355 Challenge - losing water...

Compression leaking into the water jacket would be my big worry.
Head-gasket etc

 

Rob,

Pressure test the system. you may have a leak somewhere that is not allowing the system to hold pressure. If the system does not hold pressure, the coolant will boil over regardless of the cap condition. it may be the head gasket, but I would pressure test and check all the clamps for tightness first and don`t forget about the heater circuit of the cooling system.

Best Regards, Jim

 

Yes. If air is pumped in at a point where its trapped in a high point, water will be pushed past your vent tube and cap as soon as the air pocket is at a higher pressure than your cap is spec'd to.

If you meen a water leak the answer would be no as the water pressure would vent at that point rather than the cap and overflow tube.

I'm no specialist on your specific motor though and thus can't rule out other causes, hopefully less malign. Am a bit surprised we've had no input from the more experienced pro members yet.
There's plenty of experience with racing these engines and the common issues that show up. Hopefully the cavalry will arrive soon.

A gallon is not far off half the water in your system. Quite a lot to lose really.

 

FOR SURE, I have seen it happen before. what leaks out is very little and not noticable and since it cannot hold pressure, the coolant boils at a lower temp.

best regards, jim

 

Rob,



Sounds like you have an air pocket forming while driving and it expands as the engine heats up and pushes coolant out of the cap.

Check the two small return hoses that mount to the front of the expansion tank. These are designed to bleed off system air to the tank. They become internally clogged and cause the problem you are experiencing.

Hope this is your fix, it's alot less expensive than the other scenarios suggested...


The reservoir is an expansion tank. The level should be set at the 1/2 way mark.


BTW, is your car a true Chall. spec. car, with the thermostat removed and plugged???


Adam

 

Rob,

Was it originally one of Steve Earls?

Just checking, wanted to make sure you didn't have a thermostat to consider in your diagnosis...

 

Rob,

Doc Earl is a great guy!

Doc's cars were always faster than the average bear!! He spared no expense to alwys have the best car he could and bend the spec. rules to the max and beyond!!

That should be a pretty well sorted car.

I'm possitive you're enjoying it!


Adam

 

Rob this is a good idea. You can rent a pressure tester from Autozone I believe. I am sure Buddy would help ou and its an easy test to do ahead of James getting the car.

 

I don't think the t'stat was ever removed by the factory in Challenge cars. Certainly the Challenge spec includes this equipment and only the manual radiator fan switch was proscribed as a modification to the cooling system. Removing a t'stat usually requires a blanking spacer so that would have to be custom built.

 

The Challenge cars had the thermostat deleted. The factory threaded plug or "blanking spacer" is Ferrari part# 106237

 

Rob, this may sound funny but smell the reservoir. If it smells funny like a little gaseous then its prob a headgasket. There are testers that check for hydrocarbons in the coolant to be 100% sure. Could be waterpump, inefficient radiator(s), etc..

Good luck, I hope its not the head gasket..

 

If you're starting the overflow full up, you're seeing the coolant that's pumped out due to expansion of the fluid. A quart or two looks like a whole lot when it's on the ground. try filling the overflow just up to where it's less than 1/2 full and see what happens.

 

Rob, if i may, are you just adding the coolant to the expansion tank, and going on your way? i could be wrong, but i would think you would want to open the radiator bleed(s) with the tank cap off, and remove any air in the system. if you dont bleed the system, i feel you are just pushing an air bubble around in the the lines.

i dont know much about the 355's, as i am just a 308 guy, but i wanted to ask and try to help.

michael

 

This is a good test. My Cadillac had head gasket problems and I tried to convince myself that it wasn't exhaust I was smelling when I filled up the overflow tank. Both head gaskets were blown. I don't know if that is what your problem is but I'd definitely get the system pressure tested. You'll be able to find any external leaks that way too.

 

Start with a system pressure test. Often you can hear where air is leaking out or see the puddle of water starting on the floor. if it failed I'd be doing a leakdown test next. Every racer should have these 2 very handy tools.

 

There's a bleed screw on top of the thermostat cover, you should open, when filling up the system.

As far as the self bleeding goes, it only works if the return hoses leading back to the expansion tank are not clogged...

If they're clogged, you can experience all of the issues you have explained.

 

Usually there's a diagram in the manual showing the recommended depth. Somewhere around 6-8cm is the std 355 figure I believe.and yes, there is a bleed point on the thermostat housing.

 

so the 355 radiator does not have a bleed?

seems that would be the high point to drain the air from.

 

Radiators plural in the std model. The lines emerge from the top of them so the rad headers aren't the highest point.
Never dealt with a 355 Challenge though they may be different.

 

i see, thank you.