I have a 1978 300D which was a project car my father had before he died. Determined to finish his project with no more than a Haynes manual a slip from a garage stating it was not getting compression on number four and my grandfathers old tools, I start out on this journey. I have visited this site and read for hours and days, taking in information on this and that topic, purchased new tools and devices and even another 79 300D for parts. Tore the parts car completely down to nothing piece by piece to get an understanding of how things worked and went together. I now have all the pieces bagged and labeled for further use. (door locks to the engine pieces, nuts and bolts)

Last fall I had the 78 car running after many parts changed. Drove it two days. Radiator leaked and overheated (if reading was right on car it did not red line). Replaced it. Overheated again. Thought head gasket. USed paint and marked the relationship of the chain and camshaft sprocket with the engine at TDC before pulling head and lined up all camshaft bolts. Before replacing head gasket I had the head pressure tested (failed) Pulled head off the other motor I had (passed) However I did not remove the valve springs when I had it tested ( machine shop said it would test fine without doing so this time) Cleaned the head and block and was ready to replace gasket.

The motor on the 79 that I used the head from started and ran but ran away. (It revived higher and Higher till I had to smother it with a rag) Was told it happened due to injectors and hoped it had nothing to do with the valves and springs I left in cyl head.

If I have not already failed I know I did when I paid some backyard mechanic to put it back together. It never started when it was all back together. As it turns out he finally admitted that the timing could be off by two teeth when I have spent days trying to fix the problem.


I take it apart line up the Camshaft sprocket, Injection timing device and crankshaft sprocket with the all the marks on the engine and per the book and replace the chain. Torque down head bolts to the correct amount and in the correct sequence. ( which were not tight) Put it all back together Does not start. Can not make it start with spraying in silicone. Put in new diesel fuel. Did fuel delivery start, checked glow plugs, strong battery but nothing.

After trying to start it with the head bolts not tight the fluids ran together. Could I now have forced water/antifreeze into the cyl and stopped it from ever firing and if so can I dry it out or clean it out without taking the timing off again? Im afraid if I tear this all down again I will end up with same problem once I put it all back together. Just in case I am going to read how to check the starter today or try my other one. Maybe I will get lucky.

Thanks in advance

 

I left you some a visator message.

Re-check the Camshaft Timing. Rotate the Engine and line up the Camshaft Gear Mark with the Mark on the first Camshaft Bearing support.
Look down at your degree marks on your Crankshaft Damper/Pointer.
If it was a new Timing Chain and Timing Gears it should be at Zero (that is Top Dead Center).
If it is a used Timing Chain And Timing Gears it will show degrees After Top Dead Center. How many degrees depends on the Timing Chain/Gear Wear. While Mercedes does not specify a specific degrees of Timing Chain Stretch at which the Chain needs replacing members of other forum say 6-8 degrees is not good. There are of set Woodruff Keys that can restore it to close to the Zero (TDC) it should be at but for now you just want to get the Engine started.
So if you show anything like 15 degrees after Top Dead Center (Zero) you most likely are one tooth off on the Camshaft Gear. That would also throw off your Fuel Injection Pump Timing since it is driven by the same Chain.

After you have checked the above; recheck the Valve Adjustment.

If your Engine actually did have low compression the Glow Plugs are very important durng starting so check them.

Before you start loosen all of the Fuel Injection Line Nuts at the Injectors and crank the Engine until Fuel comes out. After that thighten the Nuts and use your Glow Plugs and attempt to start.

If it will not start after that check the Fuel Injection Pump Timing.