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I recently re-routed some coolant lines on my L28ET. On the passenger side of the engine, I removed a 3-way bypass valve and 3-way fitting out of the rear of the engine and replaced it with a 2-way valve at the rear of the engine. I have seen other engines like this and read it would be OK as long as I don't go crazy while the engine is still cold. Problem: After the engine is warm, the Temp gauge sits PEGGED at 250 degrees while driving. I was initially very concerned, but what I noticed is that while idling, it goes back down to it's normal operating range of 180 degrees! As I move, it climbs again (fairly rapidly). My gauge was working fine before I re-routed my coolant hoses. Also, my heater works so I know coolant is flowing through there. Where is this temp gauge? Is it absorbing hot hair from somewhere else? Any ideas why this might be happening? Here is how I re-routed my lines. From this: To this:

Hi guys. as some of you guys might have seen from another topic I started (http://forums.hybridz.org/topic/122459-air-intake-temperature-soar-when-i-step-off-the-gas/), I've been giving some thoughts to the air intake temperature. Afer poking around the engine while it was still warm, I realized that all the metal air pipes (duh, yeah i know, but it's important for heat conduction) were exposed to the warm engine bay air, and to the engine's radiating heat, and that the radiator's fan blew hot air pretty much directly on them. Touching all these nice pipes, I realized that the pipe from the turbo to the intercooler pretty much too hot to touch (duh again, I'd read about the heat coming from compressing the air but you don't realize how hot till you experience it). I also realized that the pipe from the intercooler to the throttle body started off cool and ended up very warm (can touch for a few seconds) close to the TB. The transition was quite sharp where I've placed a heat shield (sheet metal cut to fit around the pipes to try to limit the filter breathing in air from the engine bay - it didn't make much of a difference for the air temp there). I don't know if the heat shield is helping or it's just because the hot air blown by the fan hits the pipe from there on... I started looking around on the net, and some people had also thought of insulating this particular pipe. There is some debate as to the usefulness of doing this, and none of the sites were particularly methodical with the data taking, so i figured I'd try it, and gather before and after data too. Here is a series of pictures as to what I did to insulate the pipe (after gathering data; more on this later) this is the piping system, as I got the car (plus the heat shield I made) This is the insulation I've used. It's a foam tube to insulate house piping bought at a hardware store for 5$ for 6 feet, 2inch diameter. as you can see, I cut triangles out so I'd be able to bend it to follow the pipe. I eyeballed the cuts, and had to make the triangles wider only once to be able to follow the curve of the pipe this is the other side, since the pipe is s-shaped. with the foam almost all on the pipe to illustrate the use of the cuts With it all in place. tie wrapped on, ghetto style with ugly, white, break-if-you-look-at-them-too-long tie-wraps I had around The final product, with the heat shield seen from a different angle. I know there are gaps in the insulation, but i figure this can be a prototype and i can make it better if it turns out to be useful.... I'll try to post tomorrow on the data I've gathered about the intake temperature before the insulation mod; the file is on my work computer. I've gathered a bunch of info on how fast the temperature goes up once I'm parked iddling after the drive to work. I've got graphs and all, easy to read. post insulation data will be another week or so, I'm guessing, since I don't drive it to work every day (t-tops were leaky, and I've recently cut out part of the floor to fix rust, so no driving when it's wet) I'm also planning on changing the air filter location and making a cold air scoop under the radiator mount, so that and other data will be useful on that too. Stay tuned for other topics I'll start when I gather the supplies I need, the main supply I lack being time)... Comments and suggestions welcomed, follow this post if you're curious to see how it turned out. ******************************see posts 2 and 5 for info, and post 15 for a pre-emptive conclusion********************************