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engine aint so happy, any clues on what my knocking noise might be, ive got some idea's, getting a 2nd opinion??
Mine sounded exactly like that and the outcome was not good.......could be something as simple as a loose rocker, or very bad like a rod, spun bearing, chipped piston....etc. Open the valve cover and go from there.
Mine sounded exactly like that and the outcome was not good.......could be something as simple as a loose rocker, or very bad like a rod, spun bearing, chipped piston....etc. Open the valve cover and go from there.
use a stethoscope or rubber hose to try and isolate the source of the noise. I had a hard to chase knock once and the return spring on the mechanical fuel pump arm had broken causing the arm to make the noise.
After removing the heads, I found it was detonation damage (pistons and heads) to the #2, #8, and #3,#5 cyls. #5 had part of the piston broken off. I was surprised the engine was running at all. Like I said, it sounded exactly like yours.
I wouldn't run it anymore. The more you run it, the less parts you'll be able to reuse. Start tearing it down. It's not going to heal itself. As suggested, start at the top and work down until you find it.
thanks guiys, will start at top and work my way in, got a boroscope coming tomorrow , so will have a look in at the valves and pistons via sparkplug hole
Grab a piece of heater hose. Makes a good stethoscope. THEN run it along the oil pan. This is an easy car to drop the pan. It is a rod. If brave enough to mess with rod bearings, get the size off the bad ones and post it.
Grab a piece of heater hose. Makes a good stethoscope. THEN run it along the oil pan. This is an easy car to drop the pan. It is a rod. If brave enough to mess with rod bearings, get the size off the bad ones and post it.
I wouldn't run it anymore. The more you run it, the less parts you'll be able to reuse.
Mike
Take Mike's advice.
I would first drain the oil and pull the pan. Look at the crank assembly and inspect what's visible there. Oil analysis is a good thing for identifying failed components, but if there's a lot of Metallica present in it, just save the money you'd spend the analysis and spend it on the rebuild/replacement.
Good luck.
Take Mike's advice.
I would first drain the oil and pull the pan. Look at the crank assembly and inspect what's visible there. Oil analysis is a good thing for identifying failed components, but if there's a lot of Metallica present in it, just save the money you'd spend the analysis and spend it on the rebuild/replacement.
Good luck.
Just curious: What's the engine's history?
Steve
its about 6 years old, but has only done about 2000 miles, it is a custom built sbc 383, mid 70's block and all brand parts inside, all forged, designed for forced induction
Had a very similar sound on my 406 a few years ago - a roller rocker arm trunnion clip broke and the rocker arm was loose - made an awful clacking sound.
I pulled the pan and found the clip in 3 pieces.I tore the engine down, and unfortunately found some pretty bad scratches in the cylinder walls. I considered cleaning and running it - I probably could have - but instead chose to replace the block (it was an old junkyard block anyway. It was also an excuse to upgrade).
Update - so i removed the shaft rocker from low compression cylinder, with the rocker on, it produces 120 psi, all others are 140+, with the rocker rermoved, ie valves fully closed when turning engine over, it only managed to produce about 70 psi and then after another few trys at turning over engine, ended up down at 10 psi, so what does that mean?? bent valve or ?? - there is alot of oily burnt crusts on the pistons, which is more than likely on the valves aswell, seen on my boroscope today
Last edited by corvettedave383; 07-19-2018 at 01:17 PM.
Maybe it's just the picture, but it looks like the valve stem has started mushrooming?. Maybe the rocker was pounding on the valve due to being too loose?
Also the sweep pattern looks quite wide?
Maybe it's just the picture, but it looks like the valve stem has started mushrooming?. Maybe the rocker was pounding on the valve due to being too loose?
Also the sweep pattern looks quite wide?
07-16-2018, 02:49 PM
