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95 S6 Losing Coolant, no visible leaks

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Old 06-08-2012, 09:02 AM   #1
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Default 95 S6 Losing Coolant, no visible leaks

Hi,

I have seen a couple of posts around the web about losing coolant with no oustide sign of a leak, but nothing specific about replacing a head gasket. I do not appear to be burning coolant (no white smoke) but the loss has increased over the past couple of months and I had to replace my oil sending unit recently. I have to put in about 1/2 quart of coolant a week. It only drops level when I run the car.

I am operating under the assumption that I have a head gasket problem, yet I am the original driver of the 192K miles car and it has never overheated. I will be taking it to do a cylinder leak down test, but would like to be prepared for the worst.

So, if it is a head gasket, is this something I can do, or do I need either the dealer or other shop to do it for me. My only other head gasket experience was 30 years ago when I replaced the head gasket of my 77 Honda Accord, and while that went well, a lot has changed since then. I have done suspension work and tuning work over the years, and continue to do various maintenance jobs on the older cars but I am not a mechanic.

If this has been covered in another post (and I have just been too dumb to be able to find it) please direct me there. I love this S6, it is in beautiful shape and I would hate to not save it.

Thanks in advance for any guidance,

Ed

1995 90 Sport Quattro
1995 S6
2008 S6

Previous Car: 1990 CQ (sold it with 335K on it)
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Old 06-08-2012, 10:49 AM   #2
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Just taking a stab here, and someone with actual knowledge will come along soon - but if there's no obvious leakage and you're not seeing any white smoke - is it possible steam is escaping under pressure while you're driving from somewhere - so its essentially evaporating
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Old 06-08-2012, 01:52 PM   #3
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Had a pressure test on the coolant system done a couple of months ago when this started (and I was losing much less coolant) they found no leaks at that time.

Ed

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Just taking a stab here, and someone with actual knowledge will come along soon - but if there's no obvious leakage and you're not seeing any white smoke - is it possible steam is escaping under pressure while you're driving from somewhere - so its essentially evaporating
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Old 06-08-2012, 05:48 PM   #4
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Had a pressure test on the coolant system done a couple of months ago when this started (and I was losing much less coolant) they found no leaks at that time.

Ed
Doing any meaningful long distance guesses about your problem is difficult at best, but trying to do this when the person doing the work is not even involved makes it more so. This "pressure test" was done in an attempt to find a coolant leak? Or the usual check to insure the system is maintaining the correct pressure? Because, if you were looking for a leak, a leaking headgasket is still a coolant leak, and if you are losing coolant, you have a leak.

Are you using a coolant that leaves visible traces at a leak (Hint: Audi coolants do this.) And, there are none of these traces anywhere, old or new? And you have investigated all possible areas with a thorough, disciplined approach, using a bright light, and cleaning off any old traces? You need to do all this before resorting to a check for an internal engine leak, then check the spark plugs looking for a steam cleaned plug or two. You would expect that coolant in the combustion chamber would cause some mis-firing to some degree.

The big new item on this engine is the turbo bolted to the exhaust manifold. Removing the head requires either removing some difficult bolts on the exhaust manifold or removing the head with the exhaust manifold and turbo still attached, making it unbalanced and heavy-definitely not a 1 person job, and done better with an engine crane.
Your DIY job is just to R/R the head; a machine shop will do any work required on the head-valve stem seals at least.
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Old 06-08-2012, 06:17 PM   #5
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Understood. I am less looking for a diagnosis than an opinion whether I can deal with the job. I have another car to drive and a garage where the car can sit while I do the work.

I will check with the dealer to see exactly what kind of "pressure test" they did. I had explained what was happening, so I hope they tested in such a way as to rule out a leak in the cooling system (water pump, lines, radiator, overflow tank, etc) outside of a problem with the head, but I don't know that for sure. Originally the Audi coolant was in use, but I was going through so much of it recently I switched (I know I shouldn't have) to the off the shelf green crap.

The only other clues are a rougher start & idle when cold and a slight pull back when threading the throttle at cruise. The engine still feels strong under heavy throttle and there is no hesitation (like I have experienced when I had to replace a coil pack). The funky running I think would point to coolant in the combustion chamber but there is no white smoke.

The plugs looked normal when I replaced them a week or so ago (along with the fuel & air filter). I think the coolant may be getting directly into the oil. While I didn't see any heavy milky residue, the oil looked off when I replaced the oil sending unit that failed (and maybe it failed due to coolant in the oil?)

If I am not burning any oil, and the compression test is solid, do I want to get the head redone? Do you think having a head redone while the bottom of the engine is original is going to create any issues? It also looks like dealing with the timing belt is no fun task either (always have had the shop do that).

Like I said, I love the car and don't want to give up too easily on it. I would love to see someone's write up on doing a head on these cars (reading a write up on my wife's 90 Sport Quattro EGR Valve helped me deal with cleaning that and the throttle body).

Thanks for the response,

Ed

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Doing any meaningful long distance guesses about your problem is difficult at best, but trying to do this when the person doing the work is not even involved makes it more so. This "pressure test" was done in an attempt to find a coolant leak? Or the usual check to insure the system is maintaining the correct pressure? Because, if you were looking for a leak, a leaking headgasket is still a coolant leak, and if you are losing coolant, you have a leak.

Are you using a coolant that leaves visible traces at a leak (Hint: Audi coolants do this.) And, there are none of these traces anywhere, old or new? And you have investigated all possible areas with a thorough, disciplined approach, using a bright light, and cleaning off any old traces? You need to do all this before resorting to a check for an internal engine leak, then check the spark plugs looking for a steam cleaned plug or two. You would expect that coolant in the combustion chamber would cause some mis-firing to some degree.

The big new item on this engine is the turbo bolted to the exhaust manifold. Removing the head requires either removing some difficult bolts on the exhaust manifold or removing the head with the exhaust manifold and turbo still attached, making it unbalanced and heavy-definitely not a 1 person job, and done better with an engine crane.
Your DIY job is just to R/R the head; a machine shop will do any work required on the head-valve stem seals at least.
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Old 06-09-2012, 04:26 AM   #6
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At 192K miles, I would have the valve guides checked for wear and then lapped if ok and seals replaced at a minimum. R/R of the head can be a good DIY project if you organize even before starting work and maintain control of the workplace. You will want assistance with the head removal and replacement to control alignment, etc. The right machine shop to check the head and do any valve work is the key to success here. Since there are so many things involved, making a progress listing can be helpful in organizing parts ordering and the work flow.

If there are no clues in the combustion chamber/spark plugs for coolant, I would look harder for the leak external to the engine. The pan under the engine can stop some of the spots on the driveway from giving clues. Be sure to look in the plenum chamber behind the firewall. The Bentley workshop manual would be helpful to say the least,but this should help. I don't know of any FAQ that has tackled the entire head R/R proceedure, but there are some sections that may be helpful. Motorgeek may have more on the engine work itself.

http://s2-audi.co.uk/workshop/aan/aan.pdf

http://tinyurl.com/7aeckc3
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Old 06-10-2012, 05:14 PM   #7
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You're not the only one with coolant leaking now

I've filled up my reservoir 2 days in a row and its empty again -- mine is leaking towards the back of the engine somewhere, my feet were even getting dripped on while driving, with no AC running -- ugh
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Old 06-10-2012, 06:02 PM   #8
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If you are getting coolant inside the cabin, then it might be your heater core leaking. While I have never done that job, I think it requires removal of the dash & center console, though I do not know much more than that.

Ed



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You're not the only one with coolant leaking now

I've filled up my reservoir 2 days in a row and its empty again -- mine is leaking towards the back of the engine somewhere, my feet were even getting dripped on while driving, with no AC running -- ugh
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Old 06-10-2012, 07:20 PM   #9
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Originally Posted by lliejk View Post
If you are getting coolant inside the cabin, then it might be your heater core leaking. While I have never done that job, I think it requires removal of the dash & center console, though I do not know much more than that. Ed
Neither the dash or the center console have to come out for a heater core.
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Old 06-10-2012, 08:00 PM   #10
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Its gotta be a heater core -- my front drivers floor mat is soaked -- is there any step-by-step for getting a heater core in and out -

this could be my biggest job ever, but I'm ready for it -- the only shop I've ever used here is down to 1 mechanic, and they are swamped -- not a lot of good german auto shops in Charlotte NC for older Audi stuff

Better go dry things out some.

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Old 06-10-2012, 08:27 PM   #11
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Doubt that you need the heater core right now. By pass it.
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Old 06-11-2012, 09:45 AM   #12
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Thanks Dave -- I was just reading on this thread where you had suggested that -- I should be able to figure that out

http://forums.audiworld.com/showthre...ht=heater+core

Unfortunately, my carpet is soaked with coolant, dammmmit - hope it evaporates

ETA: It appears these are the 2 hoses I need to disconnect - then get a similar type hose ~10" long and connect - I assume I can try this w/o draining all my coolant.

Ed - I dont want to high-jack your thread, sorry - just didnt want to start a new coolant thread
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Old 06-11-2012, 09:52 AM   #13
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Not a problem, I have to wait and see what comes from the leak down test and anything else I can check before deciding what to do.

If I go the R&R head gasket route, I think I have enough information at this point. I will post the results when I get them to help anyone else out with a problem like this. Be thankful you know where your leak is (although having it in the passenger compartment is a mess!)

Ed

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Thanks Dave -- I was just reading on this thread where you had suggested that -- I should be able to figure that out

http://forums.audiworld.com/showthre...ht=heater+core

Unfortunately, my carpet is soaked with coolant, dammmmit - hope it evaporates

ETA: It appears these are the 2 hoses I need to disconnect - then get a similar type hose ~10" long and connect - I assume I can try this w/o draining all my coolant.

Ed - I dont want to high-jack your thread, sorry - just didnt want to start a new coolant thread
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Old 06-11-2012, 02:05 PM   #14
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Thanks Ed -- Here's the temporary fix. I probably lost ~50oz of coolant during the changeover, so I'm not sure if I'm getting good flow, or if an air pocket got in the system.

I cranked it up and squeezed the main hose trying to work the coolant around. Then drove around the neighborhood a bit. Seems normal but it was only running ~10 minutes. Thermostat went to its normal position.
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Old 06-13-2012, 12:41 PM   #15
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Nice repair work!

Found antifreeze in my oil, will be contemplating a head gasket R&R. Started a new thread.

Ed

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Thanks Ed -- Here's the temporary fix. I probably lost ~50oz of coolant during the changeover, so I'm not sure if I'm getting good flow, or if an air pocket got in the system.

I cranked it up and squeezed the main hose trying to work the coolant around. Then drove around the neighborhood a bit. Seems normal but it was only running ~10 minutes. Thermostat went to its normal position.
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Old 06-13-2012, 07:48 PM   #16
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Default 99 audi a4 2.8 check engine codes p1392 and p1626 help please some advice

runs good 160kmiles never changed timing belt so its definatly on time.thinking its the cam shaft sensor but want another opinion and p1626 is tcm missing message but i own a manual ? so i thought there is no tcm? but i was told to check and see if there is one under the passenger seat if its wet or not ? give me your advice please
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Old 06-14-2012, 08:57 AM   #17
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runs good 160kmiles never changed timing belt so its definatly on time.thinking its the cam shaft sensor but want another opinion and p1626 is tcm missing message but i own a manual ? so i thought there is no tcm? but i was told to check and see if there is one under the passenger seat if its wet or not ? give me your advice please
Dude. Wrong forum. This is the C4 UrS five-cylinder turbo forum, not the B5 2.8 V6 forum. Try there.
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Old 07-28-2012, 04:01 PM   #18
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You're not the only one with coolant leaking now

I've filled up my reservoir 2 days in a row and its empty again -- mine is leaking towards the back of the engine somewhere, my feet were even getting dripped on while driving, with no AC running -- ugh
check at the very back of the motor, under the plastic cover that houses the ICU's. you have to take the cover off, but this is not under the cover itself, its between the motor and the firewall. there are two hoses down there about an inch wide that have a plastic t junction, with a plug at the top of the t. if one of those hoses slipped off, it will dump your coolant everywhere and could in theory get sprayed through a hole in the firewall. i know about this because that t junction broke on me and i have to replace it.
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Old 07-28-2012, 04:21 PM   #19
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Funny that you pulled this up from a month ago - I had the T pipe break last night - guess its gotten brittle

I rigged it back up - will probably hold for a while - probably better to order a new one

Think the part # is 4A0 819 497 - about $10
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Old 07-29-2012, 06:53 AM   #20
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Funny that you pulled this up from a month ago - I had the T pipe break last night - guess its gotten brittle. I rigged it back up - will probably hold for a while - probably better to order a new one. Think the part # is 4A0 819 497 - about $10
Tee = 4A0819497 (item 13 below)
Sensor = 025906041A (item 14 below)
O-ring = N90316802 (item 15 below)
Retaining Clip/Spring = 032121142(item 16 below)
Heater Valve (if needed) = 4A0819809

Click the image to open in full size.

This is what a good Tee and coolant sensor, etc. look like:

Click the image to open in full size.
Photo Courtesy of mannywdc.
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Old 07-29-2012, 06:53 AM
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