background info.

ap2 stock engine with 150k. I had the stock radiator and on track with ambient temp @ 100 i would get a spike in coolant temps. 3/4 close to red. I turned on the heater and it drops back to half. I thought maybe old radiator and clogged up so i got a new mishimoto radiator and samco radiator hoses. Ran it for 2 years no issues. occasionally it would get 1 bar past half but would cool down really quick. I have bled this thing a bunch of times and used a bucket style on the radiator and no bubbles.

Yesterday outside temp 106 and its back to 3/4. Turned on the heater and its back down to 1/2 very quickly.

On my other ap2 i never had issues no matter how hard and how hot it was outside.

everything is stock such as water pump and thermostat. on the street everything is fine and even driving home in hot temps it never goes up.

 

No mods hanging off the front of car? Radiator shroud is intact? Fans working properly?

 

Check the fins on the AC condenser, see if a large amount of them have been sandblasted shut.

 

I have CR lip and a aut cooling duct instead of shroud but I had that on my old car as well

Billman. i take back what I said. The ac condenser does look like a lot of the fins are bent shut and don't allow as much air through.

Another thing is that I used a different radiator cap on my mishimoto as everyone said it works. I was skeptical after I measured the distance and found that the neck on the radiator is about .67 from bottom of inside next to top of lip. Aftermarket caps only measure .665 so I believe this doesn't seal the pressure inside. This could be the cause of my unknown coolant smell. I have tried my hardest to find the smell and I think this is it.

I would like to count out air bubbles

Any suggestions on how to straighten the fins?

 

Still wouldn't hurt to get an air gun, pull the radiator forward a little bit and blast out the condenser, you'll be surprised how much stuff can get in there. Also the bucket trick only gets 95% of the job done, there's always that last little bit of air you can only get with the bleeder.

 

I will give this a try.

Do I just unbolt the radiator and pull it torwards the engine a bit and give it a good hit?

I don't remember there being much play

 

Right, unbolt the radiator tabs on top.

 

They actually make a fin comb to straighten them. I have not tried it. A right angle pick and a lot of patience will do it too.

I had a customer running hot on track, the bottom 8 rows were sealed shut. This is from highway driving, sand knocks the fins shut over time.

Any missing plastic (undershield, upper piece with ac access cover) that takes away from the funnel effect of the grille will cause the car to run hot when pushed also.

 

Is your plate mounted in the grille ?

 

Before you do anything - have you checked to see what temp the water actually is at this reading? You might find that you just have a more sensitive gauge and the actual temperature of the coolant is within the normal acceptable operating range.

On my BMW (I know it is a different car), they say that any temperature that is not in the red is normal and acceptable and nothing to worry about. Obviously in extremes of temperature you would expect it to be higher, as the thermostat stays fully open and the temp then climbs more than you would normally see as the radiator nears it's thermal limit. Below that and in lower ambient temps, the thermostat is obviously opening and closing to keep the temp constant.