Engine won't turn over??? Please help. - PeachParts Mercedes-Benz Forum

gkouvaras · #1 06-06-2009, 05:43 PM

Recently a 1982 300sd came into my life. Over the past week I have been fixing small problems because my girlfriend (the owner of the car) never did any maintenance.

I changed all of the oils and filters (tranny, engine, fuel, p/s, brakes), fixed the ac, door locks, sunroof, windows, cleaned all the vacuum lines and banjo bolts, replaced broken/leaking hoses on the turbo and engine.

This weekend I was going to adjust the valves but yesterday while i was driving the car it felt like it was running out of gas but the fuel tank was full. Then it just died. I pulled over and tried cranking the engine and it would not turn over. I left the car on the side of the road and went to get some food and think about what could be wrong. I returned about an hour later and tried again. She started right up and ran fine for about a minute and then died again.

I tried priming the engine but when I pumped it fuel just leaked out of the top of the pump. I replaced the pump figuring that was the culprit and there was no pressure in the fuel lines. But the engine still won't turn over.

I towed it to a garage and the guy said it needs a new starter for $600. I don't think so because it cranks the same as it always has just won't turn over now.

Glow plugs are good. Fuel has pressure.

What could be wrong? Please help.

Thanks in advance,
Greg

tyl604 · #2 06-06-2009, 05:53 PM

Wonder if you have a stopped up fuel filter? Prevents fuel from getting to the engine. Feels like you are running out of fuel while driving because the engine is starving. Not sure where all the filters are but there is one near the primer pump; if it is not clear, this could be the culprit.

When you say the engine does not turn over, it sounds like a dead battery. If you go back and it then turns over, that sounds like you have a loose wire on the battery or starter which sometimes makes contact and sometimes does not.

Or it could be the solenoid in the starter. If it refuses to turn over and you are sure the wires are tight, just tap lightly on the solenoid and see if it turns over.

gkouvaras · #3 06-06-2009, 06:00 PM

I replaced both fuel filters a few days ago. When I use the hand pump i see fuel passing through the clear filter.

Battery is only 6 months old and i tried a new battery along with a jump start box.

The engine cranks and makes a shudder sound every once in a while like it wants to start. Similar to when it is really cold outside. It just won't fire.

kerry · #4 06-06-2009, 06:01 PM

I'm guessing we have some confusion in terms. 'Wont turn over' means the starter does not spin the engine. 'Wont fire' means the starter spins the engine but the engine will not fire or run. I think from the description, the OP means the latter. If so, I'd look for fuel issues. You can hook up a separate soda bottle of fuel in the engine compartment with a feed line coming from it and the return line going into if. If it runs that way, you'll know there's a fuel delivery problem upstream from the engine compartment.
From what I describe, I don't see any problem with the starter. However, if you mean that it won't turn over with the starter, there are a lot of threads here on that topic describing problems other than a bad starter. If that is the problem, I would not spring for a new starter until all the other possible problems are excluded like bad engine ground, bad wiring, poor connections in the ignition switch, bad connections at the battery etc.

Have you tested for voltage at the glowplugs and tested their resistance?

As an aside, if it really was running out of gas, I think you may have found the problem. Use the hose with the green handle.

gkouvaras · #5 06-06-2009, 06:25 PM

My mistake. The engine turns over but it won't fire.

The fuel tank is full.

The mechanic said the glow plugs are fine.

I'll double check the plugs and all the wiring as well.

LUVMBDiesels · #6 06-06-2009, 06:29 PM

Crack open the fuel lines near the injectors and see if fuel comes out when you crank the engine. I would also try pumping the new pump 100 times, that's right 100 times to properly prime everything. It sounds like a no fuel situation. One other thing,check the vacuum line to the shut off valve. pull it and see if the car starts.

gkouvaras · #7 06-06-2009, 06:34 PM

where is the shut off valve?

kerry · #8 06-06-2009, 07:00 PM

Back of the IP between the IP and oil filter housing. Should have a brown vacuum line going to it. Perhaps when you cleaned the vacuum lines, you mistakenly re-routed a line putting vacuum to the shut off valve. I think that is what luvmbdiesels is getting at. This would account for why it started after it was sitting for a while (vacuum bled off) and then shut down again once vacuum was restored. Long shot but possible.

gear-head · #9 06-06-2009, 07:08 PM

I don't want to sound arguementive, yet I take exception to the advice about priming 100 times. First, he said he replaced the primer pump with a new one, that said, no way should it take anywhere near that many times, maybe five or six. IF one prime pumps that many times, the cylinders are very likely to get "washed down" and that is a very bad thing, plus, that's just plain ol' going to "flood" it. Having dealt with a very similiar sounding experience I sought out advice and odd as it may sound, I had been given the advice by at least three different lifetime experieced professional Mercedes diesel experts to pull the glow plugs out and use an old fashiond squirt oil can and give a couple or three squirts of 30w motor oil in each of the cylinders to relube the cylinder walls and was told that it aid in "sealing" the rings to hold compression. I tried it, and viola! the damn thing fired right up! Your results may vary! But definitely don't prime a 100 times!

kerry · #10 06-06-2009, 08:31 PM

I don't think it's possible to wash down the cylinder walls with the primer pump. There is a bypass valve that activates once the system is primed. It is the sound of that bypass valve that MB says indicates the system is primed. Even if you could push fuel up the injection lines I don't think it's physically possible to produce enough pressure with the primer pump to pop the injector.

Diesel911 · #11 06-06-2009, 08:35 PM

I do not think that you can over come the 135bar opening/pop pressure of the Injectors and squirt Fuel into the Cylinders and cause a "washout" with the Hand Primer; no matter how many times you Pump it.
As Kerry said the Overflow Valve opens when its set pressure is reach and the Fuel having no where else to go, goes back to the Fuel Tank.

However, you can get raw Fuel into the Engine if you keep cranking and cranking the Starter and the Engine does not start.

leathermang · #12 06-06-2009, 08:54 PM

Check the archives for ' starter fluid' .....
and ignore those who say things like 'washes ' 'explodes' etc...
use a three second burst into the intake before the air cleaner... while someone already has it ' turning over'....
If it starts then you know you have a fuel delivery problem...
and run it a few minutes if it does start ...

gear-head · #13 06-06-2009, 09:25 PM

okay, kerry, diesel911, I believe ya'll already! learnt sumpin' new today! thanky' very much! But really, with a new hand primer pump, do you think pumpin' a 100 times is really that necessary?!

kerry · #14 06-06-2009, 09:36 PM

Quote:

Originally Posted by gear-head

do you think pumpin' a 100 times is really that necessary?!

There have been a fair number of threads on here over the years in which starting problems were resolved by ungodly amounts of primer pumping.

Skippy · #15 06-06-2009, 09:46 PM

I've never had to prime the Benz that many times, but I had to do it quite a few times after changing fuel filters on International DT466 engines, so it's definately possible that it may be needed at times.