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FFCobra Captain
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11,695 Posts
Discussion Starter #1
setup:
Cobra Earl's SBF Adapter
Summit fill port with overflow
running hose from fill port to stock position overflow tank
16lb radiator cap on fill port
195degree thermostat
stock radiator
fill port on side of radiator capped off with rubber expansion plug. It's still solidly mounted.

Drove home from dyno yesterday...overheated on the way home.

Today: filled up car with more fluid. Quick drive around (about 1 mile). Temp climbed to 235 by the time I was home. Steam coming through the sides of the cap. Coolant on the side of the timing cover. Looks like it's coming through the sides of the radiator cap..where the steam is coming out.

Filled car up during the day at different times. Took about 1/2 gallon. It would take water to the top of the port...then it would slowly disappear into the engine. I kept filling until the level stayed to the top.

Tonight: Put the cap on. Went for short drive (about 4 miles). Temp got up to 235 by the time I pulled into the garage. Steam coming from the cap and fluid on the side of the timing cover. Fluid sits around the cap.

What gives?

Defective radiator cap? It looks & feels just like the last one.

Here's a pic of the parts:
 

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FFCobra Fanatic
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1,456 Posts
Do you have a thermostat? If so check it to see if its stuck is the engine really getting that hot that quickly? Thats a concern. Is the fan powering on? Either way change the Cap its probably $12 and is cheap insurance.
 

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Junior Charter Member
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805 Posts
Call me 509-886-1721
Sam
 

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Registered
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4,177 Posts
I just went thru something similar on mine. Turns out I had a stuck thermostat so I replaced it and the radiator cap and it works perfectly now...
 

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FFR raodaster Owner
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312 Posts
What happened at the DYNO? Did you blow a head gasket? Got to love boost! Sounds like huge amounts of pressure building up in your system. Is your overflow vented and fluid free to move to the overflow tank? When the cap relieves pressure it should follow your overflow tube to the overflow tank. Is there something plugging up the line? I feel no pressure in my overflow line even when hot fluid is moving through.

Fluid along the timing cover??? Sounds like it is either coming from your heads or filler neck. How does your exhaust smell?

have you checked all you hoses to see if there is anything loose?

Good news is the steam is coming out of the cap... That means pressure is trying to go out the right way...

I'd recommend drying up all the fluid then idling the car to temperature with the hood open and watch to see where it starts. You should check the oil for signs of anti-freeze or water (not good and will fry your bearings).

I'd also recommend not driving the car while you are trying to burp it. Start it up... let it cool... start it up... let it cool... watch to ensure fluid is sucked back into the motor as it cools. If it doesn't go back in then you have a leak somewhere in the system. A small pin hole is enough to cause the system to fail.

steve
 

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FFCobra Craftsman
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1,767 Posts
Check around the back side of that Summit neck and make sure the plugs are sealing tight. I used thread sealant on mine and they leaked like cray until I re-did them with PTFE tape. The other small leak I had was where the overflow tube conected to the filler neck. Tightening the clamp fixed that one. Coolant leaks are a PITA and I hope you find it soon,
Steve
 

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Senior Member
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8,350 Posts
Water pump rotation correct? Thermostat in backwards? Please don't be insulted.
 

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FFCobra Fanatic
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2,920 Posts
Change the cap. I've been chasing a similar problem since my first track day a few weeks ago and the gasket on the cap was toast! I've been running the new one all week with no issues. $5
 

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FFCobra Fanatic
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12,975 Posts
Dan if coolant is commeing out around the cap. either cap of fill port is bad,or fit between the two is wrong. Be sure cap is pressure/vacum cap.
When working correctlly in a over heat condition.
Cap would,like it should release but all fluid would be vented thru the hose going to the over flow.
Since caps are cheap try it first. You can also test the cap useing the pressure testers used for testing the cooling system. Most have an adapter for this. Maybe check a local shop for testing the cap.
Probally (hopefully)over heating is only due to the lack of sealing at the cap causeig loss of coolant.
 

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Registered
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675 Posts
Run a pressure test for leaks....BURP ALL AIR FROM THE SYSTEM by squeezing the lower radiator hose with the cap off. Don't underestimate the number of times to do this(6+) to get all air out. This is a common problem in cars where the top of the engine is higher than the radiator and usually requires an expansion tank as a solution to continual gassing. Mine continued to loose coolant and run hot until I put Fortes De-gas tank on the f-panel. No more problems, in fact The car runs cold!
Bruce
 

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FFCobra Captain
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11,695 Posts
Discussion Starter #11
Seems lately like I should win the dumbass of the week award.

Problem was simple. Make sure to turn the radiator cap all the way...not just to the first click.

I took it around the area and it stayed under 210. The car always ran about 10-15 degrees hotter than the thermostat...I think because I have the supercharger. With the 195 thermostat in there, it's just about right.

I probably still have some air to burp, so I'm going to let it cool down this morning and fill it up some more during lunch.

Should be able to take it out for a nice cruise tonight.
 

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Blue Oval Scribe
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9,177 Posts
Glad to hear that's all it was Dan. I'd hate to see that pretty new engine get messed up!

Mark
 

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ASE Tech & Shop Teacher
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1,936 Posts
Sorry to hear about the dumbass award, but glad to hear it was a simple, inexpensive fix.

If you don't mind, inquiring minds want to know.
What kind of numbers did it put up on the dyno?

Carry on.
 

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FFCobra Fanatic
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12,975 Posts
Good to hear when a fix is easy and cost nothing ;) Yea,like your the first to do that.
To burp all you need to do is get the engine up to temp,add some rpm's,then allow to cool again. Don't need to drive if not conveinent.
 

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FFCobra Captain
Joined
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11,695 Posts
Discussion Starter #15
I found out why my motor needed to be rebuilt. When the dyno guy pulled the chip and DL'd the tune...the file was corrupt and was giving the motor 65 degrees of timing at the higher RPM range. When he tried to retune it, the chip would keep getting corrupt, so he gave me a new chip to replace the killer chip.

This time, I went with a very conservative tune. After spending the money I did over the summer, I'm gunshy and don't want to risk more blown head gaskets. I also didn't want to have to pony up and replace my injectors & MAF meter to upgrade again.

So I pulled 300RWHP and 400Torque.

The A/F Ratios look great all through the RPM range and the torque curve is flatter than it was before, so it actually pulls harder in the mid-RPM range than it did before.

With the new ported heads and new cam, the boost starts at 8psi, then then drops to just under 6 as you get up in the 4-5.5k rpm range. Dyno guy says that the size of the blower doesn't keep up with the motor...which sounds about right. I think the lower boost in the higher rpms should help me from blowing gaskets too.

The numbers are lower than I thought...I thought that with the bigger rockers, new cam and porting of the heads, that I would make more HP. The dyno guy said he could get me more, but I was clear that I would sacrifice power for a safer tune.

When we compared the old chart to the new one, he think it will feel stronger than it did and said I can beat the sht out of it on the track and it won't blow gaskets.

I guess I'll find out over the next few days how it feels...I am happy to be able to get on the road again.

I'll scan the chart and post it later.
 

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Charter Member
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6,158 Posts
dan, If you let the engine go through heat cycles and keep the overflow tank filled 1/2 (cold) it should burp itself. No need to take the cap off. Sometimes that allows air to get in the system. Also, if you fill it more than half (cold) it will overflow when the engine is hot.
 
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