curt7448

iTrader: (1)

I was leaving the car show on Saturday, and after a quarter mile I looked down and saw my temp gauge was near the top of the normal line. So I pulled off and checked the coolant levels and they were fine. So I called a tow truck and had it hauled back home. Monday was a holiday so everything was closed until Tuesday. I took the car Tuesday to the shop and had them check it out. They called Wednesday and said it was the thermostat that I had just changed out one month ago. I went and picked up the car last night and drove it home, and it was fine. So I wake up this morning and head to work and I get about 15 minutes down the road and it is back at the top of the normal line. I took it back to the shop and they are looking at it right now. What is the world could this be?! I asked him if the water pump was working and he said yes. I thought I'd ask you guys in here. I have a 2004 350z touring with 80k miles and a short ram intake. Let me know what you guys think!

ASNTech

Since none was mentioned, I must assume there is no check engine light. Never hurts to ask, though.

Have you checked the actual temperature of the coolant with a thermometer to make sure the readings with your coolant gauge are approximately the same? If they are, you have a mechanical issue relating to your cooling system (obviously). If they are not the same, you possibly have an electrical issue somewhere between your ECT sensor and your gauge. I don't consider the latter much of a possiblity as long as the car is starting off cool (according to the guage) and is warming up as it should.

Have you tried using your heater recently? Being that it's summer, I'll assume the answer is no.

Seeing as how you just changed your thermostat (which begs the question, Why?), I'm willing to bet you have air trapped in your system that needs to be bled out. I can walk you through it but I'm sure if you search, you'll find the process. It's easy and relatively quick.

curt7448

iTrader: (1)

I don't have any check engine light on. The car starts off at cold temp, and warms up normal. I had my coolant temp sensor replaced as well because the car wasn't warming up like it should be. When I replaced that I also had them check the thermostat, and there wasn't a thermostat in there when they opened it up. The previous owner has removed it....and now I'm wondering why. I have turned on my heater now trying to pull heat away from the motor while I try and limp the car to the shop and it blows hot air. If you could walk me through how to bleed the system that would be wonderful. When the mechanic drove it yesterday after "fixing" it he said he drove it for 15-20 minutes and it didn't over heat. Would air in the line make it work fine for him, and not fine for me?

curt7448

iTrader: (1)

My last message was kinda confusing. I had the temp sensor and thermostat replaced about a month ago, and that is when I realized that there wasn't a thermostat in the car. So a month ago is when I had it changed out for the first time. Now a month later I am having over heating problems.

ASNTech

You can buy a coolant bleeding funnel to make it easier or you can jack the front end as high as possible with the radiator cap off. Let the engine idle with the heat on full blast. If there is air in the system, you'll see bubbles leaving the system. You'll want to top the coolant off b/c if there is a lot of air, you could possibly reintroduce more air by not keeping it filled. It's worth a shot before you go replacing more parts.

Try this and report back.

0jiggy0

iTrader: (13)

The previous owner removing the t stat is weird. I'm betting the car had issues and that was the easiest way to make the car seem like it wasn't overheating. Maybe he had the car boosted,developed a hg leak and returned it to stock before selling you the car.

curt7448

iTrader: (1)

I called my mechanic and told him what you said and he told me he would try that next. Worse case scenario, what if I decide to remove the thermostat again like the previous owner did? What problems will this cause? And is it ok to do this?

ASNTech

Check engine light...probably code Thermostat Function.
This next thing is purely opinion but we have run into this with our race car and I've heard (and agree with some) both sides of the argument.

Removing the thermostat means you're elminating your car's ability to heat up in a timely manner. Another thing a thermostat does is slow your coolant down. Whether or not this is bad probably varies from one manufacturer to the next. I think testing must be done to determine if this optimal. On our track 240, it actually RAISED our ECT.

Why? I think the lack of thermostat opened up the coolant system to a faster flow. At first, this sounds good. More water through the radiator...sounds win/win. Not that easy. What I believe happens is that a faster coolant flow results in the water spending less time in the radiator, essentially decreasing the radiators effectiveness. By installing the thermostat, we immediately saw a change for the positive.

You can buy "performance" thermostats that open at a cooler temp or you can go ghetto and gut a thermostat so that it flows more like an open but does so all the time.

Before you go any further, bleed it. If that doesn't solve anything, we'll brainstorm on the next step

curt7448

iTrader: (1)

Alright. I will probably post later on tonight with some sort of result hopefully. I won't get to see the car until around 5:15PM EST, and we will see if it is fixed....or if it is still jacked up! I will post an update later. Thank you again for everyones help.

curt7448

iTrader: (1)

I took ASNtech's advice and talked to my mechanic and had him jack the front up and bleed the system of any air. He jacked up the front of the car as far as he could and took the radiator cap off and let the car run for 15 minutes with the heat on full blast. There were a lot of bubbles that came out of the system in that time frame. After the last bubble surfaced he let the car run for another 15 minutes and in that time there were ZERO bubbles that surfaced. So when I got there they told me to take it for a test drive for about 20 minutes. I tested the car under hard acceleration, light acceleration, and I idled at a stop sign for about 3-4 minutes. The needle didn't move above the normal mark even a millimeter. So as of right now it looks like the problem is solved! I will test it on the way to work tomorrow (about 25 miles each way) and see what happens! Thank you all for your input to my problem! I hope this will help anyone else who runs into it.