Jump to content

Leaking MU


Recommended Posts

Hi all

I recently took my '73 TR6 to get its first Controle Technique test in French, and after a few minor fixes the car was only failing on the emissions test. I left the car with a nearby classic car garage to see what they could do but, long story short, I needed to take the car away to put a few hundred km's on the clock as it hadn't been driven recently and that could be a contributing factor.

They had already done some work on the MU (they'd left the black plastic cone off the top), but when I got home I found that I had a massive leak from what appears to be the square black cover on the side. While the pump was running I was losing about a litre every 2 minutes. In the photo the 'jet of petrol' is circled in red - it looks like it's coming from the hose but the photo is deceptive, I'm pretty positive it's coming from the black cover.

Anyone have any ideas if this is easily fixable? It's not like I can drive it back to the garage with that much petrol coming out.

Many thanks, Robert

 

MU.jpg

Link to post
Share on other sites
3 hours ago, John L said:

It should be this diaphragm, https://www.chriswitor.com/proddetail.php?prod=519870V   make sure you get a good E5 suitable product, I would trust Chris's parts, you will need to take the MU off and take the 4 nuts and bolts that hold that end plate on.

John

+1

the rubber rots horizontally at the  fuel-air interface when the engien is left standing.  Its likely to be ethanol in fuel oxidising to acetaldehyde that rots the ruubber.

Peter

Link to post
Share on other sites

Hi John/Peter

Looking at the photo in the Green Book, is this the diaphragm:

MU2.jpg.d8210ed9e2e8022aebf3bc9cbc480d99.jpg

...and I would assume that petrol should not be getting into the right hand part of the unit, is that correct? In which case, as you say, petrol coming out from under the square black cover would be considered a "bad thing".

I've always regarded the MU as a 'black box' to be left to the experts. If it's really just a case of undoing 4 nuts and replacing the diaphragm then I'm happy to give it a go, but I gather the remove/refit of the MU can also be a bit tricky. 

Link to post
Share on other sites

You are correct,  there shouldnt be petrol under the black cover.

Make sure that you turn the engine to compression on #1 cylinder to TDC.

As there is nothing adjustable in what you are taking off its a doable job.

The lower nut of the 3 that hold the MU on, can be a bit of a challenge, but a 1/4 drive socket with extension its doable.

I havent  actually changed that diaphragm, I think there were some pictures on this forum here not so long ago, perhaps a search might find it.

John

PS this video may help but I think in Dutch,  

 

Edited by John L
Link to post
Share on other sites

Make sure you get a diaphragm that's compatible with your local fuel. In Australia that's Viton. About 5 years ago I fitted a diaphragm supplied by the brothers in the UK and it failed over lunchtime. That afternoon, when I stripped the MU down the diaphragm had swelled and was a loose fit on the shaft allowing fuel to leak past. It was a tight fit when I originally fitted it in the morning.

That was a painful waste of time as the MU is not simple to remove , repair and reinstall -apart from the diaphragm supply price doubling after I paid freight and taxes from the UK.

Link to post
Share on other sites

Thanks John,

That video almost makes me want to learn Dutch. It does look like a relatively simple job, so I'll get the diaphragm on order.

Thanks for everyone's help as always, good to have knowledgeable people available.

Cheers, Robert

Link to post
Share on other sites

Hi Mike

So that I don't make the same mistake, who did you buy the diaphragm from (if you don't mind me asking)?

Cheers, Robert

Link to post
Share on other sites
49 minutes ago, rwest said:

Hi John/Peter

Looking at the photo in the Green Book, is this the diaphragm:

MU2.jpg.d8210ed9e2e8022aebf3bc9cbc480d99.jpg

...and I would assume that petrol should not be getting into the right hand part of the unit, is that correct? In which case, as you say, petrol coming out from under the square black cover would be considered a "bad thing".

I've always regarded the MU as a 'black box' to be left to the experts. If it's really just a case of undoing 4 nuts and replacing the diaphragm then I'm happy to give it a go, but I gather the remove/refit of the MU can also be a bit tricky. 

Yes that's it. The chamber behind the black plastic should be bone dry.

Peter

Link to post
Share on other sites
1 hour ago, rwest said:

Hi Mike

So that I don't make the same mistake, who did you buy the diaphragm from (if you don't mind me asking)?

Cheers, Robert

Rimmer's - but that was 5 years ago, they may use Viton now. You need confirmation-and I wouldn't trust a phone call Viton and other rubbers look too similar. Replacing that  part  is too much work to waste the effort by using a nitrile/NBR diaphragm.

Link to post
Share on other sites
16 hours ago, rwest said:

Hi John/Peter

Looking at the photo in the Green Book, is this the diaphragm:

MU2.jpg.d8210ed9e2e8022aebf3bc9cbc480d99.jpg

...and I would assume that petrol should not be getting into the right hand part of the unit, is that correct? In which case, as you say, petrol coming out from under the square black cover would be considered a "bad thing".

I've always regarded the MU as a 'black box' to be left to the experts. If it's really just a case of undoing 4 nuts and replacing the diaphragm then I'm happy to give it a go, but I gather the remove/refit of the MU can also be a bit tricky. 

If you are replacing that Diaphragm make sure that it is suitable for E10 fuel which will be sold here in the UK in late summer. I know that V Power will remain at E5 but E10 is much more aggressive for some reason and when I did my E500 trip in Scotland, V power type grade was not always available, so I had to fill up with ordinary E5. Any easy to replace seals s/b done at the same time.

Bruce.

Link to post
Share on other sites
1 hour ago, Steve1 said:

Personally I would get Neil Ferguson to refurb the unit for £130 -ish

+1

Also no need to position the engine at TDC. Carefully pull the MU off the pedestal. Take a picture with your phone of the end of the MU. 
Do not turn the engine over at all. When you go to refit, just position the MU shaft to the same orientation as the picture you took, bit of grease to hold the red plastic drive in position and refit.

dave

Link to post
Share on other sites

Hi all

After talking to the wonderful guys over at Enginuity (my old garage back in the UK), we decided that probably the best bet was to replace the MU as it has >40K miles on it already. Along with the fact that the car had been sitting idle for nearly 3 years, it made for an easy decision. There is also a certain amount of urgency on this and I decided I couldn't afford to take the chance that something else on the MU was ready to fail.

I'll keep you informed of the outcome, but I'm getting desperate to get my car registered in France before they change their mind about UK cars 

Cheers, and thanks for all the advice, Robert

Link to post
Share on other sites

Yeah, me too.

The TR Shop says that most of their EU exports have settled down now and that I should get the package within a week. Fingers crossed.

Link to post
Share on other sites

Hi Robert, I am probably a bit far away from you but if you need to call for advice etc etc I have done loads of these. So I know my way around. After your local garage has played around inside the MU it’s a wise decision to get one refurbed. I always have a 150 one spare here. Heaven knows what they have fiddled with. It happened to a friend of mine who took his TR6 to a local garage and in the end the garage suggested it would be better to fit SU carbs! The sad thing is the garage was run by brits....... who talked a great job but completely wrecked the recently New and working PI system trying to rectify it.  Clem

Link to post
Share on other sites

By the way have you got the quitus fiscal dated before brexit otherwise you will need 856a to prove you have imported your car into France and paid your duties. Ask me how I know!!!!!!!!!!!!

Link to post
Share on other sites
On 3/17/2021 at 3:24 PM, rwest said:

Hi all

After talking to the wonderful guys over at Enginuity (my old garage back in the UK), we decided that probably the best bet was to replace the MU as it has >40K miles on it already. Along with the fact that the car had been sitting idle for nearly 3 years, it made for an easy decision. There is also a certain amount of urgency on this and I decided I couldn't afford to take the chance that something else on the MU was ready to fail.

I'll keep you informed of the outcome, but I'm getting desperate to get my car registered in France before they change their mind about UK cars 

Cheers, and thanks for all the advice, Robert

+1 Enginuity are top boys as far as I am concerned, they deal direct with KMI who were the designers of the Bosch pump replacement for Lucas PI Pumps in the early 1980's. I have one of those systems and it has never missed a beat.

Bruce.

Link to post
Share on other sites
4 hours ago, astontr6 said:

+1 Enginuity are top boys as far as I am concerned, they deal direct with KMI who were the designers of the Bosch pump replacement for Lucas PI Pumps in the early 1980's. I have one of those systems and it has never missed a beat.

Bruce.

I was lucky enough to live only 5 miles from Enginuity before moving to France, they're a great bunch of guys and have kept my car on the road for the last 20+ years. I guess I'm going to have to stand on my own two feet now, they're a long way from Montpellier :) 

Having said that, they've given me some great advice on what to do (replace the MU) and they've even offered to talk me through the trickier parts of the replacement.

Link to post
Share on other sites
5 hours ago, elclem1 said:

By the way have you got the quitus fiscal dated before brexit otherwise you will need 856a to prove you have imported your car into France and paid your duties. Ask me how I know!!!!!!!!!!!!

Thanks Andy, fortunately everything is already logged with the authorities, they're just waiting for the CT and I should be good to go.

Fedex picked up the new MU, along with new injector hoses and unions, from the TR Shop on Thursday and it's schedules to be delivered on Tuesday(!). I'll believe it when I see it, but, as they've already arrived at Charles de Gaul this morning, there's still a chance that I'll have them next week. Then the fun begins....

Edited by rwest
Link to post
Share on other sites
5 hours ago, elclem1 said:

Hi Robert, I am probably a bit far away from you but if you need to call for advice etc etc I have done loads of these. So I know my way around. After your local garage has played around inside the MU it’s a wise decision to get one refurbed. I always have a 150 one spare here. Heaven knows what they have fiddled with. It happened to a friend of mine who took his TR6 to a local garage and in the end the garage suggested it would be better to fit SU carbs! The sad thing is the garage was run by brits....... who talked a great job but completely wrecked the recently New and working PI system trying to rectify it.  Clem

Yeah, I was somewhat horrified to find the black conical cap that goes on top of the MU sitting next to the windscreen wiper motor - especially as I didn't notice until I got home, which was a 10km drive from the garage. I'm still hoping that they are a good garage and that they were just having an off-day. Having spoken to Enginuity it appears that I need the 125 unit, but your offer of advice is very welcome.

Link to post
Share on other sites

Hope the parts turn up on Tuesday !

I recently ordered some motorcycle parts from California on a Friday, they were delivered on the Monday !!, so anything is possible :-)

steve

Link to post
Share on other sites

Hi Robert,  TNT are great. Just wait for the customs bill to arrive.

Link to post
Share on other sites
17 hours ago, rwest said:

I was lucky enough to live only 5 miles from Enginuity before moving to France, they're a great bunch of guys and have kept my car on the road for the last 20+ years. I guess I'm going to have to stand on my own two feet now, they're a long way from Montpellier :) 

Having said that, they've given me some great advice on what to do (replace the MU) and they've even offered to talk me through the trickier parts of the replacement.

That's the sort of service that you get from them! I only live 15 miles from them, its straight up the M4 for me.

Bruce.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.