SP Posted March 16, 2015 Share Posted March 16, 2015 Hi, I have inherited my late mothers Merc 450SLC,i have spent the last two Saturdays trying to get it running as her house has been sold so it has to move. The plan is to get it back on the road. It has mechanical fuel injection.There was no fuel getting to the fuel distributor(metering unit)?,i took off the Bosch pump and found it to be shorting out and blowing the fuse.I replaced it and the seperate filter cartridge. The car is now trying to run but only on a few cylinders(out of 8) I should say the car has been off the road in a dry garage for approximately 8-9 years,the fuel that was in it smells really stale.I put a gallon of V-power in it. Is it likely i will have to replace the injectors? or could it be the fuel distributor? Grateful for any help before i spend £200 on injectors. Steve Link to comment Share on other sites More sharing options...
2.5piman Posted March 16, 2015 Share Posted March 16, 2015 Hello Steve, first thing to try is beeding the injectors, just make sure you have a good battery or a spare to cope with a lot of cranking. Alec Link to comment Share on other sites More sharing options...
Nick Jones Posted March 16, 2015 Share Posted March 16, 2015 Is this a K-jet with a big round air flow meter flap in the centre of the V alongside the fuel distributor? If so, you can test the injectors without turning the engine over. You need 8 jam jars. For safety I recommend disabling the ignition to prevent any random sparks and having a big fire extinguisher handy. Remove the injectors from the manifold (should just pull out but will probably need a firm tug - new O rings might be good too) and place in the jam jars. Remove the rubber trunking from the airflow meter. You now need to find the fuel pump relay and link out the big terminals so the pump runs all the time. With the pump running you should get fuel continuously spraying from the injectors when you lift the flap and the rate of spraying should increase the further you lift the flap. The injectors should give a fine, even, cone-shaped spray pattern. When you let the flap return to rest the spray should stop and there should be no dripping or dribbling. If you can get something coming through all injectors then it is well worth trying a injector cleaner product in the tank as I've found that the K-jet system responds really well to it. Given the length of time it's been off the road I think you'll be needing alot of filter changes, especially once it sees E5 or E10. I've had 3 K-jet cars in the past (2 x Audi 90 & 1 x Golf GTI) and I like the system. It's simple and works really well when in good fettle. As all the cars I had were high to very high mileage I think it's true to say it's tough and reliable too. Good luck! Nick Link to comment Share on other sites More sharing options...
SP Posted March 17, 2015 Author Share Posted March 17, 2015 Yes Nick that sounds like it,it has the big round vent that sinks downwards as it tries to run,there is safety switch on the side of the fuel distributor,this only allows the pump to run on cranking or when its running.If you pull the connector off the pump runs constantly. I`ll try this weekend. Cheers Steve Link to comment Share on other sites More sharing options...
JohnD Posted March 18, 2015 Share Posted March 18, 2015 A Merc 450SLC? Oooooooooooooooooh! Green, me! That is a car you have to get going again, even if you want to sell it! Bosch K-jetronic - the fuel injection system that killed Lucas Pi - quite apart from Triumph's mismanagement. Just think, given a slight time slip, and Sir John swallowed his British prejudice, TR6s and T2.5s, maybe the Stag, with the Bosch system - they'd be world beaters! John Link to comment Share on other sites More sharing options...
SP Posted March 21, 2015 Author Share Posted March 21, 2015 Well still no success,i tested the injectors and all but one are spraying reasonably well. I`m beginning to suspect ignition,i took off the front right hand cylinder lead and plug to test for spark,nothing. There is what i think is a coil pack on the inner wing,it has four wires coming off it along with a crank sensor connection,two of the wires go into some sort of ceramic thing on the inner wing and then on to somewhere else.can i get the coil pack tested or can i test it? As i said it tries to fire but not on all pots. Cheers Steve Link to comment Share on other sites More sharing options...
spitfire6 Posted March 21, 2015 Share Posted March 21, 2015 (edited) Ceramic thing sounds like a low ohm resistor. Coil packs are relatively easy to test off load with a Fluke. On load may or may not show the HT side breaking down. Cheers & good luck, Iain. Edited March 21, 2015 by spitfire6 Link to comment Share on other sites More sharing options...
oviwan Posted March 22, 2015 Share Posted March 22, 2015 (edited) hi, it's a K-jetronic or KE-jetronic? if first, i would remove the metering unit from the airflowmetering-housing first and check if the plate is free to move. second, check the bolt/cylinder from the bottom of the metering unit which is moved up and down by the plate. its likely that it might be corroded. that would be a real problem as it is difficult to source these parts for a reasonable price today. maybe you can get it moving again, but be careful, its a precision part which don't like it to have corroded spots or scratches on the surface. depending on what system, there should be a cold-start device somwhere on the motorblock, the bi-metal spring is controlled by the motor temperature and should have a two-wire connector to. just follow the fuel lines, should be easy to find. don't know how to check this as it was easy to source & replace those days by try and error. and it was definitly sometimes a problem. there should be a lot of sources/specialists sites on the web where you should start your research, just like http://www.hehlhans.de/tipp98-24.htm. it's in german but check the pictures and get an idea of what could gro wrong. hth, harry Edited March 22, 2015 by oviwan Link to comment Share on other sites More sharing options...
SP Posted March 22, 2015 Author Share Posted March 22, 2015 Thanks for the replies,the plate moves freely and delivers fuel as it should when operated,i also tested the cold start valve and that seems ok. I need to make sure i`m getting spark on all 8. Anyone know what the 4 wires coming from the coil pack would be? One goes to ground,i presume two feed 4 cylinders each through the two ceramic things,would the fourth be a switched feed? Thanks Steve Link to comment Share on other sites More sharing options...
spitfire6 Posted March 22, 2015 Share Posted March 22, 2015 I would have thought four wires was one short. Unless the housing is ground/return ? Cheers, Iain. Link to comment Share on other sites More sharing options...
SP Posted March 24, 2015 Author Share Posted March 24, 2015 So i found a diagram from the links above,two go through ballast resistors on the wing,thats the two ceramic things,then on to the distributor.One is ground and one is from the ignition. I`m going to try and test them this week. Steve Link to comment Share on other sites More sharing options...
zelrik Posted March 29, 2015 Share Posted March 29, 2015 I have had a few 450's - I think they have a 'weak' ignition system (compared to the rest of the mechanicals). They are very sensitive to spark plugs, if you get the plugs 'wet' with fuel its then very hard to get the motor running. Get a remote starter switch so you can troubleshoot with the bonnet open. Also get a new set of NGK spark plugs (they are cheap & reliable). Pull out all the sparkplugs - hahaha this is the worst job on a 450slc and requires a lot of swearing!!! there should a special spanner for this in the tool kit. Set up a test plug on the motor & run each plug lead to that plug in turn - if 2 or 3 leads work & spark, the rest should do too, or else your distibutor cap could be rooted? When you are confident of 8 sparks, put in those new plugs. For starting - open the FI flap and put in a big squirt of Aerostart - then try a start with the air cleaner off. 450SLs dont like sitting for long periods because the return fuel pipe into the fuel tank rusts up inside & this means the whole fuel system will overpressurise (hope you dont have this!!). But I would drain the tank to get rid of the old fuel, just pull off the hose from the tank to the fuel pump & be ready with a big container. On the 450's its usually a lot of simple little things that stop them working. If a couple of cylinders fire, you should be able to get the rest (most!) going. Sorry for rambling reply. good luck with it. Peter in Melbourne Link to comment Share on other sites More sharing options...
SP Posted March 29, 2015 Author Share Posted March 29, 2015 Thanks for the tips peter, I have been picking up parts this week,new cap and rotor arm ,8 new NGK plugs.I also got a coil pack and coil from a chap who is breaking another car. Got a couple of new Bosch injectors as well. It definitely wants to start but not on all 8. Didn`t get a chance to try yesterday as i was picking up a 1500 engine for my Herald. Maybe Wednesday. Steve Link to comment Share on other sites More sharing options...
zelrik Posted March 30, 2015 Share Posted March 30, 2015 Steve I have been thinking about your starting problems on the 450slc. Another simple thing is that you may not have enough (new) petrol in tank. In these tanks there is a thing about cup size sitting on the bottom and you need about a quarter tank for petrol to go over the lip into this cup - its called a swirl pot & is normally filled from the return fuel from the motor when the fuel level is low. Check out this thread for the pictures you can see that you can only get petrol to the pump & motor from this pot. http://www.benzworld.org/forums/r-c107-sl-slc-class/1663204-gas-tank-swirl-pot-question.html (Hopefully you wont have the problems outlined there - but there is a way to fix) I usually put a small slosh of petrol down the air intake flap (along with Aerostart ) but not too much to flood the sparkplugs - and that encourages things along when some cylinders fire up. Good luck with the plugs!! I sometimes take off the heat guards from the exhaust manifolds to give me more room to move. Peter Link to comment Share on other sites More sharing options...
SP Posted April 2, 2015 Author Share Posted April 2, 2015 Well,getting a bit p`d off with this car now,it doesn`t even fire now,i cant get to most of the plugs to test but i dont think its sparking. Tested for 12v at the coil + when ignition is on,its got that,thats as far i got. The neg side of the coil comes from the 2 balast resistors, the connection on the coilpack i thought was a crank sensor actually goes to the distributor. Tried 2 coil packs,spare coil,cap,rotor arm. Arse. And i have three weeks to move it as the house is sold so the garage has to be cleared. S Link to comment Share on other sites More sharing options...
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