m7 coolant issue

[12bruckd]

I have a 2005 m7 and the other day the engine light flashed on me for overheating. So it appeared to me that one of the hoses slipped off the bottle and was leaking coolant, I fixed this with a hose clamp. So now when I ride it, it very slowly looses coolant, it does not appear to leak in the garage. I looked at the coolant bottle and it seems like the filler neck is warped (like an oval), would this cause the coolant to leak? Also when I open the coolant bottle with the sled hot there is no pressure under the cap, Should there be?

Thanks for any responses.

here is a photo of the warped bottle:

 

[moyiesledhead]

Yes, there should be pressure. I suspect the warpage is causing the cap to not seal, allowing your coolant to boil and go out the overflow tube.

 

[Modman]

Yes, there should be pressure. I suspect the warpage is causing the cap to not seal, allowing your coolant to boil and go out the overflow tube.

There might not be much pressure though, if you have a leak, the pressure will be escaping there as well and could give you a false idea that its the rad cap. Get a coolant pressure tool and pressure the system without the sled running, it should not bleed down. If if does, you have a leak someone else and that is probably where your pressure and your coolant is going. Mix up some soap and water and dab the bubbles around the cap area when its under pressure. If a bubble starts to grow, then air is escaping at the cap. Same procedure they use to test for gas leaks or propane BBQ tank connections.

If the rad cap failed, then initially your tank could have warped due to hot coolant escaping when it overheated. The hose may not have slipped off, it might have been blown off if the system was overpressured due to a faulty rad cap not releasing pressure at the required PSI. You might have another hose that is leaky due to the same overpressure. Probably prudent to check all hoses and clamps, check your t-stat, and maybe get a new rad cap.

 

[ralphsmotorsports]

Yes that coolant bottle is warped and that will loose some coolant pressure- which there should be. But if you had a major coolant leak you must be sure to properly bleed the heat exchangers. Which is elevating the front end and running with the cap off, that will give you poor circulation and no pressure if not properly bled. So when it is "loosing coolant" but no leak. That is usually air trapped in the heat exchangers.

 

[12bruckd]

Thanks for all the help guys, turns out I had 2 issues. First I got the pressure tester and immediately the bottle leaked around the sealing surface. So I replaced the bottle. Then testing the system again I saw coolant on the floor. Unfortunately this was from the dreaded hose that is in the tunnel right above the drive cogs. So I removed the track and repaired the broken cat clamp with hose clamps. Ran the sled after and after taking off the rad cap I heard the sweet sound of a pressure relief from the bottle, so its all set now.

Thanks everyone for their input!