Coolant issue.
 

Hello all, this is my first thread so hope you can help.
My wife picked up her 2001 x5 4.4 yesterday from a local dealer. This was her dream car so you can imagine how disappointed she was when after a 50 mile trip the coolent warning light came on only to find that the coolent was spewing from the top of the cap. I took the cap off and it looks like it could be damaged so we have taken the car back for them to sort. My only concern is that it could be more serious...like headgasket....The water only comes out once the car is stopped and the engine in turned off....OK so we have the warrenty which hopefully will cover....just wondered about your thought on this.

It wouldn't be a head gasket issue unless you saw it coming from a head gasket. Since it was coming from the cap, the cap was most likely faulty. The cap is there to give the radiator a certain "level" of pressure. This was obviously wrong, so simple cap change should solve your problem.

:goodluck: at the dealer!

:xoutpost: :wavey:

That's what we thought, but just wanted some clarification, many thanks

:xoutpost: Hope it is just the cap and not the neck where cap attaches. Do you have any
warranty?

Yep we have 6 months warrenty so should be OK.

:iagree: and :xoutpost:

That is only true for a head gasket leak if it was passing from the coolant passages in the head gasket to the outside. If it was leaking from the cylinder to the coolant passages, it would pressurize the cooling system and cause a problem similar to what the OP saw, pushing coolant out, complete with bubbles in the coolant. It would be more likely to be happening when the engine was running, but it is still an area to check. White smoke would be another indicator.

My point is that the problem appears to be at the cap, but it could be a symptom and not the root cause.

Well hell, there are a ton of things it could be....the cap is the easiest fix which is always the best way to start. I've never seen a head gasket issue blow a radiator cap out, but then again I've seen head gaskets go on almost every other manf. aside from BMW.

No arm wrestle here, but my response was likely a result of growing up under the wing of my father, an old-school mechanic with his own shop. He didn't hold much with parts replacers, as he termed them; he taught us failure analysis, and to look for the root cause. If I was stuck, and suspected the rad cap, yes I would replace it. But in this case, I would wonder why a newly acquired vehicle would suddenly fail a rad cap. It would have been a cheap fix for the selling dealer, if the problem was known. On the other hand, needing a head gasket ($$$) is the type of reason some people trade in vehicles, and sometimes without full disclosure. Put a higher pressure cap on there, and see if it makes it off the lot. The head gasket failure would pressurize the cooling system, causing the relief pressure on the cap to be reached. Mount Vesuvius then erupts out the cap. All of this is just a hypothesis.

I would hope that the dealer is going to pressure test the cap, pressure test the system, and look for any bubbles in the cooling system with the engine at operating temperature. Thermostat is also a potential cause.

Just my $0.02.