2 dead cylinders

[marcosx3x]

i'm stumped, z24 4 cylinder dohc, i pull the coil wire intake or exhaust dosnt matter same results and pull plug wires one at a time and found cylinders 1 and 2 are dead, amazeing it runs on 2 cylinders. i got timing and compression pulled the valve cover to check mechanical timeing, pulled the carb to see the injectors are clicking out fuel, swapped plugs and wires around ...no change, bought new cap/rotor. i checked spark by pulling a plug out still connected to the wire. without any plugs or coils connected i turned over engine with a friend spraying carb/choke cleaner just so i could see wett stuff making it thru intake manifold. ecu error codes dont seem related (13,23,24,32) it's a very simple tbi system, what really blows my mind is if it's got spark, compressin and fuel, it should run on all cylinders.. can anybody help, i know i must be missing something....

[NM50]

Check your compression with all the exhaust plugs pulled out.Z24 engines are famous for blowing the head gasket between cylinders.Thus when the next door cylinder has a plug in it there is compression.

[marcosx3x]

That makes a lot of sence. I'll try it first chance. Thanks, whoever u are.-Mark

[Big-Bird]

NM50 is a well kept secret here in the trucks forum. He's actually what I like to call our secret weapon in here. Glad you're here to offer some sound advice Steve.

PS Welcome to the NICO trucks forum Mark

[marcosx3x]

Ok, waited for a friend with compression gauge (did the thumb test before) so without the plugs i got zero compression on cylinders 1 and 2.. that was it all along all i had to do is test it without the plugs... looks like i'll be rebuilding the head. i replaced head gasket few years ago, without milling the head, gonna check it out with a flat edge and feeler gauge, but looks like the head needs milling. I non op'ed it a year ago after it failed.. to save a year on reg,smog and insurance, and maintenence, running two vehicles can get expensive on a tight budget, but its time to get my truck runnung, Thanks a million for the help. -Mark

[NM50]

Thanks Big Bird.And your welcome Mark.

[marcosx3x]

Got my income tax return, time to fix the truck. I rebuilt the head. Last time I made the mistake of not haveing the machine shop flatten it, just did a lap job, now I pay the price of redoing it along with an added breech, hole between cylinders. This time I had the machine shop resurface it(10$), but the hole was still there. Filled it with JB weld. very light 220 sand by hand and now it's an experiment. (HaHa)

This time I went all out and and ground the valves and seats myself. (I made all the tools I needed on the lathe. I bought 3 2$ stones (for the seats) 1 5$ grinding wheel (valves) and a 30$ diamond (to clean angles on the stones) I figure I'll use the tools again, next time I rebuild a head.

This is the mandrel being made.

It's all put together



I'm putting it in tomorrow and i thought of you guys. I was reading my cheap Haynes and can't find the cam dowel position. I remember I was supposed to observe this before, I had my son and the neighbor kids remove it, but alas, well I think it's supposed to be pointed straight up for TDC, but I'm not sure and It would be a shame to bend valves after all my effort.





Thanks MN and BB. Thought you'd like to hear an update to your efforts.-Mark