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Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
8/8/19 12:45 p.m.

If it's stabilized at 220, you're fine. I've seen north of 260 without hurting the engine, but I was worried! I don't have a go/no-go temp, I tend to monitor trends. Short shifting at 6000 has a pretty big effect on the cooling.

Advertisement time! Flyin' Miata has developed a coolant reroute kit that is the first on the market that takes turbo cars into account :)

Patientzero GRM+ Memberand Reader
8/8/19 12:46 p.m.
morello159 said:

Somewhat related but may be partially off topic - when do you start to worry on a turbo track car, Keith? Running my car at Atlanta Motorsports Park I was seeing mid-220's after about 15 minutes of hard track driving in 90 degree Atlanta (humid) heat. It drops back down quickly once I let off but I am a little too scared of hurting something to push it any further.

I would be ok with those temps especially in that heat.  One thing to consider though is if your turbo is water cooled or just oil cooled.  If it's just oil cooled I would get an oil temp sensor asap.  Conventional oil starts breaking down around 240-260 degrees.  Synthetic is usually good for about 300.  If your coolant temp is already 220+ then your oil is usually 20+ degrees hotter than that.


morello159 Reader
8/8/19 1:09 p.m.

Keith - I also have a VVT engine in my car. Any data on the efficacy of the reroute on engines with the factory 01+ head gasket? 

EFR6258 is oil and water cooled, and I do short shift at 6k to keep temps down already. I don't think I ever saw water over 230, but it was definitely hovering in the 220's for a good while. IAT's about 103 with a precision 350hp intercooler. I have a setrab oil cooler located in the FM spot (steering rack), supermiata radiator, and the singular hood vents. Chopped up factory under tray. No reroute though, and no oil temp gauge (only one output on the sandwich plate for the oil cooler).  Running Rotella T6.

AWSX1686 GRM+ Memberand SuperDork
8/14/19 7:48 a.m.

Sunday I replaced the Radiator and installed the plastic under tray. (Radiator was less than $60, so I figured why not.)

Monday I drove it to work, the morning was cool and the car was fine. Going home it was pretty warm out, and driving home it got up to 223*, but given the above posts that I should be good to 240* at least, I kept driving normally (didn't turn on the heat) to see what it would do, and it eventually went back down. 

I drove it to work today too, so we'll see how it is going home today. I am wondering if the "spike" from Monday was just the system bleeding itself a bit. 

AWSX1686 GRM+ Memberand SuperDork
8/15/19 8:53 a.m.

Not quite as hot of a day yesterday, but going home the hottest coolant temp I saw was 207*, and it was fluctuating back into the 190*s, so I'm pretty happy. 

AWSX1686 GRM+ Memberand SuperDork
8/22/19 2:26 p.m.

Saw 217* this afternoon. Can't decide if I should mess with it more, or leave it since it goes back down... Also because the stock gauge in the dash claimed that was still fine, I only saw the temps from my OBD2 app. Is the app just making me paraniod?

Dashpot Reader
8/22/19 2:48 p.m.

Probably a case of too much info. 217F is not boiling in a pressurized cooling system, you won't boil over 'til >250 or so with a stock cap & straight water.

Was this at cruise or  stop & go? Does either your ear or your app tell you whether the fan was activated? 

GameboyRMH GRM+ Memberand MegaDork
8/22/19 2:49 p.m.

217 on the street still seems hotter than it should be, I would be inclined to mess with it until it never exceeds 210 with gentle street driving.

AWSX1686 GRM+ Memberand SuperDork
8/22/19 5:22 p.m.

I agree, 217 seems hotter than it should be, and on the way home I hit 221. 


Here's the trip home:

5-6 Stoplights before the highway, car is getting up to temp.

Get on highway and sit in stop and go traffic for 2-3 miles, occasionally moving at ~20mph, but that doesn't help temps. (Temps reach 221* peak, and stay there till I really get moving.) (Intake temps got pretty hot here.)

~18 miles of highway. Takes a while to lower from 221, eventually lowers, and floats around 210-216 the rest of the highway. (~70mph highway)

~15 miles of rural highway, ~55mph, temps finally start getting to a more acceptable range, as low as 199, but more like 203-207 most of the way.

Once I was home and stopped, I popped the hood and verified that both fans were running. I don't have a good way to check that while driving. Also not sure if there is a high/low setting on the fans. 


Known issues:

  • P0031 (Front O2 sensor I believe. Have, but need to take time to replace as it's stuck pretty tight.)
  • P0037 (Rear O2 sensor I believe, this code is newer.)
  • P0128 (Coolant temp below regulating temp. Possibly because I drilled 2 1/8" holes in the thermostat to assist with flow and bleeding.)
  • After coming to a stop after a long drive, sometimes I'll get a fuel smell. 
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