Trying to track down a coolant leak - B5 S4 2002

[SnyperBob]

Hello,

I had a slow coolant leak that has seemed to become an increasing problem. The leak is now so bad I could see it dripping as I pulled up the driveway.

I tore apart my car, but I'm having trouble tracking down where the leak is.

My car is a 2002 S4 B5, and I believe I have a plastic thermostat housing. I'm wondering if that's what's leaking. The water pump was replaced about 5 years / 25,000 miles ago, according to service records. I can't seem to find any record showing the thermostat was replaced, and I'm going with the thermostat housing is stock/orginal.

When I removed my skid plate, the leak seems to be dripping from the front of the engine, towards the driver's side. Pretty much under the water pump. This is as far as I got tearing into the car. Do you think removing the timing covers may help me see more, or detect the leak better?

It appears there's some leaking down where the dip stick tube meets the engine block. That's around the spot where the coolant is coming down the engine and wrapping around under the oil pan. Disregard the coolant all over the passenger side where the lower radiator hose connects. It gushed everywhere when I popped the temp sensor to drain the coolant. The leak is on, or coming down, the other side of the engine block.

I tried to look under the intake in the aux water pump spot, but I didn't really notice any coolant pooled up there. From what I read online, I don't think a leak up there would come down the front of the engine.....I think they said those leaks usually run down the back?

[SnyperBob]

A couple side questions. Is my car supposed to have an intercooler shroud for each side of the car? I only had one on the passenger side, I think I'm missing my driver's side shroud.

Also, is it true that automatic (Tiptronic) cars had a transmission cooler in them? Likewise, manual cars don't have this? This is why I folded my radiator parts down, rather than swing them aside. After disconnecting my radiator hoses and wires, I still have two lines connected to the radiator assembly. Just curious if what I read was true. I didn't want to disconnect those lines and have to deal with trans fluid too.

Taking this car apart, I found a bunch of screws as well as that shroud missing. Interesting....

[Monty23]

The best way to find coolant leaks is to pressurize the coolant system to about 10-15 psi and look for coolant rushing out.

[xalents23]

A couple side questions. Is my car supposed to have an intercooler shroud for each side of the car? I only had one on the passenger side, I think I'm missing my driver's side shroud.

Also, is it true that automatic (Tiptronic) cars had a transmission cooler in them? Likewise, manual cars don't have this? This is why I folded my radiator parts down, rather than swing them aside. After disconnecting my radiator hoses and wires, I still have two lines connected to the radiator assembly. Just curious if what I read was true. I didn't want to disconnect those lines and have to deal with trans fluid too.

Taking this car apart, I found a bunch of screws as well as that shroud missing. Interesting....

Yes, you are supposed to have two intercooler shrouds one per side. And tip cars had transmission cooler. The trans cooler is located behind the driver side intercooler. And the hardlines that are connected to the radiator are trans fluid. Which will leak all over the place once removed.

And it looks like you have a bad oil leak.

[SnyperBob]

Thanks for all of the feedback. I've had the car for a few months. The previous owner had tons of repairs done to the car over the years, including valve cover gaskets. My car didn't see to be leaking oil, so I presume all that old gunk was never cleaned off and from old problems.

I couldn't spot where the coolant was leaking, which is why I tore into the car. I'm thinking I should take Monty's advise, and reconnect everything with the front end in the service position. Clean off the engine and everything first, then run it and see if I can tell where it's leaking from.

Thanks for the tips about the trans fluid X, I'll leave those connected for now :)

[SnyperBob]

The air bleed valve for the coolant system is below one of the DV valves, right? I did check and made sure it was tight/closed. That air bleed is pretty much in line with where the drips of coolant were coming off the engine.

[Monty23]

The air bleed valve for the coolant system is below one of the DV valves, right? I did check and made sure it was tight/closed. That air bleed is pretty much in line with where the drips of coolant were coming off the engine.

The only air bleed for the coolant system is on the heater core lines. The rest of the coolant system self bleeds. A small 1/4" line off the cross over pipe on the back of the heads runs to a nipple at the top coolant reservoir. This allows the system to bleed off any air. There are a bunch of coolant hoses by the oil filter housing since coolant runs through the oil filter housing. Check those out if the leak is at the front of the motor.

[Monty23]

FYI

[bps4]

Your car being an 02 it likely has a plastic t-stat housing which would leak down the front of the engine. The old style metal t-stat is more
Durable

[S4GGIN]

Just got through finding a leak just like this, cept on the pass side of the front of the motor. Turned out it was the water pump, most likely your leak as well OP.

[Zba]

The only air bleed for the coolant system is on the heater core lines. The rest of the coolant system self bleeds. A small 1/4" line off the cross over pipe on the back of the heads runs to a nipple at the top coolant reservoir. This allows the system to bleed off any air. There are a bunch of coolant hoses by the oil filter housing since coolant runs through the oil filter housing. Check those out if the leak is at the front of the motor.

#10 on the illustration is also a bleeder valve. Look at the power steering pump and then look to the right (towards drivers side) and you will see the valve on a steel pipe. It is a threaded bolt with an allen head.

You do really need to pressure test the system though.

Don't let the low mileage on the water pump fool you, idle parts fail frequently.

[Monty23]

#10 on the illustration is also a bleeder valve. Look at the power steering pump and then look to the left and you will see the valve on a steel pipe. It is a threaded bolt with an allen head.

Your right, forgot about that. Leaks are easy to find on these cars if you know where to look, just follow the dried up pink g12 trail. Otherwise just pressure test the coolant system.

[SnyperBob]

Ah, yes #10 is what I was talking about, just under the DV.

I'm going to order up an aluminum thermostat housing now. I believe I need to pull the timing belt to replace that, so I'm wondering if I should just order the kit JHM has for the timing belt. (Timing belt, water pump, thermostat, etc) and replace it all while I'm in there.

Do you have any tips/tricks for pressurizing the coolant system, outside of hooking everything back up and starting the car? I came across this video:


I really would like to leave the radiator off, and pressurize the system. I guess I'll need to find something to block off the lower and upper radiator hoses to do that. I think the lower hose is easy to pull off the Thermostat housing, not sure how hard it would be to do for the upper hose.....I'm not in front of my car right now.

I'm thinking I should just hook it all back up and pressurize, I just can't see what's going on in the front of the engine when the radiator is stood up. There's only a few inches of room, even in service mode, and I'm not that good at spotting it!

[SnyperBob]

Anyone have experience with this cheap Harbor Freight pressure test kit? Or know how they work? Do the adapter's screw onto the coolant fill resevoir, or somewhere else?

http://www.harborfreight.com/radiato...kit-61666.html

[Monty23]

Just pull the 1/4" line off the top of the coolant reservoir, cap off the nipple to the coolant reservior with a vacuum cap, and use an air chuck to blow air into the 1/4" line. I just wrap electrical tape around my air chuck nozzle till it fits snuggly in the hose and use a small clamp to keep the hose on. Make sure you turn the pressure regulator down to 10-15psi or you risk blowing your coolant reservoir up.

Obviously the radiator needs to be plumbed in.

[xalents23]

Anyone have experience with this cheap Harbor Freight pressure test kit? Or know how they work? Do the adapter's screw onto the coolant fill resevoir, or somewhere else?

http://www.harborfreight.com/radiato...kit-61666.html

If your going to spend $89 for the harbor freight kit. The UView 550000 Airlift Cooling System Leak Checker and Airlock Purge Tool Kit that amazon sells is a pretty cool kit. Check out the youtube video about it below.

https://www.youtube.com/watch?v=_b6JdAQU16E

[SnyperBob]

Thanks Monte, that's a simple tip to accomplish it. I wonder if I could just pressurize the system without re-adding coolant and try to listen for leaks? Maybe I'll try that first, before wasting more g12 coolant.

Thanks X for posting about the UView 550000 Airlift Cooling System Leak Checker. That thing looks bad ass. I will probably be doing a lot of work on this car, something like that looks really handy to use. It looks like you don't have to mess with the bleeder valves at all when adding coolant back to your system? If so, I'm sold on it, I like that.

[xalents23]

Thanks Monte, that's a simple tip to accomplish it. I wonder if I could just pressurize the system without re-adding coolant and try to listen for leaks? Maybe I'll try that first, before wasting more g12 coolant.

Thanks X for posting about the UView 550000 Airlift Cooling System Leak Checker. That thing looks bad ass. I will probably be doing a lot of work on this car, something like that looks really handy to use. It looks like you don't have to mess with the bleeder valves at all when adding coolant back to your system? If so, I'm sold on it, I like that.

Yes, that is correct with this tool you don't need to bleed anything. And it works on other types of cars as well.

[SnyperBob]

Awesome, I ordered one just now. Do you own one yourself X? Do I need to purchase any additional adapters for it to screw into my Audi reservoir? That's one tool I'm really excited about trying out!

[Michael_b5_s4]

I have one of the Harbor Freight kits and it works great. But I have three cars so it comes in handy on all of them. I got it when it was on sale for $57 and used a 20% off coupon. For $46 and change it was well worth it!!

[nvrfollow]

Good chance its your water pump if you can see coolant dripping, time for a timing belt job

[zillarob]

That side is usually the pump. They can go either way though.

[SnyperBob]

I'm going to pressurize the system and try to determine where the leak is coming from, before ordering parts. Will I most likely need to remove the timing covers to detect a water pump leak? I ordered a wrench to remove the PS pulley, and a wrench to pull the fan clutch off.

If it is the water pump, I was thinking about getting the kit that JHM sells:

http://jhmotorsports.com/shop/catalo...-dvd-p-76.html



I want to check and see if the water pump in that kit has metal impellers. I would probably also order a metal thermostat housing to go with it.

[Monty23]

I have the plastic impeller pump and its been fine. Also, like I said, the cooling system bleeds itself. All you have to do is add coolant after the thermostat opens. I have never touched an bleeder screws and I have drained my cooling system (engine rebuild included) probably 10 times now.

The only time you need to loosen a bleeder screw is if you have the unfortunate task of replacing the heater core behind the dash.

[koolkoreanked]

I'm going to pressurize the system and try to determine where the leak is coming from, before ordering parts. Will I most likely need to remove the timing covers to detect a water pump leak? I ordered a wrench to remove the PS pulley, and a wrench to pull the fan clutch off.

If it is the water pump, I was thinking about getting the kit that JHM sells:

http://jhmotorsports.com/shop/catalo...-dvd-p-76.html



I want to check and see if the water pump in that kit has metal impellers. I would probably also order a metal thermostat housing to go with it.

What wrench do you need to pull the power steering pulley off? Its just 4 bolts and maybe a hammer and pb blaster. Leak in the front from what I seen while doing my timing belt is definitely the water pump or t-stat housing. My secondary water pump has been leaking for years and it always runs down the back of the motor.

[SnyperBob]

That's good to know about the bleeders! Thank you. Unfortunately I replaced my heater core and didn't know about needing to bleed the system via the bleeder valves. I mainly just burped the system and topped off coolant when needed.

I'm going to have time tonight to work on the car and will try to check for leaks by pressurizing via the method you outlined in this thread. Thanks for your help Monty

koolkorean, if I pull my timing covers, would I be able to detect a water leak (if there's one) better? I'm wondering if I should pull those covers before I go thru the trouble of hooking everything back up and pressurizing the system.

[koolkoreanked]

Yes pull the covers since its easy at the place you are and follow the pink crusty trail. Now if you have to wait for the wrench then put it in service mode and then pressure test it if thats avalible to you now.

Edit: and that cheap harbor freight kit works great! Even their dremel tool is off the chain. I used their allen keys since I had to take off my throttle body to do my timing belt (I have custom enlarged rs4 bi pipes that are welded to the inlet) and love them. A few years ago I'd say no to harbor freight now they have decent stuff.

[airjawed]

It will either be your water pump or your thermostat housing. Pressurizing the system while assembled won't show you the difference since this stuff is hiding behind covers and such... you will have to open it up and find fresh coolant leak.

[SnyperBob]

Thanks everyone. I'll do that. I'll pull the timing covers, and if I can't see the leak at that point, I'll reattach the radiator and pressurize it with the covers off.

[SnyperBob]

I'm sure in another few hours, I'll be kicking myself for not ordering that JHM kit days ago, so I can just replace those parts tonight. Ugh. :)

[xalents23]

Awesome, I ordered one just now. Do you own one yourself X? Do I need to purchase any additional adapters for it to screw into my Audi reservoir? That's one tool I'm really excited about trying out!

Yes, I do own one myself and the kit comes with the adapter. It's a complete kit so, you don't need to buy anything else.

[zillarob]

Try for a hepu pump, I replaced 2 failed geba last year.

Go to the dealer and get the water pump gasket. That paper pos that comes with the pump will petrify to the block and be a mofo to clean up. Youll prob see what I am talking about when you are in there.
2.7 is a waxy green paper 078 121 043 A, I use the metal ones from a 3.0 06C 121 043. Both priced about the same and come off cleanly on the next go round.

Use the cam bar and the crank pin.
I swear 90% of the people who try the tool free way end up back here in a panic on sun night because the car is muffed up and they need to get to work in the morn.

Do the valve covers and tensioner gaskets while you are in there. The belt needs to be off to clean up the dside tensioner and do a nice job. Its kinda poke and hope otherwise.

Monty is right on the bleeding. Its not rocket science and will sort itself out.
I do use the one by the tbody while filling, but I stay the fk away from the heater core.

[koolkoreanked]

^for reference I didn't open any bleed screws. In fact I never have as I didn't know they existed lol. Never had a problem bleeding the system even on my 1.8t.

[Monty23]

I stay the fk away from the heater core.

[SnyperBob]

Try for a hepu pump, I replaced 2 failed geba last year.

Go to the dealer and get the water pump gasket. That paper pos that comes with the pump will petrify to the block and be a mofo to clean up. Youll prob see what I am talking about when you are in there.
2.7 is a waxy green paper 078 121 043 A, I use the metal ones from a 3.0 06C 121 043. Both priced about the same and come off cleanly on the next go round.

Use the cam bar and the crank pin.
I swear 90% of the people who try the tool free way end up back here in a panic on sun night because the car is muffed up and they need to get to work in the morn.

Do the valve covers and tensioner gaskets while you are in there. The belt needs to be off to clean up the dside tensioner and do a nice job. Its kinda poke and hope otherwise.

Monty is right on the bleeding. Its not rocket science and will sort itself out.
I do use the one by the tbody while filling, but I stay the fk away from the heater core.

Some really great insight there, thanks Rob!

I don't know much about those pumps you mentioned, but I'll try to research them. Let me ask this.....do you guys prefer plastic impeller water pumps over metal ones (JHM comes with GRAF). I believe the JHM kit one is metal. I ask because in a YouTube video I was following, they said the metal pumps tend to leak after months of use. I'm wondering if it's actually a gasket problem, along the lines of what ZRob mentioned?

I ordered a crank pin, but I'm not sure how to use it. The videos I've come across just talk about using the cam bar. Does the crank pin lock the crank, and then you install the cam bar?

Also, you recommend to change out the tensioner gaskets....are those the half moon pieces? This job is getting more and more involved. I'm not concerned about that, it's just starting to get pricey doing everything at once. I have nearly $600 in parts now. I went with the JHM timing belt kit, the metal thermostat housing, and I'll pick up that gasket you recommended. No clue how much I've spent on tools just for this job.....but I figured they'll get more use when I finally pull the trigger on the K04 upgrade. When I pull the motor for that, I'll most likely do all this maintenance again anyway.....

I need to track down the torque settings for everything too. If anyone has these readily available, and wouldn't mind sharing, I would really appreciate it. Otherwise, I'll have to do some digging.

[SnyperBob]

Is that the crank pin.....at 12:50 in this video? It goes into the side of the engine block, not the end of the crank?

He really talks about how much that pin is needed around 15:50 too.....glad I ordered one...

[koolkoreanked]

I didn't look at the video but what you discribed is the crank pin. Its a pain in the butt to install so I didn't. I refused to spend the time to install it. Instead I marked the crank after I pulled off the crank pulley. I used the lock bar up top as I did the cam seals as well. The cam seal puller kit makes life soooooooooooo easy. Less than 2 mins each side to change the cam seals. I used the metal impeller on my build in 08... Never leaked once from the water pump. I used the metal one this go around as well and dont anticipate it leaking. Using the paperish gasket that comes with the kit works great... Its a pain to take off but I've never had one leak on any car. Which tensioner gasket are you talking about?

[SnyperBob]

Cam seal puller kit? What's that? The only thing I could find was a cam seal installer kit:

http://www.toolsource.com/seal-insta...-p-114428.html



Unless you're talking about cam chain retention tool?

[SnyperBob]

Wow, those kits look bad ass, but I'm guessing very expensive!! $$

Any recommendations for affordable kits? I'll start looking now...

[zillarob]

Lots of questions

That is the crank pin in the vid. You attack it from under the car and reach over the subframe from the tranny side.
This is the hole it goes in



There will be a plastic plug in it held by a 10mm bolt. Pull the bolt, twist and pull the plug out, use your pinky to pull the oring out if it doesnt come out on the plug (it usually doesnt). Going back in, put the oring in first, and then poke the plug and bolt in. There is a step in the hole so dont worry about the oring going in too far.

Many people just use the mark on the crank pulley instead. Id say this method gives a variance of +/- 3deg or so when you check the blk90ish cam stuff with vagcom afterward. That is in spec and not a big deal, but with the pin and proper belt pretension, you will be nuts on pretty much every time.

You dont need the pin until you are putting it back together, and sometimes easier to get the cam bar in without it.
Just line up the marks on the crank pulley when it is coming apart, and put the pin in when you start going the other way.

Tensioner gaskets are up to you. I just like to do them at this time because it is easier and you can do a much better job.

Torques. Just what I can remember off the top of my head.
I tighten all the 5mm allen and 10mm bolts to 90in/lb (7.5lb/ft). Blue loctite if it can get to the tbelt, or just all of them if you want.
The tension roller is 20lb/ft and blue loctite. Dont get too crazy with this one, Ive seen people break them and wipe out the heads.
Crank pulley bolts are 15lb/ft (which isnt shit), 20 if it makes you feel better. Be careful pulling these out. They are commonly rusty so make sure you have the allen all the way in so you dont strip them.
Cam bolts are 42lb/ft.
90in/lb with an 8mm allen in the tension rocker to pretension the belt.
Pretty much everything else- tight is tight, too tight is fkn busted, and too loose is a slow agonizing death

Print this and read before you dive in.
https://drive.google.com/file/d/0B_z...ew?usp=sharing

Things to watch out for.
Be careful removing and installing the dside upper tbelt cover. It can be brittle and there is a little guide on the back of the fan pulley bracket you need to get it behind.
Speaking of the fan pulley bracket, there are 3 6mm and 1 5mm bolt that hold it on. 2 of the 6mm are in plain sight, the other is behind the pulley at 6o'clock through one of the slots. The 5mm bolt is at 11o'clock through one of the round holes.
The lower plastic cover behind the crank pulley also goes behind the fan pulley bracket. The way it is cast throws people off and it will rub on the crank pulley if you have it in front of the fan pulley bracket.
Leave the hyd tensioner off until after you slip the tbelt on. Gives you a little more slack to get te belt on.