Awkyeow

That is exactly what I plan to do. Though, I am going to replace other things while I am in there. It is time. Are you suggesting to ONLY repair the head gasket?

@powderfinger It is just strange that the truck ran fine with no sign of engine issues. I parked it, pulled distributor, changed a fuel pump filter and speedometer cable. Started it up and it was like this. That is why I thought it was a timing issue or something. No smoke or anything. It drove with a loud knocking noise so I have not driven t much, just around the block or so, just a few times after I swapped items to test if that was the issue. Only the last time I noticed smoke or more like vapor when idoling in the garage. I then did a compression test. Gonna rebuild the entire engine. Was going to anyway. Had lower compression on Cyl 3&4 about 2 months ago. Squirted oil in the cylinders and the pressure went up, so I assumed rings, not headgasket. @datzenmike I replaced a blown head gasket in 1997 or 98. Replaced rings, timing chain/tensioner etc. in 2004 or 05. So it's been almost 20 years. No I never re-torqued the head bolts. I will this time. This will be the second time the head gasket has blown since 1989. I am going to replace everything. Is it still OK to shave the head a 2nd time? Or should I source a new/different one? Much appreciated with all your advice as always. ALL OF YOU!!! A blown head gasket was the last thing I thought it would be. I will take this as a WIN! It's an answer. Finally.

Correct. Pully mark is set at 3° after warm up. Pully mark was dead on 0 for TDC when distributor was taken off and put on. #1 Piston was visible through #1 exhaust plug when removed. Rotor was pointed at #1 on distributor cap. With valve cover off, timing chain mark was lined up with #2 on cam sprocket. (After a few revolutions to get it there) Nothing looks out or obvious to me. I changed out the sparkplugs. Nothing different, but when I shut it off I noticed my coolant reservoir was really full and spouted water out the top cap for a second. Hmmm. Blown headgasket? Engine does seem hot. Much hotter than the radiator cap, and too hot for just a 15 minute idol. I also noticed this time and not any time prior that there was a bit of smoke or vapor coming from the tailpipe after warm up. I would have tested compression earlier, but this is the first time I've seen this. Very odd. I drove it before doing the maintenance, with no issues with engine. Also it is weird, the temp gauge doesn't go up as high as it used to either. I just did a compression test. Cylinder 3&4 have 40psi. Cylinder 1 is at 160psi. Cylinder 2 is 150psi. Makes sense why nothing I did would ever change. Being that I just changed the distributor is why I thought timing issue. I did drive it hard the last time i drove it. How in the heck could I drive this thing with no problems, park it in the garage, do the maintenance work, start it up 2 weeks later and the engine has either a blown headgasket or rings issues. I planned on changing out the rings, bearings and whatever possibly needed before this summer. I did compression test a few months back and cylinder 3&4 were at about 140psi. Cylinder 1&2 were about 160+/- This recent test today #1&2 have come down about 2-4psi. So bizarre. Could bad timing from distributor make compression that low? Considering that everything else looks like it is correct and nothing I do changes a thing, it does make sense that the engine is busted. It's just odd. No sign of this before. Hence why it really didn't cross my mind. Thoughts?

And yes, Cap and rotor are new. I even swapped back the old ones, nothing changed. Both new are back on now. There is one thing I did, I forgot to put the air cleaner back inside the housing before i started working on the truck... lol. I discovered this while the truck was being worked on. When I took off the air cleaner cover it was stuck on. While removing, some of the insulation was pulled off from the lid and stuck around the rim of the bottom part of the housing. Is it possible some of that got inside the carb and clogged the PCV valve or something? The Idol is about 90-95% smooth. I am just verbally saying everything I did during this process. Whether it is prominent or not, who knows.

Nothing is hitting anything external. Exhaust is solid, everything is solid. New. When engine is parked and revved the noise is slightly there. It is super loud just starting in 1rst gear and on every gear underload. Truck drove fine before, parked it, worked on it, and here I am with the issue. Not sure clanking is the correct term. The noise is definitely coming from the engine. Internally. Perhaps very loud pinging, almost like a loud diesel engine sound. One odd thing is the engine sounds quieter when at Idol, the value ticking I used to get doesn't seem to be as loud. It's there during warm up but not really there after. Happy about that, just noticed the change in sound. I've adjust air and Idol on carb, nothing changes. It's not the plug wires, I swapped them. Same problem. Could it be one of the ignition coils not firing? Perhaps an electrical issue? Anything under the dash that could cause electrical coils issues? I've checked all regular fuses in fuse box. Not the 2 big square ones. Didn't test those. Are there any other different fuses or connections that I forgot about? Nothing against the blue NGK wires, I just really do not want BLUE under the hood. Wires are not the issue. The only thing left is that the oil pump shaft is off. It is closer to 11:30 than 11:25 position. Though you said it can't move from distributor removal. So I'm just at a complete loss. What testing can I do for ignition wires? What about a PCV valve? Could this cause issues?

Swapped the plug cables, still same issue, perhaps a tad bit better, but the clanking noise is still there under load. Gonna replace spark plugs again just so I know that everything has been replaced with new. Uggg!!!

Yes, this is true. The clanking could be something not related to the distributor swap. I just find it odd that before I did this work there was no clanking and it operated good as it always has. I just wanted to replace the distributor with a new one because I wanted all parts to be replaced with newer and it has never been replaced. As well, the engine is now a bit wobbly. It used to be pretty smooth before all this. It is as if the engine is off just the slightest amount to still Idol 95% correct.

When this first happened I put back all the old parts, old distributor & coils, nothing changed. I can't find any plug wires that actually fit the 720. I honestly do not want BLUE ones. I have purchased 2 sets in black or grey color, Both #3&4 Intake wires are to short to make it to the cap when keeping all Intake wires going down Intake side and across front of the engine to the cap. So I did not try to swap them out. I find it hard to believe that the wires are the problem. But I suppose it could be possible. I WILL TRY THAT, BRB.

I have all the manuals, 84 service manual too. I know how easy it is to put plug wires in wrong spot. I've done it before... lol. They are all correctly positioned. TDC oil pump spline is positioned at around 11:28 position. Thought it was supposed to be more 11:25ish? Distributor rotor points at the Intake 1 position. Coils are new. Plugs are less than 100 miles on them. Plug wires are old, but truck was running before with the same plugs and wires. I've check all vacuum lines. All hooked up. I am so confused as to what the heck happened.

I have checked 3 times. Wires are correct.

Ok, I am at a complete loss here as to what happened. First I replaced fuel pump filter. I also replaced the speedometer cable. (Cable got caught under dash and I gently pulled back and forth to free it. Could I have disconnected a wire to cause this issue?) All this was done to replace old parts. I replaced the coils. I then replaced the distributor. When I started the truck it seemed kinda ok. Idle was pretty smooth but I felt something was off. I checked the plug wires, all in the correct spots. It acts as if it is firing off or plug wires are crossed. Idles mostly smooth. Give it gas and it has a loud clanking noise. It ran normal before I did this. I backed out and started driving. Immediately there was clanking from the engine. I turned around, Checked timing, it was off, corrected timing to 3°. Still the same problem. I then thought it was a bad distributor. Put my old one back in. Same noise. Rotor lines up with Intake 1 on the cap. Question. Is it possible for the oil pump shaft to move from removing the distributor? Maybe it was stuck at the connection and dropped back in just slightly off TDC? The shaft is at about 11:28. Not quite 11:25. I literally just pulled out distributor and put new one in. It only goes in one way. Any advice or knowledge would be appreciated.

Yes, it did quiet the noise down a bit after valve adjustment. It comes back though, and it is still too loud for me. The valve noise isn't there during warm up. Could the ticking be a vacuum issue? I don't have the oil gauge in the truck at the moment, but those numbers seem to be about where mine are at. The head seemed to be a bit wet but not too saturated. To me, the unprofessional logical eye, it doesn't look right. Shouldn't the oil be the same color as what is in the pan? It looks burnt in the head areas. The puddle in the middle of the head is dark. No puddles anywhere else near the sides. Just in the center areas. I will pay more attention the next time I take off the cover. The dipstick oil is like honey, so it seems weird to me that the head oil looks dark. Ok then, I will do the leak down test today. I don't suspect a headgasket issue. Never entered my mind. Oil test suggests rings. But I am not a professional. So if air comes out of the sparkplug hole #4 while testing #3, obviously there is a gasket leak. If air or hissing comes back out the carb there is a valve issue. So a valve sealing issue would mean worn lobes, valves, springs, rocker arms themselves? I guess, that is the reason I want to replace everything with new. Logically it shouldn't sound the same if I replace all the parts. Do you just put a wedge down in between the chain to keep the tension? Or put a long prybar like thing down to apply pressure to the tensioner, I don't remember. It's been awhile. But yes, when the head comes off I will replace everything I possibly can. I am not ready for that just yet. I still want to drive it a bit. It just got back on the road 3 weeks ago, after it has been sitting for about 15 years. Just to make sure we are on the same page. I have an 84 Z24 720, not a Z24i hardbody. I am sure you already know this. Though I hate to assume anything. The head i bought was listed for an 86 Z24i 720 compatibility. I took a chance that it would work on the 84 Z24 720. So the rockers and camshaft are the same for both Z24 AND Z24i? Bummer, I wanted to swap out rocker rack just to see if there would be a noticeable difference in sound. I won't do that now if you do not recommend it. I will just swap out the entire head and see how it runs. But I will have to wait on that because I am not ready to tear the truck down just yet. Is the 382 marked on the rebuilt camshaft the factory lift or duration? Thank you again for your expertise!

As well, would the rings/head gasket issue cause the ticking noise in the head? I also felt a slight vibration when slowly raising the rpms by hand at the carb. I could feel it against my legs while leaning against the truck. It is only at a very low rpm then it goes away. Could this be something out of balance or worn crankshaft/bearings/piston/piston rod? I do hear a slight knocking. It is very faint, but it is there, seems to be coming from the rear of the engine. Now again, I will be replacing all the timing chain stuff while I am in there. Has a slight chain noise too. But not too bad. Exhaust is 100% new so I can assume the ticking is not an exhaust leak. The noise was there before i did the exhaust. Timing is set to °3 BTDC. or very close to it. Timming mark does not bounce around, it is very still once set. Another thing I noticed was that the oil sitting in the head itself looked very dark. But my dipstick oil is golden. Why?? Could it be a bad oil pump? Pressure does go up when I rev or drive. I have the stock gauges with the center console. During this rebuild I am going to have the tranny worked on. So I will replace the crankshaft bearings since the tranny will be out. I know, lots of questions. I just know you all have much experience with these engines. My apologies for so many questions.

Thank you! So the head itself will work on my engine. As it says 10W. I will try the leak down test tomorrow. So instead of adding oil, put the air in the plug hole and listen if any air comes out? Can I assume there should be no hiss if the valves are closed properly? Probably some back pressure out the same plug hole because it has nowhere else to escape from? If all is working correctly. I did add some oil in the cylinder and the pressure went up. I did this for both 3 and 4 separately. If the head gasket was blown would the compression numbers still go up after adding the oil in the cylinders? The engine runs good, no smoke at all at tailpipe, passed smog with great numbers. The engine is old. I want to rebuild it the best I can. This is not primarily the issue I am worried about. I will take the head off soon and replace the crankshaft bearings and see if anything else is worn out. My main issue is the head noise. So the rockers are the same all across the years on the Z24? Same with the camshaft? I adjusted all the valves to .012(hot) I basically would love some conformation that swapping the top rocker arm assembly from the newer one to mine won't screw up my engine. Just to see if the noise goes away. Doubtful, but an easy attempt before I go deeper into the head. The cam says 382 stamped on the face where the pin is. Is this a stock cam?

Ok. I have a ticking noise I can not get rid of with a valve adjustment. I have done this 4 times just to make sure all was done correctly. The noise is better but I am not satisfied that this is how it should sound. I remember the engine being much much more quiet back in 87. Granted it was pretty new. I want it back to if not as close to new as possible. Cylinders 3&4 have a lower compression that adding some oil raises the numbers, so, Rings. Going to do all the rings soon. So, I know nothing about the engines specifics and what differences there are for the Z24 engines through the different years. I have picked up a rebuilt head for an 86-89 Z24 stating Vin N & S. Mine is a Vin S for the 8th character. No idea what this means? The guy who sold me this said it should work. I probably should not have bought it. But it did. I believe this is compatible for the 86 z24i. So I took a chance and picked it up. Thinking this should work for my carbed 84. Thoughts? The cam is stamped 382 on the sprocket side. 1. Will this cam work for my current stock motor? 2. Will these rocker arms/lifters work for my engine if I just swap out the top lifter rack. (Just to see if it sounds different with different parts on it) Trying simple first. 3. Will the actual head(casting) work with my engine? Stamp #'s are different than mine. (The ones that are on top back passenger side where the cover gasket goes, what do these mean) (It is also stamped 10W like mine is. The circles next to the 10W look different than mine do. What do these mean?) 20240219_142359.heic20240219_142335.heic20240219_142418.heic20240219_142555.heic20240219_142624.heic20240210_162254.heic20240219_142305.heic20240219_142458.heic