engine and drivetrain M42 Swap No Start

[hoover]

help please..im doing swap on my 69 1600...its possible the in less 6 weeks piston rings goes bad,before I remove the engine from e30..was running then we installed into the 69...car don't star...any body had the same problem before..thanks in advance.....sorry if no is the right forum..for this question..thanks

 

1 :70 psi

2:75 psi

3:70 psi

4: 120 psi

dry test

 

1:95 psi

2:85 psi

3:85 psi

4:195 psi

wet test

[Brendan]

At that compression, I'd expect it to run, but maybe not make much power.  I'd guess your no start condition is not due to the compression, but something else.

[hoover]

have spark, and gas..but if cranked for 5 or 10 seconds..and remove spark plugs..you can see very wet of gas on the spark plugs.

[FunkyLaneO]

A compression test on a cold motor won't tell you much but cylinder 4 is a little wierd, even cold they should all be close to the same numbers. Rings wear over time but don't "go bad" while sitting unless there is water in the cylinders then they could go really bad really fast.

 

I doubt that rings are your problem, I would look at something electrical (or electronic) and M42 swap isn't trivial there is quite a bit of work that has to be done to make it work in your car.

[TobyB]

The M42 has a problem shared with a lot of BMW engines of that era-

 

they can lose compression from 'cylinder washdown'.  My M42 E36 will do this,

and Jenn's M54 powered E46 has done it once.

 

What happens is that the cold- start injection is 'wet' enough that the fuel will break

the oil seal on the rings, and they don't have enough tension to seal compression without oil.

The fix is to start it like a flooded carbed car- hold the gas pedal on the floor and crank.

That shuts off the injectors, and eventually oil re- seals the rings.

 

What's really weird about it is that, UNLIKE a carbed car, you can't just let it sit a bit to dry out.

You CAN dump a bit of oil down the bores and crank it with no fuel pressure. 

 

It's not uncommon if you start the car, move it 10 feet, start the car, move it 10 feet, and repeat that 3 or 4 times.

 

Freaked me right out the first few times it happened- now I drive the car around the block if I'm just moving

it in and out of the driveway.

 

Look at the E36 forums for M42's- like M42club.  That's where I figured it out.  I thought it was valve lifter pump- up,

which made no sense given that it doesn't cure itself while sitting.

 

That said, given it's a fresh swap, I'd be skeptical of all sorts of things preventing it from starting, too...

 

t

Edited August 2, 2014 by TobyB