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Collection, Preservation and Display of Old Lawn Mowers

Suffolk engine sump oil leak

Hi all,

I got my suffolk engine running well after over six months of trying, turned out the oil splasher had broken off and was lying in the sump, i removed it and solved the problem. I have now noticed an oil leak from the sump, not the gasket! It is from a hole/bore that im not sure what it is for but it is supposed to be there. I havent had a good look at it yet. The leak is near the draining plug, Any suggestions on fixing this problem or is a new sump the best idea?



wristpin Sun, 09/09/2012

Seem to remember that over tightening the two sump retaining bolts can result in a cracked sump.

redfernmowers Sun, 09/09/2012

funnily enough there just might be.

if the casing is a solid aluminium (depending on date) the crack can be brazed with aluminium brazing rods and a blow lamp at a reasonably high temperature. this is to be done both sides of the affected area. I've done this with two engines in the past by slightly enlarging the crack with a needle file and scraper, then applying intense heat and using aluminium brazing rods. you can use a blow torch with MAPP gas (hottest generally available gas) or in my case Oxy Acetylene which provides me with a flame I want and a temperature to go with it.

after you've brazed both sides of the crack and over filled the joint, sand the area back and clean with a stainless steel wire brush. wipe the area clean, apply a new gasket liner and rebolt the engine but not too tight.


redfernmowers Mon, 10/09/2012

as an engine crank case is exposed to heat, body filler would decay due to the elements in engine oil, vibration, pressure and heat.. silicone would only be used as a gasket seal but I don't recommend it. I'd use a proper gasket compound. Silicone also has issues with hot engine oil and the risk of a silicone patch lifting off an engine sump base into the oil bath and workings would be catastrophic. issues which could arise would include the silicone getting in the path of the  valve push rods or the con rod, etc. something like this is best left alone.

If an engine suffers a crack like this to the sump case or main area of the crank case, either the case is abandoned and another engine sourced, or if specialist tools and knowledge of aluminium / cast iron welding, the use of oxy acetylene or AC TIG is needed. for aluminium. as regards cast iron, a stick welder using low hydrogen cast rods would do the trick with a steay flow.


hillsider Mon, 10/09/2012

Hello Henry,

I may have missed a point here if I understand correctly you have removed the broken oil thrower from your engine but I have not noticed if you have fitted a replacement? 

Re the oil leak from the sump you would be well advised to investigate the cause of the hole as apart from the oil drain plug I cannot think of any reason for a hole to be present - unless the oil thrower punched a hole in the sump as it broke off !!.

Keep us posted on what you find,


wristpin Mon, 10/09/2012

Might I be so bold as to suggest that the likely hood of a useful reply will be greatly increased if you supplied a picture of the damaged area. As another respondent has said, hope that you have fitted a new dipper!!!!!

HenryB Mon, 10/09/2012

Part of the oil splasher is remaining, i left it there, i did try to remove it as I have another suffolk engine sitting around in parts to use for spares. I had no luck removing it, i just fill it up a bit more so the splasher reaches the oil. 


Sump problem sorted now as I used the sump from my spares engine. Just had to remove a sheered plastic plug to fit the metal one.



HenryB Mon, 10/09/2012

The hole I was on about was something to do with the fitting bolt, it should be there.


I must have tightened the bolt up too tight, I learn from my mistakes.


All sorted now.