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First time forum member! I have a replacement heater core for my ordered and purchased new 1988 F-250 4x4 XLT Lariat with 460 ci engine and AC. My questions are:
1 What to use and best placement of the weatherstripping not installed on the new replacement core, and
2 Is there a correct directional flow within the core? I'm aware of the supply and return locations for the hoses from the engine, but like a dumb s... when I disconnected the hoses to the core to avoid the leaking coolant on the floor, I simply looped 5/8" hose from t-stat to water pump fittings, and forgot to note which hose went to the right and left oriented core connections.
My guess is that the heater core connections are not directional, unlike the engine radiator. Thanks for any replies.
First time forum member! I have a replacement heater core for my ordered and purchased new 1988 F-250 4x4 XLT Lariat with 460 ci engine and AC. My questions are:
1 What to use and best placement of the weatherstripping not installed on the new replacement core, and
2 Is there a correct directional flow within the core? I'm aware of the supply and return locations for the hoses from the engine, but like a dumb s... when I disconnected the hoses to the core to avoid the leaking coolant on the floor, I simply looped 5/8" hose from t-stat to water pump fittings, and forgot to note which hose went to the right and left oriented core connections.
My guess is that the heater core connections are not directional, unlike the engine radiator. Thanks for any replies.
ISSUE: A gurgling noise coming from the heater core at cold start may be caused by improper heater hose routing.
ACTION: Check for proper heater hose routing. Refer to the following procedure for service details.
1.Check the vehicle for proper heater hose routing. Refer to Figures 1 through 4 for the various engine applications.
2.Check the heater core outlet tube.
a.This tube has a "T" fitting with a hose routed to the radiator. This hose provides a path for air trapped in the system to bleed off to the radiator.
b.If the "T" is routed in the heater core inlet hose, the gas evacuation system will not function and cause a gurgling noise.
Last edited by AuroraGirl; Feb 16, 2026 at 05:50 PM.
Reason: NOTE: I just put the diagram for the 460 here. so its less confusing
You're the best!!! Thanks for the quick reply, and the diagram. No more wet carpet, anti-freeze smell, and a warm cab again. I just posted a second question about my wiper issues, and some pics of my truck. Thanks again.
You're the best!!! Thanks for the quick reply, and the diagram. No more wet carpet, anti-freeze smell, and a warm cab again. I just posted a second question about my wiper issues, and some pics of my truck. Thanks again.
Just realized that quick reply doesn't necessarily send all of what I wrote. Not that important, but in the last 24 hours I've begun to learn how to use this site by first searching for past threads relating to a question/problem. FTE staff's "before you post" was a great explanation as to how to use the Search function before posting and starting a thread.
Also, my thanks to AuroraGirl for a diagram of exactly what I needed, and maniacmechanic007 for beginner tips. This site is fantastic! I've been reading posts all day, and it's a good thing I'm retired.
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Heater core flow direction
