Heater Core bypass
 

Hey,

I removed my heater core after it went out and am bypassing it using HELP! bypass caps. I'd rather just do a U-turn with a piece of hose but the inlet/outlet are different diameters. Anyone out there do something similar? What is the sensor that plugs into one of the metal coolant pipes that's connected to the uppoer intake manifold? Does it take incorrect measurements when bypass CAPS are used since flow is eliminated? Can those two pipes (all one piece) be removed and the hole in the manifold be plugged? Will it set off a check engine light or will something else get screwed up if that sensor is disconnected? Thanks.

91 LX 5.0 FHP coupe

Thats the coolant temp. sensor for the computer. Leave it. There are several ways to get around your problem, but I would recomend just to replace the heater core. Its the best fix:)

If I recall, the sensor on the passenger's side of the intake is where the computer gets its temperature input from and the one on the driver's side is the sender for the temp gauge in the dash. If you block flow to the computer input, it's probably not going to be very happy about it. The ECM uses this input to determine which fuel map to use. With the flow blocked off, it'll always think that the car is still warming up. The sensor may not get hot enough for the computer to recognize that the engine is up to normal operating temperature. I plan on bypassing mine in the near future also. Let us know if you come up with any good ideas. I was thinking about relocating the sensor down into the coolant path. I'm not sure if that's possible. I haven't really spent any time looking at it since I decided to do it.

just use a U shaped piece of tubing and tighten down the hose clamps

I was working on something on my car a couple years back and accidentally BROKE one of the tubes off of the heater core going into the firewall. It was summer so I just pulled that tube out (about a 90deg bend in it) and used it to bypass the heater core. It worked great until november and I needed to use my defrost:D

You can buy male-male connectors with different sizes on either end. That's what I did until I decided to replace the core.

--nathan