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MG MG Y Type - Oil

What is the best type of oil for a '53 YB? My car leaked a lot of oil right from the start. I've been topping it up with the same thing I use in the A and B; Castrol 20W-50. The leaking has become worse and has gone from leaving spots to leaving a puddle of oil in the driveway. It seems to come from everywhere under the car because there is so much of it so I can't really tell what the source of the leak is. Am I running too thin an oil?

The engine has 76,000 miles on it and the maintenance logs show the bottom end was redone at around 60,000 miles. Oil pressure is slightly lower than my 1800cc cars but not overly so.
Steve Simmons

Hi Steve

The oil you are running is correct.

It is well worth cleaning off the engine and then doing a static run test - i.e. running the car up in the garage (with the garage doors open and the back sticking out of the doors!). Does it leak on idle - Yes, from where, No - Proceed to a short road run say 3 miles.

Places to pay particular attention too are:
1) Under the front of the gearbox there is a hole and there is a drain hole with a jiggler in it - if it is coming from here it is the rear engine seal - see later.
2) Around the rocker box cover lid - check gasket and re-align, check also top of head and inside rocker box for pieces of crud and eveness as even just a small piece can cause problems.
3) Check tappet chest cover gasket and cover plate. If this is not aligned or tightened you will be loosing a load from here.
4) Oil pump and all the tubes and banjo fixings. It is more than likely to be coming from here. Clean these up really well before you start. Vibrations from the engine (especially if thrashed or the engine support rubbers are shot, and they may be soft if oil has leaked over them) cause hairline cracks in the solder and at 50 psi you can loose loads of oil from here!
5) Dipstick is fully down and also oil cap on top of the rocker box - you would have to be going some to loose substantially from here due to over pressurisation, but since you do not know from whence it cometh, it is possible.
6) Front engine crank pulley area - in which case front engine seal is gone - see below too.
7) Check around the block for cracks. It would be unusual if a block passage had cracked thruough though.
8) Sump plug and sump cover gasket - the copper washer may be beyond its best or even missing! If the plug washer has been over tightened or has damage to it, heat it off the car until cherry red then flatten it on a clean anvil with flat blows from a large hammer. Similar treatment can also be metered out on the copper washers either side of the banjo links on the oil pump too. If the sump gasket,engine out and renew! Check also for cracks and damage to the sump.

9) Oil pressure relief valve - bottom back and left of engine - again copper washers are here and if damaged can cause ineffectual seals. Treat as above.

If it is the engine seals then again it is an engine out job and off to a good engineering shop and fit a new pair of seals from Brown & Gammons. Their special XPAG kit is not cheap and does require expert fitting as all ovalation of the crank and casing needs to be taken out. Although your maintenance log says this was rebuilt 16,000 miles ago it must be done very exactly.

Personally I suspect that you may be OK and find it is either gasket alignment / pressure from the cover plate, or banjo cracks on the oil pump. This is one of the places mine went and I lost huge amounts before I changed it and the copper washers.

Standard oil pressure should be about 50 psi on the run so it will be lower than the B series engine which ought to be running at 75 psi.

Although you are getting lots of free rust proofing to the underside of the car, if it drops onto the exhaust, it does pong when travelling!

Good luck in finding it. At least we are in good weather for doing this at the momement. This weeekend may be your last chance so don't loose it - weatherwise as well as before a pipe ruptures and you loose all your oil.
Paul Barrow

It's already on the exhaust pipe and it smokes when I'm still. Pressure on the highway if I remember correctly is around 45-50 so that sounds good. Drops to 20 or less at idle I believe. Now one thing I don't quite follow... is the oil pump outside the engine??? Pardon me if I misunderstood but I've never heard of such a thing and I'm new to XPAG engines.

Let me give you a sample of what I'm up against. This is a picture after a 40-mile drive on a hot day recently.....

http://www.camerasupport.com/oV/yboil.jpg
Steve Simmons

Hi Steve

At rest 20 odd is OK so it sounds as if you have good pressure being generated - given the inaccuacries owing to the fact that the dash gauge is not a precision calibrated instrument (neither is it on more modern cars!!).

Yes, the oil pump is external on the XPAG. If you look on the left hand side of the engine just in front of the dipstick you should see the oil pump and filter housing. Another area of leak could be that the oil filter housing/canister is not properly screwed on either. I won't go into too much detail as the Y had three different versions of oil pump! Best book on the entire subject is David Lawrence's Let there be Ys!
Paul Barrow

Paul, sell him a copy of 'Living With The XPAG Engine' from David Hague. It has all the information he needs in it. 'Y' Register regalia has quite a number of 'help sheets' and booklets for sale.

Neil.
Neil Cairns

Sounds like a help book for living with wils animals or problem children. :) There are a few books I need, I'm sure.
Steve Simmons

Steve - close on both counts!

Paul
Paul Barrow

Steve - If the engine has 76,000 miles on it without a rebuild, your cylinders are probably so worn you are blowing a lot of oil out of the breather tube as a result of blow by. At 80,000 miles on the engine i my TD, I had so much blow by and was burning so much oil, I was getting about 150 miles to the quart of oil. Rebuilding the engine and boring it out to the next size corrected all the problems. Paul has hit all of the common points for the XPAG to leak - EVERYWHERE! This is an engine that is quite different from the B series engines in the MGAs and MGBs, which are really oil tight in comparison.
David DuBois

The maintenance manual says the bottom end was redone at 60,000 miles. It runs like a champ but it does burn oil. Between leaking and smoking I've already gone through at least a quart since I bought the car a couple months ago.
Steve Simmons

Steve,

Clean all plugs (ignition) thoroughly, go for a run in the car to pressurise the oil and warm it through, return to base, take plugs out again and and seel which are fouling. It may be that you have a ring gone too. Check compressions for eveness too - cannot remember the compression rate off hand, but they should be all evenish.

The only sure fire rebuild is when you can do it yourself! I have heard the rings can fail in a short time if not 100%.

Paul
Paul Barrow

Steve,

Does it blow smoke on idle & then clear up whilst running? If the bottom end was redone, perhaps the head wasn't. Have you checked the valve-guide & seals. They could be letting the oil run down the valve stems.
FWIW.

Bob (YT4320)
Bob Simpson

It smokes immediately on startup. So quickly in fact that I wouldn't be suprised if it smoked during cranking! :) It clears up for the most part when hot, emitting smoke only under medium to hard acceleration.
Steve Simmons

That does seem to point somewhat to Bob's theory, but if it only puffs on acceleration you will not be loosing as much as you say and it would not leave the drips either as it would all be burned. Seems you may have a lot of little problems I am afraid.

Sorry for the bad news!
Paul
Paul Barrow

A lot of little problems is my middle name.
Steve Simmons

Smoke on starting is wear on the inlet valve guides, fit 'B' series valve stem seals, as the 'booklet' above sold by the Y Register of the MGCC explains.

Neil.
Neil Cairns

This thread was discussed between 19/09/2003 and 29/09/2003

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