L-Jetronic Temperature Sensor #

[Mr Clifton]

Does anyone have the part numbers to the 1975 temperature sensor? It has a 523 on the side and it has failed. It's the sensor for enrichment while cold (choke). Also, does anyone know where I can purchase a new sensor? Thanks, Neil

[Paul]

Try Auto Parts Fast at RockAuto or Online Auto Parts and Auto Accessories Store at PartsAmerica.com

[Mr Clifton]

Thanks Paul. Neither of those companies have it. Neil

[Paul]

Neil
By looking at my orginal 75 Manta, the 75 Supplement FSM and at your above post, it would appear you are describing the Thermo Time Switch... and if this is the case, Rock Auto lists that they have it... or maybe I've misunderstood your description...

[wrench459]

Mr. Clifton what kind of problem are you having?
Flooding or a cold no start?
If it was a thermo time switch problem youll have raw gas running out the tail pipe.
That cold start injector has one big orifice!
Now the coolant sensor should be negative coefficient just add oh to start with 400 ohms in the circuit or did I forget the Jetronic system?

[Mr Clifton]

Its the temperature sensor. It tells the computer that the car is cold and needs a richer mixture until warm up is complete. In the service manual it is figure 6E-3 on page 6-13. Thanks, Neil

[GTJIM]

A BMW from the same era 1975-79 (2002??) will have the same sensor as they used Bosch Injection too - try a specialty BMW shop or supplier.

[Aardvaark]

Have you tried OGTS, they seem to have many new and used items not in their catalog or can get them?
I bought a used and tested L-jet warm up regulator for my stock '75 Manta from them not long ago at a fraction of the new price.

BTW. I believe that temp sensor is 0280 130 023 also a BMW part as has been
noted previously.

[Gary Sullivan]

I looked at my manual as I have injected 75's and looked at one of the sensors you describe. The number along the side of one of my sensors is 524 and then the part number on the round section beneath the nylon connector is also 0-280-130-023. I would offer you one I stripped, but it is in pretty shakey condition (looks as though it had been over tightened). It looks to be a relatively fragile piece.
Good luck
Gary Sullivan

[Mr Clifton]

Thank you. Now I can make a purchase and fix it. Neil

[Paul]

Rock Auto lists both the Coolant Temp sensor and the Thermo Time switch.

Don't forget you can put a jumper in the contacts of the Coolant Temp sensor and remove the effects of the cold start's enrichening of the mixture... as a temporary fix/diagnostic tool...

[Mr Clifton]

Thank you. I believe that if I jump with a wire across the terminals that I would be in a permanent enriched status?

[Paul]

Without the wire hooked to the sensor the car will not start. To trouble shoot this condition, the FSM says to use a jumper wire in the terminals of the connector... to remove the effects of the faulty coolant temp sensor...

The sensor is a Negative Coefficient resistor... as in.. when the water is cold the resistance output is high and as the sensor see the water warm up, its output resistance drops...

Now here's a trick for you. Go to a store such as Radio Shack and purchase a 0-5K (5000) ohm potentiometer... they are about $5, using a long jumper wire, small gauge speaker wire works fine, wire the POT into the female contacts of the connector is the Coolant Temp Switch. Now you can simulate the action of a good working switch. It helps to have handy a Volt/Ohm meter so you can tell the resistance of the Pot...


To bench check the Sensor, the FSM says the resistance should be
@32 F... 4500 to 5000 ohms
@68 F... 2100 to 2900 ohms
@176 F.. 270 to 390 ohms

With this info you should be able to check the sensor itself and the action circuitry...

The coolant temp sensor will increase the injector pulse width, make richer, as the resistance of the sensor/Pot increases...


Sorry, I didn't actually answer your question above... the answer would be no, since the resistance of the jumper would be Zero.. this would indicate a full warmed engine needing NO increase in pulse width/enrichment...

[Mr Clifton]

With a jumper the engine will not start.

I have located a new sensor and I'm hoping for a complete cure once delivered.

Thanks for your help.

Neil

[wrench459]

Another idea
Pull the large brake booster hose off
and load it up with carb cleaner..will it run?
Sorry Ron I cant help myself

[dallasmanta]

I just replaced mine from Orileys Auto parts in Dallas. They had a universal one that fit just fine and works. Ron. OTGS had a new one for twice the price so I bought one each to see if it made a difference. They worked exactly the same. Ron

[Mr Clifton]

I purchased one that had the same values as the Opel. It is for a Fiat, Alfa and Lancia. They have Bosch L Jetronic on some years. I will let you know after installation how it works.

[75 wagon]

Originally Posted by dallasmanta I just replaced mine from Orileys Auto parts in Dallas. They had a universal one that fit just fine and works. Ron. OTGS had a new one for twice the price so I bought one each to see if it made a difference. They worked exactly the same. Ron

I need to replace mine (75 sportwagon). RockAuto has a Standard Motor Products / coolant temp sensor for $12.20. They also list a AC/Delco for $52.00. You think the cheap one will work ?

[dallasmanta]

the cheaper version works just the same as the more expensive one. The only difference I found was it was not color matched to the bosch unit and the plug was not as tight a fit as the bosch one. Neither of this issues changed the fact that the resistance function of the switch worked like it should Ron

[Mr Clifton]

Yes the new part works really well. Now I need a new Auxiliary Air Valve.

[75 wagon]

Originally Posted by Mr Clifton Yes the new part works really well. Now I need a new Auxiliary Air Valve.

Just checked mine and its closed up. Tried to clean it hopeing it might open up. Did not work. These are supposed to be open when cold and closed when warm, right? I see a old used one on e-bay for $50.00 and a new one at PartsGiant for $101.00. Got any ideas where to get one quick for a god price?

[Mr Clifton]

I'm shopping right now. The cheapest I've seen is $89. They are the same part number as some Audi's, VW, Alfa and BMW's. I'll know more tomorrow.

[Aardvaark]

Originally Posted by 75 wagon Just checked mine and its closed up. Tried to clean it hopeing it might open up. Did not work. These are supposed to be open when cold and closed when warm, right? I see a old used one on e-bay for $50.00 and a new one at PartsGiant for $101.00. Got any ideas where to get one quick for a god price?

The used and tested aux air valve I mentioned above from OGTS was
only $15 this last summer. Works perfect and was delivered fast.

Also, comparing the original aux air valve with the used replacement, I noticed a design change in that the plastic connector that the bimetallic springs fixed end
is attached to, was changed from a crimp to hold it's clock position with the outside housing, (which broke loose on my old one) to a new and improved method that pins the connector to the outside housing and can't come loose without alot of force. I may have been able to repair the old one, but had the replacement ready to go so used it.

[Mr Clifton]

Yes that is what happened to mine. The connector broke loose and will not stay put. I messed with it and it only works for a while. Time for a new one or good used replacement.

[Mr Clifton]

New parts rule! I just bought a new Auxiliary air valve for $77 delivered and the car idles perfect when cold now. The new style (as posted earlier) has a pin to hold the 12 volt connector in the right position rather than the old style crimp. Between fixing this and the new temperature sensor it makes for a great base to tune. I can't believe how much better it runs. Now all of the other settings can be set on the fuel injection. Thanks to everyone for their help.