Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - 18V Side Cover + Sump Gaskets

Dear All, apologies as I'm sure this has been discussed before, however...

Had purchased rubber/neoprene side valve gaskets and paper sump gasket for my 18V engine from MOSS. After carefully fitting all three are leaking oil so am not overly impressed. I'm asking for best recommendations for these 3no gaskets i.e. best quality and from where to buy. Having rebuilt many engines I've never seen such poor leaking as this. All surfaces were spotlessly clean/degreased and 'true' prior to install. Side covers correctly torqued etc.,

Have subsequently read that the rubber/neoprene gasket is best for the rear side cover, and cork for the front. Ideally I'm looking for a more robust/thicker gasket for the sump.

Any/all help would be greatly appreciated.

Thank you, Andrew
Andrew Wooding

Hi Andrew,

I know what you're going through, I replaced these gaskets on my B earlier this year.

I bought a sump gasket and two each of the rubber and cork ones for the side covers, all from Moss.

I think you'll find the best arrangement for the side covers is as you mention: rubber on the rear side cover and cork for the front; I fitted mine like this and have had no leaks.

I was disappointed with the Moss sump gasket - it was about half the thickness of the original one, so I was a bit concerned about a potential leak problem. I made sure that the mating surface on the engine block was scrupulously clean and every bit of old gasket removed. The sump itself was a bit distorted where the sump bolts had probably been overtightened, so I flattened it out all around each fixing hole, using a vice-mounted dolly and a toffee hammer. I degreased the sump flange and applied a thin coat of Hylomar Blue, then applied another thin coat to the gasket. After placing the gasket onto the sump flange I pressed it down with a piece of flat steel (one side of an engineers square) to get it as evenly flat all round as I could. It's important not to overtighten the sump bolts - I used a torque wrench (I think I set it at 4 lb-ft, check the archives to confirm this value). I've had no sump leaks since doing this job.

Apart from giving a better seal, the use of Hylomar also makes it a bit easier to re-fit the sump as it holds the gasket in place while you're struggling to get the bolts back in. A few days after doing this job I had to take the sump off again; it came off with the gasket intact and still stuck to the sump flange. For this reason I wouldn't recommend putting Hylomar on both sides of the gasket as doing so would mean a lot of cleaning and scraping, plus a new gasket.
Brian Shaw

After several on and offs AND over tightening the sump gets "dimpled" around the bolt holes which stops the rest of the gasket being pulled down. The sump can be dressed back with hammer and stake. Also I use silicone but only from the centre of the gasket to the outside. Surplus silicone squeezed into the sump can get on to the oil strainer!!
Allan Reeling

If your side covers are leaking, it could be a symptom of overpressurization of the crankcase.

Coat the cork tappet chest cover with a thin skim coat of Permatex Ultra Black RTV Gasket Maker. This is possibly the best silicone sealant on the market, able to withstand temperatures of up to 500 degrees Fahrenheit (260 degrees Celsius). Be sure to let the gasket cure for several hours before attempting to trim away any excess material using either an Exacto knife or a single edge razor blade or before installing it. This will result in a rubberized gasket that will not become saturated with oil and consequently ooze drippings onto your garage floor. Finally, use some Permatex Aviation Form-A-Gasket or Hi-Tack in order to secure it into position. Do not use silicone-based Permatex Blue RTV or Permatex Red Ultra RTV sealant on any of the engine gaskets as they are both prone to failure and contamination of the engine oil under hot operating conditions. When installing the gaskets onto the covers of the tappet chest, remember that the rubber O-rings on the bolts tend to take a set when left in place, so always replace them with new ones in order to obtain an effective seal. The 5/16”-24 UNF nut for the shallow rear cover of the tappet chest should be torqued to 2 Ft-lbs, while the 5/16”-24 UNF nut for the deeper front cover of the tappet chest should be torqued to 5 Ft-lbs. Exceeding these torque values may result in distortion of the tappet chest covers, as well as crushing of the gaskets, leakage being the result.

As for your leaking oil sump, the engineers at Fel-Pro have come up with a solution called the PermaDryPlus® Oil Pan Gasket (Fel-Pro Part # OS20011). Constructed of high temperature resistant, edge-molded silicone rubber on a rigid carrier, it provides a superior fit, as well as both high heat and vacuum resistance, while the included Oil Pan SnapUps speed installation. In all cases, the oil sump machine bolts should be torqued to 6 Ft-lbs.
Stephen Strange

I'd like to replace the sump gasket on my GT, which has an 18V engine. Dumb question: Is it possible to do this without removing the engine? Anything unexpected I should be aware of? Thanks. -G.
Glenn G

Theoretically, it can be done with the engine in place, but it will be agonizingly tight geting at the sump bolts at the front end. If you have the old gasket stick to the flange, then you'll have to scrape the mating suface, and lifting the engine will be mandatory at that point.
Stephen Strange

Thanks to all for your replies.

Q?? Is there a manufacturer out there who produces thicker sump gaskets i.e. Payen??
Andrew Wooding

Hi Andrew

We use sump gaskets which are approx 28 thou" uncompressed and are a grey softish paper based gasket. We use blue hylomar on both sides of the gasket, a thin line of silicone sealant on the cork strips and torque down to 11 lbsft ( no more as you will squeeze the gasket out).

Front tappet chest cover is cork and superglued in place on the cover. Rear tappet chest cover is rubber. Hylomar on front and rear cover sealing surfaces to block.

The gaskets are made by County.

Use Payen for head gaskets though.

Peter Burgess Tuning

Thank you Peter, I had forgotten about County.

Anyway, have managed to track down a UK supplier of the Fel-Pro OS20011 gasket who can supply these at only £12.65+VAT+delivery

John Woolfe Racing Ltd.
Woolfe House
Hammond Road
MK41 0RQ
Phone: 01234 220700
Fax: 01234 341440

Have ordered mine today - delivery is 14 days.
Andrew Wooding

Glenn G - I managed to remove the sump without removing the engine (1980 MGB). I've done it three times this year. At first I found the bolts at the front end a bit difficult. I then jacked up the engine by half an inch or so (without undoing the engine mounts - it's surprising how much you can lift the engine before the rubber starts to stretch), and had just enough space to undo them using a short pattern ring spanner (it's about 5" long) - alternatively buy a cheap wrench and cut it down. The gasket was stuck to the block in several places and it took a bit of scraping but it was accessible all round. I've removed the sump twice since then, without having to jack up the engine because the bolts now unscrew quite easily after having cleaned and oiled them the first time I did the job. Only downside to this is with the engine in place I found it impossible to use the torque wrench on the 5 front bolts, but once you get a feel for the correct 6 lb-torque you can guess those 5 easily enough. Definitely worth a try (unless you've got large hands).
Brian Shaw

Hi Brian

We have found sumps tend to leak/weep at 6 lbs, we have slowly raised the setting to 11 lbsft which seems to work well for us. It takes three goes to get the give out and achieve full torque.

Peter Burgess Tuning

Hi Peter, do you have the contact details for County? Have googled but search comes up blank.

Thank you, Andrew
Andrew W

Hi Andrew

They do not deal direct. You should be able to buy County parts through your local mg specialist.

Peter Burgess Tuning

This thread was discussed between 24/09/2012 and 27/09/2012

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.