drunkenup

I posted here about 2 months ago about my 2010 3.2 suffering from carbon buildup. Since then it has been through the shop once more, to replace 2 burnt out spark plugs.

I also posted here a while before then about my car suffering from excessive loss of coolant, which has occurred twice now. The first episode was late last year, and then again a few months ago. The tank as well as pump were cleared of fault both times and the reservoir was simply refilled.

Fast forward to a week ago, and the car is exhibiting some of the symptoms from when it was down for carbon buildup. Difficulty starting cold, noticeable throttle response lag (definitely engine, not computer/pedal), and now, a very bad fuel smell upon start up.

Just a few minutes ago I looked under the hood to find the coolant has once again disappeared, and the tank is only filled half-way up. Anyone think my engine problems are connected to coolant? The explained to my dealership that it may be injectors, but rather blamed on carbon buildup. The carbon cleanup sort of fixed that, but only slightly...

what do you guys think?

Bob Petruska

Two burned out spark plugs sounds strange, and if so, along with the excessive coolant lost I sure would document carefully what the dealer is doing and if he doesn't resolve it I would be heading to lemon law. If that coolant is entering the engine you could be trashing that engine. Does you oil level increase?

drunkenup

This is what I am suspecting is happening and I bet the fuel smell upon start up is actually burning coolant.

Lemon law doesn't seem feasible at this point, with 50800 miles and 3 years since it was new. Fortunately, I would expect Audi to pay for it since this is an ongoing problem we've had long before the warranty expired.

I have an appointment for next week.. I hope it doesn't hydrolock on the way there.

MP4.2+6.0

Any modern car that loses coolant has a problem. Period full stop by me, and across every Audi I have owned since the C3 (1985) with a sealed system with coolant tank.

If it loses coolant, it is either: going out a hose or crack somewhere or a bad water pump, or into the motor and either coming out the exhaust or going into the oil. Normally it's the first (external leaks) fortunately. However, a lot of times it leaks onto something hot and then just burns off/vaporizes so you never see the telltale signs. Turbo motors and very high performance motors (some S's, W12, etc.) have some extra cooling circuits too.

If you do a close inspection you can often still find the leak source. If it's actually on the ground, that's easy to then start probing from things above. Always look at the water pump too; they have a blow out port related to the seal, and often as they go bad they start leaking at what seems almost like the shaft itself near the pulley center.

If not these, variously you can also find some wetness and somewhat oily looking stuff; I have seen this along the bottom of my A8 radiator for example when I realized it had a pinhole leak and slowly lost coolant; dealer had not ever found it, but prior owner service records I got my hands on suggested to me they may have looked for something early in car's life. To find many of these, you probably need to be under the motor area with any belly pan removed. Small leaks like that near very hot parts can evaporate so you don't easily see it on the ground; or, it drips onto engine belly pan very slowly and also evaporates.

The other flavor I've found over the years is where it fully burns off with nearby heat but then leaves a dry powdery residue. It will be similar to the antifreeze in an off white color tinted toward the anti freeze hue (pink, purple, etc. depending on the version of antifreeze in the vehicle). I have seen that kind of thing at things like clamped hoses close in to the engine block where things are really hot.

Also, watch out for any water to oil coolers the car may have (near oil filter, tranny coolers, etc.) Those can leak externally too, and some are really buried, especially on a big motor like my A8 has.

As far as the nightmares, if it's an internal engine leak, it is either water into the combustion chamber, or water into oil. The latter is rare but also easy to find. If you ever find a milky mess under the oil cap when you open it, proceed immediately to expensive repair jail. Failing (or rather avoiding) that, if on a cold morning you see lots of steam out the exhaust--almost a cloud, not just the normal stuff, or it still clearly is blowing water way after everything is heated up, its probably a blown head gasket.

Last, likewise modern cars should never just "lose" plugs. An engine in decent tune can probably run a plug 100K miles; iridiums often are spec'ed like that on newer cars, platinums common to Audis could run that long likely even with a change interval of half that, and even obsolete copper cores could go a good way. If you have serious plug issues, it's a sign of either bad fouling, head gasket issues, severe overheating issues (loss of coolant, bad thermostat,, etc.), or something really wrong with the ignition system (knock sensors, etc. Much of this BTW should be a serious "light show" on the trouble ("idiot") lights on the dash (plus show up in a VAG COM/dealer scan).

Net, start looking hard for leaks, and if you don't have sufficient experience, get a pro to look at it. Mark the overflow bottle and track it carefully too for rate of loss. Literally on my 95K mile 7 year old A8 with the biggest cooling system Audi makes, I use exactly zero coolant. Literally, ever. Ditto on the 140K mile plus V8 A6 that is now 13+ years old. Same w/ older C4, C3, etc. And, if it lost coolant, eventually I always found a leak or bad water pump or thermostat that caused it to overheat and "blow its top." Fortunately no blown head gaskets or internal motor issues since the old notorious early 70's C1's I first owned and maintained.

dsackman

I think you should get yourself a new car.


.

drunkenup

Like I said, the dealer performed pressure tests on the entire cooling system twice without anything that has come up. During my visit after the spark plug ordeal (I was shown them, these things were CHARRED) I also found out it had its water pump changed at around 15K miles. No leaks in the garage floor as far as I can see.

I am convinced this is a bad head gasket or something of the sort.. I'll look out for anything unusual coming out of the exhausts when I start it tomorrow.

As for a new car.. the new 3.0T Q5 is very enticing. It is my mom's however and it'll take some good persuasion (or a generous discount) to make a move like that.

MP4.2+6.0

I found suggestions of it in the paperwork, and even some telltale Sharpie markings on the water reservoir where someone was marking the level at various points. And the dealership is a high volume one in the SF Bay Area, it was their flagship model at the time, AND it was actually the owner's PERSONAL ride in its initial life. You would think if they tried hard on someone's vehicle to find an issue, boy that would be the one!

First, I found a slightly loose clamp at an obscure solenoid valve buried under a rear plenum cover below the windshield--found it by the residue signs mentioned again below. They confirmed that and dutifully tightened the clamps. But it took me 3 1/2+ years into its life to find the slight seepage on the bottom of the radiator just before the 4/50 warranty clocked out and I went over it w/ a fine tooth comb. They were again surprised I found it, but also happy to change it out and give it all new coolant while they were at it. Before that the coolant would seem to drop ever so slightly over thousands of miles even after the clamp tightening, but it was subtle. Ever since, 100% never drops. Of course zero issues with fried plugs either, which would set off major alarm bells for most anyone in service I would think.

Yes, a pressure test should find the meaningful stuff, including a head gasket or internal passage crack, but perhaps not the smallest stuff, and of course not one that might periodically reseal itself with some amount of gunk that floats around in older coolant--no matter how "lifetime" Audi, its likely formulator BASF and other suppliers like Pentosin want to suggest it supposedly is.

As I tried to say in my prior post, the typical Audi under motor belly pan often conceals leaks or keeps it from hitting the ground until you drive it and it sloshes out later. Hides many an oil or power (hydraulic) steering leak for that matter for a while too. Plus the coolant leaks often just burn off. To be sure, it would need a really close visual inspection, a lot from underneath and w/ any belly pan off, plus a careful look see for the powdery residue as I suggested in the prior reply.

D_Frost

Wow... tons of knowledge/experience from MP4.2+6.0... very very thorough

Parsec

I've noticed a few experienced forum members coming on here recently from the other boards (i.e. A6, A4). It will create a great knowledge base for us since it seems like a lot of Q5 owners are first-time Audi owners.

D_Frost

Indeed, and it would appear that some of them have Q5's on order, so this subforum will get more active