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Overheating 924 w/ BAE Turbo....suggestions?

 
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am4000  



Joined: 21 Sep 2010
Posts: 6
Location: San Diego, CA

PostPosted: Tue Oct 15, 2019 7:36 am    Post subject: Overheating 924 w/ BAE Turbo....suggestions? Reply with quote

Hey! My 924 which I installed the BAE turbo kit onto has been giving me overheating issues at low speeds or when idling with the hood closed. Idling with the hood open seems to be okay with the temps fluctuating between the 1st bar and the middle bar. In traffic it will go all the way up into the red. I am running the original radiator and a custom fan shroud made out of an aluminum baking sheet with a Mishimoto Race Line 11" fan. Previously I was running the factory 931 single fan shroud. The current performance seems about the same as the factory shroud, maybe a little better. Can't run the dual fan setup because of clearance issues.

I am using the 944 expansion tank.

Things I've tried:
-Draining, refilling, bleeding...many times
-New thermostat
-New radiator cap
-New temp switch
-New water pump
-Making the new fan shroud to use the Mishimoto fan.

The car has factory A/C and so the condenser is mounted directly in front of the radiator.

The hood is original, no ducts.

The lower engine guard is not installed.

At this point the only original part of the cooling system is the radiator. I found that Ron Davis makes a performance radiator, but I think it will be too large. They can make me a thinner one (1-1 inch tubes instead of 2-1 inch) that should be drop in, but I want to get some feedback if this is even the issue. If I spend money on a new radiator and I have the same issue...well I've done that a lot already lol.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1983
Location: Somerset, UK

PostPosted: Tue Oct 15, 2019 7:59 am    Post subject: Reply with quote

Stock radiator is near itís working limit with stock power. Add 20% more power and you create 20% more heat. Hence your issues. Itís just not big enough. Also donít trust the stock temp sensor or gauge. Test the engine and cooling system with infra red thermometer to be certain of temps.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1994
Location: MI

PostPosted: Tue Oct 15, 2019 8:34 am    Post subject: Reply with quote

I'd also check for bubble coming into the coolant expansion tank any time the cap is off, check for your coolant system building pressure immediately at cold start which is another symptom of a blown HG, and also when the engine is running at operating temp give the rad hose a squeeze and make sure it has pressure in it while up to temp like it should.. If no pressure then it is leaking somewhere..
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am4000  



Joined: 21 Sep 2010
Posts: 6
Location: San Diego, CA

PostPosted: Tue Oct 15, 2019 8:38 am    Post subject: Reply with quote

Carrera RSR wrote:
Stock radiator is near itís working limit with stock power. Add 20% more power and you create 20% more heat. Hence your issues. Itís just not big enough. Also donít trust the stock temp sensor or gauge. Test the engine and cooling system with infra red thermometer to be certain of temps.


Isn't the NA radiator the same as the 931 radiator? The 931 came stock with a single fan as well, I assume it didn't overheat from the factory. I agree it is a small radiator though. As far as the temps go, my dash gauge matches up with what I'm seeing on Tunerstudio.
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1978 Porsche 924 + BAE Turbo + Megasquirt (a.k.a the most reliable car in the world.......jk)
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am4000  



Joined: 21 Sep 2010
Posts: 6
Location: San Diego, CA

PostPosted: Tue Oct 15, 2019 8:40 am    Post subject: Reply with quote

Fasteddie313 wrote:
I'd also check for bubble coming into the coolant expansion tank any time the cap is off, check for your coolant system building pressure immediately at cold start which is another symptom of a blown HG, and also when the engine is running at operating temp give the rad hose a squeeze and make sure it has pressure in it while up to temp like it should.. If no pressure then it is leaking somewhere..


Thanks. I checked and don't see signs of a blown HG. When it's warmed up, the upper rad hose is definitely pressurized.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1994
Location: MI

PostPosted: Tue Oct 15, 2019 9:04 am    Post subject: Reply with quote

Are you sure your aftermarket fan is even coming on? What do you have going on with your fan to temp switch electrical circuit? What degree temp switch are you running?

am4000 wrote:
my dash gauge matches up with what I'm seeing on Tunerstudio.


What? You are running tunerstudio? I am too!! What MS?

I have my stock 931 radiator, and stock dual (2) fan 931 fans running on my MS set to come on at 190 degrees F with a 7 degree hysteresis, my temp sensor is in the housing on the back of the head where the old thermotime switch used to be, and it works like a charm..

I have the lower temp thermostat installed, I forget the degrees..
My last log of hard boosting my CLT only reached 192 degrees F max, though it was cold out, but I have monitored my temps for a long time and have never had a problem with the stock fans, stock rad, lower temp thermostat, and fan on MS @ 190 D F..

Is the NA rad the same as the 931 rad? My 931 definately has 2 fans that actually kick pretty good air and always keep my temps down fine..

But, I have my radiator core and its valve bypassed so I probably flow more coolant out of the back of my head than stock.. And AC junk removed..

Where is your temp sensor? What temps are you seeing?
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am4000  



Joined: 21 Sep 2010
Posts: 6
Location: San Diego, CA

PostPosted: Tue Oct 15, 2019 9:38 am    Post subject: Reply with quote

Yeah, idling in the drive way it comes on once the temps get high enough. I'm running the 75C Wahler (new OEM) fan switch. I'm using the original primary fan circuit, my A/C secondary fan doesn't fit because of the turbo.

Yeah! Nice! I had been on MS1 for a few years, but just recently re-wired and went to Microsquirt V3.

I'm not using megasquirt to control the fans. Maybe at some point in the future I will, but since the original stuff seems to still be working I figured I wouldn't push my luck. But yeah I am using the exact same location for my megasquirt temp switch! I tapped the hole in the housing so I could screw in a GM 2 wire temp switch.

I'm running the Wahler 059121113C thermostat, which I think opens around 83C (180 F ish). Driving around my temps are somewhere in the 170s to 190s. Moving fast (50+ MPH) the temps drop pretty well. Idling it will just keep creeping up if the hood is closed...it gets very very hot under there.

Unfortunately I haven't given up on my AC yet. It gets really hot in the summers (100+ F).

Do you have the bottom engine protection plate installed on your 931 ?
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1994
Location: MI

PostPosted: Tue Oct 15, 2019 10:17 am    Post subject: Reply with quote

I do not have the bottom skidpan thing on..

Can you watch your temp and see when your fans are coming on?

If you have MS3 then you should definitely have the spare channels to control your fan right? I have a microsquirt so MS2..
Maybe bodge up a relay real quick to ground your fan instead of the temp witch and tell your MS to kick it on at 185-190 or something and see what that does for you.. If it works then wire it permanent..

If you do that then your fan will work in relation to your engine temperature rather than your radiator temperature..

I found a BMW temp sensor to fit the original hole in the housing..
My last log was 163-192 degrees F and I see my engine temps rise very little at high boost and just bounce off my fan at idle..

do you have an intercooler? I also noticed a drastic reduction in underhood temps after installing an intercooler but that was before I had logging capability..
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Cťdric  



Joined: 27 Aug 2004
Posts: 1985
Location: Sweden

PostPosted: Tue Oct 15, 2019 4:33 pm    Post subject: Reply with quote

Have you checked that the fan spins the correct way, ive done that stupid mistake myself and seen other do the same

At idle it shouldnt matter whether it has a turbo or not, since its just hangs there, something is not working obviously
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1983
Location: Somerset, UK

PostPosted: Tue Oct 15, 2019 5:41 pm    Post subject: Reply with quote

am4000 wrote:
Carrera RSR wrote:
Stock radiator is near itís working limit with stock power. Add 20% more power and you create 20% more heat. Hence your issues. Itís just not big enough. Also donít trust the stock temp sensor or gauge. Test the engine and cooling system with infra red thermometer to be certain of temps.


Isn't the NA radiator the same as the 931 radiator? The 931 came stock with a single fan as well, I assume it didn't overheat from the factory. I agree it is a small radiator though. As far as the temps go, my dash gauge matches up with what I'm seeing on Tunerstudio.


And that's my point, the NA rad on the turbo is the same and its struggling at low speed and idling. The coolant system needs to be super clean, no crud, no furring. The rad needs to be as good as new.

Plus you have an AC condenser limiting cold air on the rad.

Or instal the larger 944 S2/turbo rad with after market fan(s) The larger surface and increased volume of coolant will help.
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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