay is not a simple relay, it contains electronic components which deteriorate when unused.

Not sure if self levelling when parked ranks as the P38s most useless feature

pwood999 · Sep 3, 2023

L322 does it as well, but according to RAVE it can also activate the pump while parked. Another flat battery feature. Don’t have one so cannot confirm!!

marjon · Sep 3, 2023

pwood999 said:
L322 does it as well, but according to RAVE it can also activate the pump while parked. Another flat battery feature. Don’t have one so cannot confirm!!

Never heard that 1 :vb-confused2:

and never seen it(heard ours try) or read in any docs, so suspect “old wives tale”

J

Grrrrrr · Sep 4, 2023

romanrob said:
Not sure if self levelling when parked ranks as the P38s most useless feature

Well, yes and no. If you've just unloaded a shed load of gear from the back and the arse is in the air the self-levelling is quite useful. Most of the time it is just a PITA though.

P38A Isolating a leak.

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