DIY: Replacing driver side coolant flange on a MKIV Jetta 8v 2.o…

[MikeWire]

DIY: Replacing driver side coolant flange on a MKIV Jetta 8v 2.o…

Ok, so if you notice that you are loosing coolant and you are seeing a small puddle of coolant in your regular parking spot, you may have a coolant leak. It turns out my problem was the infamous drivers side coolant flange leak.

Symptoms:

(please excuse the filthy engine bay)

1. Red crusty residue near the transmission on the underside of the car:

2. Red crusty residue on the drivers side between the coolant flange and the engine block:

If you experience any of these symptoms you may have a leaky coolant flange.

Here are the steps I took to remedy the problem:

DISCLAIMER: This DIY is for a MKIV Jetta 2.o, and may be similar to other makes/models. This information only a guide and if you screw up do not blame me – I will not be held responsible for any mistake you do while you work on your car.

Hardware:
• Meyle coolant flange
• 1 gallon of Pentosin G12
• Distilled Water
• 10mm socket
• Gasket sealer (optional)
• Flathead screwdriver
• Paper towels

Notes: Get the OEM VW coolant flange- I noticed the OEM is much stronger and seals better than the aftermarket replacement. I got mine from my service shop for around $20. If you don't get the OEM part, you will be doing this again!!!

1. Drain your coolant. I blocked and raised the drivers side of the car a drained all of the old coolant into an old milk carton. It's not necessary to remove all the coolant, but you should drain a majority - it makes much less of a mess. And, don't reuse the coolant - please recycle it:

Raise vehicle and block the wheels:

Remove the coolant reservoir cap on the expansion tank to release the vacuum in the cooling system:

Using the coolant drain valve located on the underside of the radiator on the drivers side drain the coolant. Again, it's not necessary to remove all the coolant, but you should drain a majority:

2. Remove the engine cover (if applicable), remove your air box and the tubing that connects it to the throttle body and set it to the side.

3. Locate the coolant flange:

4. Begin by removing all the wiring, connectors and small hoses from around the flange. To make this easier I disconnected and removed the metal bracket from the top of the block this is optional:

5. Remove all the hoses from the coolant flange. There are three hoses that connect to the flange and they all need to be removed. It doesn’t matter in what order, but be prepared to have some coolant drain out because there will be some left over in the block and hoses. I used a pair of channel lock pliers to loosen and move the spring clamps and they slip off fairly easily.

6. Now you can remove the flange from the block by removing the two nuts, then the bolts holding the flange in place. There is one nut and one bolt behind the nut holding the flange in place. Using a 10mm socket, remove the bottom bolt:

The top nut is bolted on to a stud that screws into the block. Remove the nut but leave the stud in place:

7. You can then pull up on the black metal tubing (it will swing up towards the front of the car) and get to the bolt behind it. Once you remove bolt you can then remove the flange from the block. Make sure to clean up the dried up coolant and the surface of the block where the flange mounts.

TIP:

Quote, originally posted by leokempf »

OK. figured it out. I didn't realize it would pivot all the way over at the thermostat housing. Forward of the "bar" I loosened a nut pretty far down in there that holds a bracket for some wires. Then I gave the bar a tug and it pivoted. Thanks.

8. Now get the new flange and swap out the coolant sensor and O-ring.

Old VS. New:

Coolant flange part # from ECSTuning:

See my notes above step 1 about using an OEM part

Remove clip and O-ring from the old flange:

Replace clip and O-ring and insert it into the new coolant flange:
NOTE: Now would be a good time to replace that black top coolant sensor with the new green top. I did not replace mine as I have had no problems with it.

9. Prep your new coolant flange (optional). This is probably unnecessary, but I used a high temp copper gasket sealant to make sure the flange will not leak again.

10. Place your new coolant flange into the block:

11. Replace the bolt and nut to secure the flange – be careful not to over tighten!

NOTE: Thanks to TMTuned99.5Golf: bolt torque is 7ft/lbs or 10 Nm

12. Continue to replace all hoses, making sure to get the spring clamps back into the original place. Then replace the metal bracket and all wiring, connectors and small hoses.

13. Time to add coolant – NOTE: Remember to close the drain valve on the underside of the radiator, or you will drain the coolant you are about to put in. Mix 50/50 Pentosin G12 and Distilled water and fill the coolant reservoir. Start the car and turn the cabin temperature knob to full HOT and turn the blower to HIGH and let the car warm up while you continue to fill the coolant reservoir. Fill until the expansion tank is filled to just above the midpoint of the container. Coolant temp should reach the 190 degree point. You may have to replace the expansion tank cap for the coolant pressure to build – then just top it off as needed.

14. Replace the engine cover and test drive – you have just finished replacing your coolant flange!

NOTE: You may find that you need to check the level over the next few weeks to make sure the coolant level is at the correct level – based from my experience this seems normal and I have had no problems with my cooling system.

If anyone would like to add to this DIY please IM me – and if you have any questions please feel free to contact me. Thanks!

[FaelinGL]

Excellent DIY. I would recommend using some arrows to amplify the places you are talking about, but great shots. Lot of 2.slow engines out there so lots of people could use this.

Mike

[FaelinGL]

Bump for the Daystaff crowd.

Mike

[MikeWire]

New pics with arrows etc added...thx

[digraph]

v.nice!

what does the stop-sticker on your air filter box say?

[MikeWire]

It's a sticker that comes with a K&N drop in filter basically telling am oblivious service person that this is not a throw-away filter - so STOP don't throw it away. I do all my own work, but if I ever have to take it to a shop it may save my K&N...maybe.

[MikeWire]

Bump for other 2.o owners

[TMTuned99.5Golf]

Heh, I just replaced mine this past weekend. Took me like an hour taking my time. Replaced before in the quickest time of like 15min.

BTW, if I'm not mistaken, the torque on those bolts that hold it down are like 7 ft/lbs ( 10 Nm ).

Modified by TMTuned99.5Golf at 7:34 PM 12-11-2006

[McNeil]

I vote for stickiness.

[vwman099]

bah... those flanges leak in the mkIV ABAs as well? that bites

thanks for the DIY

[doodpod]

Great DIY, and a good heads up - I've been down on coolant and had yet to think of this problem. For reference though, the flange bolts to the head, not the block.

[vasillalov]

Good work!

[MikeWire]

Quote, originally posted by doodpod »

Great DIY, and a good heads up - I've been down on coolant and had yet to think of this problem. For reference though, the flange bolts to the head, not the block.

You are correct is it the head, not the block. Noted and changed! Thank you!

[MikeWire]

Quote, originally posted by TMTuned99.5Golf »

BTW, if I'm not mistaken, the torque on those bolts that hold it down are like 7 ft/lbs ( 10 Nm ).

Added! Thank You!


Modified by mross71 at 10:30 AM 9-4-2007

[mujjuman]

w00t thanks for the DIY dude!

[MikeWire]

Thanks - hoping to get this into the DIY section

[vasillalov]

... let me see what I can do...

[LangsamKafer]

Added to the DIY

[MikeWire]

Thanks! I bow to vasillalov - king of DIY

[mujjuman]

Quote, originally posted by LangsamKafer »

Added to the DIY

kool

[Athfar]

Hey found your post... How much did your flange cost when you did that?


Modified by Athfar at 5:50 PM 1-6-2007

[98wolfie]

I paid $15 in parts from the dealership. There doesn't seem to be much of a difference between the dealer price and online stores such as Potterman's and Germanautoparts.

[Athfar]

ECSTurning has the flange for like 8.95 http://ecstuning.com/stage/edp...oling

[Athfar]

I wouldn't recommend putting that gasket sealant on there for three reasons.

1) It isn't really the seal that fails it is the composite / plastic underneath in my case. It ends up melting and deforming the plastic which just happens to take the seal along with it.

2) The type of gasket sealant you are using isn't designed for these types of press on rubber seals and in some cases can make the seal work less efficiently by gumming it up.

3) You are just making it harder to take off the next go around.

Thank you very much for the DIY. Just some more advice.

Oh, and one more tip for you guys doing this. If you look at the 10th picture down there is a black bar. You are unbolting the top nut from that piece (then you can move it up, have someone hold it up or undo the hose attached to it). After that unbolt the BOLT that is bolted into the engine.

The bottom bolt is the easy one because there isn't the bar in the way and if I recall it's just a single BOLT. This kinda confused me so I just though I should clarify.


Modified by Athfar at 2:39 AM 2-1-2007

[dark-hour]

I hope it is ok that I replied to this post. I have used VW vortex for many years. The amount of info is amazing. I have never really needed to post a question before. My question is more for a sanity check.

For about a week I have been loosing coolant. I notice coolant trickling over the coolant flange (Running around the temp. control sensor."

My guess this is the coolant flange. Other then a hose is there anything else that could be causing the leak in this area? I have done a few searches on the forum, and am having problems narrowing down more information.

Thanks guys
Kirk
2001 Jetta 2.0L

[MikeWire]

Quote, originally posted by dark-hour »

I hope it is ok that I replied to this post. I have used VW vortex for many years. The amount of info is amazing. I have never really needed to post a question before. My question is more for a sanity check. For about a week I have been loosing coolant. I notice coolant trickling over the coolant flange (Running around the temp. control sensor." My guess this is the coolant flange. Other then a hose is there anything else that could be causing the leak in this area? I have done a few searches on the forum, and am having problems narrowing down more information. Thanks guys Kirk 2001 Jetta 2.0L

Mine didn't take much to break the seal - I remember undoing hoses to drain coolant and change my timing belt and after that it started leaking. I figure the movement from pulling the hoses made the seal break.

Quote, originally posted by Athfar »

I wouldn't recommend putting that gasket sealant on there for three reasons. 1) It isn't really the seal that fails it is the composite / plastic underneath in my case. It ends up melting and deforming the plastic which just happens to take the seal along with it.

Mine didn't melt, the seal just failed...

Hm...well there are always two schools with the gasket sealant. My school is to use it sparingly. Other get into trouble where too much is used and it squishes into areas it shouldn't be and clogs things up. Others use none and then end of leaking anyway, doing the job twice as often.

Quote, originally posted by Athfar »

2) The type of gasket sealant you are using isn't designed for these types of press on rubber seals and in some cases can make the seal work less efficiently by gumming it up.

I use a high temp copper gasket sealer. I've used it on other vehicles and motorcycles with no ill effect and none have leaked after service. So, I at least speak from my experience, maybe yours was different.

Quote, originally posted by Athfar »

3) You are just making it harder to take off the next go around.

?? Not even sure what you mean here...it's pretty easy to get gasket material off of a metal surface. And the flange is throw-away.

Quote, originally posted by Athfar »

Thank you very much for the DIY. Just some more advice. Oh, and one more tip for you guys doing this. If you look at the 10th picture down there is a black bar. You are unbolting the top nut from that piece (then you can move it up, have someone hold it up or undo the hose attached to it). After that unbolt the BOLT that is bolted into the engine. The bottom bolt is the easy one because there isn't the bar in the way and if I recall it's just a single BOLT. This kinda confused me so I just though I should clarify.

Good tip - I didn't do that because it's not really necessary to get the flange on/off, but thanks for adding that

[Erotas]

I've had the coolant flange fail on me twice.

Radiator fan control module was working intermittently. Didn't realise the first time.
Radiator fan control unit is not part of the ECU , have to test it independently.

This seems to be the weakest point on the colling system and that's why it fails.

Awesome DIY!


Modified by Erotas at 7:53 PM 11-17-2007

[Athfar]

Quote, originally posted by Erotas »

I've had the coolant flange fail on me twice. Radiator fan control module was working intermittently. Didn't realise the first time. Radiator fan control unit is not part of the ECU , have to test it independently. This seems to be the weakest point on the colling system and that's why it fails. Awesome DIY! Modified by Erotas at 7:53 PM 11-17-2007

Hang on are you saying that it is building TOO much pressure causing the flange to fail? How did you go about testing your control unit?

Cause check this out http://forums.vwvortex.com/zerothread?id=3546893

Edit: Added URL


Modified by Athfar at 8:20 PM 11-17-2007

[Erotas]

Yep.

Mine exploded twice like the pic below.

There is a test sequence in the Bentley.

You jumper two of the connectors and if the fans run, the control unit works.

[Athfar]

How much did the control unit cost and was it hard to replace (I may just replace it instead of testing it because chances are it is intermittent)? Where about is the control unit? Seems like it would be part of the pump...

I have gone soooo long without spending the 90 bucks for a bently manual telling myself that I will sell the car before I do it...

[Erotas]

The Cooling Fan Control Unit is around $90 -100.

Just sits next to the fans, under the battery.
Part No: 1J0 919 506 K

[Athfar]

Wait a second I read wrong. I was thinking it was like a coolant pump regulator...

How does a fan controller cause too much pressure?

Do you mind posting the testing procedures?

Oh and thanks for the replies .


Modified by Athfar at 11:17 AM 11-19-2007

[Athfar]

Bump for testing procedures or more info please

[crillforreal]

Great DIY-- i have had a coolant leak for about 3 weeks and couldnt find out where- after seeing this i decided to give it a try and sure enough my flange was shot.

[pcfrias]

I came across your DIY in search of same exact problem I am having now. THANKS and this is really great! Exactly what I'm fixing at this time.

I had problem removing top bolt with step stud on coolant flange. Hard to get the bar loosened up.

Also, any suggestions with loosening old hose connections with clamps? This is 1st time disconnecting these old hoses on my 2000 Jetta. Tried using vice grips to keep clamps open and used flat screwdriver to try to slide hoses off. I feel this 2 hr job has tripled due to tight hoses. Thanks,