1971 MGB GT - Now starts but runs rough - WHY??? - see page 19

[plasticvandan]

Something I used to do was adjust the drums so they were locked on for bleeding,so the cylinders don't move.

 

[Six-cylinder]

My MGB GT is so jealous of the pampering yours receives!

[Fabergé Greggs]

I’ve always had success with the “wedge the brake pedal down really hard overnight” method of bleeding, though to this day I do not know how it works. 

[Mally]

I don't get it either, pedal down  means the system is pressurised, so where the air goes is a mystery to me,

I sometimes find that leaving pedal up results in a better pedal the morning after, because air bubbles can rise back to the master cylinder.

[Peter C]

Christmas present for the MG from my fifteen year old. 

How true!

[grogee]

2 minutes ago, Peter C said:

Christmas present for the MG from my fifteen year old. 

How true!

Nearly bought one for my Toyota. It's literally a badge of honour. 

[lesapandre]

1 hour ago, Peter C said:

Christmas present for the MG from my fifteen year old. 

How true!

aka  'Austin Cambridge Sports'. 🎅

[tooSavvy]

🤔.... Sherpa Coupé 

🚙💨

[Peter C]

Christmas Day. I had breakfast with my wife, then watched the Bullseye remake with Freddie Krueger Flintoff, then I decided to have another go at fixing the MG’s brakes.

I bought plenty of brake fluid.

As advised on an MG Facebook group, I jacked up the  front of the car as high as possible and the back just high enough to reach the bleed nipples.

I tightened up the rear drum adjustors, thus  locked the rear brakes.

I applied plenty of grease around the bleed nipples.

I got my bleeding kit out, which I only used once earlier this year to sort the Sierra’s brakes (and failed). Unfortunately, the vacuum pump was fucked but I did make use of one of the transparent hoses.

With the vacuum pump broken, I needed a helper to pump the brake pedal. My wife volunteered*.

I started on the nearside rear brake, which is furthest away from the master cylinder.

On the first pump, the pedal was soft, as it was a couple of days ago but on the second and every subsequent pump, the pedal was rock hard, as advised by my wife, who is now an expert when it comes to pumping MGB brakes.

When I loosened the bleed nipple, a large air bubble passed into the hose. Did it come from within the wheel cylinder? Did air creep into the hose where it was fixed onto the nipple? Don’t know, can’t say but no more air bubbles came out from the rear brakes.

I adjusted the rear drums again, put the wheels back on and went for a test drive.

The pedal is hard and the brakes work perfectly.

I have no idea what happened, what I’ve done to make them work properly. Could clearing that one (large) air bubble been enough to go from a pedal that almost dropped to the floor to being rock hard? 🤔 Did lifting the front of the car and pumping the pedal cause a burp at the master cylinder end? Could pumping the brake pedal with the rear shoes locked make a difference? Answers on a Christmas card please.

[EyesWeldedShut]

1 minute ago, Peter C said:

Did lifting the front of the car

This was a 'thing' back in the nineties (the 1990s not the 1890s - I am not quite that aged) with Land Rovers. The pundits (aka LRO magazine) had it that getting the front end up helped bleeding out the system - it never did work for me tbh

(my problem was the rear drum 'snail' adjusters were shite)

[junkyarddog]

Yeah,got one of those too,great addition to any Shitbox😆

[EyesWeldedShut]

2 minutes ago, junkyarddog said:

Yeah,got one of those too,great addition to any Shitbox😆

Where do I buy one (many) ?

[Peter C]

My son got it via temu.com

[junkyarddog]

1 hour ago, EyesWeldedShut said:

Where do I buy one (many) ?

AliExpress.

https://www.aliexpress.com/item/1005007398650474.html?spm=a2g0o.productlist.main.5.3ca7bPCRbPCRoi&algo_pvid=281701e4-d45e-4825-a750-84f04a3e3df9&algo_exp_id=281701e4-d45e-4825-a750-84f04a3e3df9-2&pdp_npi=4%40dis!GBP!1.69!1.69!!!15.04!15.04!%40211b613917351555298587380e5a9f!12000040583771733!sea!UK!0!ABX&curPageLogUid=WL16L4BnAztG&utparam-url=scene%3Asearch|query_from%3A

 

[The_Equalizer]

Bit late to this party. My Dad's '73 MGB roadster has been in the family from new (my Grandad originally bought it.) Bleeding the brakes has always been a 'mare to the point it's know that they'll be somewhat spongy after any work. We've always found that this air has worked its way out of the system after a couple of months. I don't mean after use, but just sitting.

As pointed out, series Land Rovers also have a serious reputation for similar problems. In particular the 109 version of which I've lived with one for 17 years. The only thing that ensures firm pressure after working on the brakes is a pressurised bleed system. From memory I have a Sealey Power Bleed which, at nearly £100, isn't cheap, but it really has done the job. Last work I did in the spring was new rear cylinders, flexi-hose (to the rear axle) and servo which meant the removal of the master cylinder. The trick with this was to work back to front. End result was spot on with no spongy feel at all. FWIW, I've not used this on the B (my Dad and I don't live near to each other), but have no reason to believe it won't have the same results. 

All after the event, but might help someone in the future. 

[Peter C]

@The_Equalizer

Self-bleeding brakes? How very clever.

[High Jetter]

4 hours ago, Peter C said:

Could clearing that one (large) air bubble been enough to go from a pedal that almost dropped to the floor to being rock hard?

My guess is yes, that air was being compressed.

[The_Equalizer]

9 hours ago, Peter C said:

@The_Equalizer

Self-bleeding brakes? How very clever.

Perhaps I should have put that better. Whatever caused the problem of the post-bleeding spongy brakes, the system 'settled down'. On reflection obviously don't know the actual fix, but I clearly remember the problems we had trying to get a firm peddle and that it got better over time. Our B is used infrequently. I should add that the peddle was only (but always) somewhat spongy after bleeding, it wasn't going to the floor, and that's what got better. In my head I'd come to the conclusion air was trapped somewhere near the master cylinder (or at least in the top part of the system) and managed to find its way back to the reservoir. I know that if I shake a coffee jar with air and brake fluid, the resultant mess will eventually sort itself out, the air of course floating to the top. All that said, I'm quite happy to be corrected if my theory is nonsense.

Same spongy peddle behaviour occurred with my Land Rover, but having used the pressurised bleeding kit the issue now doesn't crop up. It also has the added benefit that bleeding the brakes is a solo job. Music to your wife's ears I would imagine.

Feel free to ignore the observation. All it ever was intended to be that our B's brakes were a bastard to bleed and we'd had similar problems.  I will stand by the fact the pressurised bleeding does the trick having used it several times.

[The_Equalizer]

FWIW, Sealey Power Bleeder (which can be had for about £60 and not the £100 I originally quoted):



I stick it in a large brewing bucket to contain any possibility of fluid on paintwork. Also the brake fluid reservoir will be 'brimmed' after use so a small syringe is always useful to take out the excess. I won't say using it is a pleasure (when is bleeding brakes any fun?), but it certainly makes the job more bearable and I've never had problems with trapped air in the system. 

[Peter C]

Boxing Day.

My wife promised to make me seat covers for the MGB for Christmas. Today seemed like a good day for a bit of haberdashery.

Wife bought a soft blanket, which based on my measurements should have been large enough to make two seat covers. It was.

I left my wife to it, she was in and out of the garage, trial fitting the first cover as she was making it.

About three hours later, the MGB’s deteriorated seats looked very inviting. The covers fit perfectly and are very comfortable.

There’s a hint of brothel about the material, which can’t be bad.

Huge thank you to my amazing wife for doing such a great job. 😘 

[High Jetter]

1 hour ago, Peter C said:

Boxing Day.

My wife promised to make me seat covers for the MGB for Christmas. Today seemed like a good day for a bit of haberdashery.

Wife bought a soft blanket, which based on my measurements should have been large enough to make two seat covers. It was.

I left my wife to it, she was in and out of the garage, trial fitting the first cover as she was making it.

About three hours later, the MGB’s deteriorated seats looked very inviting. The covers fit perfectly and are very comfortable.

There’s a hint of brothel about the material, which can’t be bad.

Huge thank you to my amazing wife for doing such a great job. 😘 

Wot, you didn't buy her a necklace or earrings for xmas? 😀

[Peter C]

22 minutes ago, High Jetter said:

Wot, you didn't buy her a necklace or earrings for xmas? 😀

I got her both, from Pandora, very pretty.

[High Jetter]

2 hours ago, Peter C said:

I got her both, from Pandora, very pretty.

Ladiez usually like to show them off.

[Peter C]

This Christmas, I have taken 16 days off work. My plan, other than to spend time with friends and family, was to fix the MGB’s brakes and take it for a proper drive, up the A413 to Wendover and then to the 180 degree bend up in the woods in Aldbury. Unfortunately, the weather has been absolutely gash and the MGB hasn’t left the workshop, until today!

The weather is ok, the roads are dry and I’m heading out after lunch.

A full report, maybe even with the odd live update, coming up soon.

[lesapandre]

Very nice up there. Some interesting roads up into the hills from Aldbury. Have fun!

[chadders]

21 minutes ago, Peter C said:

This Christmas, I have taken 16 days off work. My plan, other than to spend time with friends and family, was to fix the MGB’s brakes and take it for a proper drive, up the A413 to Wendover and then to the 180 degree bend up in the woods in Aldbury. Unfortunately, the weather has been absolutely gash and the MGB hasn’t left the workshop, until today!

The weather is ok, the roads are dry and I’m heading out after lunch.

A full report, maybe even with the odd live update, coming up soon.

The 180 degree bend at the top of Tom's Hill Road is very interesting when you're travelling downhill on a Pashley Trike with dodgy brakes.

Watch out for the deer.

[Peter C]

Thanks guys. I’ve driven up and down this road many times in various cars over the years but I suspect that this trip is going to be the most challenging and hopefully memorable, for all the right reasons.

[Sunny Jim]

I've now cleaned my glasses and see that the thread title is 'Aldbury here I come' - I initially read it as 'Adultery here I come' which I thought was a bit off seeing as your wife has helped with bleeding brakes and making the seat covers.

As you were, have a good day.

[Peter C]

Before I left home, a comparison between the size of the MGB and my wife’s Hyundai. I definitely don’t fancy a head on collision with anything bigger than a push bike.

First destination, my local Esso fuel station, achieved.

Second destination, the 180 degree bend up on the hill in Aldbury also achieved. I am pleased to say that the MGB is performing admirably.

And my first cup of tea in the MGB has also been achieved.

Once I finish my brew I will be heading home via the same 26 mile route.

Loving it!

[Peter C]

Destination home achieved.

Another size comparison photo. The MGB looks tiny but my Quashqai isn’t even that big!