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Correcting the sump flange, to prevent leaks


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Triumph engines (car or bike!) are notorious for oil leaks.    In the small chassis series, four or six cylinder, the sump gasket is a guilty in many cases, and the DPO (Damned Previous Owner) is often at fault.  Overtightening the sump bolts bells the metal around the holes in the sump flange, to that the falnge inbetween doesn't seal.  Further tightenign just makes it worse, and the problem recurs even if you rebuild the engine, as the belling persists.    To correct this, it's necessary to do some minor fettling to the sump flange.  Here's how, with pictures.


If I can't post enough pics, complain to the TSSC, not me.


1/ Clean up your removed sump, especially the gasket residues on the flange.  Do the same to the block.  Apart from bits of old gasket preventing a seal, you can't work on a filthy sump.


2/ With a strong light behind, place a straight edge along the flange.   The bells around the bolt holes will show up as light gleams through the slit.   Mark the holes with a felt tip.  See Pic.1.




3/ You need a 'post' in a vice.  I use a length of steel plate, 1/2 x 2 x 6", but some hard wood could do as well, but ask a local metal working company if you may look in their skip for an offcut.     It could be thicker, as long as it will fit inside the flange, and as wide as the the distance between holes, and the top must be flat.  See Pics. 2 and 3.






4/ Hold the sump so that the hole you wish to correct is in the middle of the post, and the flange is flat on the post.  I've drilled a smal hole there to help me locate it. Pic 4.




5/  Now, with a hammer, beat the bell around the hole flat.   Use a small hammer, and do not apply great force - the blow should come from the elbow, not the shoulder.   Half a dozen firm, not hard blows will often do, and you will hear the sound change from a ringing to a duller sound as the bell is flattened.   See pic 5.




6/ Check the flange with the straigt edge again.   Repeat the hammering until the gap that the light gleams through is straight.    Your flange may not be absolutely flat, indeed slightly curved, but correcting that is a much bigger job, and this amount of curvature won't cause leaks.  See Pic 6.




7/  When you fit the sump, do NOT overtighten the bolts.  The 'Book' torque is 16-18 lbf/ft, which is a bit more than hand tight.   What's 'Hand tight'?  is hard as you can turn the bolt just using hand and wrist strength.  What's "a bit more"?   GIve the bolt a final tweak with the whole arm.



Hope that helps prevent sump leaks!



PS I now have 46kb for future picture posts.  That is less than any of the small pics above, and I'll have to delete one of them to post another pic.  You choose, please.   J.

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Thanks for taking the time to post this John; very useful for any old car, not just Triumphs. As the old saying goes, the pictures speak a thousand words.


Exactly what this forum is for in my view, and more posts like this will encourage greater useage by TSSC members.


Note to self - take pictures next time I carry out a job on my Triumph!


P.S. Regarding the Polyfilla on your work bench: An insight into your bodywork techniques perhaps?  :P

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  • 8 months later...

Nice post, clean work.... I m changing the gasket to my sump on 1973 GT6 2.5, i think removing the sump with the engine in was the most challenging job i have done so far :lol:  understand why haynes says it can only be done engine out ! hope it won t be as bad to put back in

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its a good faf to refit ON Car , its all down to angles and tommy cooper, just like that


watch fan  contact and hose stretch when lifting the lump.  


and when you are about to cuss ans swear it will pop over the oil strainer and slide in place,


make sure you use short screws in the alloy front block , and as john has said  a light nip is all thats needed no wraunching up with a giant ratchet



back as an apprentice    1963 on gearbox  reconditioning the power take of blank was a pressed plate , less sophisticated but attack the fixing distortion was give it a good clump with a ball pein hammer   to reverse the denting



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stuck with the pan, don t want to get back in, desperate

Walk away from it. It really isn't that important to get it done immediately.


Do something else completely and go back to it in a few days time with a clear head and you will probably find a way of getting it to fit.

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get the engine as high as you can ,


so the racks Off 


have you changed the oil pump so it has a different strainer or pick up from what was original

as you may need to remove the splash  gauze to get the sump back on,  its not overly important .


its possible but getting the angles and keeping sealant off the fingers is a challenge


turn the crank to give the best clearance with counterweights and journals as flat as you can not poking down below the skirt 




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