Guys,
Last year I got a kink in my upper radiator hose which resulted in engine damage. In the quest to buy a spring for the upper hose, I came across this in AI. I thought it may be helpful to others. For me the spring is cheap insurance it doesn't happen again.
AI Overview
For a classic GMC Motorhome (1973–1978 with the Oldsmobile 455 or 403 engine), the upper radiator hose requires an internal coil spring or a heavy duty, thick-walled construction to prevent it from kinking, flattening, or collapsing during operation. [1, 2]
Because the upper hose travels a tight path beneath the front firewall and engine hatch, it is highly prone to hidden kinks that cause catastrophic engine overheating if not properly supported. [1, 2]
The Problem With Modern Hoses
Sourcing and Parts Solutions
Installation Tip
When transferring or adding a spring into a new upper hose, spray silicone lubricant or soapy water inside the hose first. Temporarily straighten the rubber bends and twist the spring in a corkscrew motion as you push it through the tight bends. Trim your molded hose ends carefully so it matches the factory length exactly and won't buckle under the engine cover. [1, 2, 3, 4, 5, 6]
If you are currently replacing your hoses, let me know if you need the exact NAPA part cross-references or if you are also changing out the thermostat at the same time. [1]
Am I overheating? | Page 2 - The GMC Motorhome Forum
Well-known member. ... Check your hoses. My upper hose got soft when hot and collapsed, causing an overtemp situation. The end res...
www.gmcmotorhome.org
Part Number - The GMC Motorhome Forum
New member. ... Joe, The interchange says Napa 8796 lower and Napa 9179 upper -- but mentions you have to cut them to length. Thre...
www.gmcmotorhome.org
3m
Lot's of good information, I hope it helps someone.
Take care,
Tom K.
Repl
Last year I got a kink in my upper radiator hose which resulted in engine damage. In the quest to buy a spring for the upper hose, I came across this in AI. I thought it may be helpful to others. For me the spring is cheap insurance it doesn't happen again.
AI Overview
For a classic GMC Motorhome (1973–1978 with the Oldsmobile 455 or 403 engine), the upper radiator hose requires an internal coil spring or a heavy duty, thick-walled construction to prevent it from kinking, flattening, or collapsing during operation. [1, 2]
Because the upper hose travels a tight path beneath the front firewall and engine hatch, it is highly prone to hidden kinks that cause catastrophic engine overheating if not properly supported. [1, 2]
The Problem With Modern Hoses
- Suction & Kinking: While the lower hose handles constant water pump suction, the GMC Motorhome's upper hose has a unique, sharp bend that collapses easily when the rubber softens at operating temperature. [1, 2, 3]
- Missing Springs: Most standard modern replacement hoses (like standard NAPA or Gates listings) do not ship with an internal spring pre-installed due to manufacturer cost-cutting. [1]
Sourcing and Parts Solutions
- The Preferred Method (Heavy-Duty Molded Hoses): Experienced owners recommend purchasing premium, heavy-walled molded hoses from dedicated vintage RV vendors such as Applied GMC, which stocks hoses specifically designed to resist flattening without needing a spring. [1, 2]
- The Retrofit Method (Adding a Spring): If you are using a standard replacement hose (such as the standard NAPA 9179 or Gates 26616), you should extract the anti-collapse spring from your old original hose and slide it into the new one. [1, 2, 3, 4, 5]
- Buying an Standalone Spring: If your original spring is missing or corroded, you can source a generic 12-inch stainless steel inner support spring (such as an eBay LS-Swap Upper Hose Spring or a standard 1.5" diameter GM lower support spring) and push it into your upper hose to keep the pathway open. [1, 2, 3, 4, 5]
Installation Tip
When transferring or adding a spring into a new upper hose, spray silicone lubricant or soapy water inside the hose first. Temporarily straighten the rubber bends and twist the spring in a corkscrew motion as you push it through the tight bends. Trim your molded hose ends carefully so it matches the factory length exactly and won't buckle under the engine cover. [1, 2, 3, 4, 5, 6]
If you are currently replacing your hoses, let me know if you need the exact NAPA part cross-references or if you are also changing out the thermostat at the same time. [1]
Am I overheating? | Page 2 - The GMC Motorhome Forum
Well-known member. ... Check your hoses. My upper hose got soft when hot and collapsed, causing an overtemp situation. The end res...
www.gmcmotorhome.org
Part Number - The GMC Motorhome Forum
New member. ... Joe, The interchange says Napa 8796 lower and Napa 9179 upper -- but mentions you have to cut them to length. Thre...
www.gmcmotorhome.org
3m
Lot's of good information, I hope it helps someone.
Take care,
Tom K.
Repl
