Overheated Will Not Turn Over
 

BMW X5 4.4 2002 115,000 miles

I had a hose blow off when the weather was down to 7 degrees. I had replaced all the hoses last year except for the one I didn't see which goes from the water valve on the driver side wheel well to the back of the engine. It was running fine before the hose blew then the temperature gauge spiked all the way to red and the car stalled before I realized what had happened. It would not start back up after that and would just turn over. I had it towed back to my house and I am waiting for the new hose. I tried starting it again yesterday but the battery was dead from leaving the four ways on. I am just wondering if it would not start again because there is a temperature safety cut off to prevent you from running the engine if the temperature is too high or if it will not turn over because the head gasket is blown. I am getting the new hose tomorrow but I am worried that the head gaskets are blown which is what caused the hose to blow off in the first place. In any case my real question is: Is there a temperature cut off that prevents the car from starting when the engine is too hot.

A blown head gasket will not "blow" a coolant line. I do know if the engine runs overheated you have a chance of blowing a HG or warping the head. Not sure on the auto cutoff though. It would be nice if all vehicles had this option. I've seen small engines (Honda 5.5hp) that if low on oil, will kill the ignition.

As far as I know, there is not a switch that prevents the engine from turning over. Now when you said you tried to start the car again, I am assuming you filled the motor with coolant again and temp fixed the blown hose just to see if the X runs correct? Because a head gasket is blown, doesn't mean the engine will not turn over unless the pressure loss is so much between the cylinders that there isn't enough compression in 2 cylinders or more. To do a thorough test, you will need to replace the hose, fill the system with coolant, or heck, you could just use straight distilled water for the time being. This way if it does work, you could do a flush at the same time. Anyways, bleed the system fully and then try to start it. If its still a no go, check the easy stuff first and work your way to the harder stuff.

I would advise against using straight water at this point in time not unless you live in OZ. With the Polar Vortex that has griped the USA for the past days, it is still cold enough at night for water to freeze and a crack engine block is an ending story in my book.

But a blown coolant line will blow a head gasket if you lose enough of the coolant that the engine is running in the red.

Thank you for the responses.

I was able to temp patch the hose with some hose tape and fill it back with water. It would not start at that point I was thinking that the engine was still too hot or that some ECU fault had occured which may cut off the fuel supply. I have a compression tester and will do compression tests tomorrow, the mean time I am very stressed out about the possibility of having to replace the head gasket.

I had done a search previous to this post and found numerous examples where a head gasket failure will in fact cause hoses to blow off. Here is one example.
http://www.xoutpost.com/bmw-sav-foru...-broken-2.html

Several years ago I had this personal experience with another car where a leaking head gasket caused pressure in the cooling system. The car blew out several hoses of the course of a few months before the head gasket leak was diagnosed. That car was a 92' Eagle Talon TSI.

My original question is....

Is there a saftey measure which prevents the engine from turning over when it is too hot by cutting off the fuel and or ingnition coils?

I have searched google exhaustivly and I can not find any information on this.

If the engine is not turning over you may have hydrolocked the engine. Remove all the plugs and see if the engine will crank. As alway have a fire extinguisher handy since you will be spitting out combustible mixture.

There is not such safety for the engine in the event of high heat, coil issues or similar.

I'd ask and suggest to trace the chain of events. When the car was fully functional and run, you (believe) that the issue was a blown hose. The one you didn't change (it happens). It is likely that the overheating that happened is most likely as you lost coolant and the cooling system couldn't adequately cool the engine. There was enough coolant however to cover the temperature sensor to give you a temp gauge in the red.

The car could have stalled from some seizing contact (most likely). Can you bar the engine over?

Now you saw the car wont' start. Does this mean that the engine won't turn, that the engine won't catch or something else?

If your battery is dead, charge it up and see if the starter motor will rotate the engine. WHY? Because in some cases of badly overheated engines, there can be piston to cylinder wall seizing. It also could be hydro-locked (coolant) from either a blown head gasket and/or cracked cylinder head.

If with a well charged battery, you should (just in case the engine might have some coolant in the cylinders) see if the engine turns with the spark plugs removed.

Then determine (as you pull the plug) if you have water in a cylinder. Assuming not, than with plugs and coils, see if she starts. If it starts, than shut it off and put your cooling system back together.

If (still with a well charged battery), the engine turns but won't start - it could be a myriad of things (which could include a blown head gasket or related problem).

Gregory891
Thank you for answering the question.

The engine was turning over and seem to crank without any hesitation as it normally does. It seemed like it was not getting any spark or fuel. The suggestion of hydrolocking was very helpful. It lead me to look at vapor lock:

A vapor lock can also develop when the engine is stopped while hot and the vehicle is parked for a short period. The fuel in the line near the engine does not move and can thus heat up sufficiently to form a vapor lock. -Vapor lock - Wikipedia, the free encyclopedia

I have my finger crossed that this might be the case

While it is possible, given ambient temperatures lately - it is less likely with a fuel injected car, but it CAN happen - simply not as prevalent as carburated cars of 30+ years ago.

Remember that for a gasoline engine to run it needs three things: compression, igntion and fuel. You might assume that the engine is fine (compression), but you could do a compression test & cylinder leak down test (to see if you blow a head gasket or cracked a head. There is a also a coolant test fluid you can use to see if you had any exhaust gas in the coolant (but as it mostly leaked out - you might not have very much of the old stuff to test).

You need to test for spark to see if you have a coil, plug or other possible issue.

You need to test that fuel is running and it coming out of the injectors. MAF sensor is less likely to have failed JUST as you overheated the engine, but anything is possible.