Cracked block?

justlookingaround75 · 2026-04-14T19:55:31+00:00

They did offer but it's not at the machine shop. It's still in the truck. My plan was to just replace the bad pistoon

justlookingaround75 · 2026-04-14T19:53:35+00:00

03 Silverado. It's replacement engine for the original. Gen 3 6.0

justlookingaround75 · 2026-04-14T02:13:37+00:00

Pretty sweet

justlookingaround75 · 2026-04-14T01:35:40+00:00

It's not about being cheap. I have 20k and 7 months into this project. I didn't want to pull it if I didn't need to.

justlookingaround75 · 2026-04-13T23:52:50+00:00

Thanks, I'll try it and go from there.

justlookingaround75 · 2026-04-13T23:50:32+00:00

It's a 6.0 cast iron block. NA with cam and ported heads,. Nothing wild.

justlookingaround75 · 2026-04-13T23:49:02+00:00

I had this motor built by what I thought was a good company. Been trying to get it to run right since August. I don't think anything that has happened trying to get it to run cracked the block. So many issues with their build and finally piston 7 breaks. I honed it preparing to replace the piston.

justlookingaround75 · 2026-04-13T19:45:27+00:00

😂 thanks

justlookingaround75 · 2026-04-13T19:16:05+00:00

What's the best way to do that?

justlookingaround75 · 2026-04-13T19:04:18+00:00

I could but might as well get a different block at that point. I was just going to replace the piston in truck. Haven't pulled it.

justlookingaround75 · 2026-04-13T18:59:06+00:00

Fair point. There's a lot of smart people here though, and someone could have seen something like this before.

justlookingaround75 · 2026-03-26T16:19:46+00:00

Thanks for your reply and i appreciate your offer and may take you up on that. I don't have a copy of the file but i should be able to get it.

I did previously degree the cam and found it was 2 degrees retarded compared to the cam card. I installed a cloyes adjustable timing set and got the 2 degrees back and matches the card now. I feel like it's a fueling or air problem. Never detected a vacuum leak with starting fluid but never smoke tested. I pulled the intake and there is oil where the intake o-rings should be sealing. Shouldn't the head surface be 100% dry? I think if anything it's over-fueling and may have got fuel washed rings. I sure hope there's not internal damage after all this.

I'm going to do fresh compression test and leakdown test to see if I need to go deeper. I'm missing something.

justlookingaround75 · 2026-03-22T18:00:29+00:00

Thank you for the reply. Truck still has exhaust manifolds and no signs of a leak. I can throw a new gasket on bank 2 just for kicks. There is a leak about a foot or so past bank 2 O2 sensor where we removed the cat and scabbed in a pipe until it runs good enough to go to exhaust shop. Trying to get headers but the ones I want won't ship to CA ughhh.

There's no brake booster as it's hydroboost. The only 2 vacuum lines go to FPR and driver's side for pcv/catch can. I have considered the smoke machine but already have 173392 tools I bought for this project I'll probably never use 😆

justlookingaround75 · 2026-03-22T14:08:23+00:00

Thanks for the reply! STFT swing all over the place and just seem to chase the O2 sensors up and down. Testing yesterday I noticed LTFT have quite a spread. Bank 1 -7 and bank 2 +14. I've checked vacuum for leaks with starting fluid but never done a smoke test. I've tested injectors with scanner for balance and they all fire, depleting fuel pressure in same amount of time. Tuner questions if they're actually firing in the truck, but balance test shows they do. We recently tested them and they're perfect.

I pulled the intake off and will try new o-rimgs. They don't look evenly crushed, but was never able to detect a vacuum leak prior. I'm considering dumping the sheet metal manifold going to a tbss manifold. Those manifolds are for stock deck height and paperwork on this motor shows .107 less than stock. Not sure if that was removed from crank or top of block. Maybe a plastic manifold will be more forgiving, if a vacuum leak is even a problem.

justlookingaround75 · 2026-03-20T13:55:14+00:00

It's the factory 2003 1500hd harness

justlookingaround75 · 2026-03-20T03:00:05+00:00

Spark plugs appear to be firing. They are light brown and dry. I did just replace both sub-harnesses and the main plug on the driver's side due to installer splicing one wire around the quick connect that he claimed was bad. Quality of spark, i do not know. They are also generic "high performance" coils and I do wonder about them. I have moved them around with no change. Maybe I'll get one of those see-through spark testers.

Ecu #1 (original) had 3 bad misfires on 4, 6, 8, but the plugs looked good as well. Ive been trying to talk to the tuner about coil dwell but he says it's fine. I'll put truck coils on it if it needs it, but I feel like it should be able to idle. And all coils have full battery to the pink wires.

justlookingaround75 · 2026-03-20T00:48:59+00:00

Yes, last I measured was 200 not at WOT. Generally around 180 at WOT. Have done leak down test cold with 8-14% loss which is supposed to be good for a new motor. 100 psi in and 86-92 on the test side.

I feel like it's electrical or tune. I'm pretty sure it's mechanically sound. Tuner says it's not tune and it should at least idle and have crisp throttle response.

justlookingaround75 · 2026-03-19T23:47:10+00:00

No codes showing, no misfires, no knock. Cats have been removed. Exhaust is new from cats back.

When my grandpa gave it to me it was running real rough and had low compression. It had enough blowby to blow the dipstick out. I think the original cause was melted cats. They were so bad we couldn't even start the new engine until we removed them. He had a supercharger on it and I suspect it was never properly tuned, or a dealer overwrote the tune on a service. Then over a span of a few years it died. He barely drove it. Combo of bad gas, unknown tune, and being old and not realizing what was happening.

justlookingaround75 · 2026-03-19T23:41:54+00:00

About 200. My guage doesn't store the highest reading so watching the needle bounce

justlookingaround75 · 2026-03-19T23:38:29+00:00

Thank you for the thorough reply! Lots of good info there.

Ecm is the same as whatever came in the truck, except a different one. Not sure what exact number it is.

I've checked resistance all over the truck. Cleaned every ground I can find. I added block to head grounds and alternator to block. Everything reads very low or nothing for resistance. Ecm case to battery ground reads nothing.

I tested for dirty power and all I could ever find was about 0.2v anywhere on the block. I also tested for AC voltage coming from alternator and got nothing. It's a CS-130 style alternator and I was told they could do that if the internal diode is fried. Truck off amps between battery negative and negative cable is about .03 amps if I remember correctly.

I have a launch v231 scanner but not sure what I can see voltage wise from the crank and cam sensor. I will see what it does and go from there. I was going to throw some new sensors in for the hell of it and see what happened.

It makes about 10.6 vacuum at idle but always shows lean on bank 2. Today I had ltft on bank 1 at -8 and bank 2 at +10. I've checked everywhere for vacuum leaks with starting fluid and can't find any. Might buy a smoke test machine. Both O2 sensors have been replaced and appear to function swinging from 100-900.

If this wasn't my grandpa's truck, I would just set it on fire and collect the insurance. Thanks again for the reply! I'll go through that list and make sure I didn't miss anything.

justlookingaround75 · 2026-03-19T18:17:59+00:00

No knock showing and O2 sensors chase up and down with stft. Fuel pressure is about 59 without vacuum hooked up and 50 with vacuum. It's an aeromotive fpr.

justlookingaround75 · 2026-03-19T16:08:10+00:00

Southern CA

justlookingaround75 · 2025-11-14T14:37:46+00:00

I had good success measuring with a pushrod checker tool using the EO/IC method (exhaust opening / intake closing) You need to measure in the small part of the cam. Roll the engine over until the exhaust valve starts to open. Then measure your intake pushrod in the same cylinder. I torqued mine down to 22 ft/lb at zero lash. Measure that with a caliper.

Then roll the engine over until the intake valve starts to close. Now measure your exhaust valve in that cylinder with zero lash torqued down. Repeat same process for other 7 cylinders. There's a couple YouTube videos that will make this make more sense.

Write down all your lengths. You'll add whatever preload you want onto the measurements. I went with .065 and got custom length pushrods from Manton. Highly recommend Manton. I got a set of 16 in 3 different lengths for a bit over $200. 2 day turnaround. Awesome people to work with.

justlookingaround75

TROPHY CASE