MG T-ABC

Hi there,
After a recent trip of some 4 hours I noticed that the distributor on my TC 4821 was saturated internally with engine oil.!!
Has anyone had this problem ?,and would appreciate any feedback as to what may be the cause .
The distributor is DKY4A 400488.
Thanks and cheers ...Murph TC 0284 TC8679 TC 4821

Hi Murph:

I assume it was running a bit, if not a lot, rough! It certainly sounds as if you've got an overfilled sump. It's common with that to have a distributor mist up with oil to the point of fouling the spark so bad that the car will barely run without applying a bit of choke. Check your fill level and then disassemble distributor to expose contacts, counterweights, rotor and cap. Spray with carb cleaner and blow dry with compressed air. Spray it again for good measure and dry. Reassemble and take it for a spin. If it fouls again then you most likely have an obstruction in crankcase breathing. (Not Likely unless the engine has recently been apart!) If that's the case, you'll have to back into the crankcase one element at a time starting from the valve cover to the side plate breather(s). Take out the dipstick if it fouls again, clean everything and test drive.
Good Luck...

Marv TC5141

Thanks Marv,
I,ll check all that you mention ,altho unless my dip stick is reading wrong ,and I think the best way to check that is to drain the sump and fill it with the correct amount of oil.
I suspect it may be the breather system as I have a problem with the motor blowing smoke at the exhaust when i connect the air cleaner ,(maybe that cork gasket in the side plate)!!!
So I,ll start from that point
Will report on progress.
Cheers ....Murph

Let us know how it all turns out Murph. "

Remember, there is no situation or issue so bad that it can't be made worse with some well intended tinkering!"

Marv

Murph - I recall an article on this problem which proposed that the design of the dizzy can cause oil to be pulled up into the case. The article suggests a mod to cure the problem. I will try to dig the article up today and post it or a reference for your consideration. Cheers.

Jim Davis
TC 7225

It's usually a problem with excessive crankcase pressure, caused either by the cork side cover gasket collapsing and blocking the breather holes, or a worn-out engine allowing excessive blow-by. If you remove the oil cap and feel when the engine is running, you may well feel puffs of air - that's blow-by caused by rings that no longer seal.

There are plenty of discussions of this on the mg-cars BBS in the archives.

Another option, if you replaced the distributor or had it rebuilt, is that it is set up to run the opposite direction. I've heard of distributors being set up this way and the scroll at the bottom would literally pump oil up instead of down. Never seen it, just heard of it.

oil scroll at the bottom of dizzy shaft????

No problem like that here.

Just caught up with this one. Murph, you say that the motor blows smoke at the exhaust when you connect the air cleaner. With the air cleaner off, is there pressure at the vent hole in the rocker cover?

G/day Richard,
No pressure at the rocker cover breather .
Checking a few things atm....replaced gasket in side cover plate enlarging the holes.
Now going to do a compression test .
Changed the distributor .
Will take it for a spin and see if there is any improvement . stay tuned !!

Thanks Guys for all your informative remarks.
Further checks have concluded that yes there is blow back from the rocker cover breather pipe .
After running the engine up to normal operating temp to do a compression check ,there was considerable blow back ,both from the rocker breather and the side plate breather pipe .
I can only assume that on a long trip like 4 hours crank case pressure would pump oil up into the distributor.
On short trips ,this wouldn,t show as much.
Remembering back when I "restored" this old girl ,the motor was in reasonable nick ,the bores were glazed so I put the "dunny brush" down them to deglaze them .the pistons and rings were in good shape ,so back together the motor went ,but as time has gone by obviously she is now showing me that attention is required .
Surprisingly the compression check when hot was as follows
No 1....140
No 2....125
No 3....110
No 4....120.
Still reasonable ... as is the oil pressure 55 psi!!!!!
From memory the bores were 30 thou over ,so looks like a rebore to 40 thou ,new set of pistons and rings and all will be well.
Cheers .....Murph

I would be unhappy with those compression numbers - the goal is for the low and high to be within 10% of each other, and best around 150. 110 is simply too low. The last engine I rebuilt gave 175 on all 4 cylinders after 800 miles, which I consider very strong; I was expecting closer to 150, but it does have an increased compression ratio.

An engine rebuild is indeed in order - and don't neglect the top end: check valve guides, valves, seals and springs. Lots of other things to check - the head studs, the flatness of the head and block, tight pushrod ends, etc. etc.

And for the very best and cheapest improvement, the thing to do is to send your distributor to Jeff Schlemmer at Advanced Distributor for a rebuild; your car will run much better for it.

No matter what pistons you get, use Deves rings.

Tom Lange

Murph, it seems you have your answer. But if you are looking for something to do, a compression test cold, followed by a little engine oil in each cylinder - applied to cylinder walls if possible, not the dead centre of the pistons - and a repeat test may tell the story succinctly.