KA Engine Rebuild No Start Help Please

[BoBa524]

This was my first rebuild, everything went great. now that everything is in, the engine does not start. I checked to see that all the wiring is in place. The rotor and distributor had worn out contacts and i replaced those too. I checked to see that there spark and fuel getting to the cylinders. Engine turns over fine with no bent valves the distributor rotor is set at plug 1 and cylinder 1 is at tdc...Lined up by timming marks on the pulley to make sure engine is TDC. Can someone please tell me if there is something I might be missing because I am completely stuck. i even tried switching sparkplug wires from 1 to 4 and from 2 to 3 and it sounded like the exhaust blew out of the intake because the intake valves were open during detonation instead of the exhaust.

[benemorius]

Check compression.

[BoBa524]

Just checked compression in cylinder 1. only getting 90 psi. i thought i torqued head gasket down fine. I didn't replace the head bolts though. You think its the head gasket?

[benemorius]

No. I think you didn't replace the head bolts. Did you not replace the head gasket, too?

[BoBa524]

i did replace the head gasket along with all the other necessary gaskets i got the whole gasket kit. what else could be causing the low compression?
Modified by BoBa524 at 12:32 PM 7/3/2006

[180fan]

rings or valves. what did you do on your rebuild?

[boryan]

180fan, this is still BOBA524, i'm just using a different screen name. I pulled the engine out for the rebuild and took it apart all the way down to the crankshaft. I got a re-ring kit for the rebuild. I replaced piston rings all the bearings, all the seals, water pump, and got all the valve seats and valves ground down. Also changed the cams from a lower millage 240 at the junk yard after my friend snapped one of the cams. Also changed the clutch among other things I don't recall right now. Someone told me that the compression pressure might be low because I was cranking the engine for a while trying to get the car started and flooded the pistons with some fuel.

[kermitman]

If you did the compression check, then after the low result you should have put some oil in the cylinders (just a few drops) and see if the compression comes up.ALso put up all 4 cylinder results so we can see them. A consistent 100 psi across the cylinders isn't good either.

Then do a leak down test.This will show where exactly your leak is at...intake valve, exhaust valve or gaskets.

my guess is that one of the valve seats is not sealing properly...but it'd be great if I'm wrong.

Also Check fuel pressure and make sure fuel pump is priming

[rjlong140]

Try this:

1. Make sure you are TDC on #1 compression stroke. To verify compression stroke, make a taper plug that fits snug in the top of the sparkplug hole (the top of a soda bottle wrapped with tape works), then rotate the crank clockwise with your breaker bar and 27mm socket. When the plug pops (it should hit the roof of your garage when it does) you're starting the compression stroke. Then, just turn it to the mark.

2. Set your distributor. Make sure you line up the mark on the case with the dowel, not the dimple, because the shaft will rotate when you install it due to the way the gears mesh.

3. If it still doesn't run, pull the plugs. If they have fuel on them, try pulling the fuel pump fuse and cranking it. If it acts like it wants to run, put the fuse back in, adjust your distributor a little, and try it again. Repeat as required to get it to run, then use a timing light to get it closer.

4. Once you get it running, follow the proceedure for setting initial timing/idle.

I hope this helps. Good luck.

[jam149]

Are you sure that you have the cam timing correct? If the cam timing is off, that could be causing low compression readings (if the oil in the cyl doesn't help - that should be your first try).

You can check it quickly by setting the motor to TDC - compression, pulling the valve cover, and comparing the pics to here:

<http://www.negative-camber.org/jam149/p ... 0cams.html>

If the cam timing is right, it may be worth it to pull the cams at this point and recheck the torque on the head. After that, I'd double check the ignition timing.

joe

1992 240SX Racecar1998 240SX Track Queen

[RedShred]

did you adjust your valves in anyway ? I had a friend adjust his valves to take the tick out of them. what he did was cause them to be too tight and not seal all the way. This wouldnt let the car start as then engine couldnt build enough compression to start.

[boryan]

Thanks a lot for all of your suggestions guys. So I tried a bunch of the things that you mentioned and realized that the rotor cap was cracked and the distributor was not spinning it at all. Once I got a new rotor cap the car started right up with no problem. Now it is idling kind of roughly so I need to make whatever adjustments are necessary to get it to idle. I'm gonna try and do that today.

If anyone has any suggestions on a list of things I need to check I will be glad to hear it. A friend of mine's dad who is a mechanic might stop by for a second to help me out too.