237 teardown/rebuild has begun

[wallytoo]

began the "search" to discover the reason for the two blown headgaskets a while back. i know that the #1 piston ate the upper compression ring and threw part of it through the top of the piston. what else would i find? after removing all exterior components (and taking photos and putting parts in labelled bags), i could get at the oil pan. only broke two exhaust/intake studs, and there's enough of each to get them out without special tools.

flipped the block over, and removed the pan. upon inspection, the rods/caps are all numbered. i carefully removed the caps, gently pushed the rods/pistons into the cylinder, and removed the rod bearings. i found out why the engine smoked and burned a little oil. every single #1 ring was broken, most in several places. the piston itself had a hairline crack running from the ring grooves down to the skirt. in addition to the #1 piston, the the upper ring pieces in the #6 piston had begun to distort the head. same for the #2. #5 was ok, and so was #4. #3, however, when it came out of the cylinder, came out in two pieces. a giant piece about one-quarter of the circumference of the piston, along with the remainder. amazing that it stayed together in the cylinder.

after looking at it, i'm amazed that it even ran, let alone that i ran it for over a year. so, complete new pistons are in order. i'm going to have the shop check the rods to make sure they aren't bent/cracked. the rod journals look good on the crank. camshaft also looks good, with no obvious wear marks or worn lobes.

tomorrow i hope to finish pulling the innards out, by removing the main caps and timing gear/cover.

oh, and the oil pickup was nasty.

[Dave72dt]

Have the shop check the pin bushings for wear and the big end of the rods for out of round. Now is the time check and repair as needed so you don't end up with an annoying tick when it's once again running.

[Young Ed]

We need pictures of this carnage

[Jim Yergin]

when it came out of the cylinder, came out in two pieces. a giant piece about one-quarter of the circumference of the piston, along with the remainder. amazing that it stayed together in the cylinder.

Here is what could have happened if it hadn't stayed together. This was in my 230 after 3000 miles on my rebuild with surplus nos pistons. This is what I saw when I removed the head. No loud noises just very rough running and then oil/coolant mixture surging out of the oil filler tube. Given your experience, I think my piston must have had a similar crack.

Jim Yergin

[Young Ed]

Jim that picture is just sickening.

[wallytoo]

pics of the piston carnage.

first is the piston where a chunk broke off. upon further inspection, all but one piston had cracks similar to this one, but hadn't yet "exploded".

next are two where the rings are just starting to push up into the piston head, because the multiple broken pieces overlapped

finally, the damage where the busted ring pieces pushed up through the piston head, ultimately blowing the headgasket.

[greg g]

Wow!!! I wish some one would explane the reason for these failures. I read somewhere that the original pistonw were finish machined to an oval shape to provide for some expansion, but to keep the pistions from growing to the bore. I wonder if these were after market pistons that are failing after a rebuild or "overhaul".

[wallytoo]

i suspect that the failures in mine are attributable to overheating. probably occurred prior to my ownership. with excessive overheating, the rings become brittle, and that's as good a reason as any for why 5 of the upper rings came out in multiple pieces. some had broken into more than 10 pieces. may not have had anything directly to do with the pistons themselves.

[Don Coatney]

Many forum members (myself included) have removed pistons that look like this. I drove the car into my shop with this piston.

[wallytoo]

Many forum members (myself included) have removed pistons that look like this. I drove the car into my shop with this piston.

no doubt. these are pretty tough engines. as i stated, i drove it for a year and a half with those pistons in more or less that condition, until the ring pieces finally pushed through the top of #1.

[wallytoo]

block, rods, head, and crank are at the machine shop being checked. block will be cleaned and 'fluxed to determine whether any further work is warranted. hope it checks out.

[wallytoo]

update on progress, which has been slow, but is moving forward again.

back in feb/march, the machine shop did their thing. bored the cylinders to .060 over, installed a completely new valvetrain, ground the crank .010 under, milled the head and block, fit the rod bushings and wrist pins, etc.

sat in the garage until a few weeks ago. installed the rings on the new .060 over pistons. installed the new main bearings and crank. then had to find a rear main seal (VPW - thank you very much!!), because the one i had been sold was a bolt to the outside of the block type, and my block doesn't have that. installed the rear main, then the rods/pistons fit to the cylinders.

put the oil pump back in. got the oil pickup assembly back on (taking pictures of it beforehand really paid off), then went to work on the timing gears/chain. needed to make a new oil tube for the crank gear lubrication system. used some steel brake line and a steel cable holder, and bent it to fit. should work. installed the new timing chain (after aligning the marks, and making sure #1 was TDC). used thread sealer/teflon on the timing chain cover bolts that pass into the water jacket. got the balancer installed over the crank, and added the jaw gear to the end. that's where i finished for the evening. hope to have just about everything else installed by the end of the day tomorrow.

[Dave72dt]

Well, we've seen the ugly pictures. You'll have to show us the pretty ones now.

[wallytoo]

maybe not pretty, but better than before:

[Dave72dt]

Looks much better. Definitely going in the right direction.

[Jerry Roberts]

maybe not pretty, but better than before:

Most of it is pretty . Those freeze plugs look like they haven't been set enough though , maybe it is just me .

[Jon1953B4]

More piston carnage for you guys to enjoy. Bought my jeep from a guy who said the motor overheated and eventually just stopped working. I got her home(cheap) then pulled the head.(see attached)

Jon

[Dave72dt]

Do you suppose it made a loud noise during it's last minutes of life? I remember years ago being passed by a car rattling so hard I could hear it in my vehicle. Passed us, the vehicle in front of us, pulled into our lane and promptly blew up and slowed so fast we almost ran over it.

[wallytoo]

snow (25") has been removed from truck, and truck is now in the garage, awaiting the installation of the engine. hope to do it tomorrow, and have it on the road by monday.

[grey beard]

Wally,

That oil nozzle you fabbed for the timing gears is supposed to have an oil orfice in the end - not just a piece of tubing. When I pulled my engine apart this nozzle was plugged solid with sludge and the chain could be removed from the gears with my fingers, but it ran and idled beautifully before pull-down. I also had several broken pistons and had to replace the set, but my cylinders were still fine and the taper was not too bad. My crank is still standard - rods and mains - and everything is going vefy well after more than 2000 miles this past two years.

Best thing that ever happened to my truck was the 3:76 rear change from the original 4:56 - wow, what a difference.

Good Luck

[wallytoo]

engine is now reunited with the truck. need to install the transmission, pedals, hand brake, and all the engine accessories & hose hookups.

[aero3113]

Did you take any pics? I like to see the work in progress

[wallytoo]

no pics. i'll try to take some tomorrow as i make more progress.

[wallytoo]

it runs. took a bit of adjusting to get the distributor correctly aligned so that the points opened at the correct time. once that was correct, it fired up instantly, on 1.5 year-old gas that was in the tank. without a recharge of the battery, which also sat in the truck for 1.5 years. it idles nicely. i need to adjust the clutch a bit, as the release bearing is riding the fingers.

[Dave72dt]

Gotta feel good after being down for that long. Ever determine what exactly caused the head gaskets to go?