Mrmerlin

if you have a vernier caliper you can check the head thickness to determine if the heads have been previously cut . Check the WSM for specs

fraggle

I've got that, figure I can follow the WSM and check it, but it is the flatness I'm not so sure about checking myself.

the flyin' scotsman

A glass plate with bluing applied or a good steel ruler and feeler guages can be used..............if the heads warped then you got to consider the block deck unfortunately.

fraggle

The glass plate idea is good one. If I get the right size plate I can check the block as well.

Given the fine condition of the cams (no hotspots etc), I don't think there's anything wrong here but to have it apart and not check is crazy. I'm basically praying for no machine work, as that moves me into a realm I'm not all that comfortable with.

fraggle

Heads are off. Lots of black scaling on the pistons. Gaskets weren't looking all that great but I don't see any obvious signs of failure around the combustion chamber (???) I'll be inspecting further after lunch. Is there anything I should be taking an escpecially close look at, besides everything?

Mrmerlin

look between the valves for cracks, seat to seat, also inspect the bores for cracks

fraggle

What a dirty mess. Need to get everything cleaned up so I can inspect it a bit better!

fraggle

No news in a while here!

Good news: Heads have never been decked, so I've got room there. Need to get them over to the shop so everything can be cleaned and checked for warpage. I did find a couple of divots in the combustion chamber, might be the reason my car seemed very octane sensitive.

The bad news: I'm not the first person in here. The following pics will speak for themselves.






I found NOTHING in the oil pan. Someone cleaned this out. There's no way this passed through and I missed it during an oil change.

I haven't gotten any further, but I really don't think my overheating problem is related to this damage. One of the cylinders was running 191psi, the other is one of the failed ones.

It still isn't what you want to find when you open these things up, that's for sure.

Mrmerlin

the plot thickens where are the broken pieces of metal or have they already been removed by the PO???
If you had a running engine with these pieces being broken then chances are it will continue to run

fraggle

Broken pieces are AWOL. This fail must have occurred at least two owners ago, because I know the last PO and he never had any fails. Records are weak beyond that so I'm on my own.

I have to assume it ran great in this condition for the previous 8 years before my heating problem came up. I'm sure that the fail made some big noise when it happened. I can't figure out what impacted the girdle to break it, though. Nothing seems to match up with the impact mark.

Mrmerlin

since there is damage to the block/ girdle it may have a micro crack into the cooling system

fraggle

But why would it run well for 8 years, then quit? Maybe I worsened something with the single over-heat incident - making existing damage terminal? I'm at a loss.

Leon Speed

Can it be that the rod loosened and smashed against the casing? Does the mark on the casing look somewhat similar to the side of the rod?

fraggle

THat was my first thought, too, but the edges of the rods and caps are just a little too wide to fit neatly in the impact mark. I also would think there would be a LOT more damage if a rod came lose and knocked around in there, but I'm not ruling anything out.

AT this point I'm not sure what to do. My budget here is already way smoked due to a recent salary cut, so I'm trying to do my rebuild as inexpensively as possible (notice I didn't say CHEAP!). Adding a used block greatly increases the cost and complexity a little beyond what I planned.

I'm half thinking to ignore this damage and plod onward with the original plan - Get the heads checked for flatness, machine as necessary, put in new headgaskets, then head back to putting things back together.

I haven't pulled any rod bolts off yet to check the bores any more than I can see than just cranking the motor over by hand, but they "look" good - however, I'm not an expert here. The number of motors I've taken apart is short, and the number that have gone back together is shorter.

Any and all advice would be appreciated here! My 928 is really depressing me.

SharkSkin

Wow, that's ugly. Maybe a rod let go in the past and it was replaced without too much fus?