A serious engine problem?

[Splat]

Shortly after our return from Le Mans, my car developed a very noticeable oil leak. It was black and loaded with moli-slip, which pointed to the T9 gearbox. I couldn't get onto it immediately, so I finally pulled the engine in mid-August.

With the engine out of the car it was obvious that the input shaft oil seal had failed. This is very simple to replace and I took the opportunity to suck out the old oil and refill. There's no drain plug on the T9, but with the bell-housing removed and the gearbox angled front down, I was able to suck out all bar about 50cc!

At the same time, I noticed that the aftermarket crankshaft oil seal was starting to fail. My car lost it's scroll-type seal many years ago and the bolt-on replacement kit has never worked perfectly, but it's been pretty good nonetheless. Certainly, it's leaked no more oil than you'd expect of an A-Series. But it was now starting to leak more than I would like. And anyway, the engine's was now out of the car.....

I bought a new seal from Moss, but then discovered that one of the two bolts that hold the two semi-circular halves of the seal holder had seized. Having tried just about everything else, I had to drill the head off. Anyhow...... I fitted the new seal and reinstalled the engine (with a new clutch plate for good measure!).

However, a short test run showed that the newly installed crankshaft seal was leaking like a sieve! So I pulled the engine again, and refitted the seal kit VERY CAREFULLY INDEED. There's a YouTube video (MiniMania, I think) showing it done in stages. The first part is installed and then left overnight for the silicone sealant to set. The second time around, I ditched the Blue Hylomar that comes with the kit in the UK, and used Loctite grey silicone for the rigid metal-to-metal joints and Loctite black silicone for the non-rigid joints. The reassembled engine was then left for a couple of days for the silicone to fully cure before being reinstalled.

That was a week ago. I've test run the car for about twenty miles and then been to the Goodwood Revival and back. So it's done about 150 miles since I refitted the crankshaft oil seal and it's been sat over a drip tray for 24 hours since.

And not a single drop of oil has dripped.

Something must be seriously wrong.................

[jonclancy]

Either you were lucky, and ran out of oil just as you parked up, or the garage elves have been hard at work while you slept...

[Westfield 129]

The US Press demo car had that seal. It leaked so badly that I sent the car back to the original builder, twice.

The oil was leaking so badly that it was dripping down the instrument panel, coming out the top of the bell housing, up the firewall...

Eventually, after my pristine white concrete driveway was permanently soiled, I had to rebuild the thing myself, along with the rest of the car, prior to its test appointments.

The builder had used better sealers, but eventually (within a few miles) the thing would start leaking, again. I talked to my friends at Mini Mania, and the answere was "Yea, it leaks. Those kits don't work well".

All you need to do is to drive it a few hundred miles, and the leaking should start in earnest.

I fixed the leak by blueprinting the block, replacing the rear spiral cover, line boring the main bearings to re set the proper spiral clearances. A rebore, rings and pistons helped, too, I am sure.

Re assembly and thousands of miles proved that the leak was fixed. No longer was the W11 a device for treating garage floors with a protective coating of of oil.

The crank flange is not a very good sealing surface.

[Splat]

This particular engine was built up from an eBay block about five years ago and has covered about six thousand miles since. I've a PCV valve tapped into the inlet manifold and drawing from both the timing cover and the rocker cover, with the plastic, mesh-vented filler cap allowing air back in. It took the original engine builder three attempts to get the crank seal kit to work, but in fairness it's been largely leak-free since. Just the odd spot as you would expect. After so many miles running the kit, my crank flange has a beautifully smooth and polished surface where it meets the seal. And this time around, it really does seem sound!

FWIW, I notice that MED have developed their own kit. Unlike mine, that's readily available from all of the usual suspects, MED's cannot be retrofitted onto a built-up engine. The aft crank cap has to be drilled and tapped. But this will make for a much better located, more rigid mount for the seal that I'd certainly be considering if I were building a new engine.

As an aside, the two Whitton brothers set up MED in 1981. They come from Oadby, as do I and when I needed to rebuild the engine of my GTM Coupé in 1991 I went to them. Or actually, they came to me as Steve lived about half a mile from my grandmother's, where the car was. In a recent magazine article, a photo of their build log books has the top book labled, "Engines from Number 295, 25/8/93. I wonder what number mine was?

[erictharg]

Second time I rebuilt my A Series engine (after my EBay head dropped a valve) I didn't take the time to align the top half of the original scroll seal cap correctly and it leaked so much it got through a sump full in 100 miles. Pulled it and fitted a Peter May seal kit. Lasted even less time before leaking even worse. Re assembled with the original scroll cap (fortunately not badly worn) using cut up bits of feeler gauge (002" iirc) to ensure the cap was positioned centrally to the crank. Worked fine for years. But if your original scroll seal cap is buggered then you either need another one or one of the many aftermarket oil seal kits. Sounds like the MED one is better than Peter May's! Personally I'd stick with the scroll seal carefully assembled. Nothing to wear, acceptable leak rate...

[Westfield 129]

Or, you can line bore the block with the scroll cap in place. This fixes all the clearances around the scroll.

[Splat]

Another couple of hundred miles last weekend to the Kop Hiiclimb and back. It's leaking. We can all breath again.......

[jonclancy]

I remember reading somewhere about keeping that rear cap in place when you strip down an engine to avoid later leaks.

Jan's suggestion is what I would do if I was building up my spare bitsa engine. BTW, I'm amazed at how much ratty, incomplete examples of 1275 lumps go for nowadays!

You could try a bit of tape over your oil filler cap hole to uncreated negative crankcase pressure. Worked for me....m

Or jam an old squash ball in the hole!

[Westfield 129]

You want to release as much crank case pressure as possible. More ventilation holes would make the scroll more effective, and reduce front seal leakage as well.

The front cover air/oil separator, a breather hole at the fuel pump boss and a vent in the valve cover will often reduce the leaks.

However, if you have a "main seal kit", there is no help other than replace it with the original rear cap, and re machine the block (line bore the mains).

Another fix is to install an "evacusump" system, using exhaust pulse valves or a vacuum pump to draw a depression in the crankcase. This is a bit complex, and perhps overkill when careful machine work and assembly might do the same job. Vizzard covers the evacusump in his book.

I have seen a couple of systems locally on the A Series, but none survived the problems of sealing the engine or excessive smoke, and the systems were removed.