Long trips kill my truck. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Cat Fuzz · 12-13-2003, 03:35 PM

Drove across Washington state this last summer and I thought my truck was gonna die. After driving for a couple hours at 70mph, turning 3100 rpms, it would knock really bad at low speed while accelerating and go away when I got back up to speed or if the truck sat for awhile. The engine didn't get anywhere near overheating. Maybe the vacuum advance is sticking? HEI, btw. Any thoughts?

67chevemall · 12-13-2003, 04:00 PM

Poor Build Bad Mantiance Bad seals,oil worn tired!
$3000 outha fix her!

tom hand · 12-13-2003, 06:16 PM

How old is the motor? Could just be carbon buildup...when you drive it at speed it gets hot (the carbon in the combustion chamber) and makes the motor "ping". After it cools down it stops. What octane fuel are you running....higher octane may stop it.

cableguy0 · 12-13-2003, 09:01 PM

if its a knock its probably rod bearings because after driving for so long at those rpms the oil will thin out and not protect nearly as well

Cat Fuzz · 12-14-2003, 12:02 AM

Not rod bearings. I rebuilt the engine myself about 10 years ago. I spose it could be carbon. It is definatly a pre-detonation knock. Not bearings.

12-13-2003, 03:35 PM	#1
Cat Fuzz My son, my joy. Join Date: Sep 2003 Location: Spokane WA Posts: 463	Long trips kill my truck. Drove across Washington state this last summer and I thought my truck was gonna die. After driving for a couple hours at 70mph, turning 3100 rpms, it would knock really bad at low speed while accelerating and go away when I got back up to speed or if the truck sat for awhile. The engine didn't get anywhere near overheating. Maybe the vacuum advance is sticking? HEI, btw. Any thoughts?

12-13-2003, 04:00 PM	#2
67chevemall Registered User Join Date: Apr 2003 Location: NB Posts: 3,367	Poor Build Bad Mantiance Bad seals,oil worn tired! $3000 outha fix her! __________________ 1968 Chevy C10 307 3ott fleetside 1967 Chevy C/10 V8, 3spd, fleetside lwb.Sold 1967 Chev C/10 step, 383, M21. SOLD

12-13-2003, 06:16 PM	#3
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	How old is the motor? Could just be carbon buildup...when you drive it at speed it gets hot (the carbon in the combustion chamber) and makes the motor "ping". After it cools down it stops. What octane fuel are you running....higher octane may stop it. __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS Last edited by tom hand; 12-13-2003 at 06:18 PM.

12-13-2003, 09:01 PM	#4
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	if its a knock its probably rod bearings because after driving for so long at those rpms the oil will thin out and not protect nearly as well __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

12-14-2003, 12:02 AM	#5
Cat Fuzz My son, my joy. Join Date: Sep 2003 Location: Spokane WA Posts: 463	Not rod bearings. I rebuilt the engine myself about 10 years ago. I spose it could be carbon. It is definatly a pre-detonation knock. Not bearings.



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