2002 H6: VDC light comes on and then starts to run hot 1 - 2 minutes later

[idosubaru]

Friend has a bizarre randomly occuring issue on a 2002 H6. 

I'm likely going to replace the headgaskets for them for free this week, H6 fun, so wanted to check first.

Another guy on another forum posted the same exact symptoms - VDC then overheat a few minutes later - but never followed through with what he did. 

 

Fans are working correctly. 

 

1.  VDC light comes on (temp gauge fine)

2.  within a minute or 2 of that light coming on the temp gauge starts to go up

3.  VDC light is never on otherwise - only when overheating. 

4.  VDC codes are 71 and 72 - steering sensor and yaw sensor. 

5. overheating will go away sometimes when increasing speed and sometimes when exiting interstate and idling or driving around town.

 

Other 2002 H6's with VDC i've seen overheat never had the VDC light come on....why the discrepancy?

[CNY_Dave]

Could this be one of those weird H6 weird alternator things?

[idosubaru]

crack smoker isn't that a good guess Dave! 

 

i'm about to pull the engine and replace the headgaskets on this H6 beast.  dealer confirmed exhaust gas in the coolant.

 

i'm still perplexed about that VDC thing when I had the exact same vehicle overheating before that didn't do this?  that just seems weird.  actually i still have that vehicle on hand...maybe I should switch VDC controllers and see what happens. LOL

[idosubaru]

i'll check alternator output and for crank pulley separation.

[Fairtax4me]

Good luck with the HG job.

 

That is odd about the VDC. Coincidence? Did you clear the codes and those both came back?

Possibly a grounding issue?

[idosubaru]

 

 

That is odd about the VDC. Coincidence? Did you clear the codes and those both came back?

Possibly a grounding issue?

 

Didn't clear them - light goes out on it's own so I assume codes are coming and going.

 

VDC light comes on.....temp gauge starts to creep up (with definitive overheating symptoms)....let it cool down and the VDC light goes off on it's own.

 

Coincidence - it does it like clock work, 100% repeatable, every time as described above, so that doesn't seem likely.

At first I assumed it was miscommunication over the phone...those symptoms sounded unlikely...but now that i have the car and talked to them in person that's what's happening.

 

There's a thread on subaruoutback.org from a few years ago where a guy details the exact same symptoms.  But he never followed through and hasn't replied to a private message.

Hmmmm, talking about it now - how about this conjecture:

 

Maybe it depends on where the breech happens in a particular cylinder and a particular sensor gets hot locally before the engine sensor does?

In other cases if the breech happens on a different cylinder, that particular mystery sensor doesn't get hot before the engine temp sensor.

[Fairtax4me]

Do you have a scanner that can read live data?

Engine Temperature can fluctuate quite a bit with no movement of the temp guage. Perhaps the VDC light comes on because the system is being disabled due to higher than normal temperature?

 

I would watch the temperature reading when the VDC light comes on and see of the temp is consistent when the light comes on.

[idosubaru]

 

Engine Temperature can fluctuate quite a bit with no movement of the temp guage. Perhaps the VDC light comes on because the system is being disabled due to higher than normal temperature?.

 

I don't have a live data scanner, don't think my OBDII's do that.  I have a cable for laptop...RR probably, but software install went wonky and never sorted it.

 

What you say makes sense and probably is what is happening - but why would another 2002 VDC H6 wagon (same exact vehicle) not do that even though it ran much hotter than this current one?

[Fairtax4me]

I like my Innova 3130 scanner for live data. They're kinda pricey though compared to the Bluetooth OBD2 readers you can use with a smartphone. I can graph data and email it to myself or anyone else with the Blue-driver app on my iPhone. It costs about $100 now though for the Bluetooth adapter.

 

Could be a mid-model year change. Could just be a fluke. Hard to say.

 

Maybe the transmission temp sensor triggers it, and the trans temp sensor on your other car isn't reading correctly, so it never turned the light on.

 

Or we go back to the charging system / electrical theory.

Theory's is theory's. Proving the theory is the hard part.

[idosubaru]

Issue appears resolved - no more overheating.

 

I replaced the headgaskets and they left my house for Califonia, in Arizona now and no more overheating on the cross country trip. 
 

[Skaker]

Hi Grossgary, I have excactly the same symptoms on my 2002 outback h6. Vdc light turns on and engine heats two minutes later. I had run out of coolant! I hope it will be a hose, it leaked a lot under the engine, but i couldn t see where it came from... will know soon.

 

Also once Vdc light came on and it was because of a damaged wheel bearing.... (And also it works correctly indicating that vdc is off when i switch it off and when vdc system actuates while turned on)....

 

Conclusion: it's a misterious multipurpose light that seems to say "something is going wrong somewhere" ... .?

 

 

thanks a lot for your post, i m no longer worried about the light, just about the overheating... Cross my fingers for a damaged hose instead of something broken...

[idosubaru]

i've seen wheel bearings cause enough play to impact the ABS sensor which would disable the VDC.  that makes sense, though the ones i've seen were really bad by that point.

 

the coolant means one of two things: 

1. it's leaking and you need to repair the leak

 

2.  it overheated and pushed coolant out the overflow/radiator and it sprayed/spilled all over the engine compartment.  this could also be a leak or it could be a mechanical failure - radiator, fans not coming on, thermostat, or headgasket. 

[Skaker]

Yes the bearing was already noisy when the light turned on.

For the overheating, mine is option 1. Leaks under the engine. Just run out of water.

Thanks for the comments

[idosubaru]

You said you couldn't see where it came from, if that's true then we don't yet know what the cause is - "Leaking" and "pushing out the overflow" are two different scenarios/symptoms, so if it's not known where it's coming from then it's not known if it's 1 or 2.

 

If it pushes out the oveflow tank it'll bubble out and fall down under the engine just like a leak - need to find the source to determine which it is.  

Coolant "under the engine" is nearly meaningless as a diagnostic tool regarding this difference. 

Someone needs to look at it and tell where the coolant is *originating* from, not where it's ending up.

[1 Lucky Texan]

pressure testing of the coolant system seems in order.

[Skaker]

thank you for the comments, i explain it more in detail: I could not see where it came from when i looked at the engine from above, there is no visible leakage on the top, neither from the cap, it leaked somewhere under the engine, one drop every two or three seconds. I fully refilled the circuit and carefully drove to my mechanic's 5 km away and dropped the car there. By that time it was leaving a thin track of leakage on the road and still nothing visible from over the engine... It is certainly not a head gasket problem, what i dont know is if it is the hose, the O rings of the water pump, or some "metal" cracked: water pump seals or bearing (means water pump replacement) , radiator leakage (probably means radiator change), ... or even worse (block cracked means car replacement!)... Still HOPE it s the hose under radiator. Will see tomorrow. until then,,,, fingers crossed

[idosubaru]

Oh sweet, that's awesome news then. 

 

Probably just a hose (in order of most likely to least likely):  oil cooler hose, radiator hose, heater core hoses.   

Or radiator. 

 

Water pumps very rarely leak in these, newer generation water pumps often last the life of the vehicles, particularly these timing chain equipped engines like yours, but of course it can happen.  They have a small weep hole at the bottom of the timing chain cover. 

 

With the coolant now drained I would just take this opportunity to replace the radiator and oil cooler hoses (and oil cooler gasket), and thermostat/gasket. All cheap and doesn't take long at all. 

The oil cooler gaskets always leak at some point - and require that oil cooler coolant hose to be removed so might as well just do it now while the fluid is drained.  Only a couple dollars and minutes. 

 

If it was due to rust (like is often the case in the northeast of the US), then you might consider replacing the lower ATF hoses too by the radiator if they're also looking nasty.  It only takes 30 minutes and parts are pocket change. 

[1 Lucky Texan]

+1 hoping bypass or oil cooler or other easy fix.

[Skaker]

Hello again, i am glad to announce that the winner is.... The HOSE . Ouf!

Thanks Grossgary for your advice about the gaskets and the other hoses. The problem here is the parts delivery time, Subaru official service in Spain doesn't often delivers parts to other mechanics in reasonable delays. It's a shame, the most common answer you get is "five weeks"... That's why we owners of elder subarus usually buy the parts in the internet, from Germany or UK or Poland, and usually much cheaper.

And let's see what happens when VDC light turns on next time...

[Skaker]

latest news, just to prove how right Grossgary was: after replacing the hose, thermostat remained closed and engine overheated again,,,, and of course VDC light turned on! (if fact it works perfectly well as a water temp warning light). I got the spare thermo from Germany and replaced the old one, seal had glued. hope this is my last message concerning vdc light in a long time.     

[idosubaru]

VDC light, multiple overheating events, multiple parts replaced on H6 engines - usually ends up being headgaskets but let's hope it is a few simple items at the same time.