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MG MGA - Oil on exhaust and driver's side frame rail

The rocker cover isn't leaking, nor can I see much from the speedo connection, but I've got quite a bit of oil on the exhaust just as it goes down from the manifold. Oil is burning on the hot exhaust pipe and I see it all in the area, including the outer frame rail.

Down a quart in the 325 mile trip from from the Solomons Island Regional. Used/dripped 3 quarts overall in the 1000 total trip.

Where can it be coming from?
Ken Doris

What about the two side covers in the cam follower area?



Mick
M F Anderson

the draft tube? I think the side cover gaskets are more likely, though. There is also a mechanical oil-pump blanking plate on that side of the engine.

AJ Mail

Mick - where are those two side covers located? How can I put a light on them?
AJ - do you mean the crankcase vent tube? That would be in the right place to stream oil back to the exhaust - see photo.

- Ken


Ken Doris

Mick - I found the covers and it does look like there is more oil around the front one than "normal". Also looks like at least one of the bolts is not fully tightened. This is an engine that has been running for over 25K without a leak from there. I wonder how the bolt may have loosened up recently?

Looks like I'll have to remove the carbs to get at it, but that may be it.

Ken Doris

Ken I have recently had the same problem,likely to be from the side plates located behind the exhaust manifold.Remedy, new gaskets. Sometimes the problem is a result of the securing bolts being overtightened.
Norm Harvey.
N H Harvey

Norm - What gaskets did you use?

I see Moss has some new silicone rubber one:
http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=44610
Ken Doris

Ken,
Is the draft tube showing in the photo? Is that it just to the right of the exhaust pipe? Maybe it is to the left out of the picture? Did you disconnect the hose from the valve cover to the front filter, at the front filter? Does it have oil in it?

Ralph
L Poupard

Ken I used cork gaskets (as per original)Part # 12A1139;Also new Seal Bush for Push Rod Cover Bolt(2),
Part #12A1176;new Push Rod Cover Cup Washers(2) Part #12A1177.
Norm.
N H Harvey

Ralph - that is just the exhaust in the picture. I plan to pull the carbs to get to the side cover, so I'll also check the hose to the carbs from the rocker cover.

One other item that bothers me. It seems the oil pressure at speed is higher than normal. Cruising on Sunday at 3700 rpm (66 mph)it remained at 70+ lbs all day (7.5 hours), while dropping to a normal 25 at idle. Probably unrelated, but another new development I need to look into.
Ken Doris

Ken,
Let me say that I'm not happy with side cover gaskets that are normally included with the engine gasket set. Although, the ones I got from Moss as spares for the R2R trip seem better. I recommend getting some good quality rubberized cork gasket material from the local auto supply and, with an old one as a pattern and an Exacto Knife, make your own.
Something you might want to check, however, is blow-by pressurizing the crankcase. This will cause oil to disappear, fairly quickly, with no apparent leak or smoke. Ask me how I know...:)
Gerry
G T Foster

Ken, -- Your picture looks a lot like oil escaping from the draft pipe and misting onto the exhaust pipe at speed. I had that problem once after my Alaska trim when a lot of road dirt got into the intake and wore out the top ring 1n all cylinders. Mine was spitting out a quart of oil to a tank of gas (~250 miles), and almost twice as much oil if I pushed it hard towing the trailer. Before ultimately installing new rings, I temporarily installed a length of heater hose onto the end of the draft pipe and tie wrapped it to the frame to direct the oil mist elsewhere. This might be worth a try as a diagnostic procedure to verify if this is actually the problem.


Barney Gaylord

Hi there
I had recently oil leak. My solution was to clean the engine with solvent soaked rug as much as I can, then without sparkplugs I run the engine until pressure come up, It showed nicely the side cover leaking. I used cork gasket, and as vw valve cover, used sealant only on cover side and leave engine side dry. No problem since.

Good luck

Martin
sharpeys

I agree with Barney it looks exactly like oil breathing from the draft pipe. Also an easy way to check is as Barney decribed simply push a length of hose over the tube and locate the end away from the exhaust. If this stops it burning then that was where it was emitting the oil mist. How to rectify? well that is a whole new story sadly.
Robert (Bob) Midget Turbo

I fondly remember a time in 1977 when I smelled burning oil on the exhaust on a dark night going to London from Birmingham on the M1 and found one of the side plates loose. I was grateful for the early warning given by the smell before losing the plate altogether and the oil pressure. The only other time my car failed, when it was my day to day transport all those years ago, was with a loose wire on the ignition coil which at night showed up as a small spark.

So on both occasions I was lucky there was some handy evidence of the problem allowing an easy repair.
John Francis

Don't forget the centre hold done bolt has a fibre washer, mine was missing and that's where my leak was comming from. You can get to the rear plate without taking off the manifold etc.
Dave Swinburne

ken
you indicate a oil pressure change also, check the oil pressure release spring cap nut while your back there but don't remove it .its a bear to reinstall. its unlikely it loosened because of the spring pressure but since your there check them all
pete
PETE CERKA

If a side tappet cover plate were to come off you would not loose oil pressure.

All you would loose is the oil that floods the area as it drains down from the rocker shaft back to the sump, which in some cases is considerable.

Messy yes, but not life threatening to the engine.

Steve
S L Bryant

Guys - thanks for the many great suggestions. From the angle I get looking down past the intake and exhaust manifolds, it appears that the center bolt on the front cover is slightly loose. That may be it, but I love Barney's suggestion of how to rule out the draft pipe with a simple tube, so I'll try that first. I think that is unlikely because the oil leak/burn happens without moving, but it is so simple, it is worth the first try.

Pete - I will check the nut over the relief valve.

Gerry - sounds like a story best told over another beer at the Seneca Lodge, eh? Sorry we missed you at the Solomons GT. Lots of great people there and I made some new friends including Peter Cerka who chimed in on this thread.

John - only 2 "failures" since 1977? I've had more than that in a single day! You have an incredibly reliable machine :~)


- Ken
Ken Doris

I don't think you can actually R&R a tappet cover and put the bolt back in from underneath, but you can, with a little knuckle scraping and a 1/2" open and wrench, tighten a loose tappet cover bolt from underneath.
Barney Gaylord

Barney - is it a 1/2 open end wrench? If so, if I can't reach it, maybe I can get Melon, with her skinny hands and wrists, to reach it.

That would at least stem the flow so I can see if it is the actual problem. See photo, sure looks like the bolt has vibrated loose.

- Ken


Ken Doris

Ken,
You can definitely get to both cover bolts from below the engine. Just need to have the car up on a hoist, or at least good axle stands, to get underneath. You do not need to remove the carbs or the exhaust.
The original MGA bolts only have lock washers on them (I have never seen fibre washers on these bolts). You can get a steel cup with a thick rubber washer as used on an MGB, and these will help to prevent oil leaks from around the bolt. I have these on my coupe.
Also, there are good cork gaskets to fit to the plates, and there are poor gaskets that do not fit correctly. I know from personal experience. The silicone rubber ones from MOSS may be a good option, as these were obviously introduced to improve the sealing. You should also add gasket paste to at least the plate side of the gaskets.
Lastly, be careful not to over tighten the centre bolts - you can distort the plate causing it to leak!
No-one has picked up on your high oil pressure point. Perhaps the oil pressure relief valve is sticking? This is fitted in the block below the tach drive.
Let us know how you get on.
Peter.
P. Tilbury

Oh, the front one. I dunno if you can get to that one with the draft tube in the way. Looks like time to stop procrastinating, bite the bullet, R&R the carbs and heat shield, and you may be done with it in a hour (or two).

Those tappet cover bolts should have seal washers. Moss has a few different part numbers for the simple 5/16" fiber washer. If you want that to seal you have to use the fiber washer alone under the bolt head, and thread lock adhesive, no lock washer. You also have to test the fit the cover and bolt without any washer to be sure the bolt does not bottom out in the threaded hole.

I take a simpler approach, just put a dab of RTV sealant under a steel flat washer, which also allows use of a lock washer.

18GA and later engines got more exotic with a copper washer, rubber bushing, cup washer, flat washer, bolt. I think that looks like a smaller version of the valve cover rubber bushing.

Or you can get slick and use a Stat-o-seal washer 600-0002-5/16, like this:
http://mgaguru.com/mgtech/universal/ut128.htm
You may not find those at the local hardware store, but McMaster-Carr has pressure sealing and bonded washers.
Barney Gaylord

Thanks Peter. No access to a lift, but I can put it up on jack stands and crawl under for the tightening. I think I will have to remove the carbs/manifold to replace the gasket.

As for oil pressure, I'll probably have to do a refit there. The fellow I hired to rebuild the engine back in 2004 actually didn't and I still have the original bottom end, pistons, rings and all, now at just over 100K miles and having sat for 33 years (1972 - 2005). He probably shimmed the relief valve to make it appear I had better oil pressure. Now it is staying high, even after full warm up, so I'm thinking it has "stuck" closed or close to it. 80 psi cold and over 70 at 3700 rpm fully warmed. before this trip it was never over 60 at that rpm after a long drive.

One problem at at time. I can't complain but I do envy lucky John Francis and his 2 in 34 years !!

- Ken
Ken Doris

Barney - yep, I have been putting off refurbishing the heat shields for awhile, so this is a good time to do it. The carbs are running great and have only about 15K miles on them since rebuild, so I'm not going to touch them other than a cleanup.

- Ken
Ken Doris

Here is an unlikely source, but it happened to me. The fiber washer under the oil pressure relief valve head had cracked, leaking more and more. Hard to find. If the oil pressure releif valve head backes out, (unscrews) it could show higher than normel oil pressure as well. LOTS of oil can come out of there! As Pete says, it's worth a look; well it was for me anyway!
Russ
Russ Carnes

This thread was discussed between 04/10/2011 and 07/10/2011

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