cold start removal
 

hi all
can i separate my C.S. device from its fixing plate on the pump and just leave it connected to the coolant pipes as then i would be able to monitor what its doing in cold and hot on the car . i would then be able to see any movement of the centre plunger while the coolant is flowing through the stat .
my C.S. has no movement at all just now .imfaily sure this is due to a adjustment my diesel engineers made . there comments now are that theC.S. device may have failed . if thats so there will be more to just changing it for a new one as the cable has to be set up in such a way to work the advanced timing on cold start up . or do i just change the C.S. stat part and thats it ?
i suspect also my M.P.G. is not as it should be since they have just changed 6 injectors .

You don't have to remove it, you can just watch the base of the cable as the car warms up.

The only reason I can imagine MPG going down with new injectors is if they forgot the heat shield washers?

surely if while replacing the injectors they messed up the cold start kit, then the timing would be out of optimum and this would cause reduced MPG too?

Richard

Cold start thermostatic actuator ("wax pellet") is sadly a known high-failure rate item on these old engines. As stated in the other thread "Cold Start Waxstat" http://d24t.com/showthread.php?t=822 they fail in the cold mode as the extremely powerful springs are constantly pulling the cable to the cold start position.

Those extremely powerful springs make reassembly of the device difficult. I would avoid taking it apart just to verify its functionality. Better idea is to verify the cable/lever position at cold start, and compare it to when engine is up to operating temp. Use a camera, measuring tape, whatever. The difference should be noticeable if the device is operating correctly.

Most simply manually render the device inoperable when the waxstat fails by relaxing the fancy cable-end, as in when setting the IP timing. They are getting hard to find, and pricey.

I'd probably convert to a choke cable if I thought I actually needed cold start advance.
But like I said earlier, interrupting altitude compensator power, and holding the accelerator down a little will do the exact same thing as the wax dingus.

940 tdi auto 1995
 

thank you all for your comments.
i have found a chap locally who has the same car as mine and he has disabled his . i will check and find out if the heat shields have been replaced .
how far should the cold stat cable move to work i have a spare one which moves out 9 to 10 mm is that enough or should it be more?

that's about right. AFAIK, they work or they don't without much in between..

Sometimes if somebody times the IP the hard way (moving the pump rather than the cam gear), and the pump ends up rotated too far in the "advanced" direction, the aneroid on the top gets in the way and the #5 and #6 injectors cannot be removed until the pump's turned back out of the way again. If that was the case, then it's a possibility that the shop that worked on it had to reposition the IP in order to replace the injectors, and might not have gotten it back in the right spot. That's one possibility for mileage change... also actual ignition timing changes if injector opening pressures are altered, so if your old set was severely worn, this might account for some of it. Overall, though, it sounds like either by mistake, ignorance, necessity, or some combination of these, whoever worked on it when the injectors got put in may have changed some other factors about the motor. Seems like that's the only way to explain the difference in the way it starts and runs. Incorrect timing seems like a big suspect. If the diesel shop disconnected the CS device, that might be further indication that they had to change the timing and were attempting to get it right again.

What was the original reason why you had the injectors changed?

940 tdi auto 1995
 

thanks for info .
can i safely disconnect the 2bolts that hold the C.S. device and drive car and take away cable too but not touching the spring loaded arm that goes into I.P.then i can see if cold start device plunger moves out with no pressure on it at all

Why? Seems like you are barking up the wrong tree. Are you interested in remedying the problem of reduced MPG and smoky starts?