Golf MK4 Air Fillter Box Heated Air Flap Wax Thermostate Repair

The engine cover doubles as air filter box and also houses the heated air intake flap.

The heated air intake is through the round hole under the box. It can be seen when the filter cover is removed from the bottom.

Thermostat

After many years of operation, the heated air intake flap usually gets stuck in hot air side fully open.This is not a big problem but there is no point in taking in warmer air than necessary.

Unfortunately it is not so easy to find replacement thermostats. The only one I could find was some Volvo replacements. Although there are 2 different Volvo models, with different prices, they seem to be exactly same thermostat. So buy the cheaper one.

Here is the link to thermostat:
https://www.skandix.de/en/spare-parts/engine/fuel-mixture-formation/injection-system/idle-control/thermostat-air-temperature/1006579/

Volvo reference numbers are 1266826 and 9142616

The Volvo thermostat itself is slightly longer than the original and also the pin is much longer. So the pin must be cut smaller. The old pin can't be used because it is not same thickness.

Had to cut about 4mm to be able to bring it to correct size. There is some slack space when the pin is completely out. One can cut it even 6mm and it should still be fine. I just cut the minimum required amount so the flap can open completely.

Thermostat Removal

The thermostat can be seen once the other cover is also removed.

Removing the thermostat is not an easy task. If you are not careful the flap will get broken! The flap may be brittle from extended periods of hot air.

It is possible to remove the thermostat without removing the flap. However the new thermostat was longer and I could not install it without removing the whole spring system. But, there are people who claim to have done it.

For removing the old thermostat, you can simply push the spring as far as it goes and let the thermostat fall out. I removed the flap first.

For removing the flap, first you will need to pry open the little cover piece in the middle. It is a ~1cm length rectangular piece. You can see it removed in the picture below.

Next step is to move the spring to side, which is shown on the picture above. After this point, the flap can be removed with a little bit wiggling and bending of the black upper part. Then the spring assembly can be removed.

Once the spring is removed, one can remove the thermostat and replace it easily. I stored the new thermostat in freezer first to be able to push the pin all the way in. It makes installation much easier.

Thermostat Installation

The installation is reverse of removal. You will need to glue/melt the rectangular plastic cap back after installation.

Testing

The mormal operation is:

      Above +23 °C, flap must close warm air connection.

      Below +10 °C, flap opens warm air connection.

The Volvo thermostat starts opening warm air at about 9C and fully opens it at about 3C. It is fully closed at about 16C. Which are pretty good values all things considered.

 

I tested mine in fridge.

 

Golf MK4 How To Unlock Deadlocked Passenger Side Front Door

Recently the passenger side door of Golf MK4 got deadlocked and would not unlock. I had to devise a way to unlock the door without destroying the door cart. It was possible to unlock the door without damaging the door cart.

You will need a flexible screwdriver shaft. It has to be as thin as possible. I used a precision screwdriver set's shaft. You will need T20 torx bit to go with this. You will also need a drill. I used a 4mm drill bit but you may want to use 6mm.

Step 1

First step is to remove the cap which covers the screw for the placeholder next to door handle. You will need to open the rear door for this. I used my handy plastic part remover tool for this purpose.

Step 2

Use the flexible screwdriver and T20 bit to loosen the screw

I had to tape the torx bit to the screwdriver as there is risk that it falls inside the door. Also I used an endoscope camera to be able to find the screw without looking. Below is a view from my endescope camera. Make sure the loosen it only enough to remove the placeholder, otherwise it may fall into door as well.

Step 3

Remove the placeholder next to door handle. You will be able to see part of the lock.

Step 4

Drill a hole over the plastic cover of the lock with 4mm - 6mm drill bit.

Below is a more clear picture of the hole

The plastic is very thin and it is easy to drill the hole. You do not have to drill inside, just penetrate the plastic.

Step 5

This is the most important step. You should use a hard metal wire (~4mm thick) and push it inside to reach the lock mechanism. I used a coat hanger. If you have an endoscope camera, you may want to look inside the mechanism to see what you are pushing.

Below is a picture from the side with the cover removed.

Red line shows our approximate approach. The plastic piece is the piece we want to push. This plastic may be black or any other color.

Below is a more detailed picture

Normally when the lock is unlocked the part with dark blue goes down between the release latch and unlocking mechanism. So once you pull the door handle (from inside or outside) the release latch moves with the unlocking to unlock the door.

When the door is deadlocked, the electro-mechanical part won't let the dark blue part to go down. Therefore it won't be possible to unlock the mechanism.

The red line is again our approach. We need to slightly push either the plastic piece or the unlocking mechanism which is under the release latch to be able to open the door.

Obviously you need to do this carefully as the plastic which goes between mechanisms may or may not move enough to unlock the mechanism. In my case it was not very difficult, but maybe I was lucky. You should approach this with care.

Before Installing The Lock Back

If you manage to fix the lock. You can use silicone to close the hole before installing the lock.

Quality Problems With VW Service At V-Wauhtipiste ( https://www.vauhtipiste.fi/ )

I would not have written this up if I had one or two problems. But I continuously had problems service after service at V-Wauhtipiste ( https://www.vauhtipiste.fi/ ). One good thing was that they tried to fix the issues once I pointed out the problem. However in some cases, while fixing the mustakes, they made new mistakes to be fixed also...

The quality control is non-existent and in some cases they tried to fool me at V-Wauhtipiste. Which was rather annoying. I only caught some of the errors because I had pictures proving before and after conditions. I took more and more pictures when errors occured more and more often.

V-Wauhtipiste have overfilled the brake fluid reservoir (till it was completely full!), removed inner CV boot clamp and never put it back, installed CV inner boot clamp incorrectly, put wrong grease into CV inner boot, installed catalytic converter at incorrect position, broke oxygen sensor etc. When the work was more complicated, the more errors V-Wauhtipiste made.

In some cases having before/after pictures helped proving the issues. But in some cases the problems are difficult to detect unless you watch the mechanic at work. The problem is that when the work quality is so low, you would only realize some issues after a few years when it is too late and caused a larger problem. When that happens, no doubt they will try to tell the customer that the problem was due to normal wear.

First Service

The vehicle was taken to regular maintenance for oil and filter changes. Additionally the catalytic converter was making some noises so it was to be investigated. The brake fluid change was considered but then deemeed unnecessary. However I had to leave the brake fluid bottle in the trunk as I did not want to take it back with me.

When we took the vehicle back, I found out that they have accidentally changed brake fluid (obviously I did not have to pay) and we found out that the catalytic converter needs replacing.

Later when I checked the fluids in the engine bay, I could not see the fluid level of the brake fluid. I thought it was empty. But fluid started leaking when I loosened the cap. It was filled up to the top.

So I had to go back and ask for removal of some fluid. When we were there, the mechanic said it is fine and extra will slowly leak out. I was surprised to hear such response as brake fluid is corrosive. It can strip paintwork and cause damage. Therefore it should not be allowed to leak out. In addition the maximum level mark on the reservoir is there because system needs some air gap so extra fluid can return to the reservoir without building pressure.

I had to explain to the mechanic why there should be space and that brake fluid level must not exceed maxiumum level mark. I also added that the engineer who designed the brake system decided there must be a limit to how much liquid should be inside the reservoir otherwise there would be no reason to put a maximum limit sign. V-Wauhtipiste agreed to remove the extra fluid after the struggle.

First Catalytic Converter Change And Aftermath

In my vehicle, changing the catalytic converter requires changing the front pipe at the same time. As the original pipe is one piece but replacement is in two pieces. I made the mistake of going cheap and getting a part from bm catalysts. It was a mistake as the part bends were badly made and apparently it did not fit well.

Never the less, after the part was changed at V-Wauhtipiste. We were not informed that there were any problems with installation even though there were installation problems. (as we found out later)

Due to the front pipe not fitting properly. The vehicle exhaust sound was rough and caused vibrations between 1800RPM - 1900RPM. After about a month of driving, we went back to ask for why these were happening as I was not sure if V-Wauhtipiste forgot to put some part or did not tighten something.

V-Wauhtipiste took the car to checkup and after half an hour they came back to tell that they broke the oxygen sensor and they have to replace it. They replaced the oxygen sensor for free a week later. Also told us that the exhaust front pipe was not a good fit for the vehicle and it caused the problem. I asked why we were not informed right away when the pipe was installed. But got no response...

Below is a photo of how the pipe was sitting badly (on left) compared to genuine part (on right). If you look at the rubber holder, it was pressed all the way down and therefore it could not absorb vibrations.

Also, on the right you can see how V-Wauhtipiste bashed in the heat shield just under the exhaust pipe. Their excuse was that the heat shield is soft. However, one must be careful when working under the vehicle as scratches etc. on the underbody would eventually cause rust problems.

Genuine Parts Change

When it was obvious that the aftermarket part was the problem. I have procured all genuine parts for the vehicle from VW just to be sure that everything is working perfectly. I have obtained all the bolts, nuts, seals for exhaust system from VW. Then booked a time for the change. Only if I knew what was waiting for me...

So, we took the vehicle to V-Wauhtipiste and got the parts changed to genuine ones. However after 5 minutes of driving there was a terrible burning smell. The smell was so strong that I could not tell if it came from engine compartment or it was something at outside air. I opened the window to check but the smell was so strong outside also.

We had to call to V-Wauhtipiste only to get a response that the smell is probably normal and nothing to worry about. When we looked at the engine bay, the grease was literally boiling on top of the exhaust pipe. Which was most definitely not normal. As seen in picture below:

Returning For Repairs

When we went back to V-Wauhtipiste. We asked how this could happen. We have given few different reasons for why this happened. The mechanic's explanation was that sometimes the clamps come off by themselves, another person there said that the clamp was probably never there, another explanation was that they had to remove the axle to install exhaust pipe. I will now explain why none make any sense...

For the clamps falling off by themselves. The other side was perfecly fine. It would be a hell of a coincidence for right side to fall like that. Also I could see that there were some scratch marks on the axle metal pointing to the clamp being removed. I have a picture which shows some scratches on the surface of the axle pointing that somebody was removing it.

About the clamp never being there. Luckily I took a picture right after we looked at the engine bay (the picture above). It was clearly visible that the clamp was recently removed because it was clean where it was removed. Below is the zoomed picture and I marked with red arrow where the clamp was suppose to be.

They dropped the claim that it was never there once I showed them the picture. Luckily I had a picture, otherwise it would have been tough to prove.

About removing the axle for inserting the exhaust pipe. First of all, it is not necessary to remove the axle to install the exhaust pipe. If I didn't know it, I could have believed that. But more importantly it is not how you remove the axle. Axle is removed by taking off the bolts above. Either V-Wauhtipiste did not know at all how an axle is removed  from a VW vehicle or they were trying to fool us.

Clamp Reinstallation Part 1

When I went there, I asked the guys if I could watch what they are doing. First thing that mechanic did was trying to put the clamp back. I had to stop him because a lot of grease flew out from the boot when the vehicle was driven without the boot clamp.

I asked to the mechanic if he will put grease to replace the missing amount. He first tried to tell me that there is probably still enough grease. Naturally, I told him to replenish it. If I was not there, he would have installed the clamp without the grease.

Mechanic agreed to put more grease before clamping and he came back with a tube of grease and squezed it inside the boot. I took a picture of the grease he added for reference (G 052 738 A2).

Later, I found out that G 052 738 A2 was wrong grease and you can find the details below. That was a facepalm moment as I told him to replenish the lost grease. I should have known that no work can be done without fatal mistakes.

Clamp Reinstallation Part 2

I had to leave the guys to work there because apparently they like to work in secret. I can't blame them. I would also would not want people see me working if I was doing such a terrible job.

However they called me to check the clamp installation before they installed bottom plate. It was rather funny because the clamp was installed incorrectly as I expected at that point.

First it looked good from one side as seen below. By the way, in the picture, red arrows show the marks they made when removing the clamp.

However when I turned the wheel, I realized that the rubber was not properly under the clamp all the way around. It was half way out under the clamp. The picture is somewhat blurred but you can see that the rubber is not flush with the clamp on this side easily and grease is leaking out.

When I showed it to the manager, he said I am right and they should do it again. Then I heard him shout at the mechanic that he should turn the wheel.

The bigger problem is that if I was not there. They would have done a very low quality job and this would not have been detected. After a year or two, I could have ended up with worn axle. I am sure they would have never mentioned that the clamp was installed incorrectly even if they detected it.

Catalytic Converter Position

One would assume that the mechanics at garage which claim to specialize servicing VAG vehicles should be able to install a catalytic converter at correct position. But, maybe it is too much to assume? Even if they don't know the correct position, they would stop when they see that nothing is straight, right? hmm?

It was good that I went to look under the car when they were installing the clamp. Because I realized they had installed the catalytic converter sideways. It was installed so badly that I could see the whole exhaust pipe system bent sideways and causing stress on the rubber holders.

As you can see, the middle pipe has turned left and does not sit straight anymore. Also in the picture below you can see that the oxygen sensor is downwards and it should be looking upwards about 45 degrees when catalytic converter is installed properly. Sensor being upwards also protect the sensor itself to some degree. So, install like this and it is doomed to be broken sooner than later.

So, I had to leave them to work again when the mechanic adjusted catalytic converter, then they called me back to workshop to check the result. Below is picture of how the oxygen sensor should look (upwards) when the catalytic converter is installed correctly. As you can see, sensor is better protected in this position.

Below is the picture of center exhaust pipe holder when the catalytic converter is installed correctly. Perfectly horizontal and at center. The picture is taken after the mechanic at V-Wauhtipiste re-aligned the catalytic converter based on my instructions.

Exhaust Manifolt Nuts And Grease Cleanup

When I left, I was very tired so I was happy that at least things were somewhat looking alright. However the few days later I made inventory and then checked the surrounding work area.

The exhaust front pipe is connected to exhaust manifold with 4 self-locking nuts and there is a seal in between. The self-locking nuts should be replaced if they are removed. I have provided V-Wauhtipiste with 8 nuts in the same bag with the seal and the bag was attached to the side of the pipe where they go. However when I did inventory, I found 7 nuts (not sure wher 1 went). I checked my pictures and it looked like they have used the old nuts in place. I don't understand this because they should know better to replace the self-locking nuts. Especially since I provided the nuts.

It looks like they kept the nuts which came with previous pipe as seen below.

Here is how the original VW locking nuts look like. Round hole in the back and oval hole in the front.

Then I have realized that while the mechanic cleaned the big blob on the bottom plate cover, he left a lot of grease all around the transmission, intake manifold and surroundings.

So we had to book another time for cleanup and nut change. If I did not provide the nuts. I would have never known if they changed them or not.

Incorrect Grease Usage (G 052 738 A2)

As I mentioned earlier the mechanic added more grease (G 052 738 A2). Luckily I took picture of the tube after he put it into the boot. Otherwise I would have never remembered the part number. Later when I checked this grease. I found out that the mechanic put the wrong type. Because many VW axles have triple roller joints for inner joint and universal joints for outer joint. They have different types of grease. The mechanic put the grease intended for outer joint into inner joint.

The correct grease is G 052 186 A3. The difference is that the inner joint grease is black colored, thick (high viscosity) and sticky. Meanwhile the outer joint grease is brownish color and not so thick (low viscosity).

Some inside information:
The inner joint uses tripod needle bearing (triple bearing) and the needle bearing needs more fluid low viscosity grease to be able to go into small areas between needle rollers.

Meanwhile the universal joint uses large balls which require thicker grease.

Below is a picture of what the greases should look like (more or less)

 
I have seen the original grease in the engine bay as it was spread around there.

I realized the wrong grease error when I went through my pictures a few weeks later. I had to go back to V-Wauhtipiste for inquiring about this mishap. However again, they tried to talk us out of their error. First, V-Wauhtipiste tried to tell that they used G 052 186 A3 but I had the picture I took at workshop to prove it was not the case. In addition, when we went there, it became apparent that they do not even keep inner cv boot grease in stock at all. Because V-Wauhtipiste did not have the inner CV grease in stock when I asked them to check inside the tubes if the grease looks same. I got the impression that it was because they thought all these years that inner and outer CV boots use the same grease.

Then V-Wauhtipiste tried to tell that the difference is only 20G and otherwise the grease are the same inside the tube, which is also not true. I am not sure what is more disturbing. That they do not know the difference of greases used in the vehicle or they know it but they try to fool the customers.

I tried to explain them it is not possible that contents are same since the part numbers are completely different and also grease names are completely different and grease in question were designed for different types of parts. In addition, there was significant price difference as the 140g grease was cheaper than 120g grease, which would make no sense if they were same grease inside the tubes.

In either case this issue is discussed on some forums. Where it is discussed in a VW forum thread that in UK the parts reseller TPS Trade confirmed that the grease are different. However when I mentioned it to the lady at V-Wauhtipiste the lady who works there said internet is not reliable. I guess it was good that I was at Volkswagen Center Turku which is an authorized VW repair center. Because Volkswagen Center Turku also told us independently that the inner CV boot grease is runnier (lower viscosity). When I mentioned that, the lady at V-Wauhtipiste claimed the axle is a wear item etc. and she knows what she is talking about because she has been doing that job for 27 years. I had to tell her that how long she has been doing something is not proof that she is right about this specific issue.

To be honest I was rattled with this non-sense and decided to go back to Volkswagen Center Turku and reserve time for cleaning up incorrect grease and replacing it with correct grease. I couldn't really justify dealing with V-Wauhtipiste anymore even if they agreed to replace the wrong grease with correct one as I was not sure what new faults they would introduce when they open the inner CV boot for cleaning.

VW Golf MK4 Rear Wiper Washer Jet Nozzle Pipe Repair

The rear wiper nozzle was rotating with the wiper arm. I had to open and see what was going on. Apparently the o-ring was broken and stuck between the washer jet pipe and the wiper pipe.

Luckily I checked the issue fairly quickly before it developed a worse problem. In many cases people realize this when the washer jet pipe is broken due to friction as it is not centered anymore without the o-ring. This causes washer fluid to leak inside the rear hatch and break latch microswitch and other things.

There is a repair kit for this purpose with part number 8L0 998 711. But it is as expensive as new motor and also fits only Valeo model as the washer jet pipe is slightly different in Bosch.

 
So, it is best to repair it before it develops a worse problem. Below is a picture of the repair kit but I did NOT use it. But it comes with 1 small o-ring and 2 large o-rings (one is not visible in the picture as it is on the wiper arm shaft already.). I don't know if the large o-rings are same size as the front wiper arm shaft o-rings. But it looks like they are probably same size.

Dissassembly And Re-assembly

Luckily there are only 2 screws and 1 panel to remove to reach the wiper motor. In this Golf MK4 Estate / Variant model. The screws are inside the handles for closing the rear hatch. (philips head screws)

Once the screws are opened, the panel can be removed by pulling out. Use some plastic opening tools and start from the middle and be patient. It is easy to break the plastic pieces on this panel, if panel is removed unevenly (eg. one side pops out with force), as the clips are really tight.

Once the panel is removed, you can access the motor. The only thing to do is to remove the electrical connector by opening the latches using a small flathead screwdriver and the washer fluid pipe by pulling out.

Normally, once the small torx screws are removed. The rear panel should come off quite easily. In my case it was very difficult to pull it out as the o-ring was stuck between pipes and it was very difficult to pull it out. I had to use some flathead screwdrivers to pry it slowly out while turning around.

Above is a picture where the pipe is partially out. Once it goes off a little bit, it is possible to remove the rear plate.

Once it is removed, and it is in good condition. You only need to clean inside the wiper arm pipe before re-installation.

I found pieces of the small o-ring inside the wiper arm pipe. The washer fluid pipe outer diameter is 3.4mm and the wiper arm pipe inner diameter is 4.7mm. I found some 3mm inner diameter (I.D.) and 1mm thickness (C.S.) o-rings from AliExpress and it seemed to be exactly same as the original. So this makes 5mm outer diameter so it fits quite snugly.

I only had half of the original o-ring but I measured it was slightly thinner than the new o-ring. Perhaps years of usage may have thinned it a bit. But when I put them on top of each other, the curve matched perfectly.

As I pulled the inner pipe quite a bit when removing. It seems like it moved a bit out from it's plastic holder. I had to warm it up using hair drier and hammer it back in gently.

As you can see, it fit slightly too long before hammering it. It should normally be flush with the outer pipe.

Here is a picture I took when inserting the o-ring in place. I simply put it on top and push it down using the washer jet nozzle. Yes, it is swimming in bearing grease.

The installation is reverse of removal. It appears there fits 2 o-rings (3 o-rings is about 0.5mm too much!). So I pushed in two o-rings so it is now double sealed. Perhaps better than new?

There is another o-ring which is on the wiper arm shaft but I did not remove it. Perhaps it would be wise to check it also once in a while.