Let's Play "Diagnos This" - Today: Audi Coolant issues!

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Let's Play "Diagnos This" - Today: Audi Coolant issues!

Postby Oro » Thu May 21, 2020 2:18 pm

Ok, next car on my radar. 2003 Audi A4, Quattro 1.8T, 5spd manual, 165k miles. Alternator is dead, and the coolant is "disappearing." Ruh-roh.

I am looking for a cheap german sedan with an issue or three so I can fix it up. Actually, I'm looking for two, one for my step son to replace his civic and one for me to drive instead of my SLX a lot of the time. This economic situation has made for some potential good deals in this area for the first time in about 15 years.

I looked at the above Audi last night. Cosmetically, it could be a champ. The owner said it started losing coolant, then the alternator went out. She stopped driving it two months ago and it's sat. It is indeed losing coolant, and I can't find a leak in the common spots I am told (coolant flange that cracks, possible bad wp install). It starts and drives fine - no big clouds of smoke, no sweet smell in exhaust. It idles uber-smooth. A short test drive had the light pop on and a good amount of what was in the reservoir disappear.

Oil was good (no mixing), coolant had no contaminants in it. I got out my compression gauge and I pulled the coils and plugs. All plugs looked brand-new (no single one stood out as being cleaner, indicating steam cleaning). BUT - when I went to test, my gauge would not register. I guess it got damaged rattling around that tool box for three or four years since the last time I used it (to do a line pressure test on my Trooper transmission, actually). So I got no results to report/analyze. I sniffed (literally, not with a test kit) the coolant and it smelled, hmm, "sour?" It had an off odor to it that I think indicates C02 in it, but I'm asking for your impression of that. History included a new clutch and radiator a year ago, so possible heat issue then (I forgot to ask to verify).

After going home, I found that CRACKED heads are actually quite common on some of these, so I might be looking at not just a bad gasket but a bad head. I've never had to wrestly with that before, but I am able to if I need to. I do like the car and it may be cheap enough given all these issues (dead battery, dead alternator, possible head) that it would be worth my while to limp it home (actually probably tow it; it's 30 miles away) and make it a project.

If you were to being go back to check the head, how would you go about it, besides just a compression test? Pressure test the coolant? How do you make an adapter for the weird reservoir cap? Ideas?

I ask about further diagnosis because one time ~6/7 years ago, I was working on a Lexus that had the same symptoms. After many hours of head scratching, I figured out it was a combination of thermostat installed backwards (yes, it could be done) and failing heater valve. Fixed those cheap things, and it was right as rain. But given these are prone to head issues...

I am going to figure out the repair cost to the worst case scenario (cracked head), and then if another mechanic/hobbyist doesn't get it by the end of the weekend, see what I could bargain it down to and take on the project.
1998 Acura SLX. OME 929s and front crank, KYB tubes. Retro'd Aisin manual front hubs.
Home rebuilt 4L30E doing great. Aux cooler and temp gauge. Big thanks on the rebuild to Buster28, Jerry (jlemond), CalG, and others.
Factory(US dealer) side steps and roof/ski rack (Yakima).
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Re: Let's Play "Diagnos This" - Today: Audi Coolant issues!

Postby 93trooperpooper » Thu May 21, 2020 4:13 pm

sounds likea cracked head, or head gasket issue.....

i bought a coolant pressure tester from napa, it fits EVERYTHING out there- it uses a adjustable depth inflatable rubber bladder that seals in the neck of the rad, or coolant surge tank. also came with 3 neck size adapters, and a replacement bladder.
it fits micro caps ( motorcycle, atv, import vehicles) and all the way up to front end loaders, heavy equipment, etc

it beats having the stant kit, with 20+ adapters, and the one you need is not there....grrr

coolant test strips. dip it in the coolant, and the color will change , according to the type of contamination.
received it for free, but its been costing me money-go figure! '93 trooper ls dohc auto-now over 400,000 km-! now has manual hubs,784 springs,t-bar crank, rancho 9000 shocks, all led interior lights, hid headlight bulbs, drilled/slotted rotors, custom chipped/cracked headlamps, rust. and mystery oil leaks . and unobtanium parts from JERRY LEMOND.
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Re: Let's Play "Diagnos This" - Today: Audi Coolant issues!

Postby RickP » Thu May 21, 2020 9:43 pm

You couldn't pay me to own a German car. Ex wife had a 2000 Bettle, total piece of junk. Buddies' had Audi's and BMWs and nothing but problems even with new ones.
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Re: Let's Play "Diagnos This" - Today: Audi Coolant issues!

Postby Oro » Thu May 21, 2020 10:45 pm

i bought a coolant pressure tester from napa, it fits EVERYTHING out there


I'll look that up and likely get one. I need to get a new compression tester and some ratchet extensions (have lost some over the last year), so a tool run is in order. I agree now it's a head issue, thinking it through not out working inthe cold and rain (when I was checking it out), and reading on head issues in that car, it's the gasket or a crack. How do I tell which - big difference in cost to repair.

I asked the owner and she said no overheat, the mechanic found a crack in the rad so nothing catastrophic from that. She said before she bought it four years ago, it had a $3k engine repair (had to be head), so either it was gasket then and crack now, or they did something wrong. I looked up common issues on these before going to see it but missed this really common head issue. for the right price, I'd tackle it if I could ID gasket vs. crack. besides sticking a boroscope (don't have one) into the cylinders to look where it comes from, is there a way to find a crack vs. gasket diagnosis?

Rickp - I agree with you to certain degree. You either buy them new, eat the depreciateion and get rid of them before 100k, or you are a mechanic or are married to/sleeping with one. ;) I have no illusion about that. In the 70s and 80s up to about 90, I think BMW and Mercedes really did have an edge over US cars, but since their their push into tech (and it's uncertain/unproven nature leading to break-downs) has dragged them down to or maybe below the point GM and Ford have pulled themselves up to or above. But, that's why I can get an amazing car for chump-change - the world knows this now so 100k+ german cars sell sell for so much less than parallel Japanese and US cars now. But I can fix anything except a worn block pretty cheaply and I enjoy the work.
1998 Acura SLX. OME 929s and front crank, KYB tubes. Retro'd Aisin manual front hubs.
Home rebuilt 4L30E doing great. Aux cooler and temp gauge. Big thanks on the rebuild to Buster28, Jerry (jlemond), CalG, and others.
Factory(US dealer) side steps and roof/ski rack (Yakima).
Oro
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Re: Let's Play "Diagnos This" - Today: Audi Coolant issues!

Postby 93trooperpooper » Fri May 22, 2020 10:21 am

yup, seen alot more ''kids'' driving beemers and auudees arond here- then they rice them out with stupid mufflers and wings and goofy tires and wheels with the stupid camber set-ups. wtf

my old boss has a m5 bmw- ok car, but it was starting to have electrical issues- but fun to drive. turn off traction control, turn on sport and power mode, and drift away around the corners ( whoops)
the car sits outside all year, and the last time i changed the oil in that car was 5 or 6 years ago- '' i dont drive the car enough, i dont need to change the engine oil ''
um
temperature swings, winter goes down to -40, summer its + 40......its called CONDENSATION- no piece of equipment is safe from that, not even your fancy german built car.
his brother has a audi r8, imported from germany, custom built . i saw the car once. didnt look that special to me.
received it for free, but its been costing me money-go figure! '93 trooper ls dohc auto-now over 400,000 km-! now has manual hubs,784 springs,t-bar crank, rancho 9000 shocks, all led interior lights, hid headlight bulbs, drilled/slotted rotors, custom chipped/cracked headlamps, rust. and mystery oil leaks . and unobtanium parts from JERRY LEMOND.
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