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autobroker,

Glad to hear you have the right hose and you are on your way to replace.

As to why ALFA changed that hose, I don't have the definitive answer, but I do have more clues that will bring us all down the rabbit hole further, and I know we love a good mystery don't we? ;)

Back in 2012, I changed my '91 from the linkage throttle to the wire throttle. I had to replace one of the linkages, and thought why not change to the wire throttle. I would NEVER, EVER, recommend this change to anyone as there are so many parts that need to be replaced, and frankly, I don't think it was worth it.

Anyways, lets go down the rabbit hole a bit.

Here is a picture of my '91 using linkage throttle. For the hose we are talking about, we can see, it goes from the top of the throttle assembly to the heater core.
IMG_7173.JPG


Here is a picture of my '91 after being converted to throttle by wire. We can see that the left side of the top of the throttle assembly is capped off and now the hose that goes from the bottom of the thermostat to the top of the throttle assembly on the right is changed from a curved hose to a U shaped hose.
IMG-20120222-00371.jpg


That hose from the bottom of the thermostat to the top of the throttle assembly was changed because there is now interference with the throttle by wire assembly using the original hose and ALFA had to go around it.
IMG-20120222-00366.jpg


Now here is the last clue that I have of why the larger hose on the left that goes to the heater core was changed. When ALFA changed the small hose from the bottom of the thermostat to the top of the throttle assembly, they changed the inside diameter of that hose as can be seen here.
IMG_9042.JPG


I understand now, that because of this reduction of inside diameter hose size, there is not enough coolant flowing through and would not be enough to feed the heater core, so ALFA changed where the heater core would be fed from and that is directly from the intake manifold.

The question now is, why did ALFA changed the inside diameter of the hose from the bottom of the thermostat to the top of the throttle assembly. If they would have left the flow rate the same, I believe they would not have had to change where the heater core hose was fed from and then, did not have to change the heater core hose or the intake manifold.

Vin
 

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I understand now, that because of this reduction of inside diameter hose size, there is not enough coolant flowing through and would not be enough to feed the heater core, so ALFA changed where the heater core would be fed from and that is directly from the intake manifold.

The question now is, why did ALFA changed the inside diameter of the hose from the bottom of the thermostat to the top of the throttle assembly.

Vin
Or, one could also ask why did they make that inlet nipple smaller?
If they left it as it was the heater hose could also he left as it was!

I wonder if the car disc says anything about the change from C9777 (throttle rod) and D9777 (cable throttle)
if you browse through the parts book, there are a lot of different parts, the plenum too has a different PN, not just the inlet.

Vin, I remember when you did the change, I kinda got the impression back then you wish you hadn't started!
 

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Discussion Starter #24
Here's a thought. On 1991 and earlier cars, the hot water for the heater would heat up the plenum too much - cool intake air is much better than hot. In 1992, Alfa may have identified this problem and instead of running all that hot water through the piece in the plenum, they just ran it directly from the intake manifold/head.

This is just a guess.
 

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Discussion Starter #25
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Hi Guys,

Does anyone know where I can find a heater hose for a 1992 Spider S4. It's the hose that goes from the head to the firewall. I circled it in red. My mechanic is having trouble getting the hose - he's not an Alfa only mechanic and the local parts houses don't have the hose.

Thank you.

Greg View attachment 1618323


Heater hose update.

Well, the heater hose that I received was not the correct hose. It's the same hose my 1973 Spider uses! I called Jon at Alfa Parts and he checked for the correct part. He doesn't have it and he doesn't think it's available aftermarket. So, I can wait for one from England - an old NOS part OR I can try to use the wrong part. I chose the later and I ran the part a little tight - if you look at the picture and my red lines, the upper line, which touches the valve cover gasket, is the path of my new hose.

Heater hose to heater core - anyone doing this, make sure you read this - it'll save you a bunch of time! Getting the old hose off was tough, but I did it. The new hose wasn't too difficult to get through the firewall and on the heater nipple - I used Dawn dish soap to lubricate things. Then the difficult part came - how do I get in a good position to tighten the clamp! I struggled and struggled and struggled. It was getting dark, so I used a flashlight, but it wasn't enough, so I called it a day. The next morning, I struggled some more - but this time with a very sore body from all the contortions! Then I noticed that the lower duct moves as it mounts to the heater box. My duct only had one bolt, so I removed it and I was able to see the clamp and get to it directly! I then put the duct back on - not the easiest either, since I had to re-attach the flexible accordion hose to the top of the duct - with only one hand, since I couldn't get both under the dash! Then I installed the bolt and I was ready to install the other, but I couldn't get the screw hole to line up - again with only one hand. After a few tries, I gave up and left it with a single bolt - like I found it.
 

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Discussion Starter #26
Hi Guys,

Does anyone know where I can find a heater hose for a 1992 Spider S4. It's the hose that goes from the head to the firewall. I circled it in red. My mechanic is having trouble getting the hose - he's not an Alfa only mechanic and the local parts houses don't have the hose.

Thank you.

Greg View attachment 1618323
One more update: As I was working on this project, I noticed that the VVT solenoid was dangling and the power steering pump bolts were almost out! Tightening the bolts isn't that difficult - just make sure you push the pump to as close to the position when the bolts are tight - that way you can get to the bolts with an end wrench.

VVT solenoid dangling? It was pretty oily, so I cleaned it with degreaser. Now I can see what I'm doing! I removed the bracket - three allen screws - and degreased it. The parts don't fit - they're too loose! I went on line and found something here on AlfaBB - the rubber deteriorates and the solenoid can become loose. For my car, there wasn't enough rubber and it fell out (maybe not "fell out", or it would've damaged it - my guess is that someone left it there). I cleaned off all the rubber. I removed the solenoid from the holding tube - loosen the lock nut first or you can't remove it. The holding tube unscrews from the solenoid. I then sanded everything down (where rubber was) and I have a nice clean surface. I was going to fill it with JB Weld, but I thought I'd try forcing some rubber between. I cut a 5/16" vacuum tubing to length and slit it lengthwise. I did it to two pieces - upper and lower. I then lubed it all up with Dawn dish soap and slid everything together. It got to a point and stopped moving, so I used a piece of wood and I hammered the cylinder in place. The rubber hoses moved a little, so I used my utility knife and cut the excess away. I figured I should check the solenoid before installing, so I ran 12V to the solenoid and it moved out, but not back in. I used some penetrating oil and after a few tries, it no longer got stuck. I then screwed the solenoid in place and mounted the unit to the motor. I adjusted the solenoid (by turning in or out), so the solenoid would just touch the VVT pin. I tightened the lock nut and started the motor. I moved the throttle by hand and voila! VVT is now working.

I had to try the car, so I took it around the block - wow, much more responsive and reduced pop - pop - pop when the throttle is lifted. I took her on the freeway and she ran much better! She's still not angry like my pre-smog Alfas - I don't expect her to be - she's much more of a civilized car.
 

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good catch on the dangling VVT.
as your solenoid was stuck, you might still want to remove the ceramic end cap (2 tiny phillips screws), then just pull out the piston and clean it up inside there properly.
vvt solenoid - is it really dead?
 

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Discussion Starter #28
good catch on the dangling VVT.
as your solenoid was stuck, you might still want to remove the ceramic end cap (2 tiny phillips screws), then just pull out the piston and clean it up inside there properly.
vvt solenoid - is it really dead?
I should've done it when it was apart. If I have time, I may take it apart again and pull the piston out. I did clean the piston from the outside with quite a few shots of penetrating oil and wipe downs. I did it until the piston no longer had dirty oil on it.

The difference in the performance is very noticeable. The VVT does help!

When it stops raining, I'll take some pictures of the solenoid and the heater hose.

I''m looking for radiator hoses now. The upper one I have found, but the lower one is a tough one to get. My car has AC and the hoses I found are non AC only.
 

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