Australian Belly Tank

[Dr Goggles]

The undersides of the piston crowns.  Are they black or dark brown with a coating of burnt oxidized oil? 

How about the first and second rods from the left...................


the small ends look a bit blue don't they?....

And a very old photo from back when I had hair G

now, see , I thought THAT was Marc Bolan....turns out it's Graham Bogan

[SPARKY]

rods maybe camera lens parallax 

[Milwaukee Midget]

now, see , I thought THAT was Marc Bolan....turns out it's Graham Bogan

You'll have us all speaking Aussie colloquialisms before this build is done. 

Looks like you did it right.  Pushed the old lump to the limits and backed off just before catastrophe.  Fewer shavings to clean out of the oil galleries.  Ring it out for everything it'll give, but bring it back intact.

Well done. 

RIP, ol' donk - a new and better life awaits.

[gearheadeh]

now, see , I thought THAT was Marc Bolan....turns out it's Graham Bogan

You'll have us all speaking Aussie colloquialisms before this build is done. 

Looks like you did it right.  Pushed the old lump to the limits and backed off just before catastrophe.  Fewer shavings to clean out of the oil galleries.  Ring it out for everything it'll give, but bring it back intact.

Well done. 

RIP, ol' donk - a new and better life awaits.

Yes good timming and luck on this one!

Iam thinking of a line from the movie Cool hand luke..............Only with 1 twist in the words:
What we have here is a failure to LUBRICATE  !!!!!

That or the clearances were all too tight!

[grumm441]

You are definitely seeing blue on two of those rods. I' guessing they were fitted with a bit (lot)  of heat
And you will also notice that they are standing straight up without any help

Went and had a look at the pistons in the sunlight.
They are perfect underneath, look like brand new



The rear main bearing doesn't look at all happy


So I'm going to look for my glasses and go and do some measuring.
G

[Peter Jack]

I've seen similar in an oval track engine when the oil temperature pegged the gauge at 325 F. My driver said something about he wasn't worried because he still had oil pressure, I said something about you can pressurize water but it still doesn't lubricate. A great oil pump can't help lubricate if there's no viscosity.

Pete

[wobblywalrus]

Grumm, years ago I had the same failure type.  The machinist asked me to show him some parts, including the pistons.  He said that running the engine hard enough to do the damage from heat would leave brown or black oxidized oil stains on the bottom of the pistons.  He said I had a serious lubrication failure.  My pistons looked like new on the undersides, just like yours.     

[johnneilson]

I had a motor failure some years ago that looked very much like this.
With one exception though, the shop who assemblied the motor failed to properly install the thrust bearings.
After a few short laps, the crank was generating a ton of grinding compound in the oil and it completely destroyed the motor.
The only salvagable parts were the valves, springs and retainers (cam bores ruined in head).

It sure looks to me as the clearances were just a little tight, you guys need to visit Vegas, soon before your luck changes.

John

[Nexxussian]

Grumm, the close up of the piston, with the scuffed skirt, is that a piece of ring land missing between the 2nd ring and the oil ring?

I hope not.

[grumm441]

Grumm, the close up of the piston, with the scuffed skirt, is that a piece of ring land missing between the 2nd ring and the oil ring?

I hope not.

No
that's just the ring end
G

[Dr Goggles]

Grumm, the close up of the piston, with the scuffed skirt, is that a piece of ring land missing between the 2nd ring and the oil ring?
I hope not.

Hey Erik, long time no hear!

We're ditching those slugs anyway..just getting some prices for a bit more comp and full floating pins....also looking into getting the block line bored for steel mains and investigating some suggestions we've had for oil mods....

[wobblywalrus]

My illustrious tuning career includes a couple of engines that partially seized due to tight clearances.  Like you'all, I was lucky and the connecting rods did not snap or the pistons break apart.  The tight clearance problems showed up on the pistons in the hotter running cylinders the most.  There was a clearly visible difference in piston distress.  All six of these pistons are equally scuffed, from what I can see in the pix.  The rods and crank bearings on my partial seizures were not in the best condition, but they did not have the lack of lubrication symptons.  They small ends were not blue and the bearings were not scuffed.  This motor looks like the one where I had a failure in both the pressure feed and splash parts of the lubrication system.

One of many things to check would be the drain back from the cylinder heads.  Is enough the oil getting down to the sump to keep the pump intake submerged?

[grumm441]

WW
I'm going to do some stuff with the drain back. I've been sent some pictures of things  I have to look at, which Goggles will no doubt post
We also run a vacupan setup which makes vacuum in the crankcase helping the oil fall back down. and we will look at a sump with more capacity, and a windage tray.
However the big end bearings all look good and only the main bearings at each end of the crank are damaged. The two in the middle look perfect.
I've got a chev 350 crate motor here that the the oil pickup had fallen off the pump. Without the pickup, the oil cavitates around the hole in the end of the pump.(this is normally where I go into my diatribe about oil pickups and fuel pickups on EFI pumps) So it shows oil pressure until you rev it. and then pumps nothing. The pistons in it look fine and have no scuffing and the bearings are blotchy with materiel that they have picked up.

The V6 has hammered the tripe out of the rear bearing which I would put down to the flywheel coming loose. and when you consider how much loctite we used and how tight we did it up is quite something. The front bearing I would have to put down to a harmonic in the crank caused by the flywheel . I will put it on some V blocks later and see if it's still straight.
Goggles did say he couldn't see on the last run, I thought that was just because his goggles had fogged up, but I can put that down to the crank as well.

Well MM, how's that for long sentences.

G

[Milwaukee Midget]

Good.

[Rex Schimmer]

Look at the inlet and outlet ports of the oil pump and look for signs of cavitation, it will look like small pits usually in the areas of highest oil velocity. I do not think that running case vacuum pumps on wet sump engines is a good idea as it can lower the inlet pressure to the oil pump to the extent that the pump may cavitate, which of course leads to lack of lubrication and ultimate failure.

Rex