RR B80 oil pressure/starter motor

[mtskull]

A couple more B80 queries:

Went out for a run last weekend; warm weather and engine working fairly hard. Water temp steady between 160-180F, oil temp much the same. When properly hot, oil pressure at idle was only showing 5psi, increasing to 15 at fast idle and 30-40 when driving.

Is this normal, or should we be investigating the condition of the oil pump and bearings?

My other query concerns the starter motor (Simms, 12 Volt). It works fine time after time when cold but once the engine is hot, nothing happens when pressing the starter button except that the ammeter shows a discharge of 10 Amps. 

I have taken the starter off, inspected it and bench tested it successfully through 100 cycles but when re-installed, the same issue arises. I initially thought that the pinion might be jamming on the ring gear but there is not even any clicking from the solenoid; furthermore, turning the engine manually doesn't help (although it will start on the hand crank). I suspect that the solenoid has developed a fault that only manifests itself when hot. Has anybody else experienced this?

We have a spare starter but it is military spec. and is marked 24 Volt. Can anybody tell me if there are any fundamental differences, or is the only implication of using this on a 12 Volt system the fact that it would draw twice the current?

Any thoughts/suggestions welcome.

 

[john1950]

Using a 24v on a 12v system will give you a very poor motor performance, and it will overheat sooner than work.  Have you a photo of the 12v unit? If it is working O.K. on the bench is there another solonoid in the circuit, or a poor earth?

[Richard Farrant]

1 hour ago, mtskull said:

A couple more B80 queries:

Went out for a run last weekend; warm weather and engine working fairly hard. Water temp steady between 160-180F, oil temp much the same. When properly hot, oil pressure at idle was only showing 5psi, increasing to 15 at fast idle and 30-40 when driving.

Is this normal, or should we be investigating the condition of the oil pump and bearings?

My other query concerns the starter motor (Simms, 12 Volt). It works fine time after time when cold but once the engine is hot, nothing happens when pressing the starter button except that the ammeter shows a discharge of 10 Amps. 

I have taken the starter off, inspected it and bench tested it successfully through 100 cycles but when re-installed, the same issue arises. I initially thought that the pinion might be jamming on the ring gear but there is not even any clicking from the solenoid; furthermore, turning the engine manually doesn't help (although it will start on the hand crank). I suspect that the solenoid has developed a fault that only manifests itself when hot. Has anybody else experienced this?

 

Rolls Royce manual states normal oil pressure when driving in top gear is 30 psi as I recall. Regarding oil pressure at idle,  maybe you have it idling too slow?

i think your starter is a coaxial type, I rebuilt a B61 last year and that was 12 volt, think that was a CAV starter. No visual solenoid on these.

regards Richard 

 

 

[mtskull]

7 hours ago, Richard Farrant said:

Rolls Royce manual states normal oil pressure when driving in top gear is 30 psi as I recall. Regarding oil pressure at idle,  maybe you have it idling too slow?

i think your starter is a coaxial type, I rebuilt a B61 last year and that was 12 volt, think that was a CAV starter. No visual solenoid on these.

regards Richard 

 

 

Thanks Richard,

30psi when driving is in accordance with what I've been seeing on the gauge, so if that's normal I'm not too concerned about it being low at idle; maybe I will just tweak the idle speed up a bit.

Our starter doesn't have a visible solenoid either; it is contained inside the casing at the rear of the starter. I bench tested it with the casing off just to check that everything worked as it should; it does with no problems until it is installed and warmed up.

I have now swapped starters with another 12v B80 in the fleet, so if the problem is cured we will know that it is the starter that is at fault, whereas if it persists, we will know that it is a fault on the vehicle.

Andy

[mtskull]

Things I learned this week:

1) The 24v starter won't even think about turning when connected to 12v supply; no real surprises there.

2) The fault is still present, so unless we have two starters displaying identical, intermittent faults, the problem lies with the vehicle. We are closing in on the source of the trouble......

[john1950]

Back track up the wires and find the solonoid.

[mtskull]

21 hours ago, john1950 said:

Back track up the wires and find the solonoid.

Thanks for that; we will certainly back track up the wires. We know where the solenoid is; it is integral with the starter but, in the absence of a wiring diagram, I wouldn't rule out there being another relay in the circuit somewhere. That said, evidence now suggests that it is the auto box neutral sensor which is at fault.