300TDI Rolling failure no start

NPT90

Well-known member
So I was driving last night, 15MPH engine sputtered and died, quickly but not catastrophic sounding (in fact no sound at all).

Presuming operator error (even the best of us stall sometimes?) I immediately went to restart the vehicle. Starter cranks (weakly, seemed as if there was resistance at the flywheel) then stops. Sounds like its engaging but just simply cannot turn as if there is internal resistance.

Well I am in the middle of the street, presuming the starter has failed I decide to roll start the truck (I had just started in 3 mins ago) and I am on a slight downhill. I let the truck roll, popped the clutch, nothing, doesn't seem to crank.

So I parked it, left it, went back today to do some quick diagnostics:
-Pulled the valve cover, pulled the rocker arm
All pushrods are straight, all rockers intact, engine turns over by hand​
-Used a jump pack with the rocker arm removed
Seems to revolve maybe once or twice, extremely slow, then stops up again​
I noted that without open valves the compression may cause difficulty in revolutions​
Basically behaves the same way as it did with the rocker arm attached​
-ruled out fuel issues (new lift pump, again it seems like there is resistance on the flywheel)

So:
  1. Stalled while running
  2. wouldn't restart with a 'pop start'
  3. Seems to be resistance on the flywheel vs a starter issue (also a starter would not have caused the rolling failure)
  4. All pushrods intact, all valves look good (new turner head less than 6K miles ago)
Questions:
Could a failed timing belt cause a failure that would lead to the resistance at the flywheel?
I just replaced it but it doesn't mean it didn't shred somehow

My current plan of attack is to drop the oil pan and inspect the crankshaft
Pull the timing cover and check the belt

Anyone have a similar experience that could share it this way?
 

Red90

Well-known member
With the valves closed, there should be very little resistance. Can't be the timing belt. Maybe pull the starter and see if it looks okay. Strange one.

Are you getting oil pumped into the rocker when you crank?
 

NPT90

Well-known member
Are you getting oil pumped into the rocker when you crank?
Can't really crank it fast enough to tell, basically get maybe 2 weak revolutions from the starter before it seems like it can't spin the flywheel anymore
The valves looked well oiled, all the caps were in place, aside from adjusting the lash on the rockers it seemed that the top end wasn't the culprit (I would've expected a bent pushrod if that were the case)

I think the starter isn't fantastic but I don't see how that could have caused the rolling failure, might be asymptomatic?
 

Red90

Well-known member
If it stayed engaged, it make have damaged the ring gear and causing problems....

Basically, anything else I think of is serious internal engine damage. 3 bolts to pull the starter to see if anything is wrong there.
 

NPT90

Well-known member
I mean, total hypothetical:
A. Bad starter causes battery drain
B. Bad alternator causes battery drain
C. Fuel shutoff solenoid fails causing stall

If A or B Vehicle should have started with pop start
If C engine would spin at the flywheel when 'jumped' just never fire (no fuel)

Possible A&C just seems so unlikely
 

NPT90

Well-known member
If it stayed engaged, it make have damaged the ring gear and causing problems....
Basically, anything else I think of is serious internal engine damage. 3 bolts to pull the starter to see if anything is wrong there.
Agreed, beats doing the timing belt or dropping the oil pan though the latter is a quick job and the former isn't awful either.
 

Red90

Well-known member
Any electrical issue would not stop the engine turning on a push start. It should just spin happily. I assume you pop the clutch in a higher gear and not first?
 

NPT90

Well-known member
Any electrical issue would not stop the engine turning on a push start. It should just spin happily. I assume you pop the clutch in a higher gear and not first?
2nd (presumed it would fire right up since it had been running)

Unless the battery was so dead that it caused the fuel shutoff to pop? I would imagine there isn't much voltage required to keep the fuel shutoff on. I would still expect the jump box to spin the flywheel however.
 

RDavisinVA

Well-known member
I would remove the injectors or glow plugs and then spin the engine with the starter to rule-out a cylinder partially filled with coolant as it sounds as if something is binding.
 

Red90

Well-known member
2nd (presumed it would fire right up since it had been running)

Unless the battery was so dead that it caused the fuel shutoff to pop? I would imagine there isn't much voltage required to keep the fuel shutoff on. I would still expect the jump box to spin the flywheel however.
The fuel shutoff opens with almost no power. If the starter does anything, the fuel shutoff will have enough power.
 

NPT90

Well-known member
I would remove the injectors or glow plugs and then spin the engine with the starter to rule-out a cylinder partially filled with coolant as it sounds as if something is binding.
I've never had a head gasket fail so suddenly before, I would guess I would've seen coolant loss or smoke before failure? I can't rule it out and thats an easy way to see if there is a fluid issue causing the lock.
 

4RF RDS

Well-known member
Suggest you consider pulling your serp belt off and see if it cranks better and also what spins without that load on the crank. Something could be siezed. This sounds like something is inhibiting turning it over not just voltage and a starter thing. Good luck, hope its not too serious. Keep us in the loop on what you find.
 
Last edited:

NPT90

Well-known member
Well, sure as shit, was the alternator!

Thanks for all the replies, would have never guessed the alternator could cause such symptoms... weirdly happy to be replacing only that.

Once I pulled the serpentine belt it fired up.
 

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Oh! So it was so locked up that it actually killed the engine while running? And wouldn’t allow it to turn over! Wow.
 

NPT90

Well-known member
Oh! So it was so locked up that it actually killed the engine while running? And wouldn’t allow it to turn over! Wow.
I could rotate it by hand, but yes I think with the belt tension on it the bearings must have caused enough resistance to keep the motor from cranking... long overdue for a new alternator it seems 😅
 
Top