long starting when cold on xc70: dealer says crankshaft thrust bearings

[dj_v70]

I saw a cool video on here a couple of weeks back (can’t find it now). OP took out all spark plugs and laid them on top of engine, attached ground straps to electrodes and cranked engine while taking a video. Couldn’t trying this possibly shed some insight into whether there is an issue or not?

[IslandV70]

Probably not.
Spark plugs will arc to a large piece of metal, grounded or not.
What could possible help is grounding the engine and transmission to each other and the car body. All three things need to have good electrical contact with each other.
You can put a voltmeter between them when you crank the starter and see what you get too.

[mrbrian200]

Watch for spark plug arc.. Chances are if you did this test you'd find they are sparking. I suspect a closer inspection with more advanced shop testing equipment (manually probing wires with scopes, lights, marks made on the crank pulley) the spark and injector timing is probably way out of kilter during that long crank period before it eventually starts to catch and run.

If the ECU is misinterpreting the crankshaft position from a 'corrupted' sensor signal there's nothing in VIDA or any other OBD tool I'm aware that will show to solidly confirm this. That's getting into old school 'manual' diagnostics/engineering (probing wires/specialized test lights/marks on the crank pulley) that a lot of ASEs -typical party hard and cram their way through a 2-year crash course- are in trouble. You're lookin at somebody with a 4+ year degree with a minor in engineering from a legitimate school (techs fresh off the for-profit 'votech'/online degree conveyor are probably out of the question).

[IslandV70]

Maybe I was not understanding the spark plug test. I thought it was for finding a bad ground. You certainly can take them out to see if they spark, done this about 1000 times on my boat engine. Just watching them spark will give you no idea if the timing is correct.

[mrbrian200]

Yes that test could give some sense whether the engine to chassis and/or coil pack to engine grounds are non existent.

[jimmy57]

The crankshaft thrust check is the shortest path to end this tail chasing. Someone has diagnosed excess end play and it is easy to check. If there is so much end play that the rank moves noticeably in and out when you pry out and then push in then it does not need any measurement. The normal free travel max of .08"/.27mm is not readily detectable without a dial gauge. The end play problem has caused starting issues. The starter would push the crank back and if it is far enough the edge of the apertures interferes. If there is big end play then all the ground problems in the world resolved won't make it start when the signal i not made by the sensor having distinct magnetic disturbances of passing apertures and partitions of the flywheel surface.