This (long long ago) rider of AJS, BSA, and Royal Enfield motorcycles is laughing and remembering leaks. Many of them. Too bad Hewes didn't make crankcases.
I have a 1970 MGB, and have gone a bit nutty over MGs for the past few years.
The first time I pulled the engine, I got talked into these thick silicon gaskets for the tappet galley covers vs. the OEM cork. I did the engine pull at a friend's house who is about two hours away. He followed me most of the way back(in his 77) and flagged me down to pull over. When we pulled over, he got out and had oil spots all over the front of his hat and on his windshield-it seems that I'd been "misting" oil most of the way. I added a quart, and we tweaked the crank case breather.
A week later, the car was dumping a couple of ounces on the ground every time I shut it off and I added a couple more quarts.
Finally, I called one of the top MG mechanics in the country and told him that I had a serious oil leak coming from that side of the engine. Gave him the back story, and he said "Did you use those G-D red silicon gaskets on it?" My instructions from him were to get a set of cork for an MGA and install them. I was dissuaded from cork initially as I was told that the exhaust manifold cooks the cork, but apparently it's not a serious issue. Oil only comes into the head from a small galley at the rear rocker, and then drips down into the sump via the pushrods and tappet galley. When running, crankcase gasses blow oil right past the leaky front seal(the crankcase normally vents through the front cover, and it has an integrated oil separator to deal with this), and of course when stopped everything in the head starts dripping down and a lot was coming out that side cover.
At that point I was frustrated and needed some machine work on the exhaust manifold(needed it helicoiled due to broken studs, something I'm not set up to do) and I told my mechanic to just "make it stop." When I pulled the head this past summer, I discovered that what he'd done was use Permatex form-a-gasket on the front cover(the problem child) and cork on the rear. I ended up redoing it the same way, and THAT PART is still tight as a drum.
As I mentioned, I pulled the head this summer, and actually ended up replacing it completely. I had a burnt exhaust valve(incredibly common) and decided to just buy a head to replace it. A lot of them are cracked, so I might have had to buy one anyway-I just cut right to getting a ready to go head that was crack-checked, had new exhaust valves and hardened valves(unleaded conversion). I also took the opportunity to mis-match some parts, and opted for a head with smaller combustion chambers than mine for a nice compression upgrade(stock 8.8:1, now 9.5:1).
I had a bunch of fiddly little issues, and one of the things I'd noticed was that I seemed to be loosing coolant but couldn't locate it or smell it. When I turned the heat on this past fall, I immediately got the stench of antifreeze along with steam coming out of the vents and a greasy film inside the windshield. I bought a new heater core, but before it arrived I talked to the same mechanic I referenced above. He said "In 40 years of fixing MGs, I changed 3 heater cores. It's the most misdiagnosed and over-sold part on the car. If the hoses going into it are loose, they spray coolant onto the core and give the symptoms of a leaky one." Sure enough, I had a marginal hose going into the core that was allowing just that to happen. Once I replaced it, everything was fine.
My last anecdote comes from my last oil change-I usually change the oil once a year in October or November. This year, I did it over Thanksgiving weekend. For a few weeks leading up, I'd noticed unusual oil loss and an oil burning smell along with the engine being seemingly louder. I went to pour fresh oil in, and about 1/4 of the gallon jug I used(Delvac 15W-40, fortunately on sale at Autozone at the time) came pouring out from under the valve cover. It seems that in one of my adventures in there, I hadn't seated the valve cover gasket correctly. It's a cut out piece of cork around 1/2" thick, and the only "guides" it has are tab on each side of the valve cover to hold it in place in its lip. I had a new one in the garage(I always buy complete head gasket sets as they come with that and a bunch of other gaskets plus are only $20 more-about the cost of a valve cover gasket by itself). I took care in seating the replacement(grease to hold it in place) and fortunately it no longer leaks. Plus, it's quieter .
Now I just need to send the carbs off for a rebuild as one has a throttle shaft/bushing worn and leaking enough that it's causing problems with setting the idle.
Also, in a country known for nearly day rain that can pop up out of nowhere, what were they thinking making a "hood"(top) that takes 10 minutes to put up and still leaks even when up.
