86 305 blowing up?

[crazycrak]

I have a 86 K10 with a 305ci engine I drove it 30miles or so and came to a stop at a traffic light and it died. So I started it back and noticed a loud knocking sound and it was running rough. I pulled over checked the oil it was good the knocking sound was coming from the right side of the engine and was louder under the truck. So I baby it home it makes ok and seems to smooth out I checked all the fluids they were all good. I reved it quite a bit the knock seems to have went away. What could cause that? Is it spinning rod bearings?

 

[NHGUY]

Was there a lot of black smoke? The carb could have flooded the engine with fuel and it eventually cleared.Smell the oil/dipstick for fuel.

 

[crazycrak]

I didn't notice smoke but it did have a weird smell. Not like raw fuel I dunno what it was. Ill go smell the dipstick.

 

[440Magnum]

Check the simple stuff first. An 85 engine has a distributor, distributor caps can crack and start criss-cross firing plugs, which can make a cylinder fire WAY early and sound like you're beating a piston with a sledgehammer (which isn't far from the truth).

If a knock starts from a spun bearing, it will NEVER "go away" unless the engine chucks the rod out the side of the block. And you'd notice a few other symptoms in that case.

 

[crazycrak]

Oil smells like oil. clean and clear light brown turned my idle down a little bit and noticed that the trq. converter is hmming and the tranny fluid is under the add mark. Could the torque converter make noise like that. Ill check the dist. cap also it was a raining so that could make worse.

 

[45ACP]

Is this a SBC 305 "L03" engine?

If so, i can tell you that a lot of people dont like it and put stuff from a 350 in and on it.

 

[crazycrak]

How would I tell that?

 

[440Magnum]

Originally Posted By: crazycrak
Oil smells like oil. clean and clear light brown turned my idle down a little bit and noticed that the trq. converter is hmming and the tranny fluid is under the add mark. Could the torque converter make noise like that. Ill check the dist. cap also it was a raining so that could make worse.


Any chance you splashed a puddle as you came to a stop... Sounding more and more like a cross-firing issue to me.

Been there, done that, heard the noise, thought the engine was toast.

 

[Hokiefyd]

It could be that your flexplate is cracked.

 

[45ACP]

Originally Posted By: crazycrak
How would I tell that?


Online match the make (Chevrolet) and model (K-series) of your truck along with VIN in an online lookup and you will know.

 

[45ACP]

Originally Posted By: crazycrak
How would I tell that?


Actually, OP i went ahead and checked it out for you and it sounds like you do. This is a bit lengthy, but this is more info about your engine. Thank you!

305 The 305 5.0L variant of the small-block Chevrolet which was a 262 that was bored out and stroked using the crank of the 350 was introduced in 1975 had a displacement of 305 cu in (5.0 L) with a 3.7350-inch (94.869 mm) bore, and 3.4803-inch (88.4 mm) stroke. Many performance enthusiasts shun the 305 because of the wide availability of 350 engines, along with the fact that the same parts will yield much more power in a 350 cubic inch package. Due to the popularity of the 350, items like rebuild kits are more expensive for the 305. The 305 still has power potential due to the broad selection of aftermarket parts that are readily interchangeable with the popular 350. Not all cylinder heads may be adapted to this engine due to valves having bore interference or shrouding issues with the narrow bore of the 305 engine, but there are many LO3 setups that can produce over 300 horsepower from the right combination.

Induction systems for the 305 included carburetors (both 2 and 4-barrel), throttle-body injection (TBI), tuned-port fuel injection (TPI), and sequential fuel injection (GM Vortec).

The 305 was used in the following cars:

1976–1992 Chevrolet Camaro
1980 Chevrolet Corvette (California only)
1977–1993 Chevrolet Caprice (includes Impala)
1977–1986 Pontiac Parisienne
1976–1979 Chevrolet Monza
1976–1979 Chevrolet Nova (also GM X-body clones after 1976)
1976–1988 Chevrolet Malibu, Chevrolet El Camino, and Chevrolet Monte Carlo
1978–1992 Pontiac Firebird
1978–1980 Oldsmobile Cutlass (US Market only, Canadian market 1978–1987)
1991–1992 Oldsmobile Custom Cruiser
1981–1987 Pontiac Grand Prix
1975–1979 Buick Skylark
1977–2003 Chevrolet/GMC Trucks, SUVs, Vans
1991–1992 Cadillac Brougham
1978–1987 Buick Regal