Any help greatly appreciated-no start after changing spark plugs and coolant sensor-read on other posts but just feel a bit lost here. The fuel distributor is leaking somewhat as well- so i bought starter spray to eliminate the FDand sprayed into meter plate but nothing. I checked spark by pulling a spark plug and grounding on the exhaust manifold and it was present but I read(this forum) that is not a full-proof test of spark. The rotor and cap, coil, spark plug wires have probably never been changed in at least 10 years but this occurs just after i relaced the plugs?? I put the old plugs back in (platinum) still no start. Thanks guys.

update-I changed the coolant sensor one minute before spark plugs and it appears some coolant spilled on to the crankshaft position sensor that now appears quite wet in that area/connection. Could I have done something by getting the Crankshaft position sensor wet that effect ignition,coil etc?

What kind of plugs did you use?

The M103 engine requires H9DC0 Bosch NON-RESISTOR plugs....generally only obtainable at a MB dealer or from this site. If the distributor rotor/cap/wires/coil are all original, you can start there. These are picky engines, and need to have the right stuff on them to run properly....but when they have the right stuff, they run smoooooth.

Platinum plugs should NEVER be used in an older MB engine.

__________________
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'17 Metris(VITO!) - 37k - wifes (OC-41k)
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I edited my post to say that i also changed the coolant sensor and some coolant seems to have leaked on the crank shaft position sensor as it is quite wet in that area. Could that effect my ignition?

the plugs I put in where Bosch super plus-HR9 DC+ It had platnums but it ran. Would it at least not fire? Thanks

The plugs you used are Resistor plugs.... HR9DC+.....you'll have to go to the dealer or this website to get the right ones.

It should have fired and possibly run, but not if the coil/wires/rotor/cap are not perfect. It is harder for the ignition system to get a decent spark with resistor plugs....so if it is weak in any way, it won't work. As you have mentioned all those parts are real old, you should probably replace all of it. I did on my 300E and it runs perfect now.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Ok will do that and replace all. Is there a way to check the coil spark quality other than disconnecting and looking for a fat blue spark? Do you see any connection to coolant going on to the crankshaft position sensor and having an ignition effect somehow? I m accepting your advice just a bit perplexed it will not pretend to fire up for a moment but I took in your advice regarding the resistor plugs especially. Thanks again!

PS would you recommend an in-line test of the spark plugs to confirm your feelings. I read i can buy a tester and check spark quality with plugs actually screwed in to the motor-would be nice to have confirmation.

Coolant on the crank sensor shouldn't affect it, unless it was cracked or something.

You can test spark with either an O-scope or an in-line tester. There are open, adjustable spark testers you can use, or sealed units. I don't work on small engines, so I have the sealed one from matco.

I tried to link, but it didn't work.

Just go to matcotools.com, search for "spark tester" and click on the first link. It'll show you both types.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

Ok on web site and perform the test of the spark. Could my timing be off-read about the rotor actually breaking but would seem very odd it ran then not just after replacing plugs. perhaps the new resistor plugs put a strain on the old coil, wires, rotor etc which have most likely have never been changed. Thanks again for your input and advice!

If your engine was running before the plug change, it should run after the plug change regardless of platinum/non-platinum or resistor/non-resistor. May not run optimum, but should run.

If the only abberation in the job was wetting down your CPS, and it will not start, that is your problem. UNLESS of course you did something else like bollix your plug wires. Did you cross them? Did you pull on the wire to remove the connector rather than pull on the connector?

Anything you aren't telling us?

excellent questions even though i am no expert. The other issue was the fuel distributor which was leaking as the plug on the pententiometer had slid off somewhat but this happened before and it ran. I figured I should take the FD out of the equation so I used starter spray to eliminate the Fuel distributor issue entirely if i have a possible ignition issue-maybe I have not eliminated the FD?

To be honest, i was a bit awkward with the plug wires turning the socket wrench catching/pulling/knocking the wires at times as instead of disconnecting all of the wires at once I replaced one plug then replaced the wire then on to the next plug. I checked the wires for possible mix up but it seems quite difficult with the wire lengths to cross over but I may have done that in one cyclinder perhaps closer to the front of the engine. If it is the wet crank shaft postion sensor-would it be a case of simply disconnecting and cleaning it off? Thank you very much!!

update-wire connectors were very difficult to unplug now a few seem sloppy-moving back and forth-dont think that was the case b4 plug change.

I must admit ,especially to rocky raccoon, that i pulled very hard to get the plug wires off-Now the wires are sloppy in comparison. Perhaps many years since plugs had been changed.

If it's cracked, it's probably bad. The CPS is a hall-effect sensor, and reacts to tabs on the crank to get the timing signal. The slightest change in the distance between the sensor and the tab can screw up the signal, and any liquid inside the sensor will more than likely corrode the windings.

Congrats - I believe you just solved your no-start issue.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

I may have spoke too soon. that wire does not appear to be the connection of the CPS. I did spill some coolant but another tech said the same as you with regard to spillage-very difficult to upset that connection although I read that is a possibility of a no-start if is disconnected/damaged. Thanks.

I thought you said there was a crack in the sensor itself, not the wiring...

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

to be honest, at this point i dont know where the connection for the CPS is-there was a cracked wire right behind the oil filter and down a bit but thats does not look like the plug of the CPS I saw on the net. I am about to pull my coil to make sure there is spark there. Do you or anyone here know if I buy an in line tester for the spark plugs how useful that test is. Will it only tell me i have spark? Or will it give me an idea of the strength?

I read where someone had a 190e-same year-had spark, timing was right, had fuel, etc and it turned out to be a bad ignition module or whatever the coil plugs into is named. Perhaps that is very rare.

Read my post on the 1st page about spark testers. They are useful in determining spark, but it takes a timing light to determine if it's sparking at the right time.

Ignition module is the correct part, and they do go bad; like any part. Of course, a bad ground could cause all your problems as well. People always forget about grounds... Voltage to the part is useless if it can't get to ground and complete the circuit.

At this point, I'd take it to an indy - they'll have the necessary tools to verify everything at once in less than an hour so you can replace the correct part and be done with it.

To be honest, unless you have the correct tools to check & verify things, all the FSM's, guides & advice in world can only lead you to an educated guess. As I've stated before, I've seen countless people spend many hours and hundreds of dollars replacing parts on the advice of others before coming to me (or my shop), only to find that the correct repair cost less than 1/4 of what they spent on their goose chase. An hour of 'real' diagnostic time performed by a 'real' tech with 'real' tools is worth more than you know.

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.