Coolant leak under intake manifold

[JPJ2007]

I have a bad leak under the intake manifold. I replaced the thermostat last year iirc and I assume it's that. Is there anything I'm forgetting that would be leaking coolant under there? The hoses were all new but I am just running things through my head before I order parts and pull the intake manifold off. Last time I did a carbon cleaning, but I guess it wouldn't hurt to do it again with a media blaster this time....


Need to replace some vacume hoses so I'll do those too.

Thanks

[95blkmax]

Take a look at your coolant crossover pipe (the one that connects the two cylinder heads and exits out the driver side into the upper radiator hose). That pipe tends to get brittle like the rest of the plastic cooling system... but pay very close attention to the mating surface against the cylinder heads. The o-rings there are known to flatten and harden over time, allowing coolant to seep through. It's what happened to me and I ended up having to replace the entire pipe because the nipple for the expansion tank hose broke while pulling that hose off.

[JPJ2007]

Thanks, I replaced it about 20k miles ago with the thermostat and everything else, it's not leaking. I'm getting a large amount of coolant flow out of the valley pan area under the intake, and it's literally flowing off onto the front of the motor while it's running.

I was looking through some photos, and I appears there's a pipe that comes out of the thermostat area and heads towards the firewall. I'm thinking maybe that, I don't know. I'll get around to pulling it off this weekend. I gotta build a pressure tester adapter so I can pressurized the system with the intake off and find the leak.

However, yes, that cross over pipe is extremely brittle so others need to be aware of it.

It's the original reason I did all the work I did. I broke a nipple off of it looking at my fan.
Figured since it had to come off, I'd do the tstat and everything else as well.

[95blkmax]

Dang, and i wont be able to look at my engine until Sunday. Hopefully you'll get it sorted prior!

[JPJ2007]

Just pulled the intake manifold and only god knows where it's leaking from. I even put Oil UV dye in to find my oil leaks, and Coolant UV dye in the coolant and drove around for awhile. Still can't see where the leak is. But it leaks so much coolant that at idle I can see the coolant flowing underneath the intake manifold so what in the world.
And as for the oil, I THINK it's leaking from the rear upper timing cover but i couldnt confirm it with the uv dye and a small extended mirror tool.
Both solenoids are leaking so I know I gotta fix that but I didnt think it was real bad.

It's just everything covered in an oil and coolant mix since I have both on the top of the motor....

I'm picking up a coolant pressure tester so I can see if I can push the coolant out of the area it's leaking from...

The good news is, the thermostat and other stuff I replaced 25k miles ago isn't leaking so i guess my mechanic skills are worthy of shade tree status. lol.

I'll report back after pressuring the system...

I guess really I only have a few things I could even replace in that area and one of those would have to fix the leaks.
1. The Pipe leaving the thermostat housing of the block to the cabin heater core
2. The cover in the center that appears to be for the pvc or vacuum system
3. The solenoids which I already know are leaking and will be replaced
4.... I don't even see anything else that could be leaking there.... The thermostat and where it mates to the housing block is perfectly clean...


Here's a video of how it looks.

[JPJ2007]

Update.... it's the thermostat. Went to eat dinner and came back to it having pushed out through the gasket. I don't know if it's because I left the res cap off and it caused it but regardless at least I have an idea where the leak is. Now I wonder about the oil.

I'll have to look into that center cover and see if I should replace it...
I guess since it's off I could. Not sure. Maybe if I tighten the thermostat it'll seal up.
Not sure i want to chance it..

[95blkmax]

nice! one down, one to go.

btw the video did not post. Also, I know you also did the VC gaskets back then in your big maintenance session bit over a year ago, but since you have the IM off, any chance it could be the PCV box itself? I know those lines go brittle and when they break they sweat oil out of them pretty fast... so I ASSume it would be the same with the actual PCV box under the IM.

As for the t-stat, see if Audi sells just the seal/ gasket at the base of the t-stat housing. If they do not, I recommend replacing it. It's very odd for that to start leaking 25k mi after you replaced it.

[95blkmax]

btw, the reason I recommend to replace the seal/ gasket or the entire unit if no seal/ gasket is sold by itself... is because in the unlikely event that this all happened because in the rush of getting the car back on the road, you torqued down one side and maybe only brought it down on the other end without properly torquing it... it's possible that the fresh new seal would have worked fine. But with time and heat cycles the rubber became brittle and since it's not sitting flush (this theory would have the seal squashed on one side and not as much on the other side) it's starting to allow pressurized coolant through. If you just tighten it all down, it could certainly work, but it's only a matter of time before it starts leaking again, because the seal itself isn't shaped right anymore.

[JPJ2007]

Yeah Im calling audi shortly to see. I thought it was weird too, Especially since I trqed it down to specs with a trq wrench. The other thing that is sorta odd is it didn't seep out until it cooled off and seeped out. Maybe under pressure it's a lot more obvious. I meant to order a pressure tester dammit. I forgot about that. Maybe I'll go ahead and do that.


I wonder if it's because I used high tack gasket sealant between the motor and the thermostat... I wanted to make sure it had a good seal, surely that isn't the reason. Also i'm 90% i properly trqed it down, and in the right order (Opposite of each bolt)
I guess we'll see.


Ah, here's the videos.

Looking for the leak


Finding the coolant

Sorry for verticle video, fucked that up. lol ( I hate verticle videos )

[JPJ2007]

Alright so...

Thermostat Gasket
(4) Solenoid Seals

I may just try that and see how it does. I sure looks like the PCV box gasket is leaking all over but taking the intake manifold off is a 15min job. Moving down to the pcv box is an entire other job having to remove the fuel rails and all.

Im tempted not to do it. It's a $35 gasket ( Not from Audi )

Well... Just Called Audi and they don't have ANY of the gaskets I need except the solenoid orings and ONLY 3 !

So frustrating LOL.

[95blkmax]

shit. yea I had to wait for them to get more of the solenoid gaskets too lol. They only had two in OKC and had to get the others from Tulsa. Also, doesn't harbor freight sell cooling system pressure testers??? If not them I wonder if parts stores have them for the loaner program!

[95blkmax]

So I got my IM off to remove the oil filter housing, and found puddles of oil around my PCV box. It APPEARS that it's all residual from the drip-down of the old intake cam control solenoid seals and from the oil filter housing. Before I cleaned around I saw the fresh tracks along the walls coming from these areas whereas there were no tracks along the rest of the valley's wall. Made me think of all the people with unexplained oil missing! Not burning it, no drips on the floor, yet the level goes down. Maybe those folks should lift their IMs and see lolol.

How is this coming along?

[JPJ2007]

It gets better and better. So, I went back to check it out last night and the entire middle area is full of coolant. Its caused it to drip off the front of the motor where I could see it flowing before hand while the car was running.
What's odd is that it's been off since I first posted about it, so we're going on almost a week now. And its just dumping the coolant out.

I didn't even think about harbor freight having the adapter I need. I checked with Autozone and they don't have the size I need and their tools were brand new and had 2 seperate kits with sizes so no luck there.
It's $36 for the adapter on amazon, and I think i'm just going to order that here in about an hour or so.

I haven't ordered the parts because I want to pressurize it and make sure before I need some extra gasket or something. I'll upload the photos and video. I'm on a 72hour shift now ( Maximum we're allowed to work in a row ) so I won't get off work until Sunday 7am and then
i'm celebrating christmas with my family since im back on a 24hr shift on christmas day so I'm really probably not going to mess with it until the 26th when I get back off work. Gotta love working in emergency services... :/

I'll eventually get around to fixing this. I have to... I believe my oil leak isnt the rear upper timing covers now and probably the 4 solenoids (I know all 4 leaks, so hoping its just those. I'll replace those orings before taking off the upper timing cover)

[95blkmax]

Daaaaaang. What a bad one. First off man thank you for what you do. I know it's not easy giving up that family time, but society would not function if it weren't for folks like you in emergency services keeping an eye out for us.

I feel your pain on the hold up. I almost had my oil filter housing off when I realized that ONE bolt was a damn triple square (@#^%^&#$!$%&!!! One 10mm, two T35s I think they were... and ONE RANDOM ASS triple square.... wtf!?! ). I ordered a set of VIM triple squares and they should be here tomorrow. But I was hoping to get it all done in one day on Wed when it was 65*. Now for tomorrow and Sunday I'm looking at highs of 43* and 39* respectively. I'm trying to take pics along the way so I may put up a writeup on the rear timing covers and oil filter housing.

Our cars are getting quite the xmas lol

[JPJ2007]

Haha no kidding, I feel your pain. I replaced that gasket when I did my carbon cleaning.

Heres The video I forgot to post.. makes sense now, since the cars front is up the radiator is above the thermostat causing it to fill up that void. So... I ordered the adapter and will get the tools from tlautozone loaner program and use my adapter.
If you need one, I'll link it. It's on amazon and is aluminum so looks like good quality.


I should note, I'm amazed how green the dye made the coolant. It glows of course like crazy with the light kit, but I use audi extended red coolant but this stuff looks straight from walmart green. Lol... makes me want to flush it but eh. The dye isn't suppose to hurt anything...



I really need a new vacuum pump and I think it's partly why my throttle runner plates aren't opening up but that's like a $300 part. It'll just have to wait. I may try ordering the gasket and taking it apart and just cleaning it real well...

[95blkmax]

I'd link it anyway in case anyone else needs it! Well you're making progress dude. My triple squares should arrive today, and I got a room heater at Home Depot LOL. Hopefully it will make for workable conditions lol.

Re: vacuum pump. I changed the gaskets on mine 1 yr ago. The flat one against the head was toast so that certainly helped replacing it, But there was also a perimeter o-ring that went behind the actual front plate of the pump. When I removed my front plate to replace it, to my surprise there was absolutely no o-ring there. I put in the new o-ring and I did not have any oil coming from there for months. Then during the summer, I noticed it again. Very faint at the time but a year later it has grown to what it was prior to me replacing it. So now I know I gotta replace the unit as well. Was not looking forward to spending that money. As at this point I want to replace that WITH my lower rad hose who's been taking the blunt end of that leak for a while now.

[JPJ2007]

Alright so the adapter arrives today from Amazon and tomorrow when I get off I'll be able to pressurize the cooling system and find these leaks.

So, I can't find any information online about this coolant line that runs from the thermostat area on the block to the back of the motor and appears to go into the cabin...

Here's it highlighted with a nice little hand finger...




And here's a photo of what it looks like, same as the video.

[95blkmax]

That goes to or from the heater core inside. I THINK it's the feed, but I'd have to look at the coolant circuit to know for sure. It's #22 on this diagram https://genuineaudiparts.com/parts/2...iagram=1352065 But it doesnt specify if it's feed or return.

[JPJ2007]

Sure enough, thats gotta be it. Thank you!

I was thinking it might be leaking, but we'll see this weekend. I'm really excited to be able to pressurize this system and find these leaks...

[95blkmax]

And it it DOES leak, that's great! Because as you can see on the diagram, there is an o-ring available for it so you wouldn't have to buy an entire pipe. Good luck!

[JPJ2007]

Well I was able to confirm it's the thermostat leaking heavily... AND a hose coming off the water pump to the heater core in the cabin... it's a really small leak at 18psi..

It'll be a total pain replacing that line but I'll check the cost. Considered just putting some rtv in the connector and seeing if that works but I know that's super cheap and ghetto.

Vids to come!

[95blkmax]

Good discovery! Way to track that down. When I put my IM back on just now I completely forgot to look for another hose going through the firewall other than the one I pointed out in post#18 (mostly because it's like 29* in my garage and I'm the idiot there working on the car lol).... so I am curious to see what this other hose off the water pump is! Looking forward to the vids

[JPJ2007]

I'll get em up shortly... sorry for the delay.

Now I wonder if my tea wrench is off and I just never trqed the thermostat bolts down to the correct number. I tightened them down and it holds at 20psi cold. That's when I found the other leak which is pretty minor, but still there...

Calling my local audi dealer first thing in the morning about the parts. Their same price as pelican parts or ecstuning so may as well order from audi. (The two websites were special order from audi anyway)

Will update vids

[JPJ2007]

[95blkmax]

Wow dude impressive! And that's after you torqued the t-stat back down, on a cold engine. You must have been loosing lots of coolant with the coolant cap's pressure, on a hot motor.

Making progress!!

[JPJ2007]

Thanks, not sure which freaking hose that is that The 2nd leak is coming from.

Ordered the thermostat gaskets and the solenoid Orings, calling shortly and adding the brake vacuum pump gaskets so I can fix that too.

[JPJ2007]

Alright just called my local audi dealer.

4 solenoid o rings,
Thermostat gasket
Vacumm pump gasket

Be here tomorrow. I'll see what that does to the problems.
This time I'll be using loctight

The 2nd coolant leak I'm hoping just needs to be reseated. If not I'll buy a hose, but we'll see where we are with these fixed. I'm hoping it's the solenoids and not the timing cover leaking.

[95blkmax]

awesome dude keep us updated!

[JPJ2007]

Anyone know what pressure our cooling systems runs At?
I have a small leak on a hose connector at 20psi but I think that's hoghernthab it normally runs anyway... I'm still gonna fix it but not sure what to test the system at


The only thing im finding Is b6 a4 tests at 1 bar 14.5psi, so if that's standard then I should be fine. But, I want to make sure. I don't have a bently. Might be time

[95blkmax]

Not ignoring you. I really do not know on this one and was hoping someone that did know would jump in. I've read somewhere that it was a 16 psi system, BUT I read that a long time ago, and since I don't recall the source, I wouldn't put my $ on it. Does it happen to say it on the plastic of the cap? maybe on the underside facing the tank's interior?

[JPJ2007]

No worries, I've been on here long enough to know silence just means someone doesn't know for sure. Not that they're ignoring someone.

I said eff it, and tested it at 20psi. Didn't leak, used some blue loctite and called it a day.
Replaced 4 solenoid o rings and Got it all back together.

Didn't fix the small coolant hose since ill have to order that hose.

Went to start it and the battery was dead. So I'll get back to it tomorrow night.

We'll see where it's at and if it'll work for a couple months then I'm just going to run with it. Until I can pick some days to replace one thing at a time until it's taken care of.

I'll update this weekend

[JPJ2007]

Well it's back together and not leaking so that's great. Problem is it dies when I come to a stop and it goes idle.

Code I'm getting is p0441 which is reverse evap purge flow.

It's obviously something I've done... But not sure how because it was put back exactly the way it was before..

I'm so ready for a new motor lol... I'll go through the system I guess and see if I can find the the problem

[95blkmax]

Grrr! The evap crap you must have messed with is all on top of the TB. I wonder if you accidentally banged into the purge valve (which acts like a one-way check valve, so if it's stuck open it will allow flow in any direction the pressure differential takes it) and took it out of it's misery (like I did with my fuel pressure sensor a few weeks ago... apparently by resting my elbow on it while doing the oil filter housing gasket lolol).

- - - Updated - - -

At least it's an easy replacement!

[JPJ2007]

Well I'm hoping that's all it is. When I was tighting the main pvc tower back into the pcv box I heard a crack. I'm assuming I broke it somewhere down below? However, it's not directly related to the code of a reversed purge flow I wouldn't think.
Not sure how I forgot to include that in the last post.

:shrugs: I guess I can try a new purge valve and see if that fixes it. If not, looks like the intake mani is coming back off. But certainly not right now...

I just need to get a handle on this car. One thing at a time I suppose. At least the thermostat gasket isn't leaking. That was a huge leak and issue. Solenoid seals are all new so those should be good as well.


ECStuning has it for $18 shipped. I'll go ahead and just order it.

Also, whats that website that the parts all have a lifetime warranty? Even the oil... I keep meaning to check their prices on stuff

[95blkmax]

That would be www.FCPEuro.com good sir!

[JPJ2007]

Bam, Thanks Sir! $4 cheaper than ECS Tuning before and after shipping....

Edit: I'll call audi just to make sure before ordering in 6hours. lol Why wait a week if they have it for a similar price. (Doubtful)

[95blkmax]

cost time factor indeed. I did the same with the solenoid o-rings. Local dealer wanted a dollar more per o-ring than online, but having them next day Vs 5 business days later made it worth it

[JPJ2007]

Yeah for sure. I ended up getting all my recent parts from the dealer. Both Pelican parts and ecstuning had all the parts as special order. Hell for the SAME price I could just buy
From my local dealer. Sure, they had to order the parts to but had them in 24hrs.

[JPJ2007]

Dealer wants $45 for it. I can wait a week... lol

Edit: Amazon Prime had it for $19.98 2 Day Shipping.. From VW lol... It'll be here Wednesday

[JPJ2007]

New purge valve installed and still no luck.

Replaced a small section of vacuum line at the front of the motor and the car runs stronger than it has in a long time. After 10 minutes though it still has a rough idle and will die sometimes at idle.
But No Check engine light and the intake runners seem to be working again so that's super good news.

So, I still have more vacuum issues somewhere. Unless I pinched an intake gasket or something putting the intake manifold back on. This wasn't an issue I had before... So it's gotta be.

When I was tightening down the pcv tube into the metal cover I did here a crack at the end. I wonder if I broke something and that's the issue. That parts expensive as shit, like $300.

I'll check the rest of the lines I guess first before I pull the intake manifold off again. This is turning into a pain in the ass. Still wanting to work on the headlights too.