Piston Skirt?

[rficalora]

Hey Carl - what's the latest?  Piston came in?  Right one?

[MGBV8]

No.  Piston came after the machine shop closed.

Then I broke my toe.

[rficalora]

OUCH!!  Not much you can do about tue toe but tape it to avoid movement from what I understand.  Right foot I hope?

[MGBV8]

Left pinky toe. Bent out at a 45 degree angle.

[Dan B]

I did that one time.  At Myrtle Beach.  Dislocated it I think, but there is nothing you can do.  Tape the toes together maybe.

[MGBV8]

I broke the other one many years ago, racing Robin to the bathroom when we took a movie break.  Turned the corner & nearly ripped it clean off.  It lacked less than a half a mm being broken clean in two.  They completely immobolized it. with a special brace.  If it moved & didn't heal, then it was going to be surgery & screws.

This one is doing much better.  Taped it up.  I felt it pop a few times when I accidently put weight on it.  Yesterday, the pop really hurt.  Today, it looks like I may have popped the joint back into place.  No more 45 degree angle.  Guess I'll skip the doctor appt & take my piston to the machine shop.

[ex-tyke]

Guess I'll skip the doctor appt & take my piston to the machine shop..

That's what I like about Carl - always got his priorities right!

[MGBV8]

Sadly, Graham, most of my life the opposite has been the norm.

In this case, it was the correct play!  My toe is much improved (with just my own first aid) & I now have the new piston on the original connecting rod.

Machinist swapped the piston on the connecting rod & cleaned the carbon from the ring lands for $10 cash.  Sold!

Today is my mom's Birthday so may not get much done.

[MGBV8]

Here's my old "slipper" piston next to the full skirt OEM piston sent by Mark LaGrou.  

[BlownMGB-V8]

Is that a 'reverse' slipper?

Jim

[MGBV8]

Piston is in.  Oil pan is back on.

[mstemp]

Carl,


Good to hear! Hope all is now back to normal.

Did you have to raise up the engine to get the pan off? Need to change a leaking gasket and want to know if the pan will slide out between the xmember, or if I have remove motor mounts and jack it up.

[kstevusa]

Good News  See you in Wytheville for ride to Lewisburg.

[MGBV8]

Doubt I make the Wytheville to Lewisburg Run, Kelly.  Study Ken Hiebert's proposals.

I am still staring at a short block, Mike.  My car has the stock RB crossmember, so there was plenty of room to remove the oil pan without jacking up the engine.

[MGBV8]

Final update.

Due to time constraints & a well worn engine, I went with Jim Blackwood's suggestion.  Down & dirty, fairly quick & easy. Sourced a used OEM standard bore 11:1 piston.  Reused the rings that were well seated to the bore & the same rod bearings.  New Fel-Pro head gaskets seem to have cured the ridiculously excessive blowby.

I did get the the engine buttoned back up & fired about 30 minutes before pizza time in Lewisburg.  I finally arrived at 11pm that evening.  No pizza for me.

The next few days confirmed that I did a decent jog putting it all back together, as the West Virginia roads put it to the test with many blasts thru the curves at 5500rpm.  

[302GT]

This is a very interesting story. I know that your engine has had blow-by problems for many years and now you have found that the piston replacement cured the problem. As I recall the blow-by problem was hard to diagnose because there was no obvious oil smoke from the exhaust. So, did you run a compression or leak down test to try to find the problem? If so, I assume nothing was found, presumably because when the piston was not under load it probably was centered properly in the cylinder.

Was there an obvious cause for the piston failure other than a possible manufacturing defect? I do recall that early Ford 2.3 engines suffered piston skirt failure due to inadequate piston lubrication that was solved by putting an oil squirt hole in the rod. But I have heard of no such problems with the Rover/BOP family of engines.

Anyway, it is great to hear that your repair worked well and I am impressed that the engine suffered no long-term damage.

[MGBV8]

Hi Larry,

The blowby wasn't the piston. It was caused by the bottom row of head bolts canting the heads & leaking compression into the lifter valley.  See this thread for the evidence.

http://forum.britishv8.org/read.php?6,59020

I doubt the piston had a defect.  It is a cast piston that has endured way too much time living at 6000-7000rpm. Fingers crossed the rest hold up until I can get another engine built.

Piston with the destroyed skirt is on the far right (#7).

[302GT]

Makes sense that the blow-by was the classic head bolt problem.

So, what do you plan for the eventual new engine? I assume it will be a major improvement over the old...

[Moderator]

Yes. I've been wondering the same thing!

[MGBV8]

Not major & nothing new or even a lot more.  I love these little engines.

Strongly leaning toward a Rover 3.9 with new sleeves, a 4.2 crank, & Buick 300 heads.  I already have two 3.9 blocks, the 4.2 crank, the 300 heads, a full D&D bellhousing, an Edelbrock intake, & a NASCAR Holley 390 double pumper with mechanical secondaries & 4 corner idle screws.  I would be able to reuse my headers, engine mounts, mini starter, & flywheel.

Depending on the bore, displacement about 4.35L.  I would be happy with just 225rwhp or so.

[MG four six eight]

Quote (Was there an obvious cause for the piston failure other than a possible manufacturing defect? I do recall that early Ford 2.3 engines suffered piston skirt failure due to inadequate piston lubrication that was solved by putting an oil squirt hole in the rod. But I have heard of no such problems with the Rover/BOP family of engines.)

Larry brings up a good point.

Some of the Rover/BOP replacement rod bearings do not have the notches cut out for the rod squirter holes.
Back when I built my 10.4 to 1 compression motor, I noticed that the bearings were not notched and thought that is was kind of odd. Thinking that it was simply a matter of an updated part, I installed them as is.

Then 19,000 miles latter when I decided to supercharged engine, I tore it down and found excessive scuffing on all 8 pistons and cylinder walls. Due to the excessive scoring on the pistons/cylinder walls with fairly low mileage, I determined that the squirter holes do indeed need to be functional in order for the piston/cylinder wall to receive proper lubrication.

When building the supercharged engine with cast 8.6 to 1 pistons, I notched the ends of rod bearings with a Dremmel (spelling) tool. I ran the 8.6 pistons for a few years, before I decided to tear it down again and switch to forged pistons so that I could run more boost safely.
When I tore it down to install the forged pistons, there was no piston/cylinder wall scoring found when using the modified/notched rod bearings. Needless to say I notched the rod bearings when building the forged piston motor and will continue to do so on any Rover/BOP rod bearing that isn't already notched!

Bill

[BlownMGB-V8]

Hey Carl! At least you had ONE piston that wasn't leaking blowby into the lifter valley!

Jim

[MGBV8]

I was under the gun to get it back together in time for the V8 Meet.  I really don't remember a notch in the rod bearing for the oil hole.

I am just tickled that it held together with the abuse I subjected it to in West Virginia!  

[MG four six eight]

Glad you were able to get it back together Carl! Regarding the oil spray hole in the bearings, it's something to check for on your next build.
 
For those who don't know the original rod bearings had notches that allowed oil to be sprayed up on the piston, cylinder wall and wrist pin, via a notch in the rod/cap. This lubes the piston/related parts and just as importantly cools the bottom of the piston with oil spray.
Some of the replacement rod bearings do not have the notch which effectively closes off the lube port in the rod. Notching the replacement bearings is fairly simple to do using a dremmel tool though. The main thing is to go slow and slightly bevel the edge of the notch so that there are no rough edges on the bearing surface.

Bill

[BlownMGB-V8]

Also sprays oil on the cam lobes.

Jim