RobbyZ

Hi All, I have a 2009 Z51, Dewits radiator with water wetter and ZO6 oil cooler. I am running into oil and water temp issues. I am pretty stock with LG Long tubes, Airade intake (took out my Vararam for better air flow to the radiator), and a tune. I also pulled the weather stipping at the back of the hood to let some of the hot air out. My temps have come down a little bit since I have done the mods, but my temps are still way too high. Sometimes I can't even get through a 20 minutes session before I need to take it off the track. My Oil temp gets up to 290 on a hot day within 15 minutes and my water gets up to 235-240.

I'm not very experienced as I have only done about 6 track events the last 14 months and I'm not mechanically gifted. I have been reading up on a few issues, but I am looking for some more guidance.

1. My fan relay and/or fan cooling module just went out yesterday. I got a check engine light and took it to the dealer. They said my issue was the cooling fan relay or module. The dealer couldn't confirm which one of the two was causing the code. Is the "relay" just the 60 amp fuse? I changed out the 60 amp fuse which didn't look like it was blown, but for a couple bucks i started there. The fan still is not coming on while at high temps and while idle and slow speeds.

Should I replace the fan module with an OEM replacement or is there a better aftermarket setup? I see there is a "fan controller", "fan module", and a "relay". I don't know all the components and where they are all located. What should I consider replacing/ upgrading?

2. I was reading up on the D3 brushless fan kit, is anyone running this setup? Is it worth the cash? If it will lower my temps 10-20 degrees it will be worth it. Would this also come with the fan module I need to replace anyways? The dealer said the fan module is about $250. I know it can get it for less if i shop around, but if the D3 brushless system would replace that anyways then that would take care of my current issue.

3. I am running the stock Thermostat. I spoke to a couple of folks and they recommended a 160 degree. How would this help with getting lower temps?

4. What weight oil should I use to help protect against the high heat? I have about 55K miles and didnt start racing it until 51K. There is a few posts out there, but I have seen some different suggestions. I would love some fresh opinions on this topic.

5. Vented Hood, I plan on doing this in the future. I just dont have the cash right now. I know someone with the LG hood and he said it lowered his temps by 20 degrees. I found this WH hood for $1,500 which is more cost effective than the LG. Anyone running this hood? http://www.corvettemods.com/C6-Corve...d_p_11458.html

Is there anything else should consider? A different radiator?

Frustration is mounting with these issues and I am committed to getting these temps down, but want to understand what should prioritize first.

Any suggestions or opinions are appreciated, thanks fellas!

brkntrxn

A. Put the weatherstripping back on the rear of the hood. This is a high pressure area and air will NOT flow OUT, it will flow IN. Put it back.


1. OEM fan relay module is perfectly adequate

2. No, I have an alternate suggestion. Take the OEM fan unit out and and remove all the plastic from anywhere in between any ribs. Fans turn off at 35mph (at least they do on a C5). So at speed on a track, the shroud holding the fans is actually a restriction to air flow through the radiator. Remove anything that is not structural, the small ribs are structural, to increase airflow through the radiator. This is a somewhat known "trick" for those of us that use to track "stock" cars.

3. No it will not. Run an OEM temp thermostat in the car. At speed, your car is not going to run below 190* water temp, so a 160* will not help you at all. The 160 is a drag racer trick and not applicable to road coursing.

4. I run a mix of 5/20 and 15/50 for something in between. In the heat of the summer, I lean towards more 15/50.

5. The cheapest alternative is to simply install vents in your OEM hood. There are lot of options and several have been posted on here.


B. Clean out your radiator and AC condenser. Blow them out with air or softly with water. If you can, remove the radiator and shake it out physically then wash it. You will be amazed at the crap that gets in them.

C. Install a better oil cooler. There are lots of options posted on this forum.

My suggestion for priority is cleaning the AC condenser, cleaning the radiator, and cutting plastic from the shroud. This will bring more air flow. Oh, and get the weatherstripping back on the hood. Then pursue an oil cooler.

My .02 from personal experience.

C5 Hardtop

Its hard to determine the severity of the heat issue without an ambient temperature of the days where you can only get 20 minutes in as well as what radiator you have installed (the make and model). I think a bigger rad than stock with integrated oil coolers is the way to go. Are you running with the A/C on? I wouldn't blame you if it was on, its pretty hot in AZ .

blkbrd69

First your fan not working could be a melted connector. Mine fried last week and threw a relay/module code even though the connector was fried. See this thread.
https://www.corvetteforum.com/forums...connector.html
The LG hood is first rate, the lower priced hood you show actually looks like it is a Seibon see thread here, very happy with mine however advise ordering direct.
https://www.corvetteforum.com/forums...tyle-hood.html
Someone listed venting your own, did that here.
https://www.corvetteforum.com/forums...r-louvers.html
The vented hood did a great job. But should be combined with an LG or Dewitts radiator.
Make sure your condenser is clean, they gather tons of stuff at the top.

RobbyZ

Thanks brkntrxn

A. I will put the weather stipping back on and see if this helps.

1. My plan is to replace this module asap. Will update once installed.

2. I am going to try this as well.

3. Occasionally I drive around town on the weekends, so I still might put a 160 degree thermostat in. It will be good for the 115 degree days when I am in stop and go.

4. Appreciate the feedback on this one, def going to go heavier.

5 B. I just put my 2nd Dewitts radiator in the last 10 months. There shouldn't be an build up. I have not tried cleaning the AC condensor, but will try next time I am in there.

5 C. Is the Z06 oil cooler not very good? I upgraded my stock Z51 cooler to the Z06 cooler because my shop had one laying around that they gave to me for cheap. I am going to do some research for a better oil cooler? Would converting to dry sump help with my temps?

Thanks for getting back to me with detailed suggestion, this was very helpful!

RobbyZ

I went out to do a night event and it was 105 at 8pm at night. Only about 8% humidity though. I had similar heat issues in 85 degree weather during the morning/ afternoon with low humidity sessions as well. The higher the temps the lower amount of time I can stay on track. I have upgrade to the OEM Zo6 oil cooler and a Dewitts Radiator that i run water wetter in. I don't run with the AC on, although I would if the car could handle it. I would sacrifice the power loss for the cold air when it is 100 plus if i could get away with it, but thats not my goal right now

RobbyZ

Thank you so much for these replies. Hopefully I can get under it this weekend and take a look at the connector to see if it is melted or not before I replace the module.

Def going to pick up that hood! I never really like red on the C6 until recently. Everytime I see carbon parts mixed in with the red it is sexy as hell!

Thanks again for your replies!

Dirk Miller

I too had my fan stop on my '08 C6 and was about to replace the module, but I found one of the leads had gotten crimped without shorting a fuse. After splicing in a new lead it always now comes back on when the water temp reaches 205 F. FYI: I also was running high oil temps of 315 here on hot days at Thunder Hill so I too installed a ZO6 oil cooler and a DeWitts radiator. Oil temps dropped to mid 260's so have not been concerned ever since.
Wishing you the best of luck here
dirk

brkntrxn

When looking at your radiator, make absolutely 100% of the air is going through the radiator and not around it. Take some small sheet metal and a lot of Gorilla tape and ensure there are zero gaps around all sides of the radiator.

The OEM coolers are not meant for extended track duty. You need something like this: http://www.pcmofnc.com/product/c5-co...-cooler-kit-3/

NemesisC5

An engineer with Evans Cooling told me the they can block off the bypass on the their LS water pump and run system without thermostat for best results on road courses. Although not best practice for those in cold winter states it looks like the OP lives in AZ where I'm assuming summers are blistering and winters are fairly mild. The oem water pumps have the same bypass that can be blocked off. I inquired on the Evans LS pump looking for less cavitation (reduced flow) at higher rpms typical to roadcourse events. The links below are fairly lengthy but both very informative...the bypass block off mentioned prominently in one and briefly in the other.

http://www.yellowbullet.com/forum/sh...d.php?t=621363

http://www.pirate4x4.com/tech/billavista/Cooling/

Hi Volts Z06

I second the motion for an Evans water pump and no thermostat. I switched to one of their units and it was the single biggest reduction in temps I ever saw despite all of the other mods and upgrades I made. Call and speak to them.... They are cooling engineers and will dispel all the forum myths we've come to believe.

NemesisC5

Did you purchase the unit with the bypass blocked off?

RobbyZ

The connector is the immediate issue. its melted, see below. I think i am going to bypass the connector. It is hot in AZ, im ok with it running at all times. any recommendations for doing it without pulling everything out?


Cooling Fan connector.JPG

Hi Volts Z06

Yes....ordered it blocked off. I went as nuts as to not only remove the thermostat but also ported the water neck to remove the boss that holds the thermostat.

RobbyZ

Where can we order these? There was so much in the the 2 threads you provided i couldnt find where to buy it from.

Hi Volts Z06

I spoke directly to them and I suggest you do the same. They spent an amazing amount of time on helping select the right product and making sure we weren't masking another problem. Check this website and call the number at the bottom of the page. http://www.evanscoolant.com

NemesisC5

I spoke with Dave Wright, took his time explaining explaining every detail of the LS cooling system.

I don't know if the LT pump has a bypass like the LS pump but if it does that would be the first area I'd address if I were tracking it.

RobbyZ

Sweet, thank you NemesisC5

NemesisC5

You're welcome. To be clear the unique aspect of the Evans LS water pump is their impeller is designed to operate efficiently at higher RPM's and not cavitate. They have optional billet pulleys to match your harmonic balancer diameter mostly in the case of oem, 10% UD or 25% UD and of course your targeted RPM range. The bypass mod can be done to an oem pump if you care to however Evans offers this option from them if you are tracking the car and/or live in a warm climate year round. Worth mentioning but not a selling feature is that the design of the Evans pump and impeller may free up a couple HP.


Let us know what you end up doing.

mikeCsix

Robby,
The connector melted for a reason, the fans operate on a duty cycle and I'm sure, other parameters I don't know about, like speed of the car. For example, at freeway speeds you don't really need the fans so I would be surprised if they remained running. It could be the fans were turned on for extended length of time, coupled with dirty connectors for a slightly resistive connection will cause a lot of heat.

If the fan controller is functioning properly, I would consider installing a high current relay. I don't know if your picture is the ground lead that melted, but would investigate.

As hot as it has been in Arizona these days, I'm not too surprised there are issues. You may want to keep in mind with a high current/low voltage circuit like that, it doesn't take much oxidation on connectors to cause melted contacts. Couple that with higher duty cycles in the Arizona heat demands all of the connections remain clean and tight.

Another source of great info is Dano53, you may want to pm him.