| Author | Message | ||
     Eric Molenaar New User Username: aussiewraith78 Post Number: 8 Registered: 06-2021 |
Hello All, Last week i ordered a brake pressure gauge from Kelly and it arrived late today. I thought it was Christmas as i raced outside to hook it up and try and get a better understanding of LRH32854's hydraulic system. As the sun was setting my problem is the number 2 system as the light comes on every time i start the car but goes off after about 6 to 10 seconds, so my guess was accumulator pressure must be depleted a bit. All hooked up and the gauge showed a flick up value of 900 (not 1000) Then rose steadily to 2100 (not 2500) then fell back to 1850 then back to 2100. So i think its working as it should but not reaching the desired pressures. When the motor turned off the gauge slowly lowers and i just checked it (6 hours) after initial test its reading 1000 psi. So i guess i have a leak somewhere. Will investigate more tomorrow but would appreciate any comments at this early stage. Hoping to make the drive from Adelaide to Canberra next year for my first Federal Rally. Thanks in advance, Eric. | ||
| Alan Dibley Frequent User Username: alsdibley Post Number: 340 Registered: 10-2009 |
The height control valves have an unavoidable slow leak around the spool valve. Losing pressure overnight is normal behaviour, unless your car has an exceptionally new and accurate pair of HCVs. I think the low maximum pressure is just a sign of 40/50 year old springs in the pressure regulators - it doesn't really matter. Just my opinion. Alan D. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 799 Registered: 05-2016 |
I had that same issue a few years ago, the No.2 accumulator pressure reading would rise and fall and rise and fall like a fiddler's elbow. I eventually narrowed down the problem to a small bit of crud at the valve seat of the height control solenoid valve which was allowing fluid back to the reservoir before optimum pressure was reached. What led me to the conclusion was an accidental discovery that when I jacked up the rear taking weight off the suspension the hydraulic pressure readings stabilised.My guess would be that you have an internal leak somewhere in the height control system, either solenoid valve or one or both of the height control valves but it's also possible that your accumulator control valve has an internal leak. The easiest way to find out is to continue taking readings along the system in the sequence described in the workshop manual until you pinpoint where the leak actually is. The next step after the ACV bleed screw is the ACV high pressure outlet, if the readings suddenly improve keep on moving down the line but if they don't improve your ACV has an internal leak. The readings you're getting at the moment are a sign of an internal leak somewhere but not a sign that your brakes are destined for imminent failure. If you take the lid off the reservoir and watch for fluid being pumped back in through the return pipes it will also help to narrow down where the return fluid is coming from. | ||
| Eric Molenaar New User Username: aussiewraith78 Post Number: 9 Registered: 06-2021 |
Thanks so much Alan and Larry for the tips. You can't put a price on experience. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 801 Registered: 05-2016 |
Your welcome Eric. The hydraulic pressure test gauge is an invaluable tool that will take guesswork out of the diagnostics and help avoid unnecessary removal of good components. Just follow the test sequence in the manual and you'll pinpoint where the pressure leak is. Your gas sphere seems relatively OK @ 900 PSI, not perfect but not yet shot. | ||
| Eric Molenaar New User Username: aussiewraith78 Post Number: 10 Registered: 06-2021 |
Today i tested the number 1 system and i think i have found my sometimes double feel on the brake pedal when it suddenly gives a little and travels down more. After 150 plus pumps to make the no 1 light to come on i thought then and there i was looking at a faulty brake pressure switch cos the light has never come on any of my earlier attempts mind you i always stopped at 100 pushes. Connected the gauge and NO flick up she just very slowly rose to 2100 then cut back to 1900 and then stayed at 2000 psi. So that tells me diaphragm is shot. What are your opinions gentlemen on these so called 1 use (dispoable) spheres. Thats what im thinking. Also put a seal kit through the ACV. Have ordered a new pressure switch. But now i must say brake light no 1 proudly stays on whilst the endgine is idling. (Havent gone for a drive yet) Do i need any special tools to remove accumulater and control valve? Just hoping bolt on bolt off, bleed the brakes and Bob's my uncle.. Cheers Eric | ||
| Eric Molenaar New User Username: aussiewraith78 Post Number: 11 Registered: 06-2021 |
Agh Ha! Just did some research on the net and i think i definitely need a few tools, thankfully British Tool Works are now doing comprehensive valve kits, so i will give Kelly a call in the wee hours here in Oz and get him to put something together for me. Im still thinking of the disposable sphere as that would be quicker than a refit and i think i can get one from Richard at Spur Parts. Then send my accumulator to be rebuilt and kept in the shed as a spare. Thank you all again. Cheers Eric | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 803 Registered: 05-2016 |
I have one of the "disposable" spheres fitted for the past 5 years or more and it's still working fine. Your old sphere diaphragm is definitely perished and you probably have rubber fragments floating around in the No.1 system so cleaning out and re-sealing the ACV is a good idea. Judging by the cut off pressure at the ACV the spring may be worn but this can be rectified by inserting a shim behind the spring. You will need to clean out your reservoir and reservoir filters and the gravity feed hose from the reservoir to the pump and then flush and bleed the system. DOT3 or DOT4 can be used for flushing as it's a lot cheaper than Castrol RR363. | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 716 Registered: 11-2017 |
The pressure switches that trigger the warning lamps are easily rebuilt. They can be stubborn. Sometimes a whack on the casing will make it perform. The system pressure holds the contact open and low pressure allows the internals to complete the ground circuit to illuminate the warning lamp. | ||
| Eric Molenaar New User Username: aussiewraith78 Post Number: 12 Registered: 06-2021 |
Thank you to both Larry and Robert for your advice and knowledge. I have just got off the phone with Kelly and the parts and tools needed will be on their way. I'm not sure if I've bitten off more than i can chew but you dont learn until you've failed, plus i have this great resource to tap into. I'm just wondering how many colourful words will be spoken to the car as i attempt to remove the parts from the car. Lol.. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 804 Registered: 05-2016 |
Removing the ACVs is a bit fiddly if you don't have good access from underneath but it's doable with the road wheel removed. There a 3 bolts and 2 of them have spacers between the ACV and the engine block so don't drop the spacers or they could land in awkward crevices. Separating the sphere from the ACV is just a matter of holding the sphere tightly and tapping the flat spot on the ACV with a copper or rubber mallet. You will need a new seal between the replacement sphere and ACV. Don't overtighten or the seal could be damaged. When replacing pipe work screw on each end a little at a time until both ends are attached, don't completely tighten one end before the other end is threaded on. Don't overtighten the pipes, best to nip a little at a time afterwards if there's a leak. Be prepared for brake fluid spillage, the No.1 front portion of the reservoir holds 1 litre, the rear No.2 portion holds 1 1/2 litres. Best to empty the reservoir before you start, brake fluid dripping down your sleeves is a PITA. I use a friend's pit for easier access. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 2299 Registered: 05-2012 |
Hi Eric I replaced my acv/accumulators from the side with the wheel removed, mainly because I get a bit claustrophobic lying underneath the car with a ton weight of engine just above my head. I used the keyhole surgery method, using long wobble socket extensions to remove the 3 bolts. It is a straightforward job but likely to take a while first time. My two tips are: Make sure you replace the aluminium sealing disk (UE36145) which will come with Kelly's kit. The kit I used (before Kelly's were available) did not have the disk. I was not even aware it should be replaced. The resultant leak took ages to find. Use two wrenches to undo the main high pressure pipe from pump to the acv. If you use one wrench you risk twisting and fracturing the pipe (expensive). |
