| Author | Message | ||
     John Rowney Experienced User Username: johnrowney Post Number: 109 Registered: 02-2015 |
My 1978 Corniche DRH32489 runs very well except occasionally when stopping for a while eg at traffic lights. The Solex 4A1 carburettor has been rebuilt, new gaskets and needle and seat installed, and every nut and screw tensioned as per the manual - I even use a bicycle tension wrench for the 10 in-lb tension on the 8 screws. Most times everything continues as normal, but on rare occasions the revs drop, the generator light comes on and the car starts to run rough when the car is stationary. Usually having the foot on the brake and applying a little bit more throttle, the revs come up, the gen light goes out as expected and generally the problem disappears (until the next time). Does anyone have any thoughts on how this happens? It is very frustrating as most of the time everything is perfect, just on the odd occasion. I imagine there is a logical way of tracking down what the problem is, but with the complicated nature of the Solex, it is beyond my feeble brain at this stage. Any suggestions are most welcome. | ||
| Mark Herbstreit Frequent User Username: mark_herbstreit Post Number: 238 Registered: 05-2005 |
Hi John, My only theory is the 12v feed is randomly dropping off the choke. I have yet to confirm if the 12v is required and constant even after warm up on my Camargue. It has been on my to do list for quite a while now! | ||
| John Rowney Experienced User Username: johnrowney Post Number: 113 Registered: 02-2015 |
Hi Mark. I am going to drive the Corniche tomorrow to do a few errands. I will pull off the 12V feed and see what happens. Fingers crossed I don't stall in the Gold Coast traffic jams! I'll let you know. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 114 Registered: 02-2015 |
I took the Corniche for a few small trips today. Firstly with everything connected - guess what? Everything ran well and not a problem with low idle. After lunch, I disconnected the 12 V supply to the choke, and went for a spin with lots of traffic lights and stops. Everything again ran perfectly. What we can definitely say is that it looks like losing the 12 V supply to the choke is not a problem. The hot coolant must do its trick and it really doesn't matter if the 12 V supply is interrupted. More head scratching is required. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 117 Registered: 02-2015 |
Yesterday I did a few little trips. A couple of times the Corniche dropped revs on stopping, ran rough and the gen light came on. On one occasion I was able to lift the bonnet and check underneath, but things came good and revs went back to normal. Very frustrating. I am keeping the car at home for a while so I am using it as my regular driver for a few days to see if I can pick anything up when it gives a problem. | ||
| Mark Tennison New User Username: fixstuff Post Number: 43 Registered: 11-2020 |
Could it be your AC compressor kicking-in putting load on engine at low rpm could cause the engine to stumble ? | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 823 Registered: 05-2016 |
I'm not familiar with the Solex 4A1 carb but the symptoms you describe could point to a partially clogged idle jet (assuming the carb has one). I had a similar problem back in the 70s with a small piece of crud in the idle jet on a basic Solex carb in a Triumph Herald. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 122 Registered: 02-2015 |
Mark: Thanks, I will turn off the AC when it happens next. I have some thoughts that I have done this in the past with no change. However, I will try and keep my mind on the job and really take note if the AC has an impact. Larry: I hadn't thought of crud in the jets (there are two). I have had the Solex completely overhauled a couple of years ago, so it should be OK, although you never know. I have never taken the idle screws out, the adjustment is not that easy to get to. Maybe a re-read of the manual might help me. Many thanks to both of you for your suggestions. I won't be driving the car for a couple of weeks since we are going away for a while. I have put your suggestions in my diary to attend to when I get back and I will take the Solex part of the manual with me on the holiday. I will post any outcome afterwards. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 824 Registered: 05-2016 |
Hi John, Normally when the engine is at idle the fuel is supplied through the carb idle jet but as soon as you press the accelerator the fuel then goes through the main jet. Revving it won't clear an idle jet because it is bypassed once you press the accelerator pedal. The only way to clear it is by removing the jet and blowing it clean. If you find crud there it might be time to replace the fuel filters. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 124 Registered: 02-2015 |
Larry: Many thanks for your thoughts, and also to Phil Sproston who rang a few weeks ago with lots of suggestions. I was away for a while recently, but I got back this week to trying to sort things out again. My first thing was to remove the idle jet screws and clean them. I took the screws out and squirted carby cleaner in the passage and blew everything out with compressed air. I had two wonderful days driving the Corniche around the Gold Coast with the hood down, and DRH32489 simply purred without a murmur. However, yesterday when I was enjoying the rather hot sun on a trip to Coolangatta, she stopped completely at the lights before turning into Marine Parade - much to the annoyance of the traffic behind. Anyway, she started eventually and then I spent the rest of the time on returning to the shed petrified that she would stall again. With judicious braking and accelerator manipulation, I managed to keep going relatively well. Until... a moronic woman backed her 4WC suddenly out of a parking space in Tugan. A smoking wheel-locking stop to avoid a horrible prang caused DRH32489 to stall again. I eventually got home, and today I took the Solex carby out of the car, and gave it a thorough clean with carby cleaner and horrific blasts with compressed air. Imagine my surprise when there was quite a few millilitres of water in the effluent from the liquid deposits (mainly carby cleaner). Anyway, with everything back installed, I went for a spin and all is good (so far). I will drive DRH 32489 for a few days over the next week or so and report back. Buggered if I know how water got in the system! | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2541 Registered: 09-2004 |
The running of E10 can cause problems if the car is not used for longish periods with fuel separation. Hope will all be ok now. If the problem still prosists. IMO it has all the classic signs of the starting of electronic ignition failure. Maybe check the ballast amplifier first! | ||
| David Gore Moderator Username: david_gore Post Number: 4130 Registered: 04-2003 |
John, I have never suggested the use of E10 in RR/B vehicles especially those subject to infrequent use due to past problems such as what you have experienced. I suggest you run the fuel tank down to safely near empty before refilling it with 95 or 98 RON fuel which is ethanol-free. If you are of the "belt and braces" segment of the population, I suggest another change of the fuel filter[s] as well afterward as there could be additional pick-up of sediment with the low fuel level in the tank pushing sediment into the fuel pickup in the tank. If all else fails and sediment blockages are an ongoing problem, the best preventative would be remove the fuel line fittings from the tank and flush the tank with clean fuel to wash-out any remaining sediment. P.S. are your Solex carburettor[s] fitted with E10 compatible gaskets/seals? If not, you may be having a problem with breakdown of these items from exposure to the E10. P.P.S I hate E10 fuel from past knowledge of owners using E10 fuel in various vehicles from different manufacturers made before the introduction of E10 fuel experiencing problems similar to you. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 2359 Registered: 04-2016 |
David, You are spot on. There is a huge misunderstanding of ethanol based fuels. As I have mentioned here many times, there is a huge difference between manufacturers specifications of; “E10 compatible” “Designed for E10” We can discuss this if anyone is interested. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 125 Registered: 02-2015 |
I can discount the impact of E10 since I always run the Corniche on 98 Octane unleaded. The petrol spec for this car is 97 RON, and I have never used E10. In Queensland there is always non-E10 available at all petrol stations, unlike some other states. I had planned to replace the filter after next week and I will also look at cleaning out the tank. I did find some teflon-type gunk about a year ago in the carby after the NRMA in NSW checked the strainer on the carby due to another issue. I thought that there might have been a bit more of this gunk in the fuel passages. This teflon gunk was deposited when the NRMA assisted after a large piece the O-ring between the air cleaner and the carburettor lodged in the one of the carburettor throats (due to a mechanic (not me!) incorrectly installing the air filter and accidently cut the O-ring in two!!!) Many thanks for all the suggestions - in a couple of weeks I will have worked through each suggestion one by one, so that hopefully I will fix the problem and know exactly what the cause is. | ||
| Trevor Hodgekinson Frequent User Username: wm20 Post Number: 290 Registered: 11-2006 |
With all of the rain we have had this year, water in your fuel is not a surprise particularly if the tank is not kept full when the car is not being used. The moisture in the air condenses to water overnight then drops to the bottom of the tank where it gets picked up when you corner, go up or down steep hills etc. You man need o drain the fuel tank. Excesive water will cause the problems you are having ( along with 100 other things ) Try to capture the fuel in the filter when you change it then tip it out & see what is there. . | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2542 Registered: 09-2004 |
You are lucky to be able to obtain fuel without E5 and E10 (Ethanol), in the Uk just the two ethanol types. E5 is now ethanol super unleaded. Time to start flying again and run 100 avgas in some of my classics.  Thank goodness for LPG on the Shadow. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 126 Registered: 02-2015 |
Today I drained some fuel from the tank. There was a couple of fine black sediment particles, but no water. I then replaced the fuel filter. This was previously replaced in October 2016. There was an amount of fine black sediment collected in the bottom of the filter bowl, but no water. The car is running well, so I will persevere for a few more days before taking the Solex out again if the rough idling recurs. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 127 Registered: 02-2015 |
I ran the Corniche for a couple of days, usually without incident. However, after some time, about once every 10 stops in traffic, the car would run rough. Ugh! Yesterday, I pulled the Solex 4A1 carby out. There was no water and everything was clean. I reckon the water I found the previous time I took the carby out was from the coolant running through the heater/bimetallic element. I put it back in and didn't finish the job as a mate called in and we had a beer. This morning I woke up at 1 am and started thinking again. I have been running the idle screws at three and a half turns out to keep the idle speed up a bit versus the recommended one and a half turns to two turns out. Then I thought what if one of the Anti Run On Valves was playing up? This would stop the fuel to one of the primary throats at idle and cause my problem. This morning I checked in the workshop manual, and, sure enough, one of 3 causes of rough idling is a faulty Anti Run On Valve. The problem now is that Flying Spares and IntroCar are out of the replacement valves. Can these valves be reconditioned or are they available somewhere else? It seems that a failure of one of these valves would be a good explanation of my intermittent problem - ie an electrical problem affecting the operation of the carburettor. Any thoughts on how to recondition the valves or a source of new ones would be most welcome. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 128 Registered: 02-2015 |
I went to the Bentley Heritage Parts website this morning, and it claimed that the Anti Run On Valves were in stock. I had so much difficulty with the site, I don't really know whether they got my query. I will let you know if I get a response. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 825 Registered: 05-2016 |
The valves can stick, sometimes removing them an squirting a good dose of WD40 into the hose inlet and giving it a shake can unstick it. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 129 Registered: 02-2015 |
Today I decided to remove the Anti Run On (ARO) Valves. What a pest that I had just re-installed the Solex. To remove the ARO valves, the carby has to be removed from the engine. Removing a carby twice in two days is a thing reserved for dud mechanics (ie me!). I took off the carby and removed the ARO valves. They were clean and I worked them backwards and forwards with an independent 12 V supply. Everything worked perfectly. Just for good measure I liberally cleaned them with carby cleaner. I spoke to Richard Treacy earlier today to see if he had any replacement AROs, but he didn't. He suggested that I run the car without the AROs to see what happened. I am chasing up 8mm bolts with 1.00mm pitch to try and plug the holes left after removing the AROs. A bit tricky, since the holes are at an angle and sealing the fittings might be a problem. Judicious use of small O-rings might do the trick. I am now suspicious that there might be an intermittent failure of the power to the AROs. The solenoids worked perfectly over at least 50 cycles each. Removing the AROs and seeing what happens might confirm that I have a problem with the power supply. Any feedback on what I am trying to do would be most welcome. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 130 Registered: 02-2015 |
Today I replaced the AROs and fitted a concoction of a bolt, washer, teflon tape and O-rings to seal the hole where the ARO previously existed. I put everything back in place and there were no leaks. Wow! a bit of success. After starting DRH32489 up, nothing went according to plan! Unless I had my foot well on the accelerator, the engine would stop instantly. After many thoughts, I found that I had forgotten to re-install the idling air correction jets. These are little grub screws with a small hole drilled in them. Wouldn't you know it, I dropped one of them and spent half an hour looking for it. Something about 4mm by 2mm and black in colour is rather difficult to find on a black and white floor! Finally, success. Once I put the grub screws in, everything worked well, except I had to open the stop on the main throttle to keep the revs up. This must be due to the fact that the AVO has a significant restriction with the holes in the business end of the solenoid. Without the AVO, the liquid flow must be significantly higher than normal. Anyway things are looking good. I have given up for the night and I have drowned my sorrows in a couple of rum-and-cokes. I will tackle the problems again later in the weekend. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 827 Registered: 05-2016 |
The joys of classic car ownership, it's rewarding when problems are eventually solved. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 132 Registered: 02-2015 |
I have driven the Corniche with the ARO valves removed for the past 3 days. It probably needs a tune without the AVO valves. However, I have not had a stalling situation like I had before. I will try and get the motor to run smoother at idle tomorrow by adjusting the idle mixture screws and the main throttle stop position. My money now is on an interruption to the power to the ARO valves for the cause of my problem. After a bit more of a run without the ARO valves, I am thinking of putting them back in place and driving the car with a reliable 12 V source keeping the AVO valves always open while the car is being driven. Perhaps taking the 12 V supply off the ARO valves while idling nicely will duplicate the problem. Any thoughts most welcome. | ||
| Larry Kavanagh Frequent User Username: shadow_11 Post Number: 829 Registered: 05-2016 |
That sounds like a logically good method to potentially confirm or eliminate the anti run on solenoid valve as the problem. If you discover that the valve is sticking a good squirt of WD40 inside it and a vigorous shake might free it. | ||
| Jim Walters Frequent User Username: jim_walters Post Number: 375 Registered: 01-2014 |
I've seen that ARO valve, more commonly called an idle shut off valve, on an older Mercedes that used the Solex 4A1. I just had a look on Ebay and here is a new one listed at €40, item #354405060176. So they are available a lot cheaper than at the dealer if you find one is faulty and it is not a wiring issue. SRH8505 SRC18015 SRE22493 NAC-05370 www.bristolmotors.com | ||
| John Rowney Experienced User Username: johnrowney Post Number: 133 Registered: 02-2015 |
I have now gone a step backwards. The other day, I took the Corniche for a run and the old problem of stalling/running rough at idle has returned despite the removal of the ARO Valves and a bit of tuning. What a pest! Today I thought about it a bit more. (Jolly dangerous you might say). I recall that a month or so back, when taking the Solex out of the car, the four nuts holding the carburettor to the studs from the manifold appeared to be somewhat loose. So, a few minutes ago I checked the torque. The torque on each of the four nuts was about 3 ft-lb, versus the design of 10 ft-lb. I have now re-tensioned them up to 10 ft-lb and I am about to go for a spin. Watch this space. Will there be an improvement in performance from tightening things up and perhaps sealing a gasket leak? | ||
| John Rowney Experienced User Username: johnrowney Post Number: 134 Registered: 02-2015 |
The Corniche ran much better after the re-tensioning of the 4 nuts holding the Solex to the manifold. It looks like there must have been a leak in the gaskets. I have ordered a new gasket set and the carby riser gasket (this one sits under the Solex on top of the manifold). It will probably be after Christmas before I get them delivered from IntroCar. When I get the new gaskets, I will take off the carby, reinstall the ARO valves, install the new gaskets and see what happens. I will regularly check the tension of the nuts. I will also check the tension of the 8 screws holding the stages of the carby together. Hopefully a good outcome in the new year. | ||
| Jeff Martin Frequent User Username: jeff_r_1 Post Number: 454 Registered: 07-2018 |
Why not use a little blue Loctite on the nuts ? The non-permanent kind. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 135 Registered: 02-2015 |
Thanks, Jeff Sometimes I don't think about things I would use in other circumstances. I will do this when I get the gaskets. Great idea! Cheers John | ||
| John Rowney Experienced User Username: johnrowney Post Number: 140 Registered: 02-2015 |
I have been slack and not reported on the latest. I took the carburettor off, installed new gaskets, re-installed the ARO valves and used loctite on the 4 main nuts. The car ran extremely well, but it has been idle since Boxing Day. I have been servicing my other cars and playing around with them and I have been neglecting the Corniche. Hopefully I will have it out in the next few days and then let you know how things are progressing. | ||
| David Hughes Experienced User Username: wedcar Post Number: 146 Registered: 07-2004 |
John Quoting Bill Vatter from USA, many carburettor problems are fixed when the ignition system is sorted out. Sounds very much like a faulty coil or poor earth. Just try swapping the coil for a start. Regards David | ||
| John Rowney Experienced User Username: johnrowney Post Number: 141 Registered: 02-2015 |
Hi David I completely renewed the electronics in the distributor and replaced the coil around three years ago. This was written up in the SS section (currently about the 5th thread down). I reckon I would be unlucky to have a fault with the ignition system after this relatively short time. Every time I had done something in the past to the carburettor, it works well for a while, then deteriorates. Tightening things up always seems to do the trick for a while, so I am concentrating on the carburettor at this stage. However, when I open the Corniche's bonnet next time I will check all ignition connections just to make sure. Thanks for the suggestion - I will let you know if I find anything. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 142 Registered: 02-2015 |
It has been almost 4 months since I gave an update on the Solex. The car had been running well in the rare times I have taken it out, but I was concentrating on getting my Wraith (WXA68) prepared for the run from the Gold Coast to the RROCA national rally in Hahndorf. With WXA68 fully packed up we were on our way to the rally, but after only 2 miles, she overheated and I detoured to my shed where we transferred everything to the Corniche, which I hadn't serviced or done anything special to. Things went well to start, and my wife enjoyed the air conditioning and an occasional time at the wheel to give me a break. We went round the south coast of NSW, but at Sale in Victoria, the brake fluid light came on. I had a massive leak of RR363. Fortunately, my old mate, Peter Jordan-Hill, came to my rescue and brought 5 litres of RR363 from Melbourne to Sale to enable me to keep topping the fluid up. To cut a long story short, we survived the rest of the trip to Hahndorf, where I made up 8 litres of DOT3 with 5% medicinal castor oil for the trip home. At the RROCA display day, I spent most of the time adjusting the bi-metallic choke on the Solex after some problems, using very valuable advice from Mark Herbstreit. What would a trip home be like without a full failure to proceed? Yes, it happened! A couple of hundred km from home I couldn't start the car. After much too-ing and fro-ing and several phone calls to Steve Sparks in Brisbane, I hot-wired the car and managed to get home. I have now replaced the starter relay and rebuilt the height adjuster solenoid which was the source of the leak. Since fixing the Corniche problems, I also repaired the Wraith coolant leak, her starter motor and relined her brake servo, I haven't had a chance to give the Corniche a decent run to verify that the Solex is well and truly fixed. Tomorrow is the day! Hopefully, I will have a positive report on the Solex in the next couple of days. , | ||
| John Rowney Experienced User Username: johnrowney Post Number: 143 Registered: 02-2015 |
I took the Corniche for a run the other day. When I made the adjustments to the bi-metallic choke I knew I didn't have enough flap closure when cold, but I knew that I needed to have the flap vertical when the car was at operating temperature. I knew that starting would be a slight problem with the choke not fully closed, but in Queensland this isn't much of a problem. However, on the way back from the run, I had a very slow downhill run, and the engine stalled. It took me a while to start it again, and, after some significant revving of the engine, it was OK. For some reason, low revs caused the engine to stall. If I keep the revs up all is OK. I don't know quite what to do next. I await anyone's suggestions | ||
| John Rowney Experienced User Username: johnrowney Post Number: 145 Registered: 02-2015 |
After the stalling episode a few days ago, I thought that there may be something wrong with the spark plugs, since things seem to be OK at reasonable revs. When I looked carefully at the plug HT leads, I noticed that some of them had the metal connection well up the rubber cap, and that obviously I didn't have a good connection from the HT lead to the plug. When the cap properly fits on the plug, there is a definite "click" as the cap clicks into place on the plug. The HT cap is probably the worst design possible since the cap must be pushed on with quite a bit of force, but it can only be pushed on while holding the cap at the sides. Most other types of caps in other cars, including other RR models, a downwards force is easy, since most of the leads are at 90 degrees to the plug. I had to take all the HT leads off the plugs, and painfully adjust the cap so that the metal connection was near the mouth of the rubber cap. On some of the plugs, I could not force the metal on to the plug, so I had, with a great deal of effort, to pull the rubber cap back along the HT lead and then push the metal connector on to the spark plug with a large screwdriver until it clicked into position. I then had to jiggle the rubber cap back into position. This was particularly difficult for B3 and B4 plugs, which most people will know are real pains to deal with. I took the car for a spin from the Gold Coast to Ballina and return (about 160-mile round trip) sitting on reasonable speed. Hopefully, I have blasted off some of the gunk around the plugs. I didn't want to change the plugs out, since it is such a difficult job particularly for B3 and B4. The result is that the car is running a lot smoother. I still have to adjust the bimetallic choke device so that I get a better choke effect, as well as ensuring that the flap is fully in the vertical position when the system is hot. I will give this a whirl this afternoon. . | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 829 Registered: 11-2017 |
The rubber boots on the plugs can almost weld themselves on, making removal difficult, which can be good. I use a stiff wire rod with a bent 1/8" lip on my end to pry the boot upward when removing. Pulling the cable is a no-no. When installing the boot use a swab with silicone and swab the boot interior,and they will slide on and listen for the click. BTW, before removing plugs it is best practice to use compressed air to blow any debris from the plug well. | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 845 Registered: 10-2008 |
Similar to Robert, I smear the rubber boots with silicon grease. This makes them easy to put on and easy to remove in the future. Mark | ||
| John Rowney Experienced User Username: johnrowney Post Number: 147 Registered: 02-2015 |
Thanks, Robert and Mark. I will get some silicon grease and have it ready when I next touch the spark plugs. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 148 Registered: 02-2015 |
I gave the Corniche a full service recently (it takes days for a plodder like me to complete this, my first time for a C service). After the service, I adjusted the bimetallic choke a bit further in the rich direction and went for a spin to get the car warm. There is still a little gap on the stage 1 flap when cold (about 2mm), but the flap is still vertical when hot. The car is running well with no stalling, although for the first 30 seconds due to not having full choke, it is a bit rough. My next attempt will be to check the idle mixture, now that I have a rev counter and a CO analyser. After doing that, I will see if I can adjust the choke a little richer for better starting. | ||
| John Rowney Experienced User Username: johnrowney Post Number: 153 Registered: 02-2015 |
Please see a newer, separate, thread "Solex 4A1 Float". This shows that my latest thinking is that the float is too heavy (14 g.) and I have ordered a replacement float weighing 8.5 g. |
