1975 w115 240d pump timing jumped - PeachParts Mercedes-Benz Forum

rwd4evr · #1 02-16-2020, 08:42 PM

I picked up a 75 240d 4 speed "project car" for a song. Looked it over, put oil in the injection pump fixed a couple messed up things and put it on the block heater overnight. The primer pump was replaced I think, old one with the car. It doesn't work right. You can pull it up and it springs back in, don't see fuel moving in the clear return line on the last injector(not right I know). Anyway I just cranked it a bit and it started popping and puffing smoke. Took awhile but it finnally fired and ran rough while purging the air out of the lines with some throttle. I let it slow down a little too much and it stalled and I guess backfired or something. Then no popping or smoking. Checked cam and crank timing and they look spot on. Looks like new cam sproket and chain with a master link. I cracked injector 1 line and it looks like it's starting to show fuel at like just above 10° btdc. Maybe as much as 15° Specs say 24° is correct. 40 tooth sproket is 9° per tooth. I'm figuring it jumped a tooth on the pump sproket. Would that make it not run at all though? I feel like something sounds different while cranking but maybe cause no popping. It's hard as **** to turn over, tons of compression. Am I missing something?

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Hard to see but the balancer is on the 0 and T Mark between 10 marks. Cam is dead on the witness mark.

rwd4evr · #2 02-17-2020, 12:19 AM

Ok. Update. I took the vaccum pump of and managed to bump the chain over one tooth. Not very easy but I pulled it off. So pump timing is now showing fuel creeping out of the no 1 injector fitting at 28° btdc. I'm thinking the PO had been in there and maybe it's advanced a hair to much. Would 28 be alot over the 24 it's supposed to be? I've honestly never messed with pump timing. My diesels have just always ran fine. It started pumping maybe a degree before this pic. I'm getting some popping and smoke again. It's on the block warmer till morning to hopefully get it fired up. Wondering if I should adjust it a tiny bit first. I'm now trying to figure out why there is the drip method and all that when you can turn the motor and see when it's starting to spray?

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t walgamuth · #3 02-17-2020, 06:40 AM

I had a really nice 115 240d which had so much wear in the spline that attaches the injection pump to the sprocket on the cam chain.
that it allowed the timing to slip a spline....then it would slip again. The splines would hold a while so the car would lot drive fine but put it on the highway and soon it would lose power then barely run at all. It is a sort of coupler with female splines on both sides, input and output.

rwd4evr · #4 02-17-2020, 06:57 AM

We shall see what happens after I get it fired up. It's really just to be able to move it around my lot if I gotta. I'm Not tagging this turd until it's got more power. I need w115 5 cyl mount arms if anyone has a set.

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rwd4evr · #5 02-17-2020, 08:27 PM

Well.. not too much luck. It won't start with the starter. I got my buddy to drag me down the street to get some more rpm and clear all the oil out of it and it will run poorly at higher rpm. So I'm guessing the pump is a little too far advanced? Same as it was before it jumped time. How in the hell are you supposed to get the bottom pump ting bolt loose? Just poke around with a socket on an extension is my only guess. I'm kinda over wasting time on it. Love for it to be mobile though and then I could at least sell the motor for a few bucks if it runs. Or maybe run my generator with it.

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Diesel911 · #6 07-26-2020, 09:23 PM

Quote:

Originally Posted by rwd4evr

I picked up a 75 240d 4 speed "project car" for a song. Looked it over, put oil in the injection pump fixed a couple messed up things and put it on the block heater overnight. The primer pump was replaced I think, old one with the car. It doesn't work right. You can pull it up and it springs back in, don't see fuel moving in the clear return line on the last injector(not right I know). Anyway I just cranked it a bit and it started popping and puffing smoke. Took awhile but it finnally fired and ran rough while purging the air out of the lines with some throttle. I let it slow down a little too much and it stalled and I guess backfired or something. Then no popping or smoking. Checked cam and crank timing and they look spot on. Looks like new cam sproket and chain with a master link. I cracked injector 1 line and it looks like it's starting to show fuel at like just above 10° btdc. Maybe as much as 15° Specs say 24° is correct. 40 tooth sproket is 9° per tooth. I'm figuring it jumped a tooth on the pump sproket. Would that make it not run at all though? I feel like something sounds different while cranking but maybe cause no popping. It's hard as **** to turn over, tons of compression. Am I missing something?

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Hard to see but the balancer is on the 0 and T Mark between 10 marks. Cam is dead on the witness mark.

If as pictured the Camshaft Gear and front Camshaft Bearing Tower marks were line up the if everything was great the OT mark on the Crank Damper would be lined up with the Pointer (this assumes the Pointer is positioned properly).
If that was so then that part of the timing is correct.

After that what is needed is for you to re-time the Fuel Injection Pump by way of one of the timing methods in the Factory Service Manual.

If that does not work the Fuel Injection Pump needs to be removed and put back in with the timing marks on the front of the Fuel Injection Pump lined up and the timing again checked a per the FSM.

You also have to only rotate the engine in the direction that it would be running it as rotating as the manual claims that rotating it in the wrong direction can push in the Timing Chain Plunger and have it jumping teeth.

Sugar Bear · #7 07-26-2020, 09:28 PM

Fuel is good, fresh?

rwd4evr · #8 01-17-2021, 05:35 AM

Just finally revisiting this car since I'm having some knocking in the SD I drive. I hope to adjust the pump timing and get some mileage out if it while my wagon build progresses. Any special trick to getting the bottom pump nut? I haven't gotten it on the lift yet but it looks like a real ***** from up top.

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rwd4evr · #9 01-18-2021, 06:57 PM

Well........ I was right. The pump timing was way advanced. I turned it back about 🤏 much and got it cranking. It had a couple cracked fuel lines I fixed. Got it popping on the starter but the old fuel smelled a little stale so I gave it a clean filter and a drink of my home brew black diesel. It had been kinda starting but wouldn't rev and would stall. Seemed like air in the lines, it would catch and smooth out fir a sec then stall. With the new fuel it did the same then caught and seemed like it was going to smooth out and rev clean and BAM! Rocked the whole car, locked up solid. Had to have broken a rod or the crank or something. Won't turn either way. It was blowing pretty heavy out of the breather trying to.start it so I think it was probably pretty beat up anyway. It was really hard to turn by hand as well. Oh well. That one is toast.

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Diesel911 · #10 03-19-2021, 11:51 PM

Quote:

Originally Posted by rwd4evr

Well........ I was right. The pump timing was way advanced. I turned it back about 🤏 much and got it cranking. It had a couple cracked fuel lines I fixed. Got it popping on the starter but the old fuel smelled a little stale so I gave it a clean filter and a drink of my home brew black diesel. It had been kinda starting but wouldn't rev and would stall. Seemed like air in the lines, it would catch and smooth out fir a sec then stall. With the new fuel it did the same then caught and seemed like it was going to smooth out and rev clean and BAM! Rocked the whole car, locked up solid. Had to have broken a rod or the crank or something. Won't turn either way. It was blowing pretty heavy out of the breather trying to.start it so I think it was probably pretty beat up anyway. It was really hard to turn by hand as well. Oh well. That one is toast.

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Sorry for your bad luck.

Felching · #11 03-21-2021, 12:27 AM

If you can pry enough slack into the chain to skip a tooth, your tensioner has failed or you broke it.

rwd4evr · #12 03-21-2021, 01:44 AM

Yeah could've been failed. I didn't break it any worse than it may have been already. It was blowing hard out the breather when it did fire so not a big loss really.

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