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Discussion Starter #1
Since I’ve purchased my ‘89 S3 I’ve replace the water pump, radiator, thermostat and all hoses. I have no leaks or overheating issues. I have noticed when the motor is up to operating temp that while the top radiator hose is hot to the touch, it doesn’t feel pressurized like on my other (newer) vehicles. The hose is still just as squeezable as when cold.

Is this normal Spider behavior? Thanks in advance-M5
 

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Did u get the system pressurization checked? Or you can replace the cap using the shop manual for the pressure amount.

Checked it for u: From the manual: Cap should be 10 PSI, which means the cap would release pressure at or above 10 PSI, maintaining 0=10 PSI. Ref page 7-5 ?
 

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Temp is OK? If there is a little air at the top of the radiator, I don't think this is abnormal. 10 PSI is not much.
Andrew
 

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Discussion Starter #4
Rad Cap was the culprit! But.......

So upon further inspection I noticed that when I squeezed the upper radiator hose with engine cold I could hear (and see) coolant going in and out of the expansion tank.

It seems that the plunger on fancy Italian radiator cap that came (free) with my new radiator does not seal below the port for the expansion tank as it should.

I changed it out for the one (safety cap) I bought at Autozone before I ordered the radiator and it clears the expansion port and seats properly.

I started her up and ran her up to temp and I had pressure on the hose.

All seems normal.... but........

Both the manual and the posters are recommending 10lbs on the expansion valve. The cap that came with the radiator is .8 bar (11.6 psi) and the autozone one is rated @ 13psi. Leak test pressure is 15 psi.

Is 12 or 13 psi an issue or is that within (reasonable) spec?

Thanks in advance-M5
 

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So upon further inspection I noticed that when I squeezed the upper radiator hose with engine cold I could hear (and see) coolant going in and out of the expansion tank.

It seems that the plunger on fancy Italian radiator cap that came (free) with my new radiator does not seal below the port for the expansion tank as it should.

I changed it out for the one (safety cap) I bought at Autozone before I ordered the radiator and it clears the expansion port and seats properly.

I started her up and ran her up to temp and I had pressure on the hose.

All seems normal.... but........

Both the manual and the posters are recommending 10lbs on the expansion valve. The cap that came with the radiator is .8 bar (11.6 psi) and the autozone one is rated @ 13psi. Leak test pressure is 15 psi.

Is 12 or 13 psi an issue or is that within (reasonable) spec?

Thanks in advance-M5
The pressure difference of 10-15 is not that great, head gaskets, hoses and other seals could suffer. My V8 takes 17 lb. cap pressure. The higher the cap pressure the higher your water temp can go before boiling. Good Luck, the manual couldn't be wrong either.
 

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Well, the S4 takes a 1 bar (14.7 psi) cap and that's basically got the same engine and hoses, so it's probably okay.

That being said, it's easy enough to get the right cap. Centerline carries the 10 pound cap, or Pep Boys carries a 10 lb Stant brand cap that'll work. Since your car has an overflow tank and return line make sure it's the non-vented version.
 

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Discussion Starter #7
Update-

What I thought was an Italian made radiator cap that came with my new radiator was actually a Turkish made .8 bar one that was not so good.

The company that sold me the new radiator that came with the Turkish cap offered to replace it with the proper Italian made .7 bar one. Now all is well on my cooling system.

Thanks JoeCab and Centerline for taking good care of me!
 

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I have a 7 psi cap on my rad. works fine.. always worried about too hight of pressure on the headgaskets.. not to much sealing area on our cars..
 

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Discussion Starter #9
7 lb safety radcap

I've been doing a bit of cross-referencing for certain parts and have stumbled upon a 7lb safety cap that will fit in the Spider, even though the parts store websites say otherwise.

It is part number 7707 at Autozone.

I've not seen anything like this (7lb safety) available at any of the Alfa specialty parts houses.

I still like the looks of the square cap though:wink2:
 

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Did anyone ever tell you the purpose of the pressure cap? ie the higher the pressure, the higher temperature you can operate at withour boiling. Some cars now operate above 15 PSI.
 

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Discussion Starter #11
Understood. That's why I posted.

Did anyone ever tell you the purpose of the pressure cap? ie the higher the pressure, the higher temperature you can operate at withour boiling. Some cars now operate above 15 PSI.
Yes. I understand. That is why I posted this. My manual calls for a 7 lb cap. The one auto parts stores recommend for an '89 S3 Graduate is a 13lb cap.

I was concerned about the pressure being nearly double what is called for.

The point of my previous post was to point out that there was a safety cap avail that was within the manual's spec.

I apologize for causing any confusion.-M5
 

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Personally, I would stay close to factory spec. The often maligned engineers knew what they were doing.
 

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Agreed to the factory spec. I usually tend to stay on the factory side. But, Italian Engineers????
Careful! Luigi is kinda bored and I may have to send him over to have a talk with youse!>:)
 

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Luigi can talk to the other Goomba's I am friends with. I',m Electro-Mechanical with 34 years experience with missiles and cars since the 40's and 50's.
 

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I worked with Italian engineers from the Italian Space Agency (YES, there is one) during my years at NASA Johnson Space Center and they were extremely competent.
 

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I worked with Italian engineers from the Italian Space Agency (YES, there is one) during my years at NASA Johnson Space Center and they were extremely competent.
exactly ... I do consulting some work for several here in the construction industry and they are very good at what they do and Italians have a terrific machine tool industry. its one stereotype that doesn't stand the truth test .
 
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