Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum - View Single Post - just installed koyo radiator, question now.

niSm095 · 04-13-2007, 10:05 PM

Okay, so here's what has happened since.

To resolve the issue of the temperature dropping on the interstate, I went to my friend who assisted me in changing the thermometer. We agree that we aren't sure if the thermometer was lined up correctly upon installation, with the floating valve at the top. So we took it apart again tonight, find that it was pointing to 9 o clock when it should have been pointing to 12 o clock. Maybe an issue, maybe it wasn't. I dropped the thermostat on accident, went ahead and bought another just to be on the safe side. Installed it. Refilled coolant, bled the system...

Then, we went to drive around, test it out. As we got on the interstate I noticed the factory needle pointing a little higher than it should have been, and as we got on the interstate it slowly rose more. About 3 exits down the interstate, I got off, and started through some stop lights. At first it cooled a little, then about 1/4 mile down the road it began overheating again.

So we pulled off and opened the hood, checking first for leaks. No leaks whatsoever. Then we notice a bubbling sound from the back of the engine. Easiest way to describe the sound: if you were trying to force air/water through a straw, then bent the straw as it was passing through, there would be a gurgling sound. (In this case, more like hot, bubbling liquid). It sounds like the noise is coming from somewhere along the heater hoses, but it's too dark to see anything.

So now what we're thinking is that perhaps a heater hose is crimped, not allowing enough coolant through at higher speeds, as the engine is working harder, but at idle and low speeds, it doesnt need as much coolant, so the stinted flow of coolant is enough. Is that bizarre? Could that actually be the problem?

Only other option in the system are the temp sensors. And I planned on changing those tonight too, but ran out of daylight to continue working. Now that we heard the bubbling though, it doesn't seem to explain the problem. Although, it did seem to explain the earlier issue of the temperature dropping to cold on the interstate.

Help? Input?

04-13-2007, 10:05 PM	#6
niSm095 Zilvia FREAK! Join Date: Mar 2003 Location: S. Carolina Age: 39 Posts: 1,201 Trader Rating: (14)	Okay, so here's what has happened since. To resolve the issue of the temperature dropping on the interstate, I went to my friend who assisted me in changing the thermometer. We agree that we aren't sure if the thermometer was lined up correctly upon installation, with the floating valve at the top. So we took it apart again tonight, find that it was pointing to 9 o clock when it should have been pointing to 12 o clock. Maybe an issue, maybe it wasn't. I dropped the thermostat on accident, went ahead and bought another just to be on the safe side. Installed it. Refilled coolant, bled the system... Then, we went to drive around, test it out. As we got on the interstate I noticed the factory needle pointing a little higher than it should have been, and as we got on the interstate it slowly rose more. About 3 exits down the interstate, I got off, and started through some stop lights. At first it cooled a little, then about 1/4 mile down the road it began overheating again. So we pulled off and opened the hood, checking first for leaks. No leaks whatsoever. Then we notice a bubbling sound from the back of the engine. Easiest way to describe the sound: if you were trying to force air/water through a straw, then bent the straw as it was passing through, there would be a gurgling sound. (In this case, more like hot, bubbling liquid). It sounds like the noise is coming from somewhere along the heater hoses, but it's too dark to see anything. So now what we're thinking is that perhaps a heater hose is crimped, not allowing enough coolant through at higher speeds, as the engine is working harder, but at idle and low speeds, it doesnt need as much coolant, so the stinted flow of coolant is enough. Is that bizarre? Could that actually be the problem? Only other option in the system are the temp sensors. And I planned on changing those tonight too, but ran out of daylight to continue working. Now that we heard the bubbling though, it doesn't seem to explain the problem. Although, it did seem to explain the earlier issue of the temperature dropping to cold on the interstate. Help? Input?