Appropriate Substitute for the EGR ported vacuum thermo swit

[lvacordian]

Does anyone know of an appropriate substitute for the EGR ported vacuum thermo switch on a 78 Spider? I was told by a technician in central Califonia that the Pontiac Sunbird vacuum switch should work, but I forget the model year, and I can’t get a hold of the tech I spoke with so long ago. Aside of that the switches look much different from the FIAT valves and the thread sizes seem problematic.

Finding a working BEHR THOMPSON Valve is very difficult to come by these days, and I was thinking that there must be either be a substitute valve, or another vehicle that has used a similar vacuum switch. After all didn’t FIAT use GM emissions equipment in the late 70’s? Any help would be much appreciated, especially since this is the final piece of my FIAT puzzle, and I haven’t driven the car in several months.

[So Cal Mark]

As long as the switch is connected properly it doesn't have to work. Of course, the Nox readings will be higher without the egr operational but we haven't had any problem keeping them within limits. The solution we've used is to install a brass tee into the heater hose, then use a Ford or GM thermoswitch in the tee. The domestic switches are pipe thread, so they thread right into a brass tee

[lvacordian]

Thanks! That's a great solution. Any recommendations on what model and year?

[majicwrench]

Do you have the old switch?? You should be able to determine (hopefully) at what temp it opens or closes. From there, go to an old aftermarket parts book (I've got one on my shelf) that shows the various thermal/vacuum switches, and it will also show what temp they open/ close. You should be able to find one close. Many of those switches have the temp stamped into the base of the switch. For that matter, an old book may list the Fiat switch, and state when it opens/closes. If someone doesn't have a recommendation, you may have to do a little homework. If you need help let me know.
Keith

[So Cal Mark]

most of those thermal switches open at about 100F. Ford or GM and virtually every mfg will cut out egr operation until the engine warms up. They're all going to be pretty similar

[majicwrench]

Spark plugs are all pretty similiar too. But it's nice to get the right ones.
Some of those switches are normaly open, some normally closed. Do you just need a two port switch?? Do you know if it is normally closed?? Want it to open about 100 deg F? Let me know and I can find you a ##.
Keith
I feel for those who have to meet state standards. I dealt with it back in the early 8o's what a bother.

[lvacordian]

It's the two port thermo switch for the EGR system. It sits on the intake manifold and opens up for vacuum at 80 some degrees, so it's mostly open. The original switch is brass and pot metal, with no plastic. Maybe that's because of concerns related to heat coming off the intake manifold. The plastic might melt? I've been to every major auto parts store in so cal and no one can seem to find a match on the diameter and thread. All the available switches are the standard 3/8 pipe thread. Finding an adapter is also problematic because of the odd thread size going into the intake manifold. Mark made a good suggestion, although I worry that some overly meticulous smog tech won't pass it if it looks too altered. Someone at an auto parts store suggested enlarging the hole on the intake manifold to 1/2 inch but that seems way too risky. Please do suggest a part number. The original switches are junk and evidently have a strong reputation for failing, and so I'm game for something different. This is my second switch in the last three years.

[So Cal Mark]

are you aware you can get a waiver for a part that is no longer available? The down side is that you have to deal with the referee, and renew the waiver for each smog test. We've never had one kicked for using the alternate switch. Remember, as long as it's connected properly it doesn't have to function to pass the test

[lvacordian]

I did not know that, but I do now. Thanks Mark.

[majicwrench]

"Second switch in three years" what happens to the switches??
Keith

[lvacordian]

The three that failed got stuck in the closed position and I accidentally destroyed them while trying to get them to open up. Not Real smart of me.

[lvacordian]

SoCalMark, I took your advice and fitted a GM ported vacuum switch onto a brass plumbing T, and spliced that Into the heater hose. I have a question about parts exemptions. I was on the CARB website and noticed that executive orders or issued by CARB referees on certain aftermarket parts, modifications and part substitutions. Surely anyone in California who has ever owned FIAT 124 has had the same issue with a failing EGR thermo valve, and has not been able to replace the switch because it's no longer available. Has CARB previously issued an executive order for this particular EGR thermo switch, citing that the part in no loner available? I combed the CARB website and the general web and can't find anything on it. I'm thinking that having a past reference number might save me and others the time of having to deal with a referee, and "reinvent the wheel" each time emissions testing comes. What a nightmare.

[So Cal Mark]

I haven't researched an exemption for the thermal valve. As far as I know a waiver has to be issued for each smog test at this time. That's why we came up with the replacement valve and tee

[lvacordian]

Does anyone have any suggestions on where to find a female to male threaded adapter that is 3/8-18 NPT to 18 x 1.5mm?