Need input on post-teardown evaluation/decisions. Bonus: Gory cylinder pic
 

Got tired of bodywork, so I decided to tear the engine down this weekend. Some of you may recall that a year or so ago, I discovered a broken rocker under my intake valve cover upon initial inspection. I had assumed that a valve stuck and smacked the rocker, and I moved on. No such luck!!! It appears that enough oil seeped into the cylinder (#3) (past the rings, or the exhaust valve guide) that a fair amount built up. Upon trying to crank the engine, the oil caused a massive pressure buildup. The valve did not open, and smacked the rocker. Simultaneously, the pressure in the cylinder blew the cylinder apart (see photo).

Need input on the following topics as I prepare to order parts and machine work:
-rebuild goals are cheap and reliable. The five-figure engine is next, but this project is el-cheapo. Nonetheless, if there are any obvious and/or cheap upgrades I can do while I'm in here, what are they?
-Should I replace the 2.4E cylinder and piston that died with a suitable used replacement? Or seek a good set of 2.7l P&Cs. Or 2.2. Or something else. What would be the incremental machine work and parts (and costs) required?
-Does it make sense to have the heads decked a few thousands while they're in for a valve job? Is it worth the extra effort to gain a bit of compression?
-Yes, I've got the steel studs and magnesium case. Do I see time-certs in my future? If so, bottom AND top?
-Anything else you guys can think of? Let 'er rip.

The engine's not all bad news. Bearings and crank look great, new clutch in there (the SACHS isn't even worn off the clutch surface), new alternator, new updated valve covers, carrera tensioners, and MFI.

Hmmm. Wonder what that Harley-Davidson ratchet strap is doing around your cylinder?

-zuff

I won't even get into the "Ghetto" tactics employed by the "experienced" engine builder supervising my engine disassembly. But the ratchet strap was to relieve tension on the studs from the cylinder so we could remove the broken cylinder. Props to "zuffenhausen" for this idea, and his garage, and his engine stand, and his carb cleaner :D

Probably the cheapset route is to replace the damaged parts. That is if your other pistons are within spec. There are alot of dismantlers out there that should have what you need.

Bobby

You can't go to the 2.7L pistons without upgrading the case. In fact, I would recommend replacing the studs with time-certs if you care at all about this motor.

But if cheap is your goal, then just replace everything that is out of spec.

I would pay careful attention to the rod on that cylinder. Hydraulic lock like you experienced places a lot of stress on the rods, and you might have bent it. It may be worth removing for inspection...

-Wayne

And I thought the tub had some holes in it...

:D

BUMP!

Come on guys! I figured you'd all have a field day with this. Drop some science on me!

Ahhh.....no "science" from this quarter, Dave, but do tell....is that a crack in the cylinder wall I'm seeing in your picture?

Simultaneously, the pressure in the cylinder blew the cylinder apart (see photo).

But the ratchet strap was to relieve tension on the studs from the cylinder so we could remove the broken cylinder.
:rolleyes:

If you decide to just replace the damaged P&C keep in mind that the cylinders come in height groups and the pistons come in weight groups so just any P&C won't do. Make sure you get ones from the same group as you have.
-Chris

Doug - Not so much a crack as a Chasm, crevasse, or rift

Chris - OK, will the machine shop know what measurements I need? and will used parts houses also know what I'm in need of?

DTW,
The pistons and cylinders come as a set so you may be able to go by the height group of the cylinder. I don't know what engine year you have but if it was say, a '72, there are 2 Groups "5" or "6". I forget where it is but there is a # on the side of the barrel someplace. It might be inside a triangle. I can't remember all the details but at least you have an idea.
-Chris

Chris (and JW, Tyson, Roland, Warren, et al.),
10-4 on the cylinders. But, do the pistons also have a number that notes the weight group? If not, how do I make sure I get the right one for replacement?

Here's another what-if: what could I expect if I try to replace the cylinder that's blown, then replace ALL the pistons with a set of 2.2E pistons? Would this be a good performance increase? What else would be required? (Rods, wrist pins, bearings, MFI recalibration, machine work?)

Can anyone recommend some good places to try for good-quality used pistons and cylinders?

Dave:

If the heads are "decked" the relationship between the cam gear to the cam chain, and therefore to the tensioner changes. Not a good thing unless the cam gears are changed to accomodate the difference in deck height. Very expensive, and not a good way to increase compression, IMHO.

I agree with Marc that decking is not recommended to increase compression. However, decking to make everything flat again is a Good Thing. I think is this probably more necessary with 2.7's. I just had to have my 3.2 case decked so even later cases are not immune. Check your case.
-Chris

There are definitely marks on the pistons identifying weight, saw this somewhere, (factory manual I think). One of the pros here should know where to look.