over heating issue
10-22-16, 09:04 PM
#1
over heating issue
Just wanted to ask for little help. I recently had my engine rebuilt but it's overheating. Bleed the system like crazy and idles around 80 degrees on Power FC but after 5min of driving, temp start climbing. I've looked everywhere and it looks ok.
Spec:
13b with mild street port
Akins seals
BW S300 single
Front mount IC
1300cc injectors
New water seal
New water pump
New Koyo N flow radiator
Delete Cat
Delete Air pump
Air pump delete pulley
Deleted AST
Remove thermostat (for testing)
FC coolant neck w stock 0.9 bar cap
Spec:
13b with mild street port
Akins seals
BW S300 single
Front mount IC
1300cc injectors
New water seal
New water pump
New Koyo N flow radiator
Delete Cat
Delete Air pump
Air pump delete pulley
Deleted AST
Remove thermostat (for testing)
FC coolant neck w stock 0.9 bar cap
Last edited by Gumd02000; 10-22-16 at 10:08 PM.
10-22-16, 11:22 PM
#6
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You say "Temps start climbing"... but how high? It's not abnormal for an FD to break 100C in normal operation.
I don't know how much a PFC changes this, but the FD thermoswitch doesn't kick in until 105C. If the PFC is only controlling one fan input, it may only be able to kick the fans into LOW until the themoswitch triggers.
It's also worth asking the usual question on whether or not the undertray is still installed. It's annoying to work around, but does important work directing air through the radiator when driving.
Other good questions to ask yourself: Are you running lean? How hot is it outside? Are you using the OEM fan setup, or aftermarket?
I don't know how much a PFC changes this, but the FD thermoswitch doesn't kick in until 105C. If the PFC is only controlling one fan input, it may only be able to kick the fans into LOW until the themoswitch triggers.
It's also worth asking the usual question on whether or not the undertray is still installed. It's annoying to work around, but does important work directing air through the radiator when driving.
Other good questions to ask yourself: Are you running lean? How hot is it outside? Are you using the OEM fan setup, or aftermarket?
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10-23-16, 07:28 AM
#8
*You MUST have an undertray. Air will find the path of least resistance. Without an undertray that's NOT thru your FMIC and Radiator. It'll just travel down and under the car. You may find improved IATs too.
*Put the t-stat back in. Without it a significant amount of coolant can bypass the radiator completely. Removing the t-stat on a street car just causes the car to warm up slower, it doesn't help cooling.
*Use as much distilled water to coolant as you can get away with in LA but not less than say 20% coolant to control corrosion and for lubrication.
*Check for ALL fan speeds. IIRC there's a how-to if you search.
*If all else fails to get temps under control, consider something other than a FMIC. It's a heat-soak in front of the radiator.
*Put the t-stat back in. Without it a significant amount of coolant can bypass the radiator completely. Removing the t-stat on a street car just causes the car to warm up slower, it doesn't help cooling.
*Use as much distilled water to coolant as you can get away with in LA but not less than say 20% coolant to control corrosion and for lubrication.
*Check for ALL fan speeds. IIRC there's a how-to if you search.
*If all else fails to get temps under control, consider something other than a FMIC. It's a heat-soak in front of the radiator.
10-23-16, 12:49 PM
#10
*You MUST have an undertray. Air will find the path of least resistance. Without an undertray that's NOT thru your FMIC and Radiator. It'll just travel down and under the car. You may find improved IATs too.
*Put the t-stat back in. Without it a significant amount of coolant can bypass the radiator completely. Removing the t-stat on a street car just causes the car to warm up slower, it doesn't help cooling.
*Use as much distilled water to coolant as you can get away with in LA but not less than say 20% coolant to control corrosion and for lubrication.
*Check for ALL fan speeds. IIRC there's a how-to if you search.
*If all else fails to get temps under control, consider something other than a FMIC. It's a heat-soak in front of the radiator.
*Put the t-stat back in. Without it a significant amount of coolant can bypass the radiator completely. Removing the t-stat on a street car just causes the car to warm up slower, it doesn't help cooling.
*Use as much distilled water to coolant as you can get away with in LA but not less than say 20% coolant to control corrosion and for lubrication.
*Check for ALL fan speeds. IIRC there's a how-to if you search.
*If all else fails to get temps under control, consider something other than a FMIC. It's a heat-soak in front of the radiator.
I will get the untray but I feel that I'm missing something else because tempt rises so fast
10-24-16, 10:05 AM
#15
F'n Newbie...
iTrader: (6)
As Sgtblue mentioned, you need an undertray in there. Also, running without a t-stat will NOT help your vehicle run cooler. If anything it will cause your vehicle to run HOTTER because the higher coolant flow minimizes the amount of time your coolant spends in the radiator, effectively reducing the amount of heat it can shed before re-entering the engine.
If you haven't already, I'd have a read through this guy (found in the FAQ): https://www.rx7club.com/3rd-generati...thread-571088/
10-24-16, 12:42 PM
#16
I'll weigh in here since I recently experienced this exact same thing after changing a water pump...
If your OEM fans are installed and working, you shouldn't have any overheating issues with normal cruising even if you don't have the under tray. They should be able to simulate about 30mph (or slightly more) of airflow. Since the fans operate via an integrated shroud, they won't care if there's ducting or not (but your intercooler will). If you are hitting boost hard, you'll need more than just the fans.
That being said, go buy another underbody tray. It's about $135 for a new one. I just got one because I shattered my last one at the last track day I screwed up at.
Check your system for leaks. I recently replaced a water pump and had to remove the main radiator hoses. When I reinstalled them I re-seated them properly and used the clamps. However, the hoses were old and had a "memory" of how they fit before. Thus, I had an extraordinary leak at the top of the radiator right near the passenger head light. Long way to say, if your hoses are old (or you don't know how old they are) you might consider replacing them to ensure your system is leak free. Best $60 you'll spend on the car.
If you've verified your system is "leak free" then it's likely you have air in the system. Yes, even if you think you've bled out the entire thing you still probably have some air in there. When filling/draining the whole system you'll have to heat cycle the engine once or twice to get it all out. Air in the system will cause temps to spike like crazy.
I typically use the yellow funnel (can't remember what it's called) that attaches to the filler neck. I open the AST tank lid and slowly pour water/coolant into the funnel at the filler neck while watching the level in the AST. Once it reaches the top I cap the AST. Then I continue filling the funnel till it's about 1/3 full. After that I remove the hose at the top of the throttle body and let the air escape. Use your thumb to stop it once the coolant reaches the end of the hose. This will get a LOT of air out.
From there, you may THINK you have all the air out....but you probably don't. With the funnel about 1/4 full at this point I run the car for about 15 minutes. Once the thermostat opens all of the coolant will simply vanish into the funnel. Keep filling it and let the engine continue to run. Make sure to keep coolant in the funnel. I like to rev the engine a few times to ensure the pressure/flow pushes air pockets out the funnel. You'll see the bubbles come out.
After that, I cap the filler neck and let her cool off over night. In the morning when the car is TOTALLY cold, I open the filler neck and typically see there's a fair amount of air in there. I fill it, run it till it hits operating temp, and then shut it off. (Heat cycle #2). Then the next morning, I open the filler neck and top her off. Then it should be totally air free.
Your mileage may vary but this is the way that's provided the best results for me in the past.
If your OEM fans are installed and working, you shouldn't have any overheating issues with normal cruising even if you don't have the under tray. They should be able to simulate about 30mph (or slightly more) of airflow. Since the fans operate via an integrated shroud, they won't care if there's ducting or not (but your intercooler will). If you are hitting boost hard, you'll need more than just the fans.
That being said, go buy another underbody tray. It's about $135 for a new one. I just got one because I shattered my last one at the last track day I screwed up at.
Check your system for leaks. I recently replaced a water pump and had to remove the main radiator hoses. When I reinstalled them I re-seated them properly and used the clamps. However, the hoses were old and had a "memory" of how they fit before. Thus, I had an extraordinary leak at the top of the radiator right near the passenger head light. Long way to say, if your hoses are old (or you don't know how old they are) you might consider replacing them to ensure your system is leak free. Best $60 you'll spend on the car.
If you've verified your system is "leak free" then it's likely you have air in the system. Yes, even if you think you've bled out the entire thing you still probably have some air in there. When filling/draining the whole system you'll have to heat cycle the engine once or twice to get it all out. Air in the system will cause temps to spike like crazy.
I typically use the yellow funnel (can't remember what it's called) that attaches to the filler neck. I open the AST tank lid and slowly pour water/coolant into the funnel at the filler neck while watching the level in the AST. Once it reaches the top I cap the AST. Then I continue filling the funnel till it's about 1/3 full. After that I remove the hose at the top of the throttle body and let the air escape. Use your thumb to stop it once the coolant reaches the end of the hose. This will get a LOT of air out.
From there, you may THINK you have all the air out....but you probably don't. With the funnel about 1/4 full at this point I run the car for about 15 minutes. Once the thermostat opens all of the coolant will simply vanish into the funnel. Keep filling it and let the engine continue to run. Make sure to keep coolant in the funnel. I like to rev the engine a few times to ensure the pressure/flow pushes air pockets out the funnel. You'll see the bubbles come out.
After that, I cap the filler neck and let her cool off over night. In the morning when the car is TOTALLY cold, I open the filler neck and typically see there's a fair amount of air in there. I fill it, run it till it hits operating temp, and then shut it off. (Heat cycle #2). Then the next morning, I open the filler neck and top her off. Then it should be totally air free.
Your mileage may vary but this is the way that's provided the best results for me in the past.
10-24-16, 12:44 PM
#17
And this is the funnel I referenced...
https://www.amazon.com/Lisle-24680-S.../dp/B00A6AS6LY
If you own an RX7 you should be REQUIRED to own one of these; no excuses. They are too cheap not to have.
https://www.amazon.com/Lisle-24680-S.../dp/B00A6AS6LY
If you own an RX7 you should be REQUIRED to own one of these; no excuses. They are too cheap not to have.
10-24-16, 01:18 PM
#20
F'n Newbie...
iTrader: (6)
I had the exact same knee-jerk reaction as Stylion. Even if the FD accounted for it in OEM configuration it's still NOT something I would want to consider "normal" or anywhere near acceptable in my own car. Even sitting still in traffic I'd get rather unhappy at that temp.
10-24-16, 02:34 PM
#22
When I ran the stock radiator and ECU I would average about 95-102 C (203-216 F) in stop and go traffic in about 60 degree ambient weather. Once moving temps would sit consistently between 80-90 C (176-194 F).
This is all according to my Defi water temp gauge which is plugged into the thermostat housing so maybe not the best location as my PFC reads about 2-4 C degrees warmer.
When I switched to the Koyo N-Flow, put a new Mazda OEM thermostat in for good measure, and installed a PFC and had my car mapped for its current configuration, I see about 80-82 degrees C (175-180 F) in traffic and about 76-80 (169-180 F) once moving consistently. It seems pretty cold although my PFC is programmed to only turn the fans on low at 87 (187 F) and high at 90 (194 F). Not sure how normal that is but I have had the whole cooling system checked and all seems to be in order. When on the track the temps will steadily rise but I will have to pull off due to oil temps rather than water temps each time despite having twin factory oil coolers.
This is all according to my Defi water temp gauge which is plugged into the thermostat housing so maybe not the best location as my PFC reads about 2-4 C degrees warmer.
When I switched to the Koyo N-Flow, put a new Mazda OEM thermostat in for good measure, and installed a PFC and had my car mapped for its current configuration, I see about 80-82 degrees C (175-180 F) in traffic and about 76-80 (169-180 F) once moving consistently. It seems pretty cold although my PFC is programmed to only turn the fans on low at 87 (187 F) and high at 90 (194 F). Not sure how normal that is but I have had the whole cooling system checked and all seems to be in order. When on the track the temps will steadily rise but I will have to pull off due to oil temps rather than water temps each time despite having twin factory oil coolers.
Last edited by cib24; 10-25-16 at 01:36 AM.
10-24-16, 06:03 PM
#23
Call me a pansy, but I don't even like seeing 90C on the power FC under normal driving. Typically, mine rolls at 83C during normal highway or even sitting at idle. For me to see 90C it must be flogging the hell out of it at the track. I have my fans set to turn on at 90C.
I realize 100C isn't "dangerous" but any heat over and above operating temperature is THE enemy of a rotary engine. Cooler is better for pretty much everything with regards to it lasting longer.
I realize 100C isn't "dangerous" but any heat over and above operating temperature is THE enemy of a rotary engine. Cooler is better for pretty much everything with regards to it lasting longer.
10-24-16, 06:21 PM
#24
I don't disagree with your point about cooler being better up to a point. The rotary still needs to be above a certain temperature to be running optimally. For example, the RX-8 runs nice and toasty as well to help with emissions which I imagine is the same reason the FD runs warm on the stock ECU, although perhaps we can agree they both run maybe 5 degrees warmer than they need to.
Still, I wouldn't worry about running up to even 105-110 (221-230 F) for a very short period (115 (239 F) and above for more than a very short time is when things can go bad) under normal road conditions.
On track with an uprated radiator you shouldn't have any cooling issues even with one in the stock location like mine. The oil temps will approach their comfortable maximum of c.115 (239 F) well before my coolant temps will even be getting near 100 (212 F), and that is with dual oil coolers. Single oil cooler cars must really struggle by comparison but maybe not?
Still, I wouldn't worry about running up to even 105-110 (221-230 F) for a very short period (115 (239 F) and above for more than a very short time is when things can go bad) under normal road conditions.
On track with an uprated radiator you shouldn't have any cooling issues even with one in the stock location like mine. The oil temps will approach their comfortable maximum of c.115 (239 F) well before my coolant temps will even be getting near 100 (212 F), and that is with dual oil coolers. Single oil cooler cars must really struggle by comparison but maybe not?
Last edited by cib24; 10-25-16 at 01:37 AM.