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MG MGB Technical - Help! one minute good, next minute bad

Hi,
Can anyone help?

I was happily driving my '78 mgb roadster when I went to brake the car pulled to the right, I stopped and had a look around, basically the pushrod cover had started leaking oil, this had dribbled onto the lefthand brakes.

So I got home, changed the gasket, degreased the engine and brakes, etc. ordered new pads.

In the process of replacing the gasket and degreasing I removed the Carbs in one complete lump.

I put the carbs back on and started the car...
Firstly the car runs as though it's only firing on 2 or maybe 3 cylinders...I checked for water on the leads, distributor, etc. and it all seemed clean enough.
If I put my foot down on the accelerator the revs slowly increase and it starts to run on all cylinders (or so it seems) after a couple od thousand rpm.
So is this something I've done to the carbs while pulling them off? or is there water somewhere I haven't thought of? (I pulled out each of the plugs and cleaned and checked them...they seemed ok, one was a bit oily but nothing too much).

Problem 2:
The clutch peddle goes flat to the floor with no resistance and it won't go into gear...is this just coincidence? or is there something near where I've been that is connected? can oil/water get into anything in the clutch area that would have this effect? Have I knocked something off? What can I do to check?

I'd take it to a garage for this but now of course I can't drive it so I thought I'd check here in case there's a 'simple' solution before I get a tow out!

Many thanks in advance.

D




Dave

There could be sooooo many things, but it sounds like you might have a massive air leak on the inlet. Are the carbs and the manifold bolted up tight? Have you reconnected all the pipes, brake servo, distributor vacuum? Have you got the throttle and choke cables connected up properly?

Did the distributor get wet during the cleaning? Have you thoroughly dried the inside of the cap?

As for the clutch, it sounds like the hydraulics have given up. Look in the clutch master cylinder - is there any fluid? The usual failure is of the slave cylinder, located under the starter motor. Get underneath (car safely propped up of course) and watch the slave while an assistant presses the pedal. You should see the mechanism move backwards about half an inch. If not, the hydraulics are knackered. Could it be something you did? I doubt it, it's probably just chosen now to give up.

Mike
Mike Howlett

Hi,
Thanks for that it is a big help, I'll get my mucky clothes on and have a look round.

Does anyone know of a good site for tech diagrams and photos?, I'd love to be able to see a workshop kind of manual online.

The carbs are tightened down and I used instant gasket between each layer...but would a small leak have such a drastic effect? I assumed it might run lumpy but this is as though one HT lead is disconnected.

I'll check again for water but was pretty thorough.

All pipes are connected as it was so again I don't see that being a problem.

The clutch was fine (well it was getting harder to change down) until I stopped...I reveresed up the drive no problem and engaged gears several times in parking...but after taking the carbs off and washing it the pedal was completely soft...just seems odd to me that it kinda went instantly and not while driving, I'd have expected it to either go slowly and get steadily worse...or stop while mid gear change.

I didn't notice any difference with the pedal while I was driving.

D


Dave

Check you have the correct HT leads connected from dizzy to plugs 1/3/4/2
No 1 at the 1 o'clock position then 3 in an anticlockwise directions around the dizzy cap to No 3 and onwards for 4 and 2.
C J Bryan

I agree sounds like a big air leak on vacuum side. I'm prone to leaving servo pipe off. Sounds like something similar.

Frank
Frank Amey

This may seem like a minor thing to check but make sure both of the dash pots on the carbs are full with oil 20/50 does the job sometimes the levels get low on removal ect and that causes all sorts of problems.also check out the moss catalogue for loads of diagrams on engine parts and if you can, buy the mgb restoration manual (2nd edition)from halfords loads of photos i swear buy mine its got me out of loads of scrapes
Richard
Essex
R Henderson

Did you use new carb to manifold gaskets?
All air lines, etc. back where they came from?
If it was me, I'd check the fuel delivery and ignition system for any simple signs. If ran fine before, you would think it's a simple fix. Probably just a flatulence from the brain.

I don't see how the clutch could be related. Check the fluid level. Mine leaks a little and if left too long the clutch point drifts further and further towards the floor. It'll get some attention one day.
Brad Batchelor

wow thanks for all the comments!

I'm going to get downa nd dirty with it this weekend.

there's a couple of things I want to try, not least of all the oil in the dashpots, I know I tipped the carbs upside down when I left them on the floor so I'm guessing it'll have drained out for sure.

The air seal should be ok, I didn't replace the gaskets because they had been off only a month ago and they came off cleanly...I then used jointing compund between each 'layer' so fairly sure...this is so drastic that I just don't see it being small... a pipe not connected correctly or a problem in the distributor/ht leads are my favourites.

And yes I guess it must be that the clutch is unrelated as no one has suggested that the oil could have dribbled into the clutch hydraulics in any way...so there's a fun job waiting for me...anyone handy with MG's in walking distance of Wimbledon, want to come and help?!

Thanks again everyone.

D
Dave

Dave, don't ignore CJ Bryan's comment about the correct order for the plug leads - that could be it. A swapped pair of leads would give exactly your symptoms.
As CJ said, it's 1,3,4,2 going anticlockwise.

Mike
Mike Howlett

Not that I've ever done it but... Are you certain the manifold gaskets are in the correct position. I once (ahem) put two on one side and none on the other (in haste, I assure you). In my case the car ran OK but the throttle was stiff.

Mike!
mike!

This thread was discussed between 13/07/2004 and 19/07/2004

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