Engine died at speed, won't start!'

**SammoVWT** · 26-04-2016,12:45 PM

It does sound like a dreaded head gasket failure, and battery drained from trying to turn it over.. best case scenario is that you have a split coolant hose and a bad expansion tank cap and it let air in and conked out. Doesn't sound likely though from what you describe. Really hoping it's not your HG but I fear the worst. If it didn't go too far with no coolant, you may be able to salvage it.

Its better to have air in the coolant rather than coolant in the oil, certainly cheaper if it needs a major repair.

**The Norwegian** · 26-04-2016,12:49 PM

Well, if it was a hg fail, I don't think it overheated the engine. I only had a 3 minute drive with the car and it has not lost a bi amount of coolant. It was not boiling when I opened the exp cap. Color is fine. If I get it running I will check for bubbles.

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**Micu** · 26-04-2016,12:52 PM

Naturally the battery will go flat with continuous cranking and no running. Battery voltage shouldn't go below 9v when cranking but anything near this is normal. If the alternator was gone then the car wouldn't crank at all and just chatter or click. Possible insufficient charge only enabling 10-15 cranking time.
Mic your still concerned about alternator remove belt and make sure the pulley doesn't feel gritty. They have a clutch pulley that is designed to freewheel during cranking and kick in at speed.

**The Norwegian** · 26-04-2016,01:01 PM

Right, will check that. So it's supposed to spin freely by hand? I guess there's no way of knowing if it engages when running other than measuring voltage?
I didn't measure when cranking, I only cranked for about 3 seconds yesterday and I measured the voltage about 2 hours after that, then it was still at 11,5 or so. Do you have any theories beyond the alternator?
I mean, a hg problem would not be great, but it wouldn't really stop the car unless overheating, would it? I was thinking fuel, but fuel pump runs 2 seconds when I switch ignition on, which seems about right. Sounded normal. The filter has probably never been replaced, but if it was clogged, I would expect to see more misfires beforehand. I don't know.

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**Micu** · 26-04-2016,01:10 PM

Best way to check a hg is cylinder compression test using a compression tester. (Diesel or petrol btw?) with your fuel pump priming sounds like a petrol. 2-3 secs to prime sounds about right.
What kind of car is it? And just to illiminate the obvious. It has fuel? I.e the fuel gauge is working.

**zollaf** · 26-04-2016,01:23 PM

Originally Posted by The Norwegian

Right, will check that. So it's supposed to spin freely by hand? I guess there's no way of knowing if it engages when running other than measuring voltage?
I didn't measure when cranking, I only cranked for about 3 seconds yesterday and I measured the voltage about 2 hours after that, then it was still at 11,5 or so. Do you have any theories beyond the alternator?
I mean, a hg problem would not be great, but it wouldn't really stop the car unless overheating, would it? I was thinking fuel, but fuel pump runs 2 seconds when I switch ignition on, which seems about right. Sounded normal. The filter has probably never been replaced, but if it was clogged, I would expect to see more misfires beforehand. I don't know.

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no, a freewheel pulley will spin the alternator in the drive direction but freewheel in the other. if you use a small screwdriver to turn the fan inside the alternator you should be able to turn it in one direction but not the other. it doesnt engage at a certain speed.

**Micu** · 26-04-2016,01:46 PM

Sorry misinterpretation of txt. Depending on what alternator/year it is the alternator itself will create the free spinning and not engage rotor polarisation until adequate engine speed has been achieved. For simplicity I explained this as the alternator pulley freewheeling. This leads to free load cranking and easier starting.

**The Norwegian** · 26-04-2016,02:11 PM

It's a Valeo 120A. My car is a B6 2.0 ALT with multitronic. I have a compression tester, but have never used it. Do I need to ground the spark plugs or coils, or unplug anything? The Haynes manuel didn't mention anything like that, except that I should delete any ignition error codes after performing the test.

**KevTrem** · 26-04-2016,03:14 PM

Start with a fresh new battery. You should be able to crank longer than 10-15 seconds before going flat. If the battery is shot and not spinning the engine fast enough it wont fire.

New battery on, crank the engine and see if it will fire.

Coming from Peugeots battery condition plays a big part on what happens with the car, it can cause all sorts of problems and have you chasing false problems.

You say your battery is 4 years old, that's all a lot of people get out of a battery before replacing, especially in cold climates. Cold kills batteries

**Micu** · 26-04-2016,03:23 PM

To be safe and also test that the plugs are sparking pull the plugs and replace one by one with the compression tester. Ground the screw part of the plug with a jump lead to battery negative. Get someone else to crank the engine and observe the spark on the plug gap and at the same time you'll get a reading on the compression tester. This is a non starter, but just in case you don't want it to start with a compression tester in situ so if it does switch straight off. If all compression readings are similar and each plug is sparking then compression ok spark ok. Would begin to look at the fuel system.