Yikes, this noise! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Berlinvet · 07-06-2018, 10:19 AM

Good day everyone. After perusing this forum for a while it’s time to ask directly about a problem I’ve encountered with my 327 SBC.

Backstory: recently I bought a 1968 C10 Fleetside LB 327 with a TH400 from an acquaintance. The truck had overheated on the highway but limped to a storage shed here in San Antonio. That was 18 years ago. The PO had rebuilt the engine to some extent, including a bore out. However he’s not too sure what else was done apart from piston rings and a few other basics. After evicting all the rats that had made a home in the cab I replaced the fuel tank,added inline fuel filters and installed new radiator and hei ignition. Oil levels looked good and eventually the engine fired up. After turning over by hand and leaving 10cc of Marvel Oil in each cylinder for a week. Changed the oil then. First big issue was a failing fuel pump diaphragm and copious amounts of gasoline in the engine oil. Instead of 5 quarts I must have drained about 10 quarts of oil-fuel mix. Replaced fuel pump and resolved the issue. Exhaust manifolds were both cracked and replaced. Topped up transmission fluid and took her out and back into the garage.

Next time the engine was started I noticed a grinding metal on metal sound that appeared to originate from the back and lower need of the engine. Scraping metal on metal with lots of friction would aptly describe it. Upon closer inspection the sound, which increased in intensity and pitch with increasing rpm appeared to come from the vicinity of the oil pan/starter/torque converter. Flywheel clearance to starter is within spec.

Transmission was pulled, torque converter removed flywheel inspected. Flywheel appears firmly bolted, doesn’t oscillate. The grinding noise is now gone but there is still a knocking banging noise coming from the back of the engine right above the oil pan.

Plan: install new torque converter and see what happens. Need to get brake lights to work then she’s ready for inspection. Not sure what’s going on or how to proceed with diagnostics. Any ideas?

07-06-2018, 10:19 AM	#1
Berlinvet Registered User Join Date: Jul 2018 Location: SAN ANTONIO, TX Posts: 14	Yikes, this noise! Good day everyone. After perusing this forum for a while it’s time to ask directly about a problem I’ve encountered with my 327 SBC. Backstory: recently I bought a 1968 C10 Fleetside LB 327 with a TH400 from an acquaintance. The truck had overheated on the highway but limped to a storage shed here in San Antonio. That was 18 years ago. The PO had rebuilt the engine to some extent, including a bore out. However he’s not too sure what else was done apart from piston rings and a few other basics. After evicting all the rats that had made a home in the cab I replaced the fuel tank,added inline fuel filters and installed new radiator and hei ignition. Oil levels looked good and eventually the engine fired up. After turning over by hand and leaving 10cc of Marvel Oil in each cylinder for a week. Changed the oil then. First big issue was a failing fuel pump diaphragm and copious amounts of gasoline in the engine oil. Instead of 5 quarts I must have drained about 10 quarts of oil-fuel mix. Replaced fuel pump and resolved the issue. Exhaust manifolds were both cracked and replaced. Topped up transmission fluid and took her out and back into the garage. Next time the engine was started I noticed a grinding metal on metal sound that appeared to originate from the back and lower need of the engine. Scraping metal on metal with lots of friction would aptly describe it. Upon closer inspection the sound, which increased in intensity and pitch with increasing rpm appeared to come from the vicinity of the oil pan/starter/torque converter. Flywheel clearance to starter is within spec. Transmission was pulled, torque converter removed flywheel inspected. Flywheel appears firmly bolted, doesn’t oscillate. The grinding noise is now gone but there is still a knocking banging noise coming from the back of the engine right above the oil pan. Plan: install new torque converter and see what happens. Need to get brake lights to work then she’s ready for inspection. Not sure what’s going on or how to proceed with diagnostics. Any ideas?



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