Diesel Cold Start

[Rich]

Just a small query I hope.

My diesel will not do its cold start thing. The fast idle solonoid does work when you connect 12v to it directly, so I know that works. I suspect the sender on the thermosat housing to be duff, but I tried Partco and they can't get me one. Does anyone know of a place to get these sort of devices, apart from Rover?

Also, does anyone know how to test the cold start device on the injection pump? It says in Haynes "this is best entrusted to a Rover dealer", but I just wondered if you could actually prove it was working?

Rich

[G Force]

Hi, The fast idle solenoid is fed via a fuse (I think it is C5 but I might be wrong) so check this first. Then you could try bridging the wires at the sensor. The cold start advance solenoid is on by default and the electic feed brings it off so it can only fail in the advanced state. There should be a 12v feed to it over 50C (big thermo switch front of head) and the bacolite part should get V hot to the touch if its working.

Ps You have to manually open throttle for the fast idle solenoid to come on, its not designed to push open the throttle lever, But i'm sure you already knew that.

Cheers Gary :)

[skipweasel]

My diesel will not do its cold start thing.
What are the symptoms?

[Rich]

Thanks for the replys!

The symptoms are, that on a cold morning, and I first start her up, shes a bit lumpy, and it takes a few blips on the throttle to get her to "wake up". As soon as i'm off the drive and down the road, its ok. The problem I can see, is the solonoid is not moving to advance the throttle. Even if I allow it to move by putting my foot on the throttle.

Its not a major major problem at the mo, but as it gets colder, I don't want to be sorting it out then.

Gary, I had a look this evening, had to change the oil anyway as soon as the rain eased off. Checked the fuse, all is ok there, theres voltage at both sensors. When I join the wires at the one on the thermostat, the cold start solonoid clicks to advance.

I couldnt check the other one, as the engine wasnt hot so couldnt do it. Going back on what you have said though, the other side of that switch (the one on the block) should have voltage on it when the engine is hot?

Rich

I'm thinking it must be that switch.

[G Force]

[QUOTE=Rich]
I couldnt check the other one, as the engine wasnt hot so couldnt do it. Going back on what you have said though, the other side of that switch (the one on the block) should have voltage on it when the engine is hot? [QUOTE]

Yes thats right, around 50 degrees centigrade the switch closes and starts to bring the cold start advance off. As for the fast idle solenoid you are right you just need a replacement switch.

Regards Gary :)

[skipweasel]

The symptoms are, that on a cold morning, and I first start her up, shes a bit lumpy, and it takes a few blips on the throttle to get her to "wake up".You've made no mention of the glowplugs. Can we assume you've already adequately eliminated them as a cause? Is there noticeable smoke while it's rough?

[E_T_V]

I'll jusr re-itterate what they said above.

The throttle pedal must be depressed with the ignition on in order for the idle advance solonoid to lock into the on position. (it isn't strong enough to advance the pump lever by itself).

The easiest way of testing the cold start mechanism on the pump is to apply 12v to it manually with the engine off. You should hear a click as it is applied and released as a plunger moves inside. If there isn't a click then it may well be stuck.

If you need a replacement switch I have a functioning one on my dead engine which I can bring to the AGM.

[Rich]

Thanks everyone, it seems mended now!!

Got a new sender from Rover part number BDU 1777, and all seems solved now. Changed the sender with the engine cold, then tested it. Solonoid shot out and increased the tickover, started it up, and it ran the best it ever has on a first cold morning start as I wasnt having to rev it to keep it ticking over smoothly. Then the tickover seemed to get faster and faster and then the solonoid clicked back, and it just ticked over as normal.

Purrrrfect!! :)

I'm sure the glowplugs are good. Its never had a problem to start as such, just to run when cold. To be honest though, I havent checked them, it just seems too fiddaly to get in there and do!! :laugh:

Still, very pleased its working now.

Rich

[skipweasel]

Then the tickover seemed to get faster and faster and then the solonoid clicked back, and it just ticked over as normal. Mine always does that while waiting at the lights half a mile away.