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MG MGA - Oil consumption

Hi
At what point would you say oil consumption becomes unreasonable?

Phil Parmenter
P Parmenter

Phil,
It depends-- are you burning it out of the tailpipe (blue smoke) or leaking it on the floor?
/ gil
gil

When you use more oil than gas. The standard oil consumption rate of even todays cars has been that a quart in 1k miles is "normal". Personaly if you are less than a quart in 500 miles I wouldn't worry about it unless you are having other problems. Overly rich mixture can increase your oil use as it "washes" oil off the cylinder walls and it gets burnt. Our "A" will use a quart in about 400 miles in local driving but uses less than a quart in 1k miles at 60 MPH, I know it runs a little rich at lower RPM's.
John H

John, 1 litre in 1500 km may be normal in a US motor, but it would not pass any emission or environmental standard in Europe, and a modern European or Japanese car is expected to require no attention at all between services, where the level between hi and lo on the dipstick is about 1 litre and service interval is 15-20,000 km (1 mile = 1.5km, 1qt = c 1 litre)

My A drips a bit of oil, but I can still expect to go 2000 miles before needing to top up the oil in the sump.

I burn about what you mention in Marvel Mystery Oil with the injection into the Supercharger. This would not be allowed if I was subject to env regs like a modern car.
dominic clancy

Minimal dripping from engine and no smoke that I can see from exhaust - the engine was rebuilt about 5,000 miles ago. I am getting about 550 miles to the pint which is I guess about 950 miles to the US quart. Is that acceptable do you think?

Phil Parmenter
P Parmenter

Phil

My 1800 engine has done 13K and it does not drip. Oil consumption is no worse than Dominic's.

Steve
Steve Gyles

Staggering figures from the USA there John, as most have said European cars use next to no oil at all.
Regarding MGAs mine uses about the same as yours Phil, when I tend to thrash it to France each year at a constant 75MPH. I have always considered this slightly excessive as my mate does the same with his MGB and uses only about a pint in 2000 miles.
Bob (robert) I am coming out!! yes I once owned an MGB!!

My MK-II uses about a pint to every two tanks of fuel. It is getting better, so it may be that the rings are wearing in. It improved after I installed positive oil seals on the valve guides. As for American cars, they usually go between changes without adding oil, but if you complain to the manufacturers about an engine with excessive oil consumption they will say that a quart to 200 miles is "normal". Just their way of telling you to get lost.
Ed Bell

Dominic and Bob, it may sound like a lot but try to get a dealer to repair a car under warrantee that burns les than a quart per thousand and you will be told it is normal and they will not cover it. Caddilac northstar engines are famous for using some oil.
John H

Phil

Here's your answer...

When it's doing 100 miles/pint that's when you need to look at an MGA re-bore, etc. Start by checking compressions and decide if it's caused by bores, valves or both.

With plugs removed, check compressions and record figure for each bore. Then check again after adding oil into the bores. If the compression is higher with oil added the piston bores are in trouble. If the figures are still very low the valve seats are leaking too.

Whip the head off and go from there. If you are still running a "leaded" head, now's the time to get that done, which means the guides are then sorted.

Have just done mine, re-bore & new pistons, re-ground crank plus new shells and new camshaft bearings (latter can cause quite a loss of pressure), new oil pump and oil strainer. Have just done 150 miles so far, it's really tight, but I've definitely got a new car again.

Check what head you have. Can be later than the original which is good. Can recommend a chat with Bob West, once the head is off as to whch way to go. I got a local engine specialist to rebuild the short engine.

Good Luck

Pete
Pete Tipping

Many thanks for your replies.
Pete - the head was converted to unleaded by Peter Burgess not that long ago and Bob West rebuilt the engine (or rather he had it rebuilt by some third party) about 5000 miles ago. It seems that there is no 'normal' consumption figure. My MGA is a standard 1500. It certainly uses more oil now than before it was rebuilt. My MGB which I have now sold didn't use any oil between changes. I was just interested to know what people regarded as unreasonable, when you should actually need to worry and do something about it.

Cheers

Phil Parmenter
P Parmenter

Phil,
What procedure did you use to break in the engine after the rebuild?
/ gil
gil

Phil

Hope it was run in for 500 miles at 2,500 rpm max - that's 45 mph in top gear...? Not easy but worth it - that's what it says in the handbook...

Have you checked the compressions to see if the rings are still good?

Have you put it on a ramp with the hot engine running and looked for any "gasket" type leaks. Especially the tappet covers, sump and front main seal. Does it drip a lot in the garage after a run?

Pete
Pete Tipping

Pete

I guess everyone has their own way of running an engine in. I certainly did not restrict my engine to 2500rpm. I tried to use it over as full a range as possible. What I did avoid was sustained high revs and straining the engine under load.

Interestingly, though, with my original 1500 engine I lost 8 pints of oil in the first 40 miles! I had missed removing the hardened oil filter seal and put a new one on top. It blew out on the way down to MG Silverstone, leaving a saturated underside to the car and a very slippery patch of oil on the road!

Steve
Steve Gyles

I regularly go 5000 - 7000 miles between oil changes on my daily driver vehicles, using synthetic, and I have no oil loss between changes. Note that these are newer (1994, 1998, 2006) vehicles and are different from the MGs. Any older engine that burns a quart per thousand miles is ok, you have to remember that the breather pipe pulls some, and the engines just weren't built to the standards we build them to today. When running your engine in, you can expect the oil consumption to be 600 miles /quart or less. Nothing to worry about. At 5000 miles you should see the consumption decrease to about a quart/2000 miles, with the exception of dripping, if the engine was tight when rebuilt. Things to consider: did you stagger your rings on the pistons when rebuilding. If you placed all your rings in line top to bottom, you will see oil consumption, and no doubt will have to correct this. Are you constantly driving at high rpms? Don't use cheap oil. Cheap oil carries in the engine and gets sucked out by the breather pipe when driving fast.
Just a few ideas. Good luck.
mike parker

Mike , I didn't rebuild engine so can't tell you about rings. I did run in very carefully especially not allowing the engine to labour. Talked to Bob West about this and he said that there was no problem with taking it up to 4000 or so every now and then. I suppose thats a whole new discussion point about the best way of running engines in.

Cheers

Phil Parmenter
P Parmenter

Hi Phil

As I say the 45 mph max is the figure stated in the original handbook that came with the MGA. Out of respect I'm doing what MG at Abingdon said. All part of the pleasure...

Get those pistons and rings too hot, too early and you have undone all that hard work. I feel the occasional 4000 rpm at light loads is OK for the next 500-1000 mile area once the head has been re-torqued.

Modern engines are OK run light in the 2,500 - 4,000 rpm area when running in, but I believe our old engine design needs proper TLC which pays dividends later.

Steve - I never saw your oil trail going to Silverstone. Did you do the 3 laps on Sunday and then get very wet too? Worth it though wasn't it - we were there!

Pete
Pete Tipping

Pete

My oil loss saga was afew years ago now, 1998 to be exact. Picture taken by my other half (scroll right down to the bottom of the page): http://freespace.virgin.net/stephen.gyles/Practical%20Classics.pdf

I remember in the 1950s when we used to see signs in the back window: "Running In Please Pass". I think the advice in the manual for 2500RPM was standard for that period. However, with better quality materials nowadays, far superior oils and finer engineering tolerances I think that way of running in is now dated. I have always been advised to used the engine freely but not sustain consistently high revs nor overload it.

Steve
Steve Gyles

Steve,Very interesting article. I wish I could have read the entire copy.
mike parker

Hi Steve

Couldn't open that. Agree with you about tolerances,& lubricants, but I'm doing what I'm told - actually am in the middle of making a "Running in - Please Pass" sign right now!

Cheers

Pete
Pete Tipping

Pete

Strange. Would not open for me either! If you are interested try this one and click on the Practical Classics hyperlink.
http://freespace.virgin.net/stephen.gyles/psj_903_rebuild.htm

I actually spotted the oil loss problem at about 60 mph on the M6. The oil pressure was dropping sharply. I hit neutral, switched the engine off and had sufficient speed to coast up a slip road that was conveniently approaching. Made it to a layby at the top of the road and effected repairs to get me home.

And in case you are wondering I was only running in the engine for a short strip of the M6 just to get across the Thirwall Viaduct, then it was going to be back roads for the remaining 120 miles to Silverstone.

Just off to do my routine annual oil change. Now there are other thread topics: classic 20/50, semi synthetic or fully synthetic? Twice a year or once a year etc. I used ordinary mineral oil for the run-in then changed to semi synthetic 20/50.

Where are you going to stick the please pass sign?

Steve

Steve Gyles

The first url will open if you copy and paste instead of click on it.
John DeWolf

Hi Steve

I use Millers Classic 20/50 - my local proper old MG garage doesn't go for anything synthetic. I notice Castrol GTX is now a 15/50 grade.

With the consumption thing, I have no detectable oil use at the 150 miles point after the rebuild.

The "Running-In - Please Pass" sign is now in place. Printed in portrait on A4 in big red letters, stuck on card and wrapped in clear plastic. The sign is cut to a proper imperial 4" deep, with four holes with nice brass eyelets right through, string ties it vertically onto the boot rack a treat!

Come on sunshine!

Pete
Pete Tipping

It would be interesting to get some input from the ring & piston manufactures on break in. I can here you all howling when you read this but when I rebuilt my 5.7 GM V8 in my truck, the parts manufactures instruction for break in was to perform several full throttle accelerations from a slow rolling start. Than just drive normally, 50k miles later it still uses no oil and runs fine. Materials change, the best reason I have heard for this method is that the forces on the rings during hard acceleration froce the rings to seat faster.
Maybe one of the Moss guys can talk to the present ring suppliers and get there take on breakin as none of them seem to send any info with their parts.
John H

This thread was discussed between 23/03/2006 and 27/03/2006

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