Overheating slightly on highway ONLY

[93'colttsi]

Okay, this is sorta a weird one. My 1g runs hot on the highway (220-230) on the highway, only going over 100 km/h, and only when the ambient temperature is over 30+ degrees Celsius. I can drive the car around all day in town, race the car at the track over and over again, and it never overheats. It also never boils the coolant and never uses any coolant or pushes any excessice amount into my overflow tank ( and i have a smaller honda civic overflow). Fans cycle quickly when idling ( turn on around 209 degrees (datalogger). And then drop to around 199-203 degrees and cycles on/off like normal. Full 1/4 mile races I see 209 degrees, maybe 211 degrees max.

This is also just at a steady cruise on the highway as well. Not boosting at all. I have to turn on the heater full blast too keep the temps down to 216 or lower when cruising at 120 + km/h on hot days

I have a gmb water pump, mishimoto aluminum radiator, duel engine bay side slim Fans, (wired to stock wiring). I also have a large core (vrsf style) intercooler. NO air conditioning on my car whatsoever.

I would think that at highway speeds the radiator fans wouldn't even be needed... so I'm thinking I have some weird air flow problem or something going on at highway speeds.... or maybe just my thermostat isn't opening all the way.... just put a new oem temp 195 degree thermostat in tonight but havnt hit the highway in +30 degrees temps yet.


Any ideas?

 

[boostdawd]

So this is just cruising on the highway and not going WOT. I would imagine airflow having a big effect on this. Have u recently changed anything since this started happening or has it always been an issue?

 

[93'colttsi]

This has always been a issue. Is fine all through the fall, winter and spring where the temps stay below 30 degrees. Only on hot days in the summer. Even driving in a shady part of the highway let's the car cool down ( while cruising on the highway)... as soon as it leaves the shade and hits direct sunlight
... the temp starts creeping again

I have not changed anything that caused it to run hotter on the highway. Did the same thing with the 20g I had before. I am running both oem heatshields on the manifold and turbine housing for what it's worth.

I doubt it's the water pump as when I turn the heater on the temp drops indicating the water pump is capable of flowing the water needed... I'm thinking it's either the thermostat or not getting enough airflow to the rad at highway speed. Weird thing is I have had a few other 1g dsm's with big fmic, and stock rad and even with working A.C. and they never ran hot on the highway while cruising. And that's with the A.C. ON even. I'm sorta stumped on this one. Usually get would run COOLER on the highway once speed picked up


Hoping it's just something simple and the thermostat isn't opening all the way....

 

[richardlapalme]

Maybe you need some ducting between your rad and
your fmic to improve your airflow to the rad.

I had similar problem, except when on the track, i wasn't able to do more than 3 laps before overheating.
My temp was around 200 on cruising before ducting, and now it's around 176 (datalogger) and i did'nt see higher than 190 when i do wot pulls.
Before my temp was higher when crusing, now ,it's higher when idling (192-199).

I take my idea from the road racing guys here, and I did'nt expect that much benefit from ducting.
Hope this will help.

 

[93'colttsi]

Yeah if the thermostat doesn't do anything then I may try some ducting to keep the air flowing through the rad. All the stock ducting is long gone when the fmic kit was installed so I'm sure it's easily bypassing the radiator possibly.


Also I'm thinking my ecu temp sensor may be reading off. What temp are the stock radiator fans supposed to come on at? My temp seems to be at 209 when they come on. ( Running stock fan control and sensor/switch)

 

[Justin Lauscher]

Maybe have a slightly restrictive fan shroud?

 

[93'colttsi]

No fan shroud. Just two slim fans mounted directly to the inside of the rad. Fans work awesome. If I slow down and idle the temp drops FAST

 

[richardlapalme]

Also I'm thinking my ecu temp sensor may be reading off. What temp are the stock radiator fans supposed to come on at? My temp seems to be at 209 when they come on. ( Running stock fan control and sensor/switch)[/QUOTE]


Mine come at 194 ? Very high compare to mine.

 

[93'colttsi]

Okay well then maybe it's just reading incorrect. I'll check my actual temp with a laser thermometer and maybe try a spare ecu temp sensor.

My stock gauge reads about exactly half way when I'm datalogging the 220-225 coolant temps but it's sorta a weird gauge. I know I forgot to turn my heater on one time and wasn't datalogging and I went to to 238 degrees... my gauge was reading slightly over half at that point so it was defiantly getting hot.

 

[ErikTande]

Any ducting between your FMIC and radiator? I had the same problem, it would always get warm on the highway. Ducted the FMIC to the radiator and the problem went away.

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[93'colttsi]

No, I don't have any ducting from the fmic to the radiator

 

[miliman13]

Ducting..... . It makes a difference.

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[Murdertalon]

Please check your radiator cap/ rubber seal inside the cap. I have chips in the mating surface and had to add a gasket to my radiator cap (autozone one) also if its not an OEM cap they tend to not seal well or allow pressure to escape. Also, I would double and maybe triple check your thermostat. I could feel the lower pipe on my radiator cold while my car was overheating and it wasn't opening.

 

[19gsx91]

^^ What Murdertalon said. I'm fighting a similar issue but there are other factors at play right now.. short end is I've been through 3 "stant" radiator caps and they keep leaking and pushing coolant out the cap, it's causing issues for me especially uphill.

 

[boostdawd]

Op says he doesn't lose coolant. Ducting is cheap and can possibly fix your issue. Myself personally I have a vrsf front mount with no ac and 1 stock fan and no ducting. No overheating here at highway speeds on 110 degree weather.

 

[miliman13]

Some members have gotten to know me since im always crying about overheating with a VRSF and AC on.

My last test, showed AC ON, both idle and cruising under 200.
This was since i made the shroud angled to seal more surface are and used a pool noodle to seal the rad/FM .

I can place a damp shop towel on my FM and it will stay in place, since the air is much stronger with the sealing and ducting.

But yes their ARE a lot if possibilities.

This is just in case you already addressed the rest.

 

[91talonts1]

What temp are the stock radiator fans supposed to come on at?

I know the 2gs don't kick the fan on high stock until 210*, I was thinking the 1gs kick on around 200-203. I'm also thinking the 1g has a thermo switch for the fan in the radiator vs the 2g using the ECT sensor, so there could be some variation between coolant temp at the t-stat housing and in the rad itself.
I would agree with the others that ducting is probably the solution.

 

[richardlapalme]

Some pictures of my ducting, i have a front section in front of my fmic and a rear section between fmic and rad. Once again, ducting makes BIG difference !

Rear section:

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Front section:

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With bumper with dremeled holes each side of the missing emblem:

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When the fan are on, if i put a paper or a towel in front of my fmic, it will stick in place.

 

[93'colttsi]

^^ What Murdertalon said. I'm fighting a similar issue but there are other factors at play right now.. short end is I've been through 3 "stant" radiator caps and they keep leaking and pushing coolant out the cap, it's causing issues for me especially uphill.

Yeah I don't have any issues pushing coolant. I did run into that once with a mishimoto radiator on a evo. They have a slightly deeper well for the rad cap causing the stock cap to not have enough pressure on the seal. Mishimoto makes a longer cap, but I have not had good luck with that either.

 

[Murdertalon]

I really like the idea of ducting. The things that helped my car are the following.

1. A rubber washer added to cooling cap where it seals to the metal housing.

2. Evo 9 thermostat cut to fit the dsm. This required removing 2mm around the outside or the metal on the thermostat I was able to keep the air widget just barley.

The evo thermostat opens 3* sooner and the inner diameter of the thermostat or (flow area) is actually larger thus allowing much better water flow through it.

 

[kmetiuk]

Since we're whipping ducts out....


My results were drastic. Before super hot while cruising....would cool (ish) if I was stopped and idling after a bit. Threw on the duct and I'm 85-90's crusing and under lots of constant boost 90-100 ish.

Ducting makes a HUGE difference.

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[19gsx91]

Lol @kmetiuk

I actually swapped my timing tables back to what they were 2 weeks ago and had zero cooling issues on the way home. I thought about that after previously posting.. I added timing in the cruise sections.. took that timing out and all was better. Still pushing coolant under boost but it all just dries up on the t-stat housing.. all I ever get to see is the residue.

I support these guys, get ducting.. also don't add a whole bunch of timing in the cruise area then try to figure out why it's running hotter.

 

[miliman13]

Some pictures of my ducting, i have a front section in front of my fmic and a rear section between fmic and rad. Once again, ducting makes BIG difference !

Rear section:

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Front section:

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With bumper with dremeled holes each side of the missing emblem:

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When the fan are on, if i put a paper or a towel in front of my fmic, it will stick in place.

NICE**
Are those SPAL'S ?

i noticed your isn't angled to seal the fans inside against the rad, i assume it works very well without it.

I had it cutting of half the rad at first too, and i saw a good improvement by angling it.

Since we're whipping ducts out....


My results were drastic. Before super hot while cruising....would cool (ish) if I was stopped and idling after a bit. Threw on the duct and I'm 85-90's crusing and under lots of constant boost 90-100 ish.

Ducting makes a HUGE difference.

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First of all..... SHOW OFF!!
, that looks SOLID ******

But those numbers? that Celsius right ?


Just for comparison i was around 230F with AC on before.....

But this is really beneficial to Highway speeds.
Regardless of W/E fan we have, they become next to useless at 60mph+

So definitely geting creative goes a long way.

 

[richardlapalme]

NICE**
Are those SPAL'S ?

i noticed your isn't angled to seal the fans inside against the rad, i assume it works very well without it.

I had it cutting of half the rad at first too, and i saw a good improvement by angling it.

Before ducting, due to my overheating problem at the track, my initial plan was to put an aluminum rad and 2 flex-a-lite fan behing the rad, because i know when they're placed in front, they become restrictive when in movement.

BUT:
After some research, i decide to go the ''cheap way'' and put some ducting, dremelled the 2 holes each side of the eagle emblem on my bumper. And see what happens.
And,
the drop of temps were significant. I compare the temp result with my 2 last year logged result: Cruising before: 89-94 celcius, now 78-82 celcius
Sustained wot before: 96-too high, now 83-88 celcius
Idle : the same, except, when my car was getting too hot after few laps, i had to open the hood to cool down the motor. Now, my 2 cheap 12'' 1200cfm ebay fan do the job to maintain my temp around 89-93 cecius.
My conclusion are: these fan are useless when in movement, the restriction they causes is negligible and a cleaner engine bay.

I'm more than happy, and above all, my wife is happy for nor not spending our money (again) on this toy.

 

[93'colttsi]

Yeah. I changed the thermostat and it may be a bit better but I logged around 216-219 in cruise on highway in like almost 100 degree weather. Going to make some ducting that connects the fmic to the radiator.