308 GTS QV catalytic thermo sensor probe

I have a 1985 QV. I am replacing new catalytic converter and needing a new thermo sensor probe. Anyone know where I can find one? Algar Ferrari parts Image Unavailable, Please Login online has it for $785. Do I really need the probe or just cap it? Thank you in advance.

 

Thanks for the info Kcap and Brian. I put everything back together last weekend with the new non OEM Cat and OEM Bosch O2 sensor. I capped the thermo probe for now. BTW the size of the compression nut for the probe is 8mm x 1 for future reference. When I opened up the ECU in the trunk the connector for the slow down lamp on the dash was disconnected from the thermo sensor controller. Also on my QV the thermo sensor wire runs directly to the thermo controller in the trunk and not to the dash (see pic). The old cat were gutted so I guessed the last owner had it disconnected. The 85 QV came from Maryland so I guessed they don't need to smog? like we do in California. I couldn't remove the thermo probe and the O2 sensor from the old cat since they have been cooked very good for 32 years. I made a mistake and cut the three wires from the O2 sensor without marking them. It turns out it has 1 black and 2 identical white wires. The black wire is the O2 signal going back to the ECU, catalytic is ground, white wires one + and one - for the core heater. For some reason I did not see the O2 connector anywhere near the ECU in the trunk below the antenna. According to the manual diagram it supposes to go to there. From underneath the engine area the O2 wire goes up under the fuel injection distribution unit and disappears. To make life easy I decided to cut the wires of the new O2 probe and twisted tie to the existing old wires. I got 50% chance to get the white wires polarity correct. I fired up the engine and it ran great, starting around 2000rpm for the first 5 mins and idling around 1000. I spent sometime on Utube searching for troubleshoot O2 sensor and found a clip on a 3 wire Bosch. So I hooked up the volt meter to the O2 black wire and ground, it showed 500mv when I started the engine from cold, then in about 10mins it fluctuated from 200mv (lean) to 900mv (rich). So it looks like the O2 sensor is operating like it should. Also I think I got the porality of the white wires correct because if the core heater doesn't work the O2 sensor wouldn't send voltage to the ECU until the probe temp reaches 600F.

I took the QV with the new cat for a ride and she ran great. It might be my imagination but I think it sounds better with the new cat in? The power is still there. I might scrap the idea putting back the old cat back in after done smogging. BTW it is impossible to get new metric bolts and nuts for the cat. I was able to get SEA stainless steel nuts and bolts and salvage the old stainless springs that weren't rusted up. Another the donut cat gasket is impossible to get. I went to NAPA and was able to find a truck or tractor gasket that was slightly bigger but worked great after tighten up.

About the thermo sensor, I found on Ebay 3.2 mm K probe same size as the OEM from S. Korea for $29 with SEA nut. Nut can be rethreaded Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login to metric. It doesn't say what range of temp it's good for. The OEM probe needs to go 900C? I might give it a try since it's a lot cheaper than $785 from Algar.

I was a two Dinos owner at the same time (a 73 and 74), this was a learning experience with the 85 QV with all the new advance gadgets. Otherwise it is very much the same with the Dinos I think. Got to read the manual.

 

Yes the Ebay one it comes with ss external braided wire. As you can see on my pic above of the OEM braided wires attached to the controller for comparison. The other end of the wire near the thermo probe crumbled from 32 years of heat. I did not order one but may be can ask the seller if they can put in a metric compression nut 8mm x 1?

https://www.ebay.com/itm/SSG-K-Type-Thermocouple-Stainless-Steel-Sensor-with-Plug-1-4-Thread/112218126327?ssPageName=STRK%3AMEBIDX%3AIT&var=412511286605&_trksid=p2055119.m1438.l2649

 

I did use the caliber to measure the OEM broken thermo tip it comes out about 3.0 - 3.2 mm. Tomorrow I will try a digital caliber that I have at the office.

 

Just got a reply back from the Ebay seller of the K thermo probe above only measures up to 650C. I don't think that will be adequate for the 308 catalytic converter application.