Coolant Leak after Thermostat Replacement

[my1stturbo]

Had a shop replace the thermostat and the j plug a couple of months ago and ever since I've had a slow leak. The car is normally sitting so don't notice it until I go back to drive it and the bottle is empty. Looking a bit the other day I noticed a small pool of coolant about the size of a quarter on the block right about next to the oil filter. Wondering if the best approach is to pressurize the system and look for leaks. Or is there a way to check the connections at the thermostat without taking everything back out?

[egovreau]

Since your problem started after changing the thermostat, it's a good bet you pinched one of the o-rings putting it back together.

If memory serves, there are three. One for the housing to block connection, one to the line running from the radiator and the third is from the small line that comes from the heater core return.

A pressure checked would certainly help find it.

Sent from my SM-G986U using Tapatalk

[my1stturbo]

Thanks. Either of the 2 lines you mentioned should be able to get to with just removing the throttle body? Don't mind having the drain and refill the coolant but was hoping to avoid disconnecting the alternator again if I can. Don't have access to a garage at the moment so trying to work outside when I get a decent day.

[Seerlah]

When you pay a shop for work, you also pay for a warranty on parts and labor if things go awry. Bring your car back to the shop and have them correct it free of charge, since you already paid for their service. They should not charge you for fixing their mistake, and I have never came across a shop that did not honor that system. Bring the car back there and see what they say (if they will offer to fix since time elapsed since the work was done).

[my1stturbo]

Yea I know. I brought the parts with me but I know what you mean. The owner stands by the work and I know they'll take care of it if I bring it back, just a few hours out of the way in most respects.

[JAudi23]

I did the thermostat job my self a couple months back and failed too replace the o-ring for the hard pipe. I have noticed a small leak as well.

I plan to get in there this weekend to replace the o-ring which I suspect is the culprit. Might be your issue also.

You can clearly see in this photo that is where the leak is from on my car. I'm hoping to just move the coolant tank out of the way, and remove the drivers headlight to have enough room to get in there and do what I need to.

20210109_165514.jpg

Sent from my SM-G965W using Audizine mobile app

[URS4surf]

If your old thermostat/jplug was leaking at all, you now have a pressurized system.

From your description leak could be your oring on bleeder in top heat pipe ....

[my1stturbo]

Going to try to get a good look tomorrow while I have some daylight. Which connections, if any, would I be able to see from up top of the engine without removing any parts? I can drive the car a bit and then crack the hood to see if I can determine where it's leaking if it's only doing it under pressure.

[Nirvana09]

Pretty much nothing. The bare minimum I would remove to do a thermostat replacement is the alternator. With that out of the way you can reach in and get the connections out with a little room. I've also done it with the intake removed and it makes it a lot easier as well. Neither take that long to remove if you want to do it right.

[my1stturbo]

Pretty much nothing. The bare minimum I would remove to do a thermostat replacement is the alternator. With that out of the way you can reach in and get the connections out with a little room. I've also done it with the intake removed and it makes it a lot easier as well. Neither take that long to remove if you want to do it right.

Thanks. Saw the picture above and was hoping I might be able to at least see that 1 connection. I'll double check the bleeder is tight tomorrow. I might be removing the intake manifold for a different reason in the near future so maybe I'll go that route. If the alternator has to come out I can manage that. Was just hoping to see if possible to see the leak before hand. I'll just go ahead and order all the o rings to have on hand of I do pull the thermostat out.

[JAudi23]

If you move the coolant tank out if the way and remove the drivers headlight, you can probably get a decent look. You'll need a light and either a mirror or small camera to get a pic.
With everything in place I just positioned my cell phone down there to get the photo.

Sent from my SM-G965W using Audizine mobile app

[my1stturbo]

Thanks. Trying to get myself oriented so I can figure out the pipes. Looking from the divers side I see a puddle about 1-2" back of the dipstick funnel towards the firewall. I let it run for a bit until the engine warmed up but didn't notice anything coming from the bleeder. But I can always try to give it a proper drive today and take another look.

[my1stturbo]

I got to take a chance to take a look today while it was still like out. I say a drip from above the bolt that is right next to the dipstick where the plastic meets the metal tunnel. I'll try to get a picture posted but wondering what that might be.

I tried cracking open the bleeder on the top pop but no coolant came out.

[audi-owner]

I noticed a small pool of coolant about the size of a quarter on the block right about next to the oil filter.

1. if your coolant bottle is empty after driving, then it isn't a small leak OR you have a small leak AND the mechanic did not bleed the air out of the system completely.

2. the best way to pressurize the system is to make sure bottle is full, then run the engine to temperature.

[my1stturbo]

1. if your coolant bottle is empty after driving, then it isn't a small leak OR you have a small leak AND the mechanic did not bleed the air out of the system completely.

2. the best way to pressurize the system is to make sure bottle is full, then run the engine to temperature.

Thanks for the post. The coolant empties if I eat the car sit for a couple of weeks. Day to day driving I don't notice a major loss when I drove it a few days in a row. Filled coolant bottle last week, let it run for 15 minutes. Drove it today for about 15 minutes and when I got back I checked under the hood. Still had coolant in the bottle was well above the minimum line.

I know the mechanic mentioned it took forever to bleed it so I suspect there as a been a leak since the wok was done and that's why it took so long to bleed.

[audi-owner]

have you checked the oil level recently?

what was the original reason for the thermostat replacement?

[my1stturbo]

I'll check the oil level tomorrow, haven't checked it recently but as I'm actually able to see coolant on the block I figured its a leak. Looking at some pictures I was able to take it looks like either the j-plug or the hose connection that goes into the top of the thermostat.

I needed a new heater core as I had no heat. Thermostat had a code for it previously (P1292 if I recall). Figured while the coolant was being drained made sense to do both.nJZvKY9.jpg

[audi-owner]

make sure you wipe down the entire dip stick. it is difficult on these audi sticks to see if the level in the oil pan is above normal.
you need to make sure that the oil level is not abnormally HIGH

I needed a new heater core as I had no heat.

o.k. just curious was the heater core blocked? or leaking?

to be clear, did the mechanic change the heater core?

how often have you found the coolant bottle empty since the repair work was performed?

[my1stturbo]

The heater core was blocked. It was changed and the heat issue was resolved. There isn't any coolant leaking into the car from what can see.

I'll check the oil today. I see the coolant on the block itself but I will check for coolant in the oil.

[my1stturbo]

Double checked oil and it looks to be at normal level and consistency.

[audi-owner]

was the coolant bottle low or empty each time you refilled it?

how many times have you refilled the coolant bottle?

[my1stturbo]

I've had to refill it twice. It was practically empty each time after having let the car sit for a couple of weeks.

[audi-owner]

you have posted that you opened the bleeder but no coolant came out.

can you see coolant in the bleeder hole?

you need to completely bleed and fill the system.

until you completely bleed and fill the system, you cannot properly test for leaks

once you have properly bled and filled the system, then run the engine to temperature and check all connections.

make sure to check the water pump !

you have posted that you checked the oil level and it does NOT look over-filled. that is good as an indication that coolant is not leaking into the engine

[my1stturbo]

I didn't back the bleeder screw out all the way but cracked it expecting some coolant to flow as the engine was already hot. I'll refill the system and back it out all the way to see if I can confirm there is coolant in the line. I can see the coolant leaking on the side of the engine block (saw it dropping with the car running) so just trying to track down from where now.

[my1stturbo]

Finally got a few minutes outside while the weather was ok and it was till light out. I was able to see a drip coming down from directly below the circled item in the picture here.

IMG_20210313_120630~2.jpg

I'll try to take out the headlight and see if I can get a better view of it but curious if anyone might know what that is before I start pulling it apart.

[my1stturbo]

I did the thermostat job my self a couple months back and failed too replace the o-ring for the hard pipe. I have noticed a small leak as well.

I plan to get in there this weekend to replace the o-ring which I suspect is the culprit. Might be your issue also.

You can clearly see in this photo that is where the leak is from on my car. I'm hoping to just move the coolant tank out of the way, and remove the drivers headlight to have enough room to get in there and do what I need to.

20210109_165514.jpg

Sent from my SM-G965W using Audizine mobile app

Did you ever get a chance to work on this? Curious what you found you had to remove to get access to it. From what I can see it looks to be that o-ring and hoping to get to it after work 1 night

[JAudi23]

Did you ever get a chance to work on this? Curious what you found you had to remove to get access to it. From what I can see it looks to be that o-ring and hoping to get to it after work 1 night

I did it a couple weeks ago. The car has been parked in the garage since January when we got a new vehicle, so it hasn't been a priority.
I ended up replacing the hard pipe O-ring, which was an easier job as I was able to do it without removing the alternator.

• Removed the drivers headlight
• unscrewed and lifted the coolant reservoir out of the way
• removed the throttle body tube and throttle body
• removed the vertical steel bracket support
• unbolted the rear bolt holding the hard pipe
• unbolted the front most bolt holding the hard pipe to the thermostat
• was able to pry the hard pipe out of the thermostat
• watch a bunch of coolant drain out to the floor and catch pan
• replace the O-ring and reattach the hard pipe
• assemble it all back together

No leaks from what I can tell now, however it hasn't been driven much or put under pressure, as it's still parked.
I'm positive the O-ring was my issue, and everything should be good now.

[my1stturbo]

I did it a couple weeks ago. The car has been parked in the garage since January when we got a new vehicle, so it hasn't been a priority.
I ended up replacing the hard pipe O-ring, which was an easier job as I was able to do it without removing the alternator.

• Removed the drivers headlight
• unscrewed and lifted the coolant reservoir out of the way
• removed the throttle body tube and throttle body
• removed the vertical steel bracket support
• unbolted the rear bolt holding the hard pipe
• unbolted the front most bolt holding the hard pipe to the thermostat
• was able to pry the hard pipe out of the thermostat
• watch a bunch of coolant drain out to the floor and catch pan
• replace the O-ring and reattach the hard pipe
• assemble it all back together

No leaks from what I can tell now, however it hasn't been driven much or put under pressure, as it's still parked.
I'm positive the O-ring was my issue, and everything should be good now.

Thanks for the detailed list. I'll try to get started this weekend. It's the 2nd car now so doesn't see much time on the road, but I took it for a spin this week and realized how much I miss it. So it'll get done soon.

[my1stturbo]

Got this out last night. O ring on the hard pipe was torn so put another on and buttoned that back on. Having a hard time getting the bolt to the cooler back in but other than that went together pretty easily.