Coolant Issue

[DanDriftS13]

Before today I had no rad. overflow tank on my car so today I rigged up a water bottle as one and I found out the coolant is coming out of the cap. I had just put a new 16lb rad. cap on before my radiator hose blew on Wednesday so, I put back on my old cap which I know for sure is good. Still the same problem losing coolant out of the cap. I also changed my oil earlier today and there was no water in the oil. A friend of mine said that it was a possibility that it could be that the headgasket is bad and could be letting the compression from the motor slip past it and into the cooling system and pushing open the rad. cap and making my coolant spill out. I am going to do a compression test later on today and was wondering if anyone had any ideas of anything else I should look at before or during the compression test?

Thank You
-Daniel

[MadMaverick]

Originally Posted by DanDriftS13

Before today I had no rad. overflow tank on my car so today I rigged up a water bottle as one and I found out the coolant is coming out of the cap. I had just put a new 16lb rad. cap on before my radiator hose blew on Wednesday so, I put back on my old cap which I know for sure is good. Still the same problem losing coolant out of the cap. I also changed my oil earlier today and there was no water in the oil. A friend of mine said that it was a possibility that it could be that the headgasket is bad and could be letting the compression from the motor slip past it and into the cooling system and pushing open the rad. cap and making my coolant spill out. I am going to do a compression test later on today and was wondering if anyone had any ideas of anything else I should look at before or during the compression test?

Thank You
-Daniel

If its combustion pressure pushing out of the head gasket, you will be able to see it bubbling before it even gets hot. I suspect that your rad might be warped where the cap attaches, Ive seen it a few times. Just to be clear, you had an open hole where your overflow tank was supposed to be? I would do a cooling system pressure test before a compression test. They also make a kit that tests for combustion gasses in your cooling system.

[DanDriftS13]

Originally Posted by MadMaverick

If its combustion pressure pushing out of the head gasket, you will be able to see it bubbling before it even gets hot. I suspect that your rad might be warped where the cap attaches, Ive seen it a few times. Just to be clear, you had an open hole where your overflow tank was supposed to be? I would do a cooling system pressure test before a compression test. They also make a kit that tests for combustion gasses in your cooling system.

Yes, basically an open hole where the overflow tank was supposed to be. I had a hose that ran through the hole where my coldpipe for the intercooler runs and just sprayed out on the ground if the pressure rose too high. The cap DOES NOT leak at idle and only leaks when I drive around and the car is above idle UNDER LOAD. I can rev it up in the drive way and it DOES NOT leak either. The hole where the cap goes being warped could be a possibility I guess because the top of the radiator seems to be bowed up a little bit and I know it wasn't like that when I got the Koyo. I don't think I have access to a cooling system pressure tester but I do have access to a compression tester so either way I am going to do a compression test to see if that will tell me anything.

[MadMaverick]

Originally Posted by DanDriftS13

Yes, basically an open hole where the overflow tank was supposed to be. I had a hose that ran through the hole where my coldpipe for the intercooler runs and just sprayed out on the ground if the pressure rose too high. The cap DOES NOT leak at idle and only leaks when I drive around and the car is above idle UNDER LOAD. I can rev it up in the drive way and it DOES NOT leak either. The hole where the cap goes being warped could be a possibility I guess because the top of the radiator seems to be bowed up a little bit and I know it wasn't like that when I got the Koyo. I don't think I have access to a cooling system pressure tester but I do have access to a compression tester so either way I am going to do a compression test to see if that will tell me anything.

Well, you WILL loose coolant from that overflow line even at normal driving temp. When the coolant expands, the pressure pushes coolant into the overflow, which then gets sucked back in when the car cools. Since you had nothing to suck back in, you have coolant loss. The radiator swelling at the top tells me that you have overheated the car in the past. The conjunction of these two things still leads me to believe you have an air pocket in the head. I would bleed the cooling system again and see if you still loose coolant. If you think its leaking into the head, pull your spark plugs and look at the color, if they have a greenish tinge, a headgasket is a possibility.

On a side note: I have seen a shitload of turbo volvo engines come in with blown headgaskets, combustion pressure leaking into the cooling system. In every case, running the car with the rad cap off and revving it produced a fountain of coolant from the radiator. Boosted cars blow huge amounts of pressure through the cooling system, you should be able to see this when the car is cold. If it is hot and the rad cap is off, bubbling and overflowing is just coolant boiling in the block (because the system is not under pressure to lower the boiling point).