can anyone diagnose this problem? Thanks in advance.

1986 740 non turbo
Driving to work, the engine suddenly stops, just completely zero rpms
instantly. Tried to restart and starter sounds like it is not engaging
flywheel, I don't hear it turning over. But why would a starter
problem knock out the engine?
Timing belt?
Clue: drove through some serious high water last night.
Any advice greatly appreciated.
Thanks

 

In an earlier contribution to this discussion,

Sounds like you may have killed the alternator, and flattened the battery
due to lack of charging. When you operate the starter with a low battery,
the starter motor will rotate but the solenoid doesn't have enough urge to
slide the gear into engagement with the starter ring on the flywheel.

Are all the dash lights on at normal brightness? Do the headlights work?

 

I doubt this, the same solenoid that engages the pinion on the starter also
closes the contacts to power the starter motor.

Check the obvious things first, look under the hood while someone cranks the
engine, does the engine turn over? If it does, open the oil fill cap and
peer in at the camshaft, have a helper crank the engine again, is the
camshaft rotating? If so, check for a spark. Follow the thick rubber wire
from the ignition coil to the distributor cap on the back of the cylinder
head, pull the wire off the cap and hold the exposed end about 1cm away from
bare metal on the engine and crank the engine, if it sparks then the
ignition is working. I would guess one of these steps will narrow things
down, could be a coincidence that multiple things failed after getting
excessively wet.

 

Sounds like it. It is probably turning over, but there is no
compression and sounds much different.

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Pull the spark plugs. Let the water out. See if engine will turn over.
Hopefully hydrolocking the motor didn't do major serious damage. If you
were moving at speed through the water it's not likely that that motor
will ever run again. Hydrolocking a motor will bend or snap connecting
rods. Running an engine with water in the crankcase will ruin the
bearings in a very short time (30 seconds or less).

Bob

 

Robert Dietz wrote

I got the impression that this happened the day *after* he drove through
the high water, which sorta leaves out the hydrolocking[1]. I'd suspect
some electrical connection may have got yanked by the physical shock of
the wall of water, and it jiggled loose on his way to work the next day.
I'd expect a whole lot of fun looking around for loose wires.
Sounds the simplest explanation to me, and Occam makes very good razors.


If, on the other hand, it stopped *when* he drove through the water, I'd
agree with Robert, and suspect that the cost of installing a junkyard
engine may exceed the value of the car.



[1] I did this to a Plymouth Breeze last year. I drove through about 8-10
inches of water in a car the same way I do with a truck (by which I mean a
Freightliner, we usually drive a Century Class), namely, just give it gas
and see how large a wave you can make. The air intake for a Century class
sits at about 7 feet up off the ground.
The ground effects on the Breeze dug down into the water, and pushed some
up onto the curve of the bumper. At that point, it turned into a bow
wave. I saw that start, and realized the extent of my stupidity and
reached to shut the engine off. Too late, it sucked water while turning
about 2500-3000 rpm. Total loss (94 Breeze, 124000 miles, worth three
hundred less than the cost of the engine).


--
Lane Gray
get the .lead out before replying (sorry for munging, I can only take so
many copies of automat)
And they were both naked, the man and his wife, and were not ashamed. Gen
2:25

 

You couldn't find a good used motor in a scrapyard? '94 is old enough that a
few should be trickling into the U-pull yards by now.

 

Replacing an engine probably doesn't lie outside of my available skills,
but it would lie outside of my patience, and time (we don't pay for the
rental car coverage on our insurance, and we're landlords, with a heavy
maintenance schedule at the time), so I'd have paid to have it put in.
Junkyard engine installed=2500, car worth 2200.

--
Lane Gray
get the .lead out before replying (sorry for munging, I can only take so
many copies of automat)
And they were both naked, the man and his wife, and were not ashamed. Gen
2:25

 

1986 740 non turbo
I had this problem and it drove me crazy as it was
intermittent. The problem: correoded wires to the
battery. They looked good, but were actually 90%
corroded thrrough underneath the insulation.(small
gap between the insulation and the terminal connector
allowed battery overflow to seep in)

Definately electrical, though.

 

Are all the dash lights on at normal brightness? Do the headlights work?

Yes, all electrical is normal and it cranks strongly.
Thanks

 

So the engine turns over? Does it have compression?

 

Ah. then it's either the timing sensor(IIRC, it uses an
electronic distribitor) or the distributor packs got
wet and mangled.

If you get spark but it won't run - or barely does,
then it's a soggy and mangled MAF/airflow sensor.

My guess is toasted coil packs. oor the controller/mount
underneath them.