The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 1979 Chevrolet C70 Conversion to OEM Air Conditioning

Airdirect · 12-10-2023, 02:20 AM

Time for a update. We have driven this truck almost 40,000 miles. The drive train has been flawless except for the Air Conditioning. I am on my 4th A/C compressor. First Compressor locked up forcing me to flush the system and replace the dryer and evaporator. The second one developed a bad Freon leak, the third had the clutch start slipping. The A/C works great, just wished GM had used a different compressor in this era.

I hauled a tractor and other equipment up to a show in Southwest Missouri. I noticed that the engine started to miss and smoke at idle. Once off idle it was clean and smooth running like normal. I decided the rack and valves needed to be adjusted. When I got home, I removed the valve cover and adjusted the valve clearance. Overall everything was real close. The rack was perfect and needed no adjustment. Once this was completed I still had the miss and smoke.

I did another 2,700 mile trip to Northern Indiana. The engine ran find above idle and did not use or leak oil. We continued to have the miss and smoke only at idle. I am thinking I have a broken piston top, or failed Top compression ring. When I get some time and room in the shop I will remove the head to see what the problem is.

12-10-2023, 02:20 AM	#208
Airdirect Registered User Join Date: Oct 2016 Location: Powderly Texas Posts: 299	1979 Chevrolet C70 Conversion to OEM Air Conditioning Time for a update. We have driven this truck almost 40,000 miles. The drive train has been flawless except for the Air Conditioning. I am on my 4th A/C compressor. First Compressor locked up forcing me to flush the system and replace the dryer and evaporator. The second one developed a bad Freon leak, the third had the clutch start slipping. The A/C works great, just wished GM had used a different compressor in this era. I hauled a tractor and other equipment up to a show in Southwest Missouri. I noticed that the engine started to miss and smoke at idle. Once off idle it was clean and smooth running like normal. I decided the rack and valves needed to be adjusted. When I got home, I removed the valve cover and adjusted the valve clearance. Overall everything was real close. The rack was perfect and needed no adjustment. Once this was completed I still had the miss and smoke. I did another 2,700 mile trip to Northern Indiana. The engine ran find above idle and did not use or leak oil. We continued to have the miss and smoke only at idle. I am thinking I have a broken piston top, or failed Top compression ring. When I get some time and room in the shop I will remove the head to see what the problem is.