kwong2001

I just want to get people's take on my problem. I bought this car about 6 months ago. It has a built n/a B18c that made 209whp on a mustang dyno (so it's not stock). Everything regarding the cooling system is stock except for a mishimoto 2-core radiator and samco radiator hoses.

It's done this since I've gotten it, but it's losing coolant. There isn't any white smoke coming out the exhaust (i.e. it's got a good head gasket), no oil in the coolant, no coolant in the oil, there isn't coolant on the floor mats (i.e. heat core issues), and there is no evidence of external leaks. Also, there doesn't appear to be any leaks from the water pump.

I bled the system using the Lisle funnel kit and let it cool overnight before removing the funnel. Upon closing the system, I can idle it all day in the garage with the level in the reservoir/overflow tank staying the same. Upon the engine cooling down, the level in the reservoir/overflow tank goes down. I have not found any evidence of coolant getting on the ground and nothing was found in the engine bay.

I've put new clamps on every single external hose and made sure to seal anything going to the engine. There is no indication that's the problem.

The engine has never overheated while I've had it. I did a compression test which did not indicate any issues. When I did a coolant pressure test, the pressure did go down. I could hear the air coming out near the radiator cap, but couldn't find where. I've since replaced that radiator but haven't done another pressure test.

The only possible thing I can think of is the reservoir/overflow tank is faulty. I've read that some work off of pressure. The cap is quite loose on it and I doubt it is able to create any type of seal. I've since ordered a new one which should be here in a few days.

Is there anything I may have missed?

grumblemarc

iTrader: (4)

Yes. Rate of coolant loss.

kwong2001

It's quick, but varies. I put maybe 20 miles since bleeding it last and have already had to add a little over half a gallon to it.

I can idle it in the garage to full temperature and the coolant in the reservoir will eventually go down about 3 inches give or take. Typically at least an inch.

Sometime even driving it for maybe 5-10 miles the reservoir will be empty or close to empty when getting back.

Dekorum

The coolant level in the reservoir is supposed to rise when the car is at operating temp and then fall when it cools down. Are you sure you are losing some or does it keep rising and falling to the same respective levels?

Former User

It's normal for the coolant level in the reservoir to drop as the engine cools. The pressure in the cooling system rises as the engine heats. When the pressure rises above what the radiator cap will hold, coolant spills into the reservoir.

When the engine cools after turning it off, the lower pressure in the cooling system pulls coolant back into the system.

kwong2001

I've added half a gallon since bleeding the system. It's not just going up and down. It stays at the same level in the reservoir until it cools down, then the level goes down.

After the intial bleed, I can feel there's the right amount of pressure in the cooling system. Eventually, after serveral starts, even after adding coolant in the reservoir, there will be less coolant in the radiator and the system won't maintain pressure.

Dc4LsTeG

iTrader: (7)

So 20 miles and you have to add over half a gallon?

Former User

Pressure test the cooling system.

kwong2001

It might have been 50 miles, I can't remember. That includes 3-5 times of idling the car in the garage starting from cold, shutting down after the fan comes on, and letting it completely cool overnight.

But yes, I've added a little over half a gallon. Also that includes idling the car for maybe an hour in total.

I'll pressure test it when I get home today.

EJ8_Man

If you're adding/losing that much coolant there is obvious evidence of leaking coolant somewhere that you are missing. Look around the edges of the timing belt cover, is it the water pump? Look at the thermostat housing, is it the thermostat?

You should be smelling it and seeing it if you're losing 1/2 gallon over 20-50 miles at stop lights, at stop signs, when you park, you'd smell it.

Take some pictures above and below from different angles of the motor and post them. I want to see a dry motor with a good head gasket that leaks 1/2 gallon every 20-50 miles.

Robin6

have you checked the color of your oil?

kwong2001

There's a cover (I think) where the water pump is. But I've inspected down there with a flash light and no signs of any liquids. The timing belt has never been wet (except for oil from a bad valve cover gasket).

I've kept a good eye on the thermostate housing since it's easy to see. No evidence of any leaks. I changed the thermostat gasket not too long ago. In addition, I made a gasket for the water outlet and haven't found signs of leaks since.

I would periodically smell coolant, but couldn't find it even when I popped the hood and got under the car.

I'll take pictures after I get the new reservoir and drive it for a little bit. It won't be representative since I just degreased the block (had oil on it from a leaky valve cover gasket).

Yep, I dropped the oil twice. The first time after going through over a gallon. It was chocolate milk color, but that was from condensation from the car sitting for 2-3 months. The amount that came out was not more than is to be expected (I have a 5.5 quart oil pan).

The second time I changed it was after driving 7 miles in the car. I believe I had somewhere around 300-500 miles on that oil before changing. The oil looked absolutely normal, and the amount that came out was not excessive.

kwong2001

I pressure tested the system using a different tester than previous. I must have missed a rubber gasket as this one had it. I let it sit at 19psi for about a 30 minutes to an hour and it only went down about .25 psi. So it's probably sealed as it should be.

The only conclusion that I can come up with is it's something with the reservoir. The pressure tester would have taken that out of the equation and since that's the only thing that would have changed, that has be the problem.

I'll have to see how it goes once I get a the reservoir.

Arthas

You said your radiator cap was leaking?

grumblemarc

iTrader: (4)

If you're not leaking it then you're burning it.

d15bvtechatch

iTrader: (2)

Simple Physics

If you said you periodically smell it, you must be missing the leak...
The rad cap issue needs to be fixed if you can hear it there, then its steaming out(consdensating/evaporating into the atmosphere).

Are you using straight water?

kwong2001

It's got a new radiator and cap. I pressure tested it and it seemed fine. Left it overnight and it lost about 3-4psi overnight.

It doesn't burn coolant so the only thing I can think of is the reservoir needs replacing.

kwong2001

Update!

Not long after starting this thread I changed the head gasket and unfortunately it didn't solve the problem. I pulled the head and took it to the machine shop that did the work on the motor. The tech who worked on it was pretty adamant that all it was was the head needing to be re-torqued after heat cycling.

To make sure the head was fine, he pressure tested itmwhich showed that wasn't the problem. He also did a little bit of machining because the pistons were hitting the head. Thankfully he ran it through the resurfacing machine and found it was slightly warped.

After I got everything back I put the motor back together using a Cometic headgasket. I ran just water in the cooling system so if it leaked into the oil, it will just evaporate. Initially it did leak water into the oil. After two heat cycles I re-torqued the head per instructions.

I've done maybe 7-10 miles with it all back together and so far it's holding just fine. The hoses appear to hold normal pressure when the motor is at operating temperature and the reservoir remains full after cool down. Also the car idles better instead of falling on it's face and almost dying. I just need to switch back to antifreeze and I can call it repaired!