QuestionQUESTION: Hello Dennis,
I have a 95 HSE which I have owned for about 4 and 1/2 years. About 12 months ago I started getting a soft fault in my air suspension. It would stay like this no problem and I simply took it down to my local range Rover motor mechanic who would clear the fault on test book. Each time the fault that showed up was "Inlet Valve stuck permanently open" or something similar. Anyway after it was cleared the system would work fine again for, at first as long as a month or two, but then gradually for shorter and shorter periods before the soft fault would come up again to the point where it would sometimes come back up as soon as five minutes after having it cleared. Anyway, as you have probably already guessed about three months ago hey presto it suddenly advances to the hard fault stage, down on the bump stops. Funny thing is though, sometimes if you leave the car overnight and then start it in the morning(usually, but not always, with door openso as to disable the system)the system somehow clears itself, sometimes completely, other times back to the soft fault stage. Then other times it won't clear itself so it is off the the mechanic to have it cleared on test book. Same fault again, "Inlet valve stuck permanently open". Once cleared on test book the system works fine again and then after a while it starts the same process all over again. Now I am not an expert on these systems but I can tell you that it is unbeleivable how much I have learnt about it over the past three months. These are things that I have done to try and rectify this problem
1.Checked all air springs for leaks with soapy water at various levels of inflation - Result, possibly the left rear is slightly suspect but not what you would even remotely call severe. Infact I have left the car overnight with the door open so as to disable that stupid self activating levelling thing that it does overnight and none of the corners have gone down overnight apart from only slightly in the rear left corner
2. Soapy water at all the 6mm hose connections including all springs, connection to tank, all valve block hose connections, all solenoids, pressure switch and pressure relief valve etc (I take the valve block right out of its casing and then pressure it all up) - Nothing found
3. Cut, trimmed and cleaned all hose connections at the valve block and on the dryer
4. Keeping in mind the fault that was coming up I replaced the pressure switch - No difference
5. Also keeping in mind the fault that comes up I pulled all solenoids apart to check all the O ring seals and even swapped over the solenoids in case it was a faulty solenoid on the inlet valve (even though I can't really see how a solenoid could be faulty when you look at its internal workings - you may be able to enlighten me there) - No difference
6. Now thinking that it might be an electrical fault rather than an air fault I got hold of another known properly working EAS valve Driver and bolted it on to my valve block - Result for about two weeks it all worked perfectly to the point where you are actually starting to get excited because you think you have fixed it when bam it cruelly destroyed all my hopes and dreams and faulted out again, again with the same fault (coupled with "right front height sensor out of range" which I think only came up when it went down on its bump stops and probably may have temporarily got out of range)
7. Got hold of a known properly working EAS ECU and bolted that it in under the seat. First tried it with the borrowed Valve Driver and same thing - worked well for about ten days to 2 weeks and then faulted out again. Then tried the computer with my Valve Driver and same thing again - 10 days or so then faulted out again (By the way once it faults out for the first time after the ten days or so, for the next couple of days when you turn the car off and leave it a while and then turn it back on it would clear itself completely then progress to the soft fault being permanently there then progress to the hard fault eventually coming up all in the space of two or three days after the initial fault if this makes sense.
8. Pulled out and checked all collet O rings and they seem to be okay but in any case no obvious leaks with the soapy water
9. Kick the living crap out the car in frustration and nearly break my foot.
10. Checked the voltage levels on the ride height sensors at different levels and all seem to be operating correctly between 0 to about 4.5 volts
As you can probably imagine I am about at my breaking point and I could probably take it into a dealer but I know they will just start replacing parts starting with the cheapest and gradually going up (which I have learnt the hard, and very expensive way from experience) is the way they operate. In any case they will probably only do half things and spend a fraction of the time that I already have spent on it.
Can you please tell me I am I missing something very obvious. I would appreciate any other tips or pointers that you can give me. I haven't actually pulled the valve block apart yet but that is about my next move. Also I am hoping to temporarily get hold of another valve block that I will put into the car which may or may not tell the story.
I am determined now to fix this problem myself. I have been lucky as my local Rangie mechanic (not a dealer) has been very helpful and has lent me all the above parts and continually cleared the faults for me without charge. He is at a loss to come up with anything definite other than that there must be an air leak somewhere which i sort of agree with other than why is it so intermittent and why does it work properly for so long with for example the other driver on it than it suddenly starts to fault out again. I also have a friend who does work for a large Land Rover dealer here in Melbourne Australia, as a foreman in the workshop mind you as well, and he has also had a good look at it and is just as perplexed as the rest of us. I really hope that you can tell me that I have completely overlooked something very simple and obvious, even though it will make me feel like an idiot, because quite frankly I am past caring.
Regards Rob V.
ANSWER: Hi Rob,
Thank you for the detail, it helps narrow things down.
very good troubleshooting as well. You have eliminated all potential electrical problems except the wiring loom. I've not seen that (yet) so there's 2 more things you can check.
The "inlet valve stuck open" signal is possibly triggered by air leaking past the non-return valves, causing the springs to constantly raise, forcing the computer to constantly lower each corner. Another possibility is the inlet valve is mechanically binding, a good cleaning will remedy that. It is the 2nd valve back from the front on the top of the block.
---------- FOLLOW-UP ----------
QUESTION: Hello Dennis,
Thanks for the prompt reply. Just a couple of more queries for you in relation to the advice you have given me,
1. If it was the first fault would it do this all the time or only intermittently and I am assuming to look at the non-return valves means I will definitely need to pull the valve block apart. If I was to do that would I need to replace all the seals etc or can I put it back together with the existing seals, orings etc if they seem OK and how do I test the non return valves and which one of them do I test or do I do all three. Can you readily buy non return valves at dealers or do you sell them or know of a supplier here in Australia and
2. When you talk about the inlet valve (or any of the valves being spring, inlet, outlet etc) is that the thing that sits inside the solenoid casing and is screwed down onto the the top of the block and has the little spring loaded plunger inside it because if that is it (which I have always assumed is)I have already cleaned it as well as swapping it over with the exhaust valve (as they seem to be exactly the same thing).
Further to my last e-mail I have actually now notice(having pulled the timer delay relay out and leaving the car for 24 hours) that the right front corner was down (but not a great deal) which was only slightly interesting at first due to the fact that I quite often had the "right front height sensor out of range" fault coupled with the "inlet valve stuck open" fault whenever we cleared it on testbook, but then on closer inspection of the actual right height sensor I discovered that the screws bolting the sensor to the chassis were loose, but still holding the sensor in place, but I'm wondering if it was enough to sometimes cause the fault to a)come up intermittently and b)to then become bad enough at times to send the car to hard fault with the fault showing by the computer as Inlet valve stuck open. Do you think this is a possible scenario. I will obviously bolt it all back together but I don't like to abuse the hospitality shown to me by the local Rangie dealer who has already cleared the faults a number of times without charge, so I only go down now once I think I have tried everything. Thanks for your help i really appreciate it. One last thing, if I buy one of your complete valve block recondition kits can you please tell me how much they are, what the postage cost is to Melbnourne Australia Postcode 3910 and if you whether or not the parts are subject to any extra taxes/charges etc or can they just be sent straight thru the post.
Regards Rob V
AnswerHi Rob,
The sensor being loose may have been enough to confuse the ECU and throw the "inlet valve stuck open" code as well.
The non-return valves are hard to test, but odd operation will show if they're leaking by. A visual inspection will give a good indication. If you go far enough to remove the block to get to the NRV's, you might as well replace all the seals while you're in there.
My oring kits are $20, post to Oz is $4, courier is about $50. You can order them online at www.rover-renovations.com in the "valve blocks and parts" category. Import taxes seem to be random, but if you order just the rings they will probably get by. I don't have any distributors there yet.
The valve is the part you describe, screwed to the block under the solenoid. The inlet and outlet valves are the same externally, but the ports are different sizes and will change the airflow characteristics within the block. I don't know if it will cause a fault, but operation won't be "as original".
