MIG welding to alloy sump-plate

[peterd51]

Hi,

repairs to a Mondeo diesel, I've got the head off, one piston is slightly melted.

To remove the sump needs the gearbox, clutch & flywheel off...not an option!

I considered drilling/cutting a hole in the sump under no.2 piston, unbolting the big end and then pushing the piston out the top.

Pop a replacement piston in, bolt it up and weld a mild steel plate over the hole.

But the sump bottom isn't mild steel, it's some sort of alloy.

Any ideas please?

What wire, what gas, what metal to use for the plate?

I thought of bolting the plate on but the oil-pressure is around 70 PSI so that could be a bit suspect.

The only other option is to risk it with the piston as it is.

Regards
Peter

 

[piman]

Hello Peter,

I'm guessing at cast aluminium.

The oil pressure wouldn't be an issue as the sump has very little pressure. Other point is are you sure the pistons come out that way, some don't, rare but worth checking?

Alec

 

[timinder]

I won't comment on trying to weld oily sump alloy, but that 70psi oil pressure is just what's in the oilways, not the pressure of the oil hanging around in the sump - that's not pressurised at all.

 

[shenion]

Will be hard to MIG alloy an have it leakproof due to cold starts.

Could be done with TIG, but will be near impossible to keep the weld clean as the oil will contaminate from the back side.

Then there is the issue of the oil residue on the back catching fire.

I would pull the engine and have a serious look inside.

 

[TAITSIE]

Inside the sump is not an open space it contains baffle plates and an oil pick-up

 

[peterd51]

Hi,

thanks Guys!

I was thinking about it over lunch and it suddenly struck me that I was talking balls on the pressure...it'd leak out of the dip-stick port.

Looks like a 'mechanical' fix...

weld a bolt onto a washer and attach a piece of string...

depending on the size of socket needed for the big-end bolts, drill a suitable hole, probably about an inch diameter. Pop the piston, place the bolt/washer in the sump with the string out the hole.

Install and bolt the replacement piston then pull the bolt-washer into the hole with the string. Goo it up with instant gasket, add an external washer and nut. I may have a piece of rubber 'gasket' on the washers too if I can find some.

I'll get a second-hand piston and that'll allow me to check things like amount of clearance between big-end and sump-bottom, and what other bits are in the way, etc, while I'm at the scrap-yard.

It's a nine year old Ford, I'm not spending too much time on it as long as it runs for another 3 or 4 years it'll do!.

Regards
Peter

 

[MarkMG]

Bodgefantstic

 

[oddball90]

It will be quicker to take the engine out and swap it for one from a breakers, without taking the sump off you will never get the big end bolts back in or fit the big end cap, knowing that the shell is in right.

 

[shenion]

Forget the string. Make up one of these:

Screw on bolt, feed wire through and pull out hole.

Came with my trailer hitch as you needed to feed the bolts through the chassis. Once I saw one, i realized I could have made one long ago using MIG wire.

 

[oddball90]

Good one shenion but it won't put the big end cap back on or the bolts back in.

 

[shenion]

Good one shenion but it won't put the big end cap back on or the bolts back in.

Don't know what you mean.
Feed it from inside, will work fine.

Will need a way inside the pan to feed the bolt (or nuts/string.) Maybe through timing cover or drop pan far enough to come from side.

Edit: oh, once th piston is out, there's a nice big hole to feed the bolt through.

 

[oddball90]

Yes to take piston out you have to remove the big end cap from the con rod. This is usually held with two bolts/nuts and then you take the cap off. This is a heavy bit of steel, which holds half of the bigend shell. Don't think you will put this back on through a small hole and reattach the 2 bolts/nuts whilst lying under a car. Normally you have to tap the big end caps off once you undo the bolts, so to get a hammer in the hole will have to be the width of the sump.

Big end cap holds con rod to the crankshaft.

 

[TAITSIE]

Hi Peter
Why dont you pull the box and do it properly it will be quicker in the long run?

Book time for sump replacement is 7-8 hours and if you intend to use sh piston/conrod make sure it is compatable ie std or oversize.

 

[James]

There is a baffle plate between the sump bottom and the big ends. so drilling the sump won't achieve what you're after. you wont be able to see the bolts at all.

the baffle plate is mild steel so you'd have to drill through that as well

the mind boggles what would happen to all the swarf. and you'd forever have a piece of baffle rattling around in there

 

[peterd51]

Hi Guys,

Bodge! It's re-engineering to get the thing how it should have been if it was developed by 'engineers' rather than 'designers!

Removing the gearbox isn't an option. Nor is changing the engine. If I can't fix it then it gets used as-is.

The piston isn't so badly burned. It's just that I'd like to replace it if I could but Ford's seem to have gone out of their way to make this difficult.

Back in the good old days dropping a sump was easy as the bolts were all on the outside rather than hiding a couple behind the flywheel...

Ok, the old in-line engines had a cross-member underneath (except for cars like the Morris Minor, of course) but it was still easier than this bugger!

But anyway...

thanks for the input, it looks like I may have to re-think.

I could possible go in from the side of the engine...that it the front as you look at it.

In that case I'd feel hapier about cutting a bigger hole as there'll be less 'weight' on it afterwards.

James, to save your 'boggling mind' have you never heard of flushing oil? :-)

Regards
Peter

 

[TAITSIE]

Try again,you will not get access to the conrod bolts from that area of the engine

 

[James]

flushing oil just causes even more problems, potentially dislodging burnt oil from crevices and jamming the oil pressure relief valve. nightmare stuff best avoided.


you've already got the head off, so obviously have tools. and even if you don't have a crane you can hire one for £40.

You'd be better off running it with the damaged piston than filling the sump with alloy and steel swarf... then trying to get it all out using a can of wynns!!

 

[peterd51]

Hi Taitsie,

with the piston up at the top of the bore and my hand through a 3" square hole I reckon I'd be able to get to the big end bolts.

James, now you're just being silly...if flushing oil was a problem then every oil change would see thousands of cars grinding to a halt.

The engine and gearbox is /not/ coming out of this car this time.

Whatever, this started out as a query about mig welding, it's not the right area to discuss general mechanics on car engines.

Thanks for all the tips, I think we should leave it at that.

Regards
Peter

 

[rtbcomp]

I'd be inclined to scrap it now rather than doing all this work and then scrapping it.