Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: ctaylor738 on July 20, 2016, 01:07:04
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I am working on a 250SL, back in my garage with hot start issues. Three years ago, I installed my timer-relay hot start solution (HSS) that fires the cold start valve for one second when the starter is engaged. This solved the problem (until now).
Now, the HSS is working electrically, but does not seem to be delivering any fuel to the cylinders. After attempts at a hot start, the plugs are bone dry. I removed the CSV and re-connected it putting it in a plastic bag. I observed fuel in the plastic bag after cranking. I tested the fuel pressure at the CSV and found it to be .7 bar. Spec is .8 to 1.1 bar. I put the valve on my injector tester, pressurized it to .7 bar and put 12V to it. The result was somewhere between a squirt and a dribble from the valve. Raising the pressure to 1.1 bar made it a little better but not exactly a spray.
So my theory is that the valve is releasing fuel into the intake manifold but it's not a spray and it's just running down to the bottom of the manifold and not making it to the cylinders to help with hot starting.
Oddly, no problems with cold starting.
Does anyone know what the spray from the CSV should look like?
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Update.
After I posted this, I drove the car, let it sit for 15 minutes, and clamped the return line shut. Car started easily. So obviously, some additional pressure helped.
Also verified from receipts in the car that a local dealer installed a fuel pump three years ago.
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Hello Chuck, check the inlet fitting of the CSV it has a fine screen in it which is often times clogged or restricted.
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Filter is clear. Here is a video of the "squirt." The bench tester is calibrated to the pressure at the CSV in the car.
You'll need to download and rename to .mov to view. Sorry.
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Chuck, Try cracking the throttle slightly so that the fuel charge can be carried down the intake during cranking. With the throttle closed theres not much air flow down the intake path. Its all coming from the idle air screw and down to the runner rail. This is because the wrd airflow is cut off when hot and is where the csv normally gets its air from when cold.
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The fuel coming out of the CSV nozzle/s should be very well atomized kind of like a spray can of paint. If it's dribbling out the nozzle/s could be plugged. At .7 bar it should still spray reasonably well.
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Tyler - every conceivable starting technique has been tried.
Dan - getting fluid out of both nozzles.
Its looks like a newish CSV. Any idea what would cause this lack of atomization?
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I am guessing that you are dealing with leaky outlet valves on the injector pump. By clamping the return line you are in effect acting performing the function of the outlet valves of the injector pump and are keeping fuel from pushing backwards past the valves. This system is very fussy when it comes to leaks from the injectors or the outlet valves, Every system since ours has had some form of outlet regulator (In addition to an outlet check valve at the electric pump) and fuel accumulator added to the system which allowed for some leakage at the injectors etc so I am guessing they learned a lesson on our cars.
Try removing the clamp just before starting and see what happens.
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Chuck, I watched your video. That looks completely normal to me. Your not going to get atomization like you would a fuel injector because it is only supplied with 12 psi and also it does not have a spray tip like an injector. Its just 2 holes. Its the fuel system equivalent of a windshield washer nozzle. This is one reason this design when away and a proper cold start "injector" was used.
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On Gernold's advice, this morning I retested the valve on the car, I recruited a Helper because it's hard for me to fire the valve and watch the spray. I connected the fuel line with the valve turned around from its normal position so it sprayed outward. When I hit it with battery voltage, the Helper (knowledgeable Pagoda owner) reported that the spray was a fine mist from both nozzles. Go figure. It might be the difference between gas and the BG44 I was using on the bench.
Good news is that the car doesn't need a new valve or electric pump. Bad news is, still no explanation for hard warm start.
I should mention that before I messed with the valve, I cleaned and tested the injectors - perfect spray pattern, no leak down. Also adjusted the valves, installed new non-resistor plugs, checked dwell and timing, set idle mixture a little rich. Car is running as good as it gets. No reason that I can see for the hard hot start.
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Just for grins, have you tried disconnecting the start solenoid when starting hot? There is another thread dealing with this very thing. I personally can say it helped my car. Easy to do and will tell you quickly if too much fuel could be the issue. What to do after that is another story.
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Last week, after sitting for ten minutes or so, it got in a real snit.
I gave it probably four 10 second cranks with maybe 1/4 pedal. Each separate crank, my Hot Start Solution fired the cold start valve for one second. I finally gave up and pulled a couple of plugs out. They were unfouled and bone dry. So I am reasonably confident that it's a lack of fuel.
Today, I have been experimenting with a) run pump for 5 seconds b) pedal-to-the-metal crank hot starts. Three out of three have been successful, firing after less than a second of cranking.
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Remember that the injection pump fuel gallery doesn't keep any fuel pressure at rest. Only the lines from the injection pump to the injectors do. There is a check valve at the outlet of the electric pump and no check or regulator in the return line(I do remember there may be a check valve or regulator of sorts at the outlet fitting on the latest cars). Even a little leakage from the outlet valves(delivery valves) will cause the fuel lines from the injection pump to the injector to lose pressure and may cause the fuel to vaporize in the lines and push the liquid fuel further away from the injectors. This is what is commonly referred to as vapor lock which would be even more aggravated by any fuel that contains alcohol which is fairly common on the west coast.
This can also be caused by leaking fuel injectors but since you are seeing dry plugs I am guessing the outlet valves are to blame.
I really think you were on to something when you said that the car started fine after leaving the return line clamped. If you shut if off, clamp the return, wait 15 minutes and unclamp it and try to start you will probably know the story.
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Another thing to check is if the fuel is staying in the supply side. Shut it off, wait 15 min and open the line on the supply side of the pump. Even though the pump is recent it doesn't mean the check valve is working correctly. When I taught for BMW "NEW" stood for "Never Ever Worked".
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Hmm. Even if the alleged check valve on the output side of the pump failed, wouldn't the system re-pressurize itself as soon as the pump started to run? I have always let the pump run for 5 seconds before cranking.
Another Hmm. Hard to believe that all the check valves on the injection pump would fail at the same time.
I think the hot metal lines were known to produce vapor lock. That's why they put the hot start relay on the 230, and made it available for other cars as a kit. Supposedly the 280 pumps had a venting feature to alleviate this, but the 250s had nothing, and seem to have the worst time with this.
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When the car vapor locks when the supply valves are leaking the fuel boils at the hottest point which would be the injector which is nestled right near the exhaust ports in the head. When it boils at the injector it will push the liquid fuel back up the injector lines leaving a nice pocket of fuel vapor behind. The injection pump is a piston pump so it needs to turn a certain amount of revolutions to displace the vapor and push it out the injectors hence the warm start issue.
You will notice that at no time did I use the word gasoline. Modern fuels are a mixture of all manor of stuff particularly in the great states of California and New York. If I were to go way out on a limb I would guess the car isn't driven much and it was last fueled in the winter when federal and California mandates require higher concentrations of alcohol and other oxygenates which will cause the fuel to boil at an even lower temperature. Higher Octane fuels typically have the lowest boiling points.
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Hook up a test light to both the CSV and the injection pump solenoid. Monitor the function at all engine temperatures and compare it to the chart for your starting aids. Deviation from the correct function could be a bad thermo time switch or a starting relay. Check the fuel pressure in the system also during starting. Make sure the CSV is spraying nicely. If no success, the check valves or injectors as suggested can be the culprit. Don't miss the simple fix like low fuel pressure from a clogged fuel filter.
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I've got an early R11 pump and after shutdown, the fuel lines between the injection pump and injectors lose pressure after sitting awhile. All 6 injectors are new so I'm confident the check valves on the output side of the pump are leaking down. Can these valves be cleaned and/or replaced without removing the pump? I've noticed that several members modified their injection pump outlet/delivery valves with newer ball and seat valves.. can this mod be done on an old R11 pump?
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Related question: where on a '69 can I find the starting relay?
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Chuck, I apologize for highjacking the thread to ask about the check/outlet valves.
Regarding your 250SL hot-start problem, upon firing are you noticing initial misfires on any cylinders - possibly indicating leak-down?
I'm having this same (hot start) problem with my R11 pump; when it does fire, I've got a definite misfire on one cylinder till the fuel line has a chance to pump up. I suspect my other five check valves are also leaking to some extent, causing me to crank the starter till they pump up enough to open the corresponding injector.
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Charles,
The outlet valves can be changed in the car but they do require a tool to pull them out after the outlet fitting is removed. You will also require a new plastic seal to put them back in. I made a tool to pull mine and then was gifted the factory tool. I still have the homemade tool it is yours for the asking. I believe that he outlet valves are the same across all models with as you mentioned an early and later Ball and seat design. If I am not mistaken the later design is marked with a groove around the valve.
Homemade tool, factory tool and outlet check valve showing both the groove that denotes ball and seat and the white plastic sealing washer.
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Yes and the Torque is very important as well as the procedure to seat the seal. It is all in BBB. Just for grins, here is the tool I made.
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Shvegel, thanks for offering the tool... but where can I get six new seals for the outlet valves? I thought they were NLA.
If i can just get new outlet valves and/or seals I may reconsider sending my pump out for a complete rebuild. thanks for the advice, Charles
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Hello Pat,
The early cars had a cone and seat type check valve instead of the ball and spring type.
Cees, the starting relays for a 1969 should be on the fender apron near the brake booster. One is for the enrichment solenoid on the injection pump and the other is for the cold start valve on the intake. An additional relay can be for the de-celleration solenoid on the IP. Are you having starting issues?
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Charles,
From the fine folks at Bosch mobile Tradition. Bosch #F 026 T03 028 is the correct kit for your R11 pump. You get every seal and gasket you can change without recalibrating the pump. Not sure if you can get the kit in the US yet but I ordered mine from Europe.Not sure but I think Amazon UK? If you Google the part number you will find a supplier.
http://www.bosch-automotive-tradition.com/en/internet/automotive_tradition/parts/reproduction/motor/dichtungssaetze/dichtungssaetze___mit_teaser.html
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I just found this. Sounds like some machine work is required but luckily you do not need to remove or recalibrate the pump. This guy spent a ton before he found the problem with his car.
http://samplestar.mbca.org/i/371608-sep-oct-2013/66
I am a firm believer in the the adage that everything happens for a reason. They increased the size of the bore of the outlet fittings later in the run. I am willing to bet they were having issues with the smaller fittings stripping out in the body of the pump. I would be very careful tightening your outlet fittings back to spec with a torque wrench and more importantly holding the outlet fittings in place with a wrench when you tighten the fuel line nuts.
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yes, that's a great tech session by Richard Simonds.
According to the article, leak-down on the R11 pumps is caused by the cone-valve's surface being worn such that it no longer seats sufficiently enough to hold pressure. At the end of the article Richard states that pressure valve assemblies for the R11 are no longer available and are not rebuildable. If that's the case, then why are there seals in the Bosch R11 kit? Would replacing the plastic seals alone (and not the cone valves) reduce the leak-down?
Sorry so many questions.....
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Please note that there is an updated and expanded version of Richard's article in Pagoda Notes Volume 8 no.1.
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Charles,
There is a remote possibility you could just change the seals and solve the problem but with a known history of worn delivery valves I would assume you probably won't. The Bosch seal kit is all of the seals you can replace without re-calibrating the pump and the delivery valve seals can also leak to the outside as well.
Jonny,
Thanks for the update!
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aaahh, ok.
Jonny, thanks - I didn't realize this topic was addressed in the Pagoda Notes. I should be more attentive to what's available on this site.
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I've attached the illustration provided with Bosch Seal Kit F 026 T03 028 and item 16 (highlighted) is one of the six plastic seals.
In the illustration the cone-valve appears to be sitting/seated on top of the cap. If this is indeed the cone-valve it would appear that upon removal of the pressure valve housing, the cone valve could be easily accessed and simply re-lapped with the bottom cap.
Has anyone ever attempted this with an R11 pump?
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#16 is the seal and there are six. That is not the same pump as the W113, so not sure you can draw an inference on the type of valve. The cone valve that is shown in the MBCA article is the same type as the CSV. Yes it can be lapped but, but not sure how long it would last. The CSV only operates when starting. The cone valve for the injector line is constantly moving. IE, the wear is much faster and greater.
BTW, where do you buy these seal kits? I noticed on the same Bosch site they have batteries and the NLA short fuel pump. Is that pump now reproduced or is this old? If available, where do you buy if in the US?
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Wallace,
I've not bought the seal kit yet, I just followed the link Pat provided and downloaded installation instructions for the F 026 T03 028 Kit. Appears this kit may be used for a number of Bosch pumps including the R11. I've not been able to find the seal kit in the US,, I did find one on Ebay (in Latvia) http://www.ebay.com/itm/BOSCH-Fuel-Pump-Seal-Repair-Kit-F026T03028-/172235353971?hash=item281a06ef73:g:W6MAAOSwAYtWQgMt&vxp=mtr.
I can't answer your question about the Bosch battery or short fuel pump neither could I find the FIP seal kit on the Bosch USA website (https://www.boschautoparts.com/en). Looks like I'll be ordering the seal kit from Latvia.
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Replacing the seals will not help with internal leak down. The needle and seat wear a ring around them from use. Lapping may work but its only a temporary fix. Would be like trying to lap a worn out intake valve. The valve and seat are steel. Not brass like the CSV. The wear inside causes the valve to hang up and the springs also lose their strength. I'm sure someone could re-machine them but if your going through the trouble you minus well machine the newer ball valves to fit. The circumference needs to be taken down. Here is a pic of one of my old cone style valves.
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Tyler, now i get it - as they say, a picture is worth a thousand words.
You noted in an earlier string that you and Wallace both upgraded to the newer ball/seat check valves. Did you machine and install the check valves yourselves? Or were the upgrades done while your pumps were being rebuilt (ie. Pacific Fuel Injection)? Is it possible to get the check valves already machined to fit an R11 pump?
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The valve and seat are steel. Not brass like the CSV.
Good point. I had forgotten they were steel. Mercedes/Bosch used this same valve style on my old '60 220SE for the oil inlet check valve for the 2 plunger IP. So this cone design goes way back and no wonder it was finally upgraded.
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Charles, I installed them myself. I salvaged already modified check valves from a damaged pump that I came across. I left the old seals in the new/old valves and got lucky with them not leaking externally. Since they had already been replaced when that mod was done on the junk pump. Any newer style r24 pump will have ball valves. You can find damaged unusable pumps fairly cheap n e-bay and harvest the valves. Then take all 6 to a machine shop with one of your old valve seats to match the diameter. Or if you know anyone with a lathe. Its pretty straight foreward to cut them down.
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I think I bought my seal kit on Amazon UK and had it shipped to the US.
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Ok, thanks.
I take it that the seals in the Bosch Seal Kit will fit the new (machined-down) check valves. I'll let the group know how it goes.
thanks again for your help, Charles
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I apologize if I'm belaboring this topic,, but I plan to upgrade my old R11 cone-valves to the newer R24 ball valves. Yesterday I removed the old cone valves and as suspected, they were worn sufficiently enough to cause leak-down. I've posted several pictures of the valves - unfortunately you can't see the worn surface of the cones very well. Pat (thanks!) graciously offered a tool to extract the valve seats and I'll be removing them as soon as the tool arrives.
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Pictures like this are worth a thousand words. Thanks for posting.
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I've decided to go ahead and remove the FIP to replace the valve seals rather than try to tackle the job while the pump is still in the car. There's an oil leak in the governor section that I've been meaning to correct for several years now and this would be the perfect opportunity while I have the pump out
Does anyone know where I can source a Bosch seal/gasket kit for the governor section? thanks,Charles
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You might see if Pacific FI will sell you the parts. Also Fairchild industries or H&R.
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Yes, I was going to give Robert at Fairchild Industries a call on Monday but I've since found the seal kit on the Bosch-Automotive-Tradition site:
http://bosch-automotive-tradition.com/media/automotive_tradition_1/teile_1/nachfertigungen/motor_2/dichtungssatz/F026T03032_F026T09014.pdf.
I've got a EP/RLA 1/1R governor on my pump and seal kit F026 T03 032 has all the seals I need. now to find the kit....
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Are talking about #117 on the back plate? If so, I am pretty sure it, the side cover and bottom pump plate are molded to shape O-ring gaskets. In a pinch, you can take a larger diameter metric O-ring and cut it to that size. Regular super glue will totally glue split O-rings back together. Actually stronger than the rubber itself. I do it all the time.
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yes, #117 is one that I need, where can I get such a large O-ring?
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If you know the section size (ie 2mm, 2.5mm etc), then you find the length (circumference) and calculate the diameter you need. McMaster should have what you need. http://www.mcmaster.com/#o-rings/=13qt58y Select metric, Buna -N, and Multipurpose. Should be able to find it. The hardest part is determining the section size. O-rings are slightly taller than the depth of the machined O-ring groove. Usually around .020" or so. So measure the depth of the groove and add .020" (.5mm) and that should be the O-ring section.
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Keep in mind the cover also likes to leak at the big threaded nut (or 2 hole plate) for the idle CO adjustment. The nut version has no seal or gasket. The plate version has a simple paper gasket. Both have a small o ring on the inner part of the adjustment screw. It is only sealed when the adjustment knob is in its "relaxed" out position. Constant adjustment will cause what you think is an oil leak.
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yes, that tiny o-ring on the backside of the adjustment screw is easy to overlook.
I couldn't find a seal kit (F026 T03 032) anywhere for the governor. Naj checked (thanks Naj) and there's no stock in Germany nor are any kits being produced.
I asked Robert at Fairchild Industries where I could get a couple of the seals and he offered to send me what I need. He's a super nice guy and Fairchild has definitely got my business when I decide to have the pump rebuilt.
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Keep in mind the cover also likes to leak at the big threaded nut (or 2 hole plate) for the idle CO adjustment. The nut version has no seal or gasket. The plate version has a simple paper gasket. Both have a small o ring on the inner part of the adjustment screw. It is only sealed when the adjustment knob is in its "relaxed" out position. Constant adjustment will cause what you think is an oil leak.
Every time I do an idle adjustment, I always wipe the knob shaft with a rag. A guaranteed drop or two of oil gets on the rag. It will add up over time for sure. Robert is a great guy and rebuilt my 220SE two plunger pump.
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hello Wallace/Tyler, how did you install the check valve seats back into your pump? were you able to simply press them back in by hand, or was it necessary to use a dowel or something to tap them back in? Note that my valve seats will have new seals so I assume they'll be pretty tight going back in. Pat loaned me his tool to extract the seats and I'm wondering whether it should be used to reinstall them. thanks for the advice,, Charles
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They will just push down in if the seals are new. Torquing the fittings down on top of them is what slightly expands the seals and makes them difficult to remove. Make sure they go in straight. You may also want to install the seals after you install the valves.