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I'm a newbie to the site, but I'm glad to be here. I have a quick question. I am thinking of getting a rebuild kit for my 85 K5 Blazer, but I can't decide whether the knock i'm getting from my engine is worth the effort. It doesn't seem to knock when it first starts up, but as it gets warmer, it gets louder. By loud, I don't mean extremely loud, but loud enough to where you know it's there. My engine doesn't run any different since it started knocking, I can still fully accelerate and I don't seem to notice a loss of power...it just knocks. Any suggestions as to the type of knock that could be categorized? Thanks!
 

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I had a similar knock on my toyota a few years ago. It turned out to be spun rod bearing that eventually crapped on me and i threw a rod.

I have heard lifters that start to go and knock like you describe.

The reason for the knock after it warms up is more then likely your oil starting to thin out as the oil temperature starts to increase. If you run a tad thicker viscosity oil it might save the engine for a little bit longer from completely crappin on you
 

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I've seen plenty of 305's with cam bearing knocks. The best thing to do if you have a 305 is to throw it over the hill and let it rot. Swap in a 350. Here's a good way of locating the knock. Take a really long screwdriver or a plastic handled prybar and put the end on various places on the engine, and put your ear right against the handle. It works like a stethoscope.
 

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Dr. Donkey Punch said:
I've seen plenty of 305's with cam bearing knocks. The best thing to do if you have a 305 is to throw it over the hill and let it rot. Swap in a 350. Here's a good way of locating the knock. Take a really long screwdriver or a plastic handled prybar and put the end on various places on the engine, and put your ear right against the handle. It works like a stethoscope.
It's funny you mention that because it originally had a 305 in it, and I managed to break a piston, yeah, dumb idea to put that in a Blazer anyway... So I had a 350 4-bolt main put in there in 2000, without ANY emission system (this means no EGR valve as well). Anyway, in 2002, a friend was helping me move from Colorado back to Washington, and he ran it out of oil, running it in Second gear, and not paying attention to the oil pressure. It started knocking 4 months later. Anyway, my buddies pitched in and are getting me a rebuild kit, but unless the knock is detrimental, there are some other areas on the truck where I could use the rebuild kit money. Just making sure it's worth it to rebuild.
 
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