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[MV6Danny]

Hi guys i have a bit of a problem with my 3.0 MV6. About a month ago my car started to mis-fire or is running rough when i start it up, after about 30 secs to 1 min it stops and the car runs fine. well on the way to work today the temp gauge went right to the top  then back down to normal and did this a few times. I got to work and decided to have a look to see if it had enough coolant in it, upon inspection i discovered that there was no coolant in the tank. after 2 hours when the engine had cooled down i topped up with water. It took about 3.5 liters to fill it up. I warmed the car up with the expansion tank cap off to make sure all the air was out of the system. It looked like there was some sort of scum on top of the water. I decided to have a smell and i think i could smell fuel or exhaust gas coming from the tank.  I dont know if it was coming from the tank but pretty sure it was. Does anybody have any ideas on this or any advise on what to check as the car shouldnt have used that much coolant. Could this mean the head gasket is gone or maybe the heads are cracked. there is no water in with the oil. Thanks guys hope someone can help. 

[TheBoy]

Test compression.

Very rare for V6 HG to fail (firerings, anyway). 1998 3.0l have a failure mode where coolant leaks to outside of block.

[MV6Danny]

Update. Went out this morning to check the water after the car been sat overnight. Completely cold and the cooling system was pressurized. when i opened the cap it released pressure and i smelt the tank and it smelt of fuel. Is this a sign of a cracked head?

Test compression.

Very rare for V6 HG to fail (firerings, anyway). 1998 3.0l have a failure mode where coolant leaks to outside of block.

Do you mean test the compression of the cylinders?

[Entwood]

Update. Went out this morning to check the water after the car been sat overnight. Completely cold and the cooling system was pressurized. when i opened the cap it released pressure and i smelt the tank and it smelt of fuel. Is this a sign of a cracked head?

Test compression.

Very rare for V6 HG to fail (firerings, anyway). 1998 3.0l have a failure mode where coolant leaks to outside of block.

Do you mean test the compression of the cylinders?

IMHO if it held pressure that long then it is a "sealed" system .. and there are no leaks ..so the chances of it being a head gasket are very slim .. and there is no other way of fuel getting into coolant that I can think of.

[MV6Danny]

Well that is what i would have thought to. But when cold the system should not be pressurized. And there is definatley a strong smell of fuel or exhaust gas coming from the expansion tank. Could the head be cracked?

[tigers_gonads]

Might be worth popping to a mot station and ask them if they can do a "sniff test" on the bottle.

If the water is leaking onto the exhaust manifold from a pipe or the hbv, the antifreeze can can smell  a little

When it was coughing and farting, did you pull a plug lead off to see if there was any water in there ?

[Darth Loo-knee]

Might be worth popping to a mot station and ask them if they can do a "sniff test" on the bottle.

If the water is leaking onto the exhaust manifold from a pipe or the hbv, the antifreeze can can smell  a little

When it was coughing and farting, did you pull a plug lead off to see if there was any water in there ?

Personally find the Sniff Test a load of rubbish.

If your head gasket had gone on the firing ring the compression could push water out of the reservoir at every upward stroke of the piston if that makes sense. Water would come out of the exhaust...seen it that bad water was coming out of the exhaust like it was a firehose.
You say you do have a water leak but dont know from where? If you system is still holding pressure over night I would think it seemed to be water tight... Try turning the heating to hi for the day see if the water leaks. The following day turn heating to Lo, then see if it leaks then too.

[feeutfo]

3.5 litres is a lot to loose, there'd be steam out the exhaust like the orient express.

I'd say the hbv is leaking in either hot or cold position. Depending on the CC setting used when the water was lost....?

Some light scum on the surface of the coolent is not unusual, ESP if the coolent is old.


Might be worth getting the coolant level warning fixed too.

[feeutfo]

And yes, sniff test is suspiciously unreliable. In favour of the mechanic with the large bill.

[MV6Danny]

i understand what is being said but the cooling system was flushed about 4 months ago with fresh new anti-freeze being put in. TBH i havent checked it since i changed it, it shouldnt loose water. If the HBV is leaking that would not explain why the system is pressurized when cold and the coolant smelling of fuel or exhaust gas, where as if the head is cracked the compression in the cylinder would keep the system pressurized and appear to be water tight. Is there any know case of the head cracking.This is the only thing that i can think of to explain this. also its strange that it runs lumpy for upto a minute when first started until warmed up slightly.

[MV6Danny]

3.5 litres is a lot to loose, there'd be steam out the exhaust like the orient express.

I'd say the hbv is leaking in either hot or cold position. Depending on the CC setting used when the water was lost....?

Some light scum on the surface of the coolent is not unusual, ESP if the coolent is old.


Might be worth getting the coolant level warning fixed too.

does mine have a coolant level warning and how would i fix it?

[Entwood]

i understand what is being said but the cooling system was flushed about 4 months ago with fresh new anti-freeze being put in. TBH i havent checked it since i changed it, it shouldnt loose water. If the HBV is leaking that would not explain why the system is pressurized when cold and the coolant smelling of fuel or exhaust gas, where as if the head is cracked the compression in the cylinder would keep the system pressurized and appear to be water tight. Is there any know case of the head cracking.This is the only thing that i can think of to explain this. also its strange that it runs lumpy for upto a minute when first started until warmed up slightly.

Just how does that happen on a stationary engine overnight It would overpressurise like a bandit whilst running I agree .. but not overnight ....

Given you haven't checked the water level for 4 months, and there are no leaks on the floor .. my bet is still the header tank lid, however .. what you haven't said is if it STILL leaks ... one loss of water over 4 months means absolutely diddley-squat .. other than you don't do maintenance on your car properly ..

So, fill it properly, run the car and monitor it DAILY for at least a week ... if it is still losing water then I'll believe you have a problem .... if it does not .. problem does not exist.

[biggriffin]

cooent level warning is underneath the exp tank little plug.
   the fact that you may have cooked it a bit may not be good the other thing is get a pressure test done on the system.

[feeutfo]

3.5 litres is a lot to loose, there'd be steam out the exhaust like the orient express.

I'd say the hbv is leaking in either hot or cold position. Depending on the CC setting used when the water was lost....?

Some light scum on the surface of the coolent is not unusual, ESP if the coolent is old.


Might be worth getting the coolant level warning fixed too.

does mine have a coolant level warning and how would i fix it?

Would have thought so. My 99 cdx had coolant level warning. Hbv and oil coller cover plate tested it regular as well.

Head cracks are not even remotely common on the v engine. It's not that.

Coolant will leak and then not leak from the hbv depending on settings.

Grumpy running could be a number of things unrelated. Ht issues. Air lake. Sticky icv. Did the coolant loss start at the same time as the rough running?

Was the coolant level monitored after the service?

[MV6Danny]

i understand what is being said but the cooling system was flushed about 4 months ago with fresh new anti-freeze being put in. TBH i havent checked it since i changed it, it shouldnt loose water. If the HBV is leaking that would not explain why the system is pressurized when cold and the coolant smelling of fuel or exhaust gas, where as if the head is cracked the compression in the cylinder would keep the system pressurized and appear to be water tight. Is there any know case of the head cracking.This is the only thing that i can think of to explain this. also its strange that it runs lumpy for upto a minute when first started until warmed up slightly.

Just how does that happen on a stationary engine overnight It would overpressurise like a bandit whilst running I agree .. but not overnight ....

Given you haven't checked the water level for 4 months, and there are no leaks on the floor .. my bet is still the header tank lid, however .. what you haven't said is if it STILL leaks ... one loss of water over 4 months means absolutely diddley-squat .. other than you don't do maintenance on your car properly ..

So, fill it properly, run the car and monitor it DAILY for at least a week ... if it is still losing water then I'll believe you have a problem .... if it does not .. problem does not exist.

That doesnt explain the smell of exhaust gasses or petrol in the water though does it? I will be monitoring it daily to see if the water level does drop. when i changed the coolant (when you met me at skurrays to get the antifreeze with your trade club card) The coolant level was fine and hadn't checked it for months be for i changed it.