| Author | Message | ||
     Brian Vogel Grand Master Username: guyslp Post Number: 783 Registered: 6-2009 |
 Today after finishing with the wiper relays I decided to take SRH33576 out for a good exercise run. That part of the day went quite well, what followed was not. I parked the car with the idea of taking Mom for a Mother's Day drive a bit later. When I went to start her, she started then stalled shortly after and I could smell raw gas. I discovered a puddle near the very front of the car, which had been parked with the radiator above the curb and over the grass, so I knew it wasn't water. A sniff immediately told me that it was gas. I know this means that one of the carb floats has become "sticky." I had the carbs redone (I can't say fully rebuilt due to my own lack of knowledge at the time and not knowing exactly what the mechanic who worked on them did) several years ago. This was in response to fuel leaking at the base of the carbs. Things have been working without issue since. This will be my first foray into doing any sort of carb work myself, and I never have gotten into anything in the same area on LRK37110. Is it possible to pull tube 'E' and tube 'F' to determine which one of the two carbs is the problem. I am presuming it's only one, and the amount of fuel is not huge by any measure. I know I'd need to put a small bottle at the end of the tube to catch the fuel during this check. I would like to minimize the extent of disassembly to make this repair as much as possible and am looking to the voices of experience as to what step one should be, then keep going based on what I actually uncover. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 386 Registered: 5-2012 |
Hi Brian That is what I would do. The problem of course is that the sticking float is likely to be intermittent. If your car has the SU pumps then, as you will know, the problem is quite simple; just wait until such time the clicking of the pump does not stop and then check each line to see which is dripping fuel. More hit and miss if the car has the rotary pump. The nice thing about this check is you do not have to carry it out with the engine running, which makes it a much safer procedure. Geoff | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1194 Registered: 6-2006 |
Is it possible to pull tube 'E' and tube 'F' YES Disconnect the oil pressure switches if your pump doesn't run with the ignition on. (makes it easier) Have you changed the carb and main fuel filters? Carb filters especially get neglected and disintegrate. Dirt stuck in the valve can cause flooding. Clamp the feed hose, run the car until the fuel runs out. When you take the clamp off, the fully lowered floats / wide open valves and rush of fuel may dislodge the dirt. It only takes a spec. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 393 Registered: 4-2009 |
I had the same leaking issue on my 78 Wraith II. I tore into the carbs and found one of the floats full of petrol. The plastic had somehow lost its seal and petrol entered the void. the float was replaced and the problem has been solved. Months later, the old foat is sitting on my desk at work still full of petrol. In case your problem is the same as mine, be sure to have a spare float handy so you dont spend forever waiting for a small part that keeps your car immobilised for no reason. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 784 Registered: 6-2009 |
Paul, The pump on this car, since it's European spec, is an SU that does priming when the ignition is switched to "Run." The main fuel filter was changed by me but I don't know about the carb filters, which I can definitely check and use the technique you propose as part of that process. Omar, I can also believe your situation. I had the same sort of thing happen with one of the floats in the brake fluid reservoir. In that case one could take the float apart, clean things up, and put them back together with epoxy and have all work well. I'll probably try Paul's suggestion first since I can easily source the carb filter locally. If that doesn't work then I'll keep what you said in mind. Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 845 Registered: 6-2009 |
Does anyone know how the small brass tubes that the vacuum lines slide on to that are just inside the carb dash pots toward the center of the car are attached to the carb itself? Today when removing the vacuum line that has to come off to get to the left side carb fuel filter the little brass tube for the right carb came out with the vacuum line. The ease with which it lifted out makes me believe that it's been this way for quite a while. I don't see any evidence of either solder or threads. Brian | ||
| Jim Walters Experienced User Username: jim_walters Post Number: 21 Registered: 1-2014 |
Brian, it's a push fit. Put a very light smear of red Loctite on it and push it back in. SRE22493 NAC-05370 www.bristolmotors.com | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 848 Registered: 6-2009 |
Jim, Thanks much. That will be on my list once I free the thing from the death grip that the original vacuum line has on it. I'm actually surprised at how small these things are. It appears that the little 'L' sections of line were custom made to have a very small diameter on the carb end with a wider diameter on the opposite end. I've been following the recommendations of Jon Waples in The Shadow Owners' Companion as far as silicone vacuum line replacement but the size suggested is a tiny bit too great in diameter at this particular spot. Brian | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 927 Registered: 6-2009 |
OK, back to discuss this issue a bit more. I haven't had an incident since the end of May. Today I got some lift time and needed to tweak one of the connections for a height control valve hose that had a slight leak. That fix appears to have been successful. However, when I went to start the car when it was on the lift I experienced my first "waterfall" of petrol/gasoline when I first tried to start the car. Of course, once I promptly applied kitty litter to soak all this up and lowered the car, everything was back to normal. I have replaced the carb fuel filters. This issue has only happened when starting the car warm, and by warm I mean it has been run enough to have been thoroughly warmed up before being turned off and sitting for a period of time not sufficient for things to go anywhere near to cold. The only pattern I'm seeing is the warm start pattern. If I had a float with a leak in it I wouldn't think it would be possible to have the sort of "on/off" situation I have. If the thing was sunk from being filled with fuel it should stay there, I'd think. Any ideas about what might actually be occurring? Brian P.S. to Jim: Did reattach the little brass vacuum pipe at the carb body but used Loctite blue rather than red since I wanted to be able to remove the thing a bit more easily if that were to become desirable. | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 192 Registered: 10-2010 |
Hi Brian, Could just be hot-soak with modern (more volatile) fuels. There was a series of articles written by a Shadow expert that the Aussie club reprints that has an installment on the subject. Can't remember the name of the series for the life of me (it's different from Tee One Topics). Cheers, Jeff. Edit: I think it's "From the Shadow's Corner" by Cal West, but I could be mixing it up with something else.... Moderator input: you are correct the author was Carl West from the US RROC and the title is "From The Shadow's Corner". It has been out-of-print for some time however it may be available from a Club Library. | ||
| Omar M. Shams Grand Master Username: omar Post Number: 423 Registered: 4-2009 |
Dear Brian, I have a float chamber sitting on my desk at work which I removed from my Wraith II after I had the same symptoms as you. The float is still half full of petrol many months later. Not fully - just half full. It amazes me how the fuel got inot this tight void and it continues to amaze me that the fuel is unable to leak out. People come to my office, pick it up, shake it and ask what it is. It is a converstaion piece. Your float may have a leak that has partially filled it such that when the choke is on, the extra fuel useage masks any visible leak. When the choke stops working, the excess fuel that used to be burnt as choke has nowhere to go and pours out of the overflow. | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1536 Registered: 4-2003 |
Omar/ The Achillies' heel of floats seems to be crook solder in the case of metal floats and rivetted joins where the plastic float joins the actuating arm. The leak in the carburetter installation is obvious but a recent one that threw me was in the tank itself! There the float again leaked and got heavier which made it sink more until the level switch finally tweaked the warning light on the dash. But when it came to filling the tank it only took about 75 litres to be brim full and even then the gauge showed less than full!! There is a new batch of float mechs available if you need to change it. | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 1537 Registered: 4-2003 |
Jeff/ I have a complete set of the Shadow Corner Notes and want to reproduce them for our library - obviously with full accreditation.. Given that I have a large collection of 'technical' photographs, I hope to insert these to provide illustrations to the detailed writing. Cal I think was an RR employee during the Shadow regime - an experience that always brings a comforting feeling of 'authority' to any advice! | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 929 Registered: 6-2009 |
I have a copy of the collected From the Shadow's Corner articles by Cal West that were published by the RROC-US. If this issue is discussed somewhere in there would someone please point me to the article? I will have to go up to my archives to locate the book. Also, I don't think it's possible for this to be choke related as it only happens on warm start and the choke is definitely not set. Brian | ||
| gordon le feuvre Experienced User Username: triumph Post Number: 44 Registered: 7-2012 |
For reasons I do not remember, the drain valve(5) has a disc/spring that only opens under a head of fuel that has been dumped down the overflow pipe. I think it may be three inches before disc opens. This of course means fuel could have leaked at any time? In the late-ish 1970,s S.U. moved the production of floats to new factory. To say there was mayhem is an understatement as HIF carbs were fitted to R-R, Jaguar, and Leyland product. We had loads of these leaking from joint of two halves, our roadside fix was to drill small hole to let petrol out and then "Superglue" the hole and seam, It did work! | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1238 Registered: 6-2006 |
there was a mod issued to try and stop hot soak flooding problems. The metal and rubber pipe and hose leading to 5 in the weakener Syston (photo way above) SHOULD have a small bore plastic pipe inserted into the metal pipe and extending about four inches into the rubber hose. The metal pipe should also be bent downwards so it is sloping from the weakener to the hose with a drop of (I think) about one inch. Check for the plastic pipe. | ||
| Bob UK Unregistered guest Posted From: 94.197.122.81 |
I have lpg so I do not get petrol leaks. The SU is very prone to this. However on all SU the parts are easy to get and cheap from Burlington carbs who are actually part of SU and Weber. I once brought needles that were in Bentley RR boxes. A method of removing petrol from floats is to boil the float in water. This is not dangerous providing it is watched as you would with fat. I am very smug because I have lpg and you don't, I,m so childish. (Message approved by david_gore) | ||
| Chris Miller Prolific User Username: cjm51213 Post Number: 173 Registered: 5-2013 |
Hi Brian, I hope this is not inappropriate, but would you pay, say $50, to know what the problem is? If so, you might be able to go to your local RR/B shop and buy half an hour of time just for the diagnosis. I suspect that if you knew exactly what the problem was, then you could easily fix it. It might be the easy way in the long run, assuming you have a local shop that you think knows enough to be helpful. For your consideration, Chris. | ||
| Bob uk Unregistered guest Posted From: 94.197.122.84 |
It is fine to suggest that £27 is spent to save money. Absolutely appropriate. A few bits here there soon add up and consider the agro. No body knows it all. Mobile tune up guy? (Message approved by david_gore) | ||
| Bob UK Unregistered guest Posted From: 94.197.122.73 |
Fuel pressure? (Message approved by david_gore) | ||
| Jan Forrest Grand Master Username: got_one Post Number: 582 Registered: 1-2008 |
Although my Shadow normally runs on LPG I still have to start it and run it for about a half mile on petrol before I can switch to gas. In the first few seconds while the float chambers fill up the 'A' bank carb will leak a little petrol, but that stops as soon as the engine fires and the jungle juice starts to actually flow into the engine. I think that it's either a worn float chamber needle or slightly maladjusted float. Either way the leak is so tiny that it's not a problem. I'm hoping that this will be a thing of history once I've added the closed loop feedback circuit gubbins. | ||
| Bob uk Unregistered guest Posted From: 94.197.122.75 |
Improvements in where the gas goes in and the car Will start without choke on lpg The gas pipe need to be in the carb mouth. Hole in the metal u bend close to carb Short pipe elbow short pipe almost touching slide 15mm copper tube. Small leaks where pipe goes though don't matter apart from noise and dirt. To disable choke wire linkage in open position. (Message approved by david_gore) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 934 Registered: 6-2009 |
I'm now in catch-up mode after having been away last Monday & Tuesday then at the RROC-US Annual Meet on Friday evening & Saturday. Chris Miller wrote, "If so, you might be able to go to your local RR/B shop. . ." Chris, for those of us "in the hinterlands" there is really no such thing. There is one specialty RR/Bentley shop about 88 miles away, but my initial experience with them in 2006 made me decide to never darken their doorway again. The closest Bentley dealership is 146 miles away and was established very recently, so it's not at all likely that they have anyone who has a clue about cars of the SY era. One thing I've learned over the years I've owned my cars is that, with very few exceptions (most of which are located at great distance from me), there's virtually no one out there who knows anything about these cars. The mechanics I've used who've been very good and very helpful have relied on their own background and the workshop manual (frequently consulting me if they can't find what they're looking for). These forums and others have been essential to my being able to maintain my cars myself or to accurately guide others I've been able to engage in the area that I can trust to do good work and to stop and ask questions if they reach a "what should I do now?" situation. Brian | ||
| Jan Forrest Grand Master Username: got_one Post Number: 593 Registered: 1-2008 |
When the LPG setup was installed the fitter placed the venturies way back near the point where the two air feeds split off from the central 'choke' flap housing. They didn't work worth a damn. After some input from me he removed the gas venturies and employed a simple 'spud' pipe that dumps the gas into the airflow. In theory this means that the gas should mix with the incoming air as it works it's way around the 180 degree bend before entering the carb venturi for more mixing. That works nicely when warm, but doesn't allow the engine to start from cold. If I now wire the flap slightly open (I hate this kludge) it will start from cold, but doesn't run too well. Hopefully the closed loop feedback system (when fitted) should eliminate this problem, but I'll have to wait and see. | ||
| Bob uk Unregistered guest Posted From: 94.197.122.86 |
My rational of putting the gas as close as possible to the carb butterflies was that I thought that the distance from the choke housing was to far. I imagine air stretching due to vacuum and the gas having to wait for stretching every time the throttle is moved. My choke is wired fully open, is no disgrace. (Message approved by david_gore) |
