Hopefully not a cracked block....

[1979C20]

So, I was driving down the highway to go out fishing with my buddy, and I was cruising 60 or 65 at 2600krpm or so. And when I came to a stop sign after a few miles of driving, my truck was idling like crap. It sounded like timing, and like a misfire or two. So I kept driving. When I left the stop sign my truck had zero power. When I got to Saguaro I moved my distributor a bit to see if the problem would change and no difference. When I got home, first thing I did was grab a squirt bottle and spray my header tubes with water to see which cylinders were firing and 3 and 5 were dead. I checked for spark and had it. So I figured maybe I was low on oil, starved the cam of oil and flattened 2 lobes. I pulled my valve cover off and all of my valves were moving equally when I started it. I'm uploading a video of the rocker arms on youtube and will post a link when its done. But, After I checked the valves I thought maybe my vacuum advance was sticking. I pulled my distributor, checked my cap and rotor, and then swapped my distributor with a different one. Still no fire. So I'm not sure what the problem is. I tried a carbon drop, where you rev up the engine and slowly poor water into the carb to try and clear any carbon off of the valves, thats not the problem. I checked for vacuum leaks around those two intake ports, and one of the intake bolts was loose and it sucked in a very tiny tiny amount of the carb cleaner and raised the RPMS but I snugged down the bolt and It doesnt do it anymore. So I'm wondering if there is a hole/crack in my pistons, crack in my block between the two pistons, blown head gasket(not leaking any fluid into one another), cracked or warped head, or even piston rings. My engine has always run very rich. Maybe during this drive and over time it has been fuel washing the cylinders and took out the rings? I need to do a compression leak down test to find where exactly I am losing compression, as I'm sure I am. But I cant find a leak down tester for rent. So, other than what I have listed, What would any of you recommend? The noises I can hear are: A constant ticking sound, and a metallic slap sound in the exhaust when I hold the rpms up a bit. I was thinking, the compression leak wherever it may be is the ticking and the slap sound is piston slap or something? It also sounds like its backfiring through the exhaust at higher the idle RPMS. sorry for rambling. But I really need some help!

[1979C20]

http://www.youtube.com/watch?v=oNI-zHFzDVk&feature=youtube_gdata_player here is a link to the video. It was hard to start it because of the 2 dead cylinders. And dont mind the techno, my stereo was on random.

[zieg85]

Compression test should tell you what is going on.  Backfire from the carb sounds like the exhaust valves in your 2 suspected cylinders.  

[Grim 82]

Did you remove and inspect the plugs?

[1979C20]

I forgot to mention that, I replaced the 2 plugs. And its backfiring/thudding in the exhaust, not the carb.

[jaredts]

Harbor Freight has a pretty cheap leakdown tester.  Maybe bite the bullet and just buy it ($40 item 94190).  Does your motor blow smoke?  If so what color?  When you had your valve covers off for the video, did you see good oil flow after a few seconds?

[beastie_3]

Id start with a compression check and report back the findings for all 8 cylinders.

[1979C20]

My truck always burned oil, it had 60k original miles on the engine when I rebuilt it, but I didnt bore the block and I used stock pistons. So I'm sure it needs to be bored. It goes through 2 quarts of oil in 2-3 weeks. Since those cylinders are dead there is black smoke from all of the unburnt gas. The engine is running very rich now. There was great oil flow. That was the first thing I checked. Its all over my block. Haha. I need to go rent a compression tester and I guess Ill have to buy a leak down tester. I can build one for like 30, but I guess 40 isnt bad.

[topp]

I am wondering why oil wasn't squirting out all over without the valve covers on? I didn't see any clips on the rockers that prevent the oil squirting out.....

[1979C20]

The oil was splashing and kind of squirting, but it wasnt SPRAYING. Its all over my headers and the side of my block. Its a high volume oil pump, 30wt oil and the pressure is always between 40-70 depending on temp and how long i was driving.

[topp]

Ah...Couldn't tell in the video...

[slammed79]

So did what have you found out? Inquiring minds want to know.

[1979C20]

Im still waiting on a leak down tester. I need to be saving money for the blazer im getting next week so i can have a daily driver and then im digging into whats wrong with my truck. But ill post back as soon as i figure anything out. But i gotta put like 150 bucks into the blazer once i get it for a torque converter, windshield, and registration/insurance.

[1979C20]

So, i went down to harbor frieght today and bought that 40$ leak down tester. Brought my number 3 piston to tdc and hooked it up. As soon as i started putting air in it i could hear it leaking. Set the regulator to about 50 and then checked for the leak and it was coming out of number 5 spark plug hole. And vise versa. So im assuming that means a blown head gasket. Its not burning any oil or water. Theres no water in my oil. so, i jumped the gun and bought a head gasket and intake gasket set. Gonna jump into it tomorrow. Hopefully the gasket will be obviously blown. If it iant ill take the head down and have it magnafluxed.

[Psycho71]

Hopefully it's a simple head gasket fix. But check real good to see if it torched the block between the cylinders too. if you ran it very long with the blown gasket, it might have damaged the block surface.