My ‘96 Daimler 2x6 has been off the road since february 2023. It started with a clean-up of the rh-side of the engine bay, then ran into a split core of the starter motor and all kinds of other NLA parts that needed replacement. After completion engine had a misfire on rh bank so all fuel injectors were sent out to be ultrasonically cleaned and all ignition leads were renewed. Inlet manifolds came off and were cleaned as well.
In a different post I informed about the green gaskets in the fuel rail which seemed to be NLA so that took time to investigate. After putting it all together again I filled up the cooling system and ran the engine for a minute or two and everything seemed fine. The next morning though there was blue coolant under the car. It turned out to be the connecting tubes of the idle speed control valves, both left and right.



The blue indicator dye is clearly visible.



The connecting tube was also corroded of course so I got a stainless steel tube 19mm and cut it to size 6cm. The rubber sealing bushes, #3 in the parts picture, were readily available as were the gaskets (#16). In the description it says you will need 2 for each side but there are 3 to be replaced. So order 6.
When putting it back in place make sure that the distance between the two coolant jackets of the front part and the rear part are 11cm apart for the rh bank and 10,5cm for the lh bank. The connecting tube does not go all the way into the idle speed control valve so when you adjust it just before bolting it down you might push the tube in too far on one end and not enough on the other end. I marked the spot where the tube meets the bushing so after installment the mark will tell you wether it has moved in or out or stayed in place.






The gasket of the idle air control valve is also NLA.(#13 NNA5207aa). That is why I do not dare to take the control valve apart. Any suggestions on alternatives for this gasket?
Also I would like to test if it is still doing its job. Does anyone know how to test this control valve. The connector has 3 pins.

Thanks for your help.
Olav

 

G’day Olav,

I have done exactly the same work as you have done on my car and it all works well.

I believe the ISCV does a self test, on the first prolonged stop of the day, by altering the idle setting briefly to see whether the system self corrects. It tests one bank at a time. When it happens it feels like a brief idle speed stumble or miss so if your idle speed is correct and you can feel this idle stumble then I would say your ISCVs are working correctly.

Re Item 16 in your diagram, the gasket, I have used thick gasket paper material with a smear of sealant on each side and have had no problems.

Cheers,
Jeff.

 

Thanks Jeff, it does indeed idle around 1200 rpm but does not come down when warmed up. So I need to hunt for vacuum leaks I guess.