That awful colour MGB GT

[SiC]

After a two month or so secondment to my father in law, she's back again. He's been running around in it, giving it some use and having fun. Not as many miles clocked up as I hoped, but probably about 300 or so since I left it with him.


Drive back was successful and I pretty much fully trust her now.

She did start playing games with her fuel gauge though. My FiL filled it up before he gave the keys back, but it's quite hard to get a full tank on this with modern vapour recovery petrol pump nozzles. When I left, the gauge was reading the notch under full (not quite three quarters, more 4/5ths) and was steady. Thirty miles in, I noticed the gauge was dropping down to half and going quicker as I put the miles on. 35 miles in, it was at the quarter mark.

I pulled over concern that I had a leak somewhere. Fuel pump looked dry, so I popped the bonnet to check stuff under there. Fuel filter attached, pipework all good. Feeling the carb overflow ports found them to be dry.

Decided nothing was obviously seriously amiss I decided to motor on. As I carried on, the gauge decided to creep just under half. This was reassuring but still a lot lower than it should have been.

A few miles on it dropped again and as I was passing a Sainsbury's, I pulled in to fill up with some cheap Super Unleaded. First click put in 12 quid, so I did the usual pull the nozzle out slightly while peering down the spout and put another gallon in. This fill-up would tally with the fourty or so mile journey since the last fill up.

Starting up and pulling away the gauge rose again. This time to just over half. Another few miles and it was back to full. Down the road some more, back to half...

I can safely say that the gauge is not playing ball. Its got a new (decent) solid state regulator powering it (need to double check it's output voltage to be sure though) and the sender is relatively new too. I have recalibrates the gauge, so that should be in a rough ball park. Since I did all that, it was fine until now. Irritating.

I'll have a look at it soon, but for now I'll just go back to filling up after 200 miles or so on the trip counter.

Back safely home, I did a few under bonnet checks. Brake fluid level fine, clutch fluid fine ... but this cap seems very loose...

Bugger.


I don't think I can blame bad manufacturing of the cap here, as I reckon I may have kack handily overtightened it previously. Then the hot weather caused it to compress some more until it split.

Thankfully I don't throw anything away. So I had a spare with appropriate patina on.


Does the job.


Next up was the oil level. When my FiL drove it, it hasn't dropped a smidgen from just over max. After I checked it from my drive, it had dropped down to half.

I think I know what the problem is here! My driving...

Admittedly I only had it stopped running about five minutes previously. I need to do a recheck now it's been sitting for a while. Oil should drop down relatively rapidly, but it still may take a bit of time.

One thing I have done is cleaned out the old filler cap and fitted it back on with the o-ring off the new one. The new one was very loose in the cover and the old one with its old o-ring wasn't much tighter. However the new combination of old cap and new o-ring made a very tight and snug fit.

I'm hoping/wondering this may help with the oil consumption. With greater vacuum in the rocker cover on overrun, it should hopefully prevent too much oil getting sucked by the rings. That is if the rings are what at fault.

Now it's home, I can give a compression test and leakdown test to check the general health of the engine. It's not going to be changed out anytime soon (Dolomite needs to get back on the road first), but it does allow me to plan what needs work next on the fleet and where the priorities lie.

I'm also intregeued to see what state a 158k mile 70s engine is in. Especially as it still pulling pretty well.

[mercrocker]

Don't blame yourself for that reservoir cap. The old one will last infinitely longer than that modern tosh. Your post reminds me though that I need to sort out the fuel gauge/sender on the Cowley before the speedo buggers up and leaves me dipping the tank with a bendy stick.

[SiC]

So I took the day off to recover from my bike injury. Really wanted to get on with a bit of welding on the Sprint, however I can't face lying on my side right now.

Decided instead to do a compression test on the MGB. I have done one before, not long after I bought it, however that was on a cheapy Chinese red box special gauge. This time I've gone and bought a Gunson unit. Not going to be calibrated precise but should be a bit better built.

Anyway enough waffle, here are the results:

Dry
Cyl 1 - 170psi
Cyl 2 - 165psi
Cyl 3 - 169psi
Cyl 4 - 169psi

Wet
Cyl 1 - 198psi
Cyl 2 - 196psi
Cyl 3 - 195psi
Cyl 4 - 195psi

What does the HBoL reckon it should be?


A few pictures to show I'm not lieing!
Cylinder 4 Dry


Cylinder 2 Wet


As you can see, it isn't that easy to read to a single unit precision on this gauge. Is that last picture 196, 197 or 198psi? Who cares to be honest - the gauge is not likely that accurate.

I'm rather chuffed with this result. Explains why the car pulls so well. This is a good engine. Not too shabby for an engine with 158.6k on the clock.

It doesn't help explain where my oil is going though. I would do a leakdown test now, however I can't because of technical issues (can't find it).

[PhilA]

"Not too shabby"?

That's better tolerance than it had from day one out of the factory. You do realise that?


So, what is the difference in driving style between your papa and you? He drives it slow, fast?

--Phil

[SiC]

"Not too shabby"?

That's better tolerance than it had from day one out of the factory. You do realise that?

Ahh, you've been in the USA long enough to start miss the British understating.

This is the quandary I have with this engine. At 158k with these sort of pressures, it must be either have been very well looked after or had a rebuild at some point surely. But then why is the top end so rattly (other forumites have agreed when listening in person, so not just me) and the oil pressure is more on the low side. The rocker arm was pretty heavily worn too.

So, what is the difference in driving style between your papa and you? He drives it slow, fast?

--Phil

My father-in-law sees it as an old car that needs to be treated with respect. So he keeps the revs below 3k and drives it sedately.

I however see it been called a sports car. Thus I drive it spiritedly. Not afraid to rev it and chuck it around a bit. Admittedly I rarely go above 4.5k, as the engine sounds flipping awful (tappet noise mostly). Rev counter stops counting above that point anyway.

My thoughts are it is either valve stems or rear main seal. Both I guess could have gone hard from sitting around for 15+ years.

[Junkman]

It's not the compression test as such, but the accompanying lyrics that gave me the biggest rofls this century so far.

Thank you so much!

As you can see, it isn't that easy to read to a single unit precision on this gauge.

I almost fucking died!

[SiC]

Verbal diarrhoea, a family trait.

Glad it's keeping you amused though Heir Junkman.

[PhilA]

Curious you mention the tach not counting higher than 4.5k

Have you tried disconnecting it to see if it is the cause of ignition issues at high RPM?

Phil

[SiC]

Curious you mention the tach not counting higher than 4.5k

Have you tried disconnecting it to see if it is the cause of ignition issues at high RPM?

Phil

I don't think I've really had any ignition issues at high revs. My suspicion is that something is stopping the needle moving that far. Above those revs it starts to stick at around 4k, then lurches to 4.5k and not move any further.

Could also be the electronic point assistance unit I have attached is causing it to not get a strong enough signal too.

I've got another old Smiths rev counter that has an IC driving the coil on the gauge. The poly caps had split and dried out. Depending on the vintage of this unit, I wonder if it's the same setup and done the same thing.

[SiC]

This morning I did a quick check over on the ignition side as it's been a bit jerky.

Points had did this. Not sure why it's done this.


I set them back in place, reset the gap and retimed.

Also nicked some fuel out of the Dolomite... Better than it going off!



Then went off for a little 120 mile drive across the Wiltshire countryside to see a big steam engine in a building. A trip where the type of roads that this car was born in and exactly for. Even if the 29C weather gets a bit sticky in a GT. Temperature gauge was rock solid steady the whole time. Including sitting at traffic lights in the sun. Nowt wrong with stock MGB cooling systems with a mechanical fan.

Crofton Beam Engine




I've seen it once before in steam and it's good to be back. This exact area and countryside is where I grew up in. So have very fond memories buzzing around. I hoped to go Milton Windmill and Avebury, but Mrs SiC wasn't feeling too well so decided to just enjoy the drive.

A video of it in action as it was steam day today
[youtube][/youtube]

The engine basically pumps up water for the Kennet and Avon canal. Nowadays it's done by an electric pump but on bank holidays they fire up the engine and take over for a bit. Unfortunately someone had managed to damage a lock further down and so their reservoir was getting very low. So they had to shut down near the end of the day. No doubt some holiday makers will be annoyed that they can't carry on up the canal.

Drive back had the car being juddery again. It's not awful but it's noticeable. Basically (unsurprisingly) feels like timing is out. Enough for me to know it's out of place. Points had did this again


Reset them a couple of times on a journey but they quickly went out of place. At least it's running I suppose. I imagine that's only because I have an electronic points assisted box attached.

I hate points.