overheated vq30de = toast?

[johntints]

At 65mph noticed noise under hood, no smoke out of tailpipe and normal reading on temp gaige, let off gas and motor then died and no restart, after cooling tried again and starter sounds like spinning only half a motor? pullys turning, no firing or anything but water ran straight out tailpipe and coming out behind air compressor and close to front oilpan, very clean water?no water in oil, drove only 10-15 miles probably, found heater valve hose came loose, filled with water, was wondering why it held 3 gallons, going straight out tailpipe, I hate it when a car does this! what will be the potential damage be ?

[Q45tech]

Why a head temperature sensor is a useful safety addition when coolant system is not maintained to as new standards and checked frequently!

Allowing an overheat is owner vehicle abuse.

[johntints]

ok, so we all agree we need correct fluids in our VQ, but the question and point of my post was to find constructive advice, from a experienced person about the VQ specifically. Very few real people have a backup temp monitoring system. we all rely and trust that the manufacterer has a dependable system. because our unsuspecting mothers and young kids are driving maxima's also. So again, what can you say about overheated VQ engines and the likelyhood of just need a new VQ, I can install myself! And already have promised my wife we would install a backup system.......

[Q45tech]

The point was changing coolant hoses is a mainteance requirement, when they become aged, hard, or exposed to ozone.

Generally you can expect to change them at or prior to every 70,000 miles or 6 years of exposure. Just as you replace coolant every 30k if maximum life is desired.

Generally one restores the coolant system to new [refill and stops leaks] then does compression, leak down and hydrocarbon gas in coolant tests to decide if engine is worth saving.

If it doesn't crank, or makes noises with fresh new oil and filter further research is necessary.

Really difficult to analyse over Inet, pay an experienced expert.................all aluminum engines are a different animal from mixed or all cast iron.

" unsuspecting mothers and young kids are driving maxima's also" should be trained to understand and deal with modern technology or suffer consequences.

[johntints]

I have driven hundreds and hundreds, of average cars by all companies, have been in dozens of overheated and neglected or (abused) vehicles. But never have I seen a situation where the car lost fluids instantly and the temp gauge did not respond to motor temp rise. Motor was seriously hot, gauge was reading below halfway point on scale, a normal reading, so my takeaway on this was, a 95 Maxima, had a poorly designed system that monitored the COOLANT but could not accurately monitor head or block temp. so if fluids "exit quickly" driver will not notice and continue driving. No driver error here, would never let my "MOM " think it was her "abuse" that led to the death of her Maxima. IF the VQ30 needed a better way to monitor its fluids, the Japanese should have done this improvement themselves, or at least mentioned in owners manual that the motor could be "sizzling" without notice. I have already purchased a very low mileage motor to replace and will use a backup head or motor monitor. Very cheap insurance, Japanese could have done the same. It is a very classy motor to be subject to this anomaly.

[Q45tech]

Without a doubt any overheated engine is purely the owner/drivers fault.Failure to check fluids and perform mainteances.

The results are almost always the same - a new engine.

[johntints]

so I would then conclude that IF your car gets a flat or blowout driving at 65, that it would be your fault also, Right! I that were true then Firestone would have never bothered to recall all those tires. There would never be a recall=ever! But not in the real world we all live and drive. We expect better..

If you do not have experience with this particular problem, then your remarks are more inflamitory than helpful, but IF you know something about this subject please explain why or how "the temp gauge will relay a normal reading but be completely out of water and smoking hot." And how does that demonstrate driver/owner neglect?????? I Think this is the original problem I had, i have since bought a new motor and love the Idea of a fresh VQ. So (Q45tech), what do you really know about this particular problem?

[Q45tech]

Nothing two engineering degrees doesn't teach you and 18 years of dealing with Infiniti engines.

Very simple the inside gauge sensor is an immersion type thermistor.When the water is low or leaks out, the space around sensor is just air and eventually steam and thus cannot read above 212F.

Without coolant the engine keeps heating the aluminum until it decreases the bearing clearance and the oil cokes , engine siezes.

Q45tech doesn't stant for technican but TECHNICAL

As to tires and as a member of the Tire Society*, I would never buy Fstone or allow them on any car a friend owned. I won't drive a rental car which has more than 8,000 miles on its tires.In fact I've used nothing but Michelins for the past 600,000 miles and 34 years. Haven't had a flat during that time nor pulled a jack. I carry an electronic tire gauge every day everywhere.

*http://www.tiresociety.org/mainpages/nhtsa.htmlThe Tire Society grew out of the ASTM Committee F-9 on Tireshttp://www.tiresociety.org/pdf...b.pdf

[Q45tech]

Even my 1985 300zx, as did my 88 Pathfinder, had the same coolant sensor and I believe it began in the mid 70's so every dealer tech or race shop I know is aware of the situation and KNOWS not to allow any all aluminum or any bimetal engine to overheat.

Ignorance of this FACT assures extra income for many repair personnel.

Happens to every brand especially Toyota and Honda.

[arsenix]

If it truly overheated it is probably toast. Once an aluminum head or block overheats they almost always warp.(all aluminum engines... every manufacturer) Since you were getting water out the tailpipe... that almost certainly means your head warped enough to blow your head gasket.

Sorry but I'd start looking for a replacement engine. It is possible you could rebuild it but there is a good chance your block and/or heads are warped beyond use.