5.2 FSI coolant burning and exhaust fumes in coolant system

A6 All/ S6 All
#1

Hello,

I have noticed that sometimes I have steam coming from both of my exhausts. I belive it is stock, so banks should not be connected one to another. Coolant loss is minimal, but I have done a test for exhaust gasses in coolant and it came back positive after 4 tries with cooling in between, becouse coolant started to boil. Other than that I don’t have overheating issues.
Also did compression check, and it is as follows
5 12,5 10 13
4 11,5 9 12,5
3 12,5 8 13
2 12,5 7 13
1 11,5 (?) 6 13

I had a slight issue on cylinder 1 with my measuring setup, but I’d say it has at least 12 bar in reality.

Do you think that it is possible I have blown head gaskets on both banks at the same time? Smoke from both exhausts seem to be the same amount. I guess i could have coolant leak to manifold through PCV tube heating, but it would not give me CO2 in the cooling system.

Anything I missed, or I just have a bad luck?
I guess there is a possibility for cracked head or block, but I guess it would make even less sense to have a crack in both heads, or two cylinder liners, one in each bank.

#2

I might be mistaken here, I dont have, nor have ever had the original exhaust, but I do believe it has a small H pipe between the resonators.

#3

I will check that, but I belive that any connections between banks are just mounting points. But thanks :wink:

#4

Yea there is an H pipe connecting the two banks. My car burns off water in the exhaust also but for long, creates steam… Buy this off amazon works wonders and sets your mind at ease. Fluid is also reusable. Do you smell the sweet burn of coolant in the exhaust?

Screenshot_20221025-111401_Amazon Shopping
Screenshot_20221025-111401_Amazon Shopping1440×2960 606 KB

#5

No sweet smell. I have already done CO2 test in coolant, and it is very slightly positive. So giving that H pipe is there I guess i could fairly confidently say that my passenger side bank has a leak in cylinder 4. Hoping it is only head gasket issue.

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#6

So I don’t know what to do. Dropped the heads, and got both of them checked - and they are fine. No signs on head gaskets as well. Has anyone heard of a head gasket internal failure between it’s layers? I know, that block could be cracked, but I didn’t overheat the car or anything.

#7

Does anyone possibly have some good info on permissible block distortion?
Heads were pretty much fine, machine shop told me that they machined them by 0,07mm.
Also, has anyone heard of a cracked 5.2 block? I have not found a single post about cracked block, and I am starting to get a little bit nervous that I might just be the unlucky one.

#8

I think it’s not a bad idea to do an oil sample test. This should tell you if you have any coolant in the oil. This can help give a better perspective on what is going on and help in the cracked block question.

#9

I have already dumped the oil, but i Don’t think it was mixing with coolant