Lucas CAV stop solenoid

Hi,
First post here for Ne and hoping for a bit of advice about servicing or replacing the solenoid. I have Cummins 6 BT with 4000 hours. Runs well, starts well but when hit fails to stop when turned off. Turns off ok when cold but when hot it tries to stop but keeps ticking over. Using the manual stop lever it immeadistely stops.
Since it is a solenoid that closes when it has no electrical power do you think it is a solenoid problem or a valve problem. Should I try replacing the solenoid or any other advice.
I live in Vanuatu and parts are not easily available.
Many thanks for your help?

Greetings,
Welcome aboard.

I think you are the first member from Vanuatu, so welcome aboard and enjoy!

L.

Lou_tribal said:

I think you are the first member from Vanuatu, so welcome aboard and enjoy!

L.

Click to expand...

Welcome aboard Nigelk. One of the mechanical guys should have your answer. Lou, Nigelk is not our first member from Vanuatu, the less said about the earlier one(name of nightsoil or something similar) the better.

Given the unavailability of local parts I'd suggest that you rule out wiring issues. Check voltage at the solenoid and make sure connections are good, both on the solenoid and stop button.

Do you have the rotary pump? There has been earlier discussion here on removing the solenoid. Not that difficult, I had mine out and played with it on the bench. Most of us have energize to run rather than energize to stop, keep that in mind if you read up further. But the issues are similar, except if we have issues with the solenoid the motor stops. Think I'd rather have your problem

I'm sure the real experts will chime in soon...

Edit:. I see from the title it's the CAV pump. Not specific to Cummins, that pump is on lots of old marine motors. May make sourcing parts easier.

Welcome to the forum! Have you tried an adjustment to the linkage?

Ted

A solenoid is a pretty simple device, a coil of wire with a plunger in the middle. Apply electricity and the plunger is pulled in, turn off and the spring pulls the plunger back out. The plunger can get gummed up over time Try some WD40.

Welcome aboard!

Usually, 6BT solenoid problems are related to shutting off at inappropriate times. Can be pretty disconcerting! As far as linkage, there is none. The solenoid lives at the back of the pump, and consists of the solenoid that houses a small plunger with a rubber cone on the end. Behind the plunger is a small spring, a bit smaller than one you'd find in a click pen. Since your problem is not shutting off, I'd suspect there's an issue with the plunger or the spring, perhaps the spring has broken or the plunger is not seating.

As others have suggested, I'd check the connection, although this solenoid is energized to run, so a bad connection would likely manifest itself with inappropriate shut down rather than a problem with not shutting down. You can use the shutoff lever on the pump until you get a replacement solenoid. There are a number of applications for the CAV pump as others mentioned, so you may not need to get OEM Cummins parts, you can probably get the solenoid from a diesel pump shop that handles Lucas (now Delphi) pumps. Just be sure that you get one that is' energize to run', as they're available in either that or 'energize to stop' configuration.

There's a nameplate on the pump, have that data available for the pump shop, or the Cummins CPL # or better, the serial # to order Cummins. The solenoid is EZPZ to change, simply screws into the body of the pump, single wire connection.

Good luck with the solution.

I've two Cummins 4BT engines in my boat, with the Lucas Cav system. Back in Oct 2016 had same problem on one engine as seems you have. Did some posts on the Bayliner Owners Club forum re what I did to fix problem. Also posted on boatdiesel.com. Tony Athens also a good help, as usual. On the BOC forum, a search for posts by "hodaka" should bring up what I did to fix the problem. May help you, I hope.

Best, Hodaka

"On the BOC forum, a search for posts by "hodaka" should bring up what I did to fix the problem."

Why not copy and paste so all can read of the procedure?

Do you have a push to stop button or key? Many times the push to stop solenoids aren't the problem. It's either push button itself or the wire between the push button on the dash and the solenoid. I've replaced both of mine on both engines.

You can test it, by running a jumper wire from a +12v power source, ie. Pos. battery or starter terminal, and touching it to the contact on the solenoid. If it fully engages ok, then you know its in the switch or wire. If not then it's the solenoid.

Many thanks

Thanks everyone. My is a powered on model so it seems from your collective advice the problem is more likely mechanical. Will have a potter at the weekend and see where we get to???

Jeff F said:

................ Most of us have energize to run rather than energize to stop, ...................

Click to expand...

Where did you get that information?

Mine is energized to stop. It's a Volvo.


As for the OP, if you are somewhat mechanically adept, you can probably get the solenoid out and find out why it's not moving properly. Many times, a good (internal) cleaning is all it takes. If the solenoid is energized to run, there may be a problem with the spring that returns the shaft into the coil.

WesK said:

Where did you get that information?

Mine is energized to stop. It's a Volvo.

Click to expand...

Agree that energize to stop is common, but not on the Cummins BT. I should have made clear that my comment was specific to those motors.

Nigelk said:

Thanks everyone. My is a powered on model so it seems from your collective advice the problem is more likely mechanical. Will have a potter at the weekend and see where we get to?dc4d?dc4d?dc4d

Click to expand...

I somehow assumed from your original post you had a energize to stop. My mistake.

I had the exact same issue with the same motor last year, and it took me some digging to figure out. It turned out that I was passing a lot of current through the ground wire in the wiring harness at times due to a wiring issue elsewhere, and it had heated up enough where the wires were tightly bundled together to melt the insulation on several. Bit of a mess, and not immediately obvious. I had a cascading set of issues including this one, where the wire feeding the solenoid came in contact with another hot wire. Hence my recommendation to check wiring carefully before jumping to assume it's the solenoid, as I did.

Yes, the first logical step in diagnosing a problem with an electrical device would be to see that it's receiving the proper electrical power.