well I am having a different kind of issue than normal. When I first got my Maro I was having overheating issues, but got them all fixxed. thta was 2 months ago. now my car wont heat up!

I drive 96 miles one way to work, normally with the AC on and cruise set at 75-80mph. normally my temps aree just under the 220 mark. well that changed yesterday. the whole way to work my temp needle was at the mark between 100 and 220, which according to my math is about 160. I had a 180 deg tstat in with a manual switch for my fan. I confirmed that the fan was off, but hte temps still stayed to low. when i got t home this morning I pulled the tstat. it was locked open. guess that explaines it not warming up right? welli replaced the bad stat with a new 180 deg one. still wont get hot. while driving at 75mph, tach sitting on 2800-3200 depending on hills and such the temp stays about 160. if i get into traffic and slow down a BUNCH ie stopped at a light it will warm up to 220 and the fan kicks on automatically, but if I start driving gain it cols right back down to 160. if I let it get up to about 200 so that the fan hasent kicked on yet and start driving fast, it cools off the 160. I checked this stat in a pot of boiling water, once the water hits 180ish it starts opening li9ke it should.

things I think are causing it...

1. I always drill two holes inteh stat plate so there is always a bit of flow. I couldnt find my 1/16 bit so I used 1/8th and drilled two holes.

2. My car is a RS with the factory louvered grill insert in the bumper. I recently pulled the insert out as I mounted a pair of 100W driving lights on the metal bumper support behind it.

coud the holes be to large and allowing to much flow through the motor not keeping enought heat in it? but if so why would it heat up properly once standing still.

Coud the louverless bumper be allowing to much airflow across the radiator thus cooling it to much?

I have a factory prom so I know it is not programmed to be cold.

What shold I check?

 

I know some people would like to have your problem

The first thing I would do is check the temperature
gauge or sender.

Later

Irocing

 

You answered your own question. Dont drill holes in t-stat.
POZ

 

ok, if the holes are the problem, thenwhy does it heat up at a stop and then cool off at speed? wouldnt it stay cold all teh time? I bought a new tstat today and will throw it in tomorrow. I have been putting small holes in my Tstats for the last 15 years and never had a problem. normally I put 4 1/16 holes, but this one time I put 2 1/8 holes. arent they the same cross section?

 

ok, replaced Tstat with factory 195 since winter is coming and did NOT drill my normal holes in it. somehow managed to crack my Tstat housing, bought a new one, stripped on of the bolt holes in the mani for the housing, drilled, tapped, and installed Helicoil in the WRONG bolt hole, so I repeated for the right side... Temp on the guage STILL only goes up to the mid mark between 100 and 220. I bought a new guage sender and once the car cools down Ill throw that in, but Im curious if it was the guage, the fan would still be coming on. But it isnt as the car is NOT getting over 220!

I guess maybe it is the fact that i took the RS louvered Grillout of the bumper when I installed my driving lights. car looks MUCH better iwthout it I think, but if it is causing this much issues Ill put it back in.

Ill post up my results later today....

The saga never stops does it?

 

I seriously doubt that it is your grill... I think your temp sender may be faulty. The thermostat should not even open until the given temperature, so that kinda makes airflow a non issue (the water wont flow until it has heated past that mark). As far as the fans not coming on... I dont think that they will kick in until it reaches a cirtain temp (like 220* or so with the stock chip I believe). If your car isnt reaching that temp, the fans wont kick on. You could also have a bad CTS, which would not notify the ECM of the proper temperature.

 

Well a properly working airdam, will cool it down quite a bit, I had it happened before my airdam got lost.

 

well, I have kinda given up on this right now. I think the actual guage in the dash is messed up. I replaced the sender and it still does the same thing, goes to 160 adn stops. I found out that my fanswitch IS cutting on the fan, but the guage just isnt reading that high. I am waiting untill my B-day and my wife BETTER get me the autometer water temp guage I told her I want. If she dont thats fine, Ill just get it for me. Now I m fighting a different issue... not cooling related. Ill add to this thread after the new guage is in with its results.