Jump to content
  • 0
mtskull

Rolls Royce B80

Question

Posted (edited)

Hi

 

Not strictly an MV issue but I hope some of the wealth of experience on this forum may be able to assist me.

 

I am carrying out some work on a fleet of old Dennis fire appliances, all of which are fitted with B80 or B81 engines, some of which are military-spec replacements for the original engines. I am reasonably experienced in maintenance of older vehicles but I have never worked on a RR B series until today.

 

I would be interested to hear any general tips regarding maintenance of these engines, particularly where to obtain spares such as filters, gaskets etc. Also, some advice would be welcome regarding a specific problem:

 

One of the appliances (civvy-spec B80 Mk50a) starts and revs ok but has a persistent misfire/loss of power when under load. Compression is notably down in No.1 cylinder (all others ok) but the power loss feels worse than can be explained by one weak cylinder; it feels as though it is only running on 4 or 5 out of 8.

 

Apart from a compression test, we have swapped everything in the ignition system (Jolley engineering electronic distributor) for known good items and checked that none of the valves are sticking; the ignition timing has been statically set at 2 deg. ATDC and the firing order checked.

 

The appliance is said to have previously run well and the problems only manifested themselves after a period pf standing idle.

 

The plugs are sooty, suggesting over rich mixture; I haven't investigated the carburettor yet but I would rather know a little more about it before I do.

 

Are there any known weaknesses or issues with the B80 that might cause the problems I describe?

 

Has anybody on this forum experienced such an issue?

 

Can anybody confirm that the cylinders are numbered such that No.1 is at the the front (i.e. not the flywheel end)?

 

Compression in the poorly cylinder is restored when oil is poured in through the sparkplug hole, leading me to suspect broken piston rings. Is this a known issue?

 

Any help would be much appreciated.

Edited by mtskull

Share this post


Link to post
Share on other sites

29 answers to this question

Recommended Posts

  • 0

You can wash them out in petrol and reuse them. You can also either make up, or find an adapter that will take a modern spin-on filter instead.

 

Cheers,

Terry

Share this post


Link to post
Share on other sites
  • 0

Is it the same filter assembly as a Ferret? Can you show me a picture?

 

I know someone who has a spin on filter adapter in stock . . . .. . . .

Share this post


Link to post
Share on other sites
  • 0
Is it the same filter assembly as a Ferret? Can you show me a picture?

 

I know someone who has a spin on filter adapter in stock . . . .. . . .

Sorry, I have no idea what filter is fitted to a Ferret. I'll try to take a photo on thursday, when I am next on site. A spin on adapter would be a good idea if not too expensive; ideally we would need five of them!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×