m52b25 jumper chain?

[yng_750 247]

So a friend of mine has a 1997 e36 323i

m52b25.

has been running sweet no noises or issues. relatively well maintained, no crud in engine etc.

he went to start it this morning and while the engine was turning over he slipped his hand off the key which flicked back to the ACC position very quickly just as the car was about to catch. this caused the engine to get a full compression cycle but not fire. so it sort of made a clunk sound and stopped rotating fairly quickly.

Then on turning over again its turning and firing but not quite catching to start. so it making a firing noise and turning faster than usual.

still has compression on all cyl.

to both of us this sounds like it may have skipped a tooth on the timing chain.

theory being while not running the tensioner has no pressure to hold the chain tensioned. and it may have essentially hydrauliced on air pressure

any input as to if this could be right?

no warning lights on but haven't had someone out to read the codes yet.

[trottsky 24]

I've known them to flood before for no obvious reason?

It's highly possible that isn't the issue but for free it's worth a go, if you've checked the compression I'm guessing you've already had the plugs out? Leave them out over night or if your in a rush, (this is pretty unconventional but I've done it before and it works) put the plugs on a tray in a warmish oven (doesn't need to be hot you just need to warm the plugs through so that the fuel won't settle on them). Then install them into the engine and give it a go like normal.

Like I say it could be any other number of things but I'd give that a go from what you've described.

Cheers, Tom

[yng_750 247]

Tried again this morning.

it is firing as the exhaust gets heat in it (easy to tell when its -1'c)

im guessing if nothing comes back on the code scanner i will have to get the bottom pulley to tdb pop the rocker cover off and check the cam alignment at the back where the locking tool goes.

so his three options if the chain has skipped is either reset it (i would suggest replacing tensioners etc while there)

chuck in a new motor

or sell as is.

will keep everyone posted

[polley 916]

I had a 328 do this, thought it had snapped a can chain so pulled valve cover off and checked and everything was alright. Put it back together and it started first time. No idea what was wrong with it, never did it again

[Lubed 55]

Before you condemn the engine with worst case scenario how about dry the plugs out as suggested then after reinstalling plugs start the engine at full throttle to allow as much air in as possible to lean the mixture out on start up.

[B.M.W Ltd 950]

Had one towed in yesterday with the same problem. Remove plugs, blow out combustion chambers with air, one small squirt of oil in each chamber, new plugs, hook up a jumper pack, full throttle and crank over till engine starts properly, do not release the key until it starts. If you keep trying you will flood it again and you'll pool up the combustion chambers with fuel again. It will smoke like crazy when it does start, but it will clear very quickly

[yng_750 247]

Cool thanks. Will try that

[yng_750 247]

Did as above.

Pulled plugs very wet.

Turned.over and got fuel squirt out.

Blew out with compressor.

Little oil in each.

Brand new dry plugs.

Turned over at full throttle.

Wanted to kick and sounded better but after 30 seconds went back to what it was with wet plugs again.

Will take plugs out tomorow repeat process and let it sit for a while to dry out plugs etc as much as possible.

[Jo Blogs 11]

May take longer than 30 seconds. Other thing that can make them sound as if they are locking up is a faulty crankshaft position sensor. They don't always throw a code. Disconnect the plug under manifold and pull back rubber boot and check to see if the insulation on the wiring has disintegrated. If so replace and repeat.

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