413
Check your plastic breather pipe is not missing

Derek Squires highlights a check worth making on your RV8 back axle. (Dec 15)
Derek said "went into my garage a couple of weeks ago and saw something lying on the floor under the back of the RV8. Turned out to be the plastic rear axle breather (19), which had sheared off at the top of the short threaded section that holds it into the axle, and so I now have an open hole of about 7mm diameter in the top of the axle to let in water and grit! Readily obtainable, but if it had fallen off on the road, I'd never have noticed that it was missing. My RV8-owner friend here in southern Spain has just crawled under his car, and found his is missing as well. Might be worth a check that you still have one on your RV8! You can find it on top of the axle, right-hand side, just outboard of the differential".

Derek Squires later posted a note saying "further to my previous post concerning the RV8 rear axle breathers, I've just fitted a correct replacement (ZKC5726) from Brown & Gammons. This is about 6mm shorter/lower than the (MGB) breather that was on my car, as it doesn't have the unthreaded narrow section, and it has a small ball-bearing inside the cap to act as a non-return, which the old one didn't have - although it may just have been missing. So I can confirm that the RV8 breather is slightly different to the 21H6060 for the MGB which is illustrated on the B & G website. An article was released on the V8 website in early January 2016.

Three months later the V8BB thread came alive again when Tim Smith said "noting a recent article on the RV8 back axle breather pipe I have checked mine and found nothing except the hole! Looking on Brown and Gammons' website the product is now no longer available. Does anyone know: an alternative supplier, the thread in the axle and of a homemade alternative?" He later reported "I have found one on eBay for an MGB which I will purchase and check out. I would think that if the threads are the same as a brass breather for a Land Rover that would be a lot better".

Dave Morris responded "the RV8 axle is a Salisbury 12HA I believe, very similar to the 9HA used on Land Rovers as you say. The off-roaders use nice little aluminium breathers with one way valves or tubes attached to prevent water ingress. Worth a look as an alternative to the original plastic part".

Richard Withington with an RV8 and MGBGTV8 noted "I am also looking for one of these breathers as it looks like they all fall out! The rear axle is basically a 9HA casing so on checking Rimmers


Comparison of a replacement plastic breather with brass breather valve fitted to Land Rover back axles. On inspection the
quality of the replacement plastic part was not very good.


Brass breather fitted to an RV8 back axle

Bros website I note that they have a part 21H6060 for £3.10 which looks very similar, there is also a brass alternative. I will buy one next time I go to Rimmers but if anyone has tried it I would be interested to know what they found".

Jonathan Buckley then contributed some useful information on his experience saying "after reading the article by Derek Squires on his losing a rear axle breather, and in view of the above similar experiences by some of our other members, I decided to have a look at mine and not surprisingly the plastic breather tube had sheared-off and was missing. As the correct MG RV8 part (ZKC5726) seems to be NLA, I ordered the ‘equivalent’ part to fit an MGB (21H6060) with the same thread. When this arrived, I was rather disappointed with the poor quality of the plastic part, and was convinced that it would soon go the way of the previous breather tube fitted on my car. I therefore looked around for a better quality metal breather tube that would hopefully fit the same hole and thread.


I found that Land Rover Defender/Range Rover (LR) use a similar rear axle breather (515845), but of better quality in brass, and incorporating a ball-type non-return valve to exclude water and dirt. These breather valves are widely available from LR dealers,and on a well-known auction site, generally for less than £5. The thread size is 1/8” BSP. I removed what remained of the plastic breather tube in the axle via the battery compartment opening using a sharp knife as recommended, and then fitted the new Land Rover breather valve. Attached is a photo of the brass breather valve fitted in place in the rear axle. I think you will agree this alternative breather valve provides a more substantial and better-designed part than the plastic MG RV8 and MGB versions. It should hopefully be a ‘fit and forget’ replacement. I also hope this response provides some of the information requested in the above other members’ queries, and a useful alternative breather tube for those who have yet to check if it is missing from their car's rear axle, and would prefer to fit a suitable replacement".

Jonathan Buckley later sent in a pair of photos and noted "I believe the only risk with fitting the brass Land Rover breather valve is that the ball in the valve can become 'stuck', as has been reported on some Land Rover chat sites, however, bearing in mind the difference in conditions around the back axle with an off-road Land Rover and that an MG is likely to experience, I am personally not too concerned about this. The benefits it provides in normal operation will be useful".

See our later note on thread compatibility with replacement back axle breathers. See RV8NOTE418

See larger photos of the breather comparison and the brass breather on an RV8
RV8 information and support
See our popular RV8NOTES listing, information gateways, top tips, spares and services specialists and spares for sale and wanted.
RV8 Workshop Notes
Information Gateways
Top tips for new RV8 enthusiasts
Technical topics
Spares & services specialists
V8 spares for sale and wanted