Underbody tray & air filter box?

Hello,
I have a few more questions.

I have a Golf III Estate (station wagon) from 1997 with a 1.9L AAZ engine and a TD (diesel) engine.

What do you think about removing the underbody pan to get even more cooling from below (which would allow for better airflow around the oil pan and other engine components)?

What do you think about modifying the air filter housing on alternative (LLK) systems to allow it to be supplied directly with fresh air from the front (which would provide cooler air)?


Thank you, and best regards, Mark.

Hi,

VWGOLFIII wrote:

... What do you think about removing the underbody pan to get even more cooling from below (which would allow for better airflow around the oil pan and other engine components)? ...

Is the bathtub still there? After it flew off twice on me (the last time on the highway), I decided not to install any more.
However, I doubt that it will result in significantly better cooling performance. The design of the airflow is such that enough air can escape from the engine compartment at a moderate speed. Furthermore, the cooling of the oil pan by the airflow is minimal without cooling fins on the oil pan. At low speeds, you will naturally significantly reduce the heat buildup in the engine compartment.

Furthermore, you'll be using more diesel fuel, because the cover is also an aerodynamic component.
If the car is lifted off the ground, there will inevitably be turbulence around and under the vehicle.

Furthermore, you will use more diesel fuel, because the cover is also an aerodynamic component.
If the is detached, you will inevitably have turbulence inside or underneath the car.

'...could it be that the vehicle would lose its operating permit (ABE) without this container? After all, this part primarily serves to reduce noise (according to a VW workshop). We also used to have two G3 TDI models.' One had a tub, and one didn't. The one without the tub was noticeably louder.

Regards,

Eike.

hi,

eike wrote:

... could it be that the vehicle would lose its approval (ABE) without this container?

... strictly speaking, yes. It is a) an aerodynamic aid and b) a soundproofing measure. Both are important when obtaining the ABE approval.

Quote:

Ultimately, this part primarily serves to reduce noise (according to a Volkswagen workshop).

... Okay.

Quote:

We once had two G3 TDI models. One had a tub, and one didn't. The one without the tub was noticeably louder.

Understandable!

I, however, believe that this part is not of much interest to anyone. Mine was inspected at the TÜV without any protective covering, and the inspector didn't even ask about it.

What do you think about modifying the air filter housing on alternative (LLK) systems to allow it to be supplied directly with fresh air from the front (which would provide cooler air)?


With the TDI engines, they initially implemented a direct air intake system, but they reverted to an indirect air intake system due to problems with the mass airflow sensors.

My old 'alt-opa-kiste' (tm) (gasoline-powered) unit sucked air in directly behind the grill, which was problematic in heavy rain because the air intake turned into a water filter. I wonder if that makes sense with the TD (presumably a different engine) and its higher airflow. Also, literally everything ends up in the filter box, from all kinds of insects to half the forest...

'If there's an air filter installed, it won't make a difference if you try to draw air directly. My Octavia sucks air in from the left fender, and with that amount of airflow, the air is definitely not warmer than the air coming directly from the grill.'

CU Gremlin.

'Hmmm... in the Golf IV TDI, the air intake is also standardly located at the front, near the headlight. However, there's often a filter there that can become completely clogged after a few thousand kilometers. This then causes a spring-loaded flap to open towards the engine compartment, which naturally draws in warm air. I verschandeln the filter approximately every 5,000 kilometers, as it's not included in the maintenance schedule, and I have the feeling that the car then runs a bit better.' Perhaps it's also wishful thinking; I don't have any comparative figures.

I removed a strange horn-like piece from the air filter box on my 35i. It probably served as a noise reduction device... It had a smaller diameter at the end than the opening of the air filter box. Subjectively, it seemed to make a difference on the highway, starting around 150 km/h.

Thank you for the many answers.

I just disassembled the bathtub, and I also removed the 'trumpet' from the air filter housing; let's see if it makes a difference.

I will post my experiences here once I have them.

Best,
Mark

P.S. The grill design, like the one on the Golf 4, is a good idea, and I'll probably adopt it for my car as well, especially if it improves the airflow to the air filter housing.

Hi,

Okay, so I drove my car 500km today without the underbody protection and without the 'trompete' (likely referring to a specific part).

I didn't notice any difference, neither in the oil pan cooling or other engine parts, nor in the engine's improved performance due to the cold air.

Best,
Mark

Was your engine's sound duller without the 'trumpet'? I think mine is making quite a noise...
Judging by your other thread, are you worried about your oil temperature? Is it too high or too low? Please tell me how much you have.

Hello fellow mechanics!


Okay, please provide the German text you would like me to translate into English. I will only provide the translation.
Okay, today is my debut as a poster!
I have been following this forum with great interest for the past 3 months and am impressed by the high level of expertise and the very productive discussions and problem-solving.

Subject:

Last year, when I was changing the air filter, I also looked at the trumpet-shaped piece on the air filter housing and considered removing it because of its smaller diameter.
I did that, but I didn't notice any significant improvement or speed increase (although I did notice better airflow).
I thought about it and eventually came to the conclusion that it's quite pointless to remove that part, because the trumpet tubes actually protrude from the side of the fender and draw air in from there.
When the trumpet valve is disconnected, the engine (at least in the G3) sucks in warm air from the engine compartment.

Therefore, this is more of a (-) optimization...

Regards,


Tdi_lover

Hello everyone!

"If I remember correctly, there was a significant problem with the A6 regarding 'air intake.' The air intake duct was designed in a way that utilized the static pressure at the front of the radiator to draw more air into the air filter box, essentially a form of forced induction. However, this duct, which was directly exposed to the airflow, allowed very fine mist, including water and, in winter, salt, to enter the intake manifold. Over time, this salt and other fine contaminants would pass through the filter and damage the mass airflow sensor (MAF). This happened with considerable frequency. And replacing the MAF sensor every year can be quite expensive. This information comes from a VW mechanic, but I believe there's some truth to it."

Or? Okay, I prefer it when my T4 rattles .

Greetings, Peter.

@kapernaum

Welcome!

I thought that the Golf 3 and the Passat 35i B4 were actually quite similar, but apparently not .
In my case, the area where the trumpet connects is structurally separated from the engine compartment, meaning that the air is drawn in from the fender, with or without the trumpet. In golf, this distinction apparently doesn't exist .

DocSnydor wrote:

In my case, the area where the trumpet connects is structurally separated from the engine compartment, meaning that the air is drawn in from the fender, with or without the trumpet. In golf, this separation apparently doesn't exist

.

Hi Doc.

On the G3 model, the inlet of the air filter box faces forward (behind the right headlight).
The trumpet, which is clipped in place, turns 90 degrees to the right -> into the inner fender.

In other words, without the trumpet, you practically get no back pressure through the narrow gap under the headlight, nor much "hot" air, but at least some (salt) spray that is forced past the headlight.

If you want to circumvent the constricted trumpet inlet, you can drill additional holes "at the rear and bottom" in the transverse section of the trumpet, so that they are not visible when looking into the engine compartment.
Gischt would then need to be sucked in "from around the corner," but IMO it will more likely splash against the front of the air intake box.