Ok I am new to your board but I have browsed it quite a few times as a guest so thanks to all the post's that I have already searched in regards to this problem. So let me give a lil history.

I have a 1998 GT Coupe that I have recently done quite a bit of standard work on before my current problem happened. In the last 3 months I have replaced the Tensioner Assembly, Belt and Valve Cover gasket's, as well as flushed the radiator which from what I could tell previously had dexcool. Shortly after flushing the low coolant light came on so I topped it all off and it went away. Recently however the light came back on, when researching I saw that the cap on the overflow bottle had busted and fluid was spraying all over so I also replaced that, but after doing all this and topping off radiator fluid I noticed when at idle for 5 min or more than temp shoot's up to 210 (no higher) but stay's normal (185) when the car is moving...210 is the halfway point for those that need a visual, and another thing, it never goes higher than that.

I did my research thru your topics and checked a number of things, starting with Thermostat, replaced it with a 180 TSTAT per suggestion's and monitored the car again.... after engine warms the same problem occur's... temp shoot's to 210 when sitting at idle. I saw while watching engine though as soon as it hit's 210 the fan's come on and temp shoot's back down to normal range again. this process continues, the fans always kick on at 210 and engine temp drops back down to normal, only to go back up again.

I also have bled the air significantly out of cooling system so I know that's not the problem, I can feel the water moving thru upper hose...I am confused as hell here....

The car NEVER got over the 185 range by much in the previous year and half I have owned, and with summer coming here in Phoenix I want this resolved...If you have ever been here you would know why!

My only other thoughts are a sending unit maybe?

HELP!!!!!!

One more thing, the low coolant light no longer come's on.

AN update about this, I started thinking and all this seems to have started around the time that I Replaced the tensioner assembly, I remember replacing the O-rings on the elbow that run's from the bottom of tensioner into the block, and also the car is leaking medium amounts of coolant under the passenger side of the car once I stop driving and the engine is shut off....

I am wondering if this is all related to the tensioner assembly replacement or the water pump, I looked at it pretty thoroughly yesterday with the wheel shroud off and the car jacked up and could only see the fluid on the ground but couldnt see where it was leaking from.

One more and final update, I was just looking at the engine from the top, I am all but convinced now it's coming from Tensioner area, the coolant is pooling in small amounts above the back Valve cover. the only thing close to this area that could spill coolant I believe is the tensioner?

I didnt torque the bolt's on the assembly when installing the tensioner which I now believe to be a mistake.

What do you all think?

Honestly, temps going to 210 when sitting idling isn't that bad for a stock PCM that hasn't had the fans adjusted.

Coolant above the valve cover? Sounds like a possible lower intake leak.

It is when you live in Phoenix you have 100+ degree temps 5 months a year and it NEVER went above 180 up until I flushed it and replaced the tensioner.

I am 100% positive it's NOT coming from LIM, I just changed my oil yesterday and oil color was normal

You can have external LIM leaks that don't fall into the valley and into the oil.

Anyway, my old engine used to hit 210 all the time in traffic in my weather.

Well I guess it COULD be the LIM but the timing is just to much of a coincidence for me to think that is the problem.

Well, I've had most of my current engine apart and only torques things that really mattered. I sure didn't torque the tensions assembly and it seems to be doing fine.

However, I'm curious where you got orings for the elbows: were they the right size? I replaced the whole coolant elbow and used an oring off the lower one in the pack for the metal piece of the arm that goes into the block ('99+ use two plastic elbows).

The new tensioner came with new O-rings when I replaced it.

I am a victim of my own circumstance, I was thinking back again to when I replaced the valve cover's, the alt bracket and some of the tensioner bolt's had to be removed or loosened and at the time I noticed after doing so that I had leaked a small amount of coolant. but thought it was due to loosening the tensioner

I am going to remove the alternator when I get home it is restricting my view but I want to check and make sure the tensioner bolts are tight and that it's mounted completly flush.

Could it be the coolant elbow?

I thought about that too, I cant remember a second elbow on it though, just the one in the front of the tensioner, I keep reading about a lower and upper elbow but I only see the one and I don't remember a lower one, Anyone know if on the 98's there was indeed 2 elbows on the tensioner?

As I said in my last post, only '99+ use two coolant elbows. On '97-98 the lower one is made into the tensioner.

Ok I found out exactly where the leak was coming from, and am providing pic's,

The location is in the valley behind the rear valve cover next to a bolt and one of the bolt valley's is filling with coolant slowy as the engine warms and the car run's, as it fills it spills over to the adjacent valley's and eventually down the side behind the alternator and down onto the ground. I believe what I may have done is loosened this bolt when I was trying to take off the alternator bracket to replace the valve cover a couple weeks ago.

First time I have done this kind of maintenence on this car and the Hayne's was a lil sketchy on removing the alt bracket...

First pic with the arrow is the leak, second pick is the next bolt to the right which you can see much better, the coolant fills this valley and then spills over to the right and left.

Pics didnt take, here are the links.

http://i65.photobucket.com/albums/h224/awallburg/leak1.jpg

http://i65.photobucket.com/albums/h224/awallburg/leak2.jpg

hey, another Desert Rat! I call NW PHX home. Ya know Luke? Yeah, from right around there? Graduated Dysart High School. Also, Ifitwasnt4u is there in Glendale, IIRC.

On to the car: Here in Las Cruces, NM my car normally idles in traffic at 210* during the summer. I would suggest you make sure the coolant line and clamp that you pictured are in good shape. The hose may be degraded due to dry rot or the clamp gave up the ghost.

Welcome to the boards. good folks, great info. hope you enjoy your stay here.