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hi guys,

i just did a head swap with new gasket. i put everything back the way it came apart(as far as i can tell), but i can't get it to start. i get one big backfire a few seconds after cranking. i assume thats the fuel from the cold start valve. then just cranking. is it possible to get fuel for the cold start and not the injectors?

i don't want to sound stupid, but top dead center for the head is with both valves closed on #1 correct? and the the crank on the oIt mark with the #1 piston all the way at the top? i did replace the injectors with good used ones also, but i just don't see that as the problem.

any help or direction will be much appreciated!!

joe

joe_keefer wrote:hi guys,

i just did a head swap with new gasket. i put everything back the way it came apart(as far as i can tell), but i can't get it to start. i get one big backfire a few seconds after cranking. i assume thats the fuel from the cold start valve. then just cranking. is it possible to get fuel for the cold start and not the injectors?

No, cold start line comes off the main fuel rail.

i don't want to sound stupid, but top dead center for the head is with both valves closed on #1 correct? and the the crank on the oIt mark with the #1 piston all the way at the top? i did replace the injectors with good used ones also, but i just don't see that as the problem.

any help or direction will be much appreciated!!

joe

Is it timed right? Sounds dumb, but easy to miss. Pull the cap and make sure firing order is correct and pointed at the #1 cable when the car is at TDC for #1, you could easily have it 180 out. And even if you're in the right general spot, it's easy to be way off on timing.

FAQ's are good for photos. ( Timing, valves.)

i don't want to sound stupid, but top dead center for the head is with both valves closed on #1 correct? and the the crank on the oIt mark with the #1 piston all the way at the top? i did replace the injectors with good used ones also, but i just don't see that as the problem.

any help or direction will be much appreciated!!

joe

Is it timed right? Sounds dumb, but easy to miss. Pull the cap and make sure firing order is correct and pointed at the #1 cable when the car is at TDC for #1, you could easily have it 180 out. And even if you're in the right general spot, it's easy to be way off on timing.[/quote]

it looks like it's timed right. rotor points at #1 when the crank/flywheel marks are lined up. Can the timing chain move when putting the distributor back in? only thing i can't tell 100% if it's lined up right, are the valves.

Are you using a Haynes Manual diagram.....for the plug wire locations to distributor ? Ignore the USA Model diagram.

alotawatts wrote:Are you using a Haynes Manual diagram.....for the plug wire locations to distributor ? Ignore the USA Model diagram.

actually i am. i even had them this way before i took it apart. it seemed to run fine. whats the correct way then?

thank you

Just be sure the wires are connected accordingly e.g. in relation to where the vacuum advance diaphram housing is.
Clockwise # 2 and #4 connect next to the diaphram
page 92 in my Haynes Manual

Rather than edit my prior post ...after rethinking what I said about wire numbers / relation-position to the diaphram.....is bad info.

Hello !?

Read the Ignition Timing FAQ. There's a nice big fat color photo of the distributor with numbers on the wires.

My 635, '79-'81 528i's all run real nice using those numbers.

T.Hanson wrote:Hello !?

Read the Ignition Timing FAQ. There's a nice big fat color photo of the distributor with numbers on the wires.

My 635, '79-'81 528i's all run real nice using those numbers.

hi guys,

i'm less concerned about the plug wires as they are the same as when i had the car running. are the valves on #1 supposed to be closed for setting the timing? with the #1 piston at top dead center?

also is the signal for the cold start valve, the same the the injectors get to work? with these they only work when given a signal right?

how important is the plastic(insulator) around the connector on the wire to the distributor? mine cracked and broke. the wire is good, but the case right near the top broke apart. should i put a drop or 2 of solder on it and wrap it with electrical tape? or is it easaly replaced?

again guys thank you very much, if i wasn't already bald, i would have pulled my hair out. lol.

joe_keefer wrote:
hi guys,

i'm less concerned about the plug wires as they are the same as when i had the car running. are the valves on #1 supposed to be closed for setting the timing? with the #1 piston at top dead center?

Yes. The TDC mark should be lined up with the valves closed on #1.

also is the signal for the cold start valve, the same the the injectors get to work? with these they only work when given a signal right?

No, the CSV is only periferally connected to the injection system thru the combo relay. It has to do more with the starter circuit than the FI system.

how important is the plastic(insulator) around the connector on the wire to the distributor? mine cracked and broke. the wire is good, but the case right near the top broke apart. should i put a drop or 2 of solder on it and wrap it with electrical tape? or is it easaly replaced?

It's pretty important, you've got to get signal to get spark. But... you can test things. Pull the cap off and the coil wire out of the cap and run it close to a ground. Then with the ignition on of course, grab the rotor on the dist and move it back and forth past the trigger points. You should see spark. You might have to rotate the engine some, but with it in the right spot you can generate spark with the play in the centrifugal advance. The exposed wires may or may not be a problem, it seems like on one car I insulated it with some silicone caulk. Splicing in a good plug is a possibility too.

Mike W. wrote:

joe_keefer wrote:hi guys,

i just did a head swap with new gasket. i put everything back the way it came apart(as far as i can tell), but i can't get it to start. i get one big backfire a few seconds after cranking. i assume thats the fuel from the cold start valve. then just cranking. is it possible to get fuel for the cold start and not the injectors?

No, cold start line comes off the main fuel rail.

i don't want to sound stupid, but top dead center for the head is with both valves closed on #1 correct? and the the crank on the oIt mark with the #1 piston all the way at the top? i did replace the injectors with good used ones also, but i just don't see that as the problem.

any help or direction will be much appreciated!!

joe

Is it timed right? Sounds dumb, but easy to miss. Pull the cap and make sure firing order is correct and pointed at the #1 cable when the car is at TDC for #1, you could easily have it 180 out. And even if you're in the right general spot, it's easy to be way off on timing.

well i feel a bit silly. my problem was that i had the cam 180 off. my #1 valves were closed alright but on the wrong stroke. so that problem is solved.

as always another door opens right? lol

well i seem to be getting coolant in/on the cam and timing chain. not quite sure how. i know the new gasket was good. the head is flat so it's not that. but it sure coming in from somewhere on the #1 end. any ideas?

thanks!

The thermostat housing could be leaking or the hoses that attach to it.

If the cam was 180 off, perhaps the valves and pistons were colliding when the engine was turning over and this caused a crack in the head??

Did you retorque the head bolts?