# Temp gauge fluctuation



## mikeROLEXX (Feb 27, 2014)

Hello all, I have a 2009 Routan SEL 4.0 engine. Last week I smelled a little antifreeze as I was at the gas station, I didn't think anything of it because I thought maybe it was another car. Then as I was idling I noticed that the temp gauge was around 205-210 and went back down. So I checked the coolant level and it was a little low so I added more to the MAX line. I notice that when I drive it stays at 195, then as I slow down at a light it will go down to about 185-190. I was idling for about 5 mins and it went up to 200 then the needle literally bounced to 205, then went back down to 195, I have not seen it go past 205-210 so I am a little confused about this one. The fan was not on when I popped the hood at when I first started idling. As I said earlier I do smell a faint smell of coolant but I dont see any spots on the ground, I also checked the oil and it looked normal, no milky look. Any opinions?


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## 58kafer (Jun 27, 2007)

The smell is coming from the Y in the hoses, just over the transmission. There are 3 hoses roughly an inch in size that joint is a plastic Y, and the plastic Y cracks. Mine went around 36k. There is a thread on that here some where, probably a few pages back maybe. As far as the fluctuation, that probably should get repaired first. I vaguely want to say our 4.0 will climb a few degrees if I'm on it. Honestly never paid that close attention. 

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## georgef61 (May 16, 2011)

58kafer said:


> The smell is coming from the Y in the hoses, just over the transmission. There are 3 hoses roughly an inch in size that joint is a plastic Y, and the plastic Y cracks. Mine went around 36k. There is a thread on that here some where, probably a few pages back maybe...


Here are two of the threads discussing the plastic Y:

Heater Hose Assembly Leak?

Aftermarket Heater Hose Y assembly now available for the cracked pipe


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## mikeROLEXX (Feb 27, 2014)

Thanks for the help, I did find that it is the Y fitting, I am hoping to get one of the replacement parts posted in the other thread and fix it this weekend.


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## cscsc (Jun 14, 2009)

Here's the one I'm watching in case I need to replace the hoses:

http://www.amazon.com/Dorman-626-30...automotive&vehicleId=4&vehicleType=automotive

Let us know how it turns out.


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## mikeROLEXX (Feb 27, 2014)

So I finally got around to replacing the y conector. However I am still having fluctuation issue, I noticed yesterday it got up to about 220 and it stayed there for awhile. I also had the AC on during this time and it was about 90 degrees outside. I'm guessing the next step is the thermostat. Also, I noticed my oil was a little low, could that have issues with the temp?


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## ncpsu (Aug 14, 2008)

I notice that my temp will fluctuate when in traffic on hot days to about 215 compared to normal 195 range on my 09 4.0l recently was on a quick day trip with family in a newer t and c with the 3.6 and theirs was acting in the same manor. Once back up to highway speeds, temps dropped back down almost immediately... Never see this behavior on my other vehicles only the van... 

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## Zambee500 (Jun 23, 2011)

That doesn't sound to me like a thermostat issue, ncpsu. When t-stats fail it's usually in the open position, which means takes longer to warm up but once warm then never going hotter than normal. Have you checked your coolant level and that your cooling fans are working? 

Maybe coolant temp sensor gone bad, but in my personal experience that's usually a bouncing needle or the needle either works (normally) for awhile and then doesn't work at all (i.e., needle is left of "C" like when motor is shut off).


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## ncpsu (Aug 14, 2008)

Yes coolant levels are good on my van as well as my father's newer t and c with the 3.6. Very odd and only when in heavy stop and go traffic on very hot days. I'm about to hit 100k on the van so will be doing a flush coming up soon.

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## TCM GLX (Jan 2, 2000)

Im at 90k on my Routan, it's a 2010 3.8, having the same issue. Subscribed for more update.


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## der58sc (Feb 4, 2010)

My 2009 SE Routan is having the same issue. Mine will be fine one minute and the next bounce from 190 to 210 to 100 to 150 to 0 and so on. It does from time to time return to normal but never really that long. The coolant is normal. I thought of replacing the temp sensor but thought I would look into a cause before I start replacing parts. 

Also my wife has had the car steam a few times when sitting in traffic. I have checked the coolant and it is still normal. She said the last time when it steamed the temp said 200. 

So I am hoping to find an answer for this soon since the last thing I need is for this car to overheat and cause problems.


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## trbochrg (Dec 1, 2004)

Our Routan was the only vehicle i have ever had that the temp gauge moved at all once it reached "operating temp" . Idling in traffic in the summer it would climb until i started moving and then it would go down.


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## der58sc (Feb 4, 2010)

I believe I might have found the issue since it is no longer happening on my Routan. 

I found that my reservoir tank was empty so I filled it up with coolant. I also took the time to fill the radiator since it seemed to be low. After filling both with coolant, I have not had the temp gauge bounce on me. So I would highly suggest to try to put coolant in the radiator to be sure it is full. Then check your reservoir. 

I am monitoring the coolant level to make sure I don't have a leak somewhere since I see no signs of coolant leaking anywhere now. 

Why my coolant got so low? My only guess is that when the Y tube broke twice, it was not filled by the dealer or myself when we both replaced the connector. Stupid on my part. I should have checked and filled it when I fixed the Y connector.

Used to having an air cooled VW, not a water pumper


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