Chris Lockhart

I have 2 adaptors, and am unsure of which one would be better to use. They are: 928 104 713 2R (which is a one piece cast unit with an ID of .535")

and: 928 104 713 OR (Which is two piece with a pressed in nipple that has an ID of .580")

Is there any benefit of one over the other? I am conflicted because the 2 piece appears that it would flow more, yet being 2 piece yields an extra failure point. The one piece eliminates that issue but all the way through is a smaller ID and doesn't appear that it would flow as well. I'm probably over thinking it, but I figured I'd ask anyway.

Chris Lockhart

Another view: 2R on the Left, OR on the Right.

dr bob

How much of a flow improvement are looking for? It's the heater-core loop after all. Use the newer one.

Mrmerlin

I would use the single part ,
the two piece has been known to slide apart.
It can be fixed by JB welding the parts together

worf928

+1

ROG100

+2 +3 +4

Chris Lockhart

Thanks guys. That was my thought as well, but I wanted confirmation.

davek9

I've never seen the all cast part, guessing its from an early car and they went to the Steel insert due to pitting of the casting over time?

outbackgeorgia

I have used both, but the pressed in tube fell out and dumped coolant, so replaced it with the single piece part from 928 International. Should not have corrosion if coolant is properly maintained.
Dave

scottw383

Here's another vote for the one piece design.


My 87 developed a coolant leak a few weeks ago -- I traced it down to where the short hose attaches to this part. The hose on my car was apparently replaced with a short piece of standard heater hose at some point in the past -- it wasn't the Porsche part. I tried tightening the hose clamps on the hose as a stop-gap measure and ordered a new short hose. Tightening the clamp seemed to help -- the leak stopped...for about a week, then it came back.


I replaced the hose with the correct Porsche part, started the car and let it get up to temp. (I couldn't drive the car -- the driveway was still iced over from the snow and ice the Portland/Vancouver area had received a few days earlier.) At first it seemed to be leak-free, but there were a couple of drips on the floor after several minutes. OK, problem NOT solved.


I had a look at the fitting and the short hose, and sure enough it was seeping. I had a good look at the hose clamps -- still tight. I wiggled the hose a bit and noticed that the fitting in the adaptor appeared to be moving a bit. After pulling on it a little bit more the tube started to separate from the cast aluminum housing (the hose was flush with the housing before):





After pulling a little more, coolant started flooding out:








And finally the part completely separated:







It really was not difficult to separate the parts once it started to let go. I'm very glad that it didn't suddenly burst apart when driving due to the cooling system pressure, but it certainly could have.


Suffice it to say that I ordered a new single-piece part from Roger at 928sRUs and I'll be installing it next weekend when I have the time to work on the car.


Just showing what CAN happen to the two piece part. And I'm definitely a fan of the one piece design...one less failure/leak point.

Rob Edwards

This two-piece coolant pipe insert thing was beta tested on the 928, and they worked so well they use 8 such 2-piece hose inserts on the 996 Turbo. Ask those owners how that worked out....

outbackgeorgia

One less point of failure, no downside.

Chris Lockhart

Definitely a bad design. Thanks for showing what CAN happen Scott.

scottw383

Agreed!


As a mechanical engineer I never would have designed that relatively simple part as a two-piece assembly, especially given the harsh environment that is going to have to live in: large temp swings, vibration, pressurized fluid, the possibility of corrosion from inside, etc. I wouldn't expect either a press fit or an adhesive to hold up over the long haul in that environment. And guess what? It doesn't...

dr bob

I think it's a -great- idea to put a thin steel sleeve into an aluminum housing, then heat it up and cool it down under internal pressure. There's surely lots of interference in the fit, so the faster-expanding aluminum stays nice and tight around the steel. What could go wrong?

There are plenty of adhesives that would do the job these days. Bad news is that they weren't around when the parts were made originally.

Rob-- 993 guys snicker at the fittings that the 996 guys use, i'm sure.


The real street-race crowd has everything mached from billet. They may be on to something.