Why you should backdate your heat on a 3.2

[KFC911]

Graham, I guess it's "fiber" (lined inside with a foil like material as I recall). It is indeed very stiff and that's why I said it was such a PITA to get those tight bends and why I had to loosen everything up, and then work it all back together. I don't think it would be possible (in fact, I know, 'cause I tried) to simply make the bends and get it connected to the crossover pipe. Your hose sure appears to be the same...I'm sure you can relate .

[scarceller]

Originally Posted by KTL

It's part number 901.211.195.00

http://www.pelicanparts.com/cgi-bin/ksearch/PEL_Search.cgi?please_wait=N&forumid=&threadid=&command=DWsearch&command=DWsearch&REFINE=Y&FORUM_REFER=&description=90121119500

The hose you choose should obviously be heat-rated. Remember it's connected to the shrouding of the exhaust system. But the pipe is isolated from getting super hot by some rubber and silicone hose couplings, so it doesn't get as hot as the surface temp of the exhaust manifolds themselves.

And by the way the Napa oil filter is actually a good filter. So is a Wix which Napa typically carries. I know most people think the Mahle is the end-all be-all of filters. But there's other good ones out there. Mobil 1 and K&N are good too. Sal, what kind of air filter is yours? It looks a little better than the POS $25 (I know- get what you pay for) eBay thing I bought for grins.

My Air Filter is a K&N filter, came with the car so don't know much else about it

[scarceller]

You can also get hoses from many VW suppliers. The normal hose is 63mm (about 2.5") hose. Then you can also use the narrow 50mm hose (about 2") on the right side if you have AC installed. But for the AC setup you will need to modify the stock right hand side block off plate and add a PVC elbow to it by simply cutting a hole in the stock plate and epoxy the elbow in place (See the pic I posted in this thread post #105) not super clean looking but who cares it's hidden under the AC Bracket. If you go this route you simply use the 50mm hose on the right side but you'll also need the adapter to go from 50mm to 63mm at the exchanger. The part # for this adpter is: 911-211-275-01-M100 (Our Host sells this) This adapter was used from 75-80 on the CIS cars with AC, these cars used 2 of these adapters to reduce the hose from 63mm to 50mm so that it would fit under the AC bracket. Just search from the part # and then look at the picture, you'll get the idea. But if you do the 50mm modification to the RHS tin then you'll already have the 50mm (2" PVC elbow) at that end so you'll only need one 50mm to 63mm reducer for the RHS exchanger.

In my car I had this 50mm setup for a while but I decided to remove the AC system so I went back to the 63mm RHS setup.

[York]

Thanks to all the great info in this thread, I just finished a backdate project on my car. Had to keep the A/C though, too darn hot where I live. So, I removed the heater blower and two plastic ducts, installed the adapter plate, connected new hose and soldered a wire across the reed switch in the relay. It all looks and works great, still have plenty of heat and defrost. Also cut out the top of the air filter housing, sure cleans up the other side of the engine bay and sounds great at WOT.
Now it looks like there really is an engine back there.

[911st]

Nice York! Any pics?

[scarceller]

Folks have asked for pics, so here goes.

First, my car has SSI exchangers not the stock ones.

Overall backdate:


RHS Top side Details:


RHS Bottom side Details:


LHS Top side Details, note I routed the 63mm duct through the existing Carrera large hole in the tin. For a cleaner look you may want new backdated tin.


LHS Bottom side Details:

[York]

Here is an "after" photo:

[Monza_dh]

Originally Posted by Monza_dh

I just found this and ordered a few feet:

http://www.nostalgicairparts.com/air-conditioning/2-5-inch-flexible-duct-hose-57.php

DO NOT USE THIS HOSE!!!!

The woman I ordered it from said it was used for heat and was heat rated but the exchanger cross pipe was too much and it distorted the entire length and turned useless. Lesson learned! Just ordered the aircraft style hose.

[KFC911]

Originally Posted by Monza_dh

DO NOT USE THIS HOSE!!!!

The woman I ordered it from said it was used for heat and was heat rated but the exchanger cross pipe was too much and it distorted the entire length and turned useless. Lesson learned! Just ordered the aircraft style hose.

That'll teach ya to listen to a woman...oops, did I just type that !
Seriously, you should have known better...one glance at that link (and pic) would have indicated to me it wouldn't work just by the description.

[Monza_dh]

Well the $2.00 per ft hose didnt work but the aircraft hose sure did. Like the others this shipped in a few days and bent up perfrect to fit in the exsisting cross over pipe.

Should have started with this one!!





Test drive right after!!

[alniki]

Remember reading about the extra cooling function of the heater blower in the engine bay. When the temperature is reached the blower turns on automatically to help draw hot air from under the engine tin. I personally have observed its function when the heater is off. So, if you are driving in hot regions, like me, keep the original heater piping/fan may help lower the engine temperature if it ever gets too high. Correct me if I'm wrong becasue I also would like to get rid fo those piping.

[richde]

Originally Posted by alniki

Remember reading about the extra cooling function of the heater blower in the engine bay. When the temperature is reached the blower turns on automatically to help draw hot air from under the engine tin. I personally have observed its function when the heater is off. So, if you are driving in hot regions, like me, keep the original heater piping/fan may help lower the engine temperature if it ever gets too high. Correct me if I'm wrong becasue I also would like to get rid fo those piping.

Nope, engine fan driven air is diverted from cooling the engine to be run through the heat exchangers. So if you actually wanted maximum cooling, you'd block off the heating duct.

[alniki]

All right, guess my memory is not reliable. Searched and found the following. So I must have read it in the Bently manual, too. So it seems that maximum cooling at speed and additional cooling at idle cannot be had at the same time.

"The Bently manual states that the rear blower also opperates as an additional cooling fan for the engine, if the engine is running, the temperature is too high and the car is stationary." by Wavey

heater blower delete in 3.2

[KFC911]

Originally Posted by alniki

Remember reading about the extra cooling function of the heater blower in the engine bay. When the temperature is reached the blower turns on automatically to help draw hot air from under the engine tin. I personally have observed its function when the heater is off. So, if you are driving in hot regions, like me, keep the original heater piping/fan may help lower the engine temperature if it ever gets too high. Correct me if I'm wrong becasue I also would like to get rid fo those piping.

Get rid of it, and clean the engine bay up is my .02. My car has never had a need for the "extra cooling", and I'd question the effectivness of the design anyways. I'd have to see empirical evidence to believe it since the blower fan diverts cool air ("away" from the top of the motor as designed), and routes it through the blower, past the heat exchangers and then releases the hot air beneath the car. IMO, removing all the heater plastic ductwork, the AC compressor and the condensor (blocks hot air from naturally rising) does more for removing obstructions and allows the heat to escape as originally designed. All have been removed from mine, and overheating has never been an issue...not even close.

[scarceller]

Originally Posted by alniki

Remember reading about the extra cooling function of the heater blower in the engine bay. When the temperature is reached the blower turns on automatically to help draw hot air from under the engine tin. I personally have observed its function when the heater is off. So, if you are driving in hot regions, like me, keep the original heater piping/fan may help lower the engine temperature if it ever gets too high. Correct me if I'm wrong becasue I also would like to get rid fo those piping.

100% correct, the Heater Relay has a function that will turn on the rear blower if the oil temp goes above a certain level (250-260deg). This causes large amounts of cool air to be sent through the heat exchangers and this air is then dumped under the car near the top of the top of the transmision at the heat deverter valves (the ones connected to the orange heat levers between the seats). Engine temps are lowered because you are cooling the heat exchangers and removing large amounts of heat from the exhaust section under the car.

You can achieve the same result by simply lifting the orange heat levers slightly, when you pull up on the levers just a little the switch at these levers tells the Heater Relay to activate the blower as well. I did this often in stopped traffic to help with engine temps.

My suggestion is that if you live in very hot areas I would not remove the rear blower. When I lived in South FL. I always ran the rear blower on hot days. But now I live in RI and I backdated my heat and my engine temps are just fine.

[KFC911]

Originally Posted by scarceller

100% correct, the Heater Relay has a function that will turn on the rear blower if the oil temp goes above a certain level (250-260deg)....

My car has never approached those temps either before or after backdating the heat...a total non-issue from my perspective as it's designed to fix a problem that doesn't exist on my car. It still reeks of an "engineering bandaid afterthought") imo, just like the auxillary heater blowers and A/C were

[scarceller]

Originally Posted by KC911

My car has never approached those temps either before or after backdating the heat...a total non-issue from my perspective as it's designed to fix a problem that doesn't exist on my car. It still reeks of an "engineering bandaid afterthought") imo, just like the auxillary heater blowers and A/C were

Keith,

Under normal conditions you should never see greater than 250deg oil temps. But in very hot climates with AC running at full capacity and in stopped traffic it is possible to have oil temps hotter than 250deg and I think the Engineers where thinking of these conditions.

I simply wanted to explain that the Heater Relay does have this function, it will turn on the rear blower if oil temps get hot.

Here's another thing the relay also seems to monitor but we never figured out why or what it does: the relay also has the Speedometer pulse signal sent to it via a wire as well. I never really looked into this but was surprised to see the speedo signal pulses wired into the heater relay. Any thoughts here?


See this post for the schematic, look at heater relay pin #1:
Carrera - Removing Engine Compartment Heater Blower

[alniki]

Well, I've been keeping asking myself can I possibly outsmart those Zuffenhausen (over-)engineers and now the answer seems quite clear.

So, IMHO, one should judge for himself whether to keep the blower or not based on the climate and driving situation.

[efhughes3]

The speedo sensor may be part of the overheat circuit....if the engine goes hot, and is moving slow, then the circuit turns the blower on?

[scarceller]

Originally Posted by efhughes3

The speedo sensor may be part of the overheat circuit....if the engine goes hot, and is moving slow, then the circuit turns the blower on?

Ed,
I think your guess would be a good one, I have been meaning to investigate this speedo conection to the relay and test it. Need to find more time, but it's always been in the back of my mind.

Thanks.