View Full Version : Visible rust on pistons

11-17-2018, 07:17 PM
Hi folks, Tom here, brand new to the Jeep world. Just beginning to dismantle a 51 3a. Allegedly has 23,000 miles but has sat since 1977, in a chicken coop. Planning to get down to frame, toss the body, and build it back up. Todayís question, (the first of many), upon pulling the spark plugs,I can see and flick around with a screwdriver rust flakes.... lots of rust flakes... I imagine now Iím gonna pull the head off for further inspection. Should I be scared and start planning for a new engine or is there hope?

11-17-2018, 08:30 PM
There is always hope. I would pull the head and check it out. Being that you were able to remove the spark plugs, tells me the head isn't in too bad of shape. I would not try and turn the engine over even by hand, until pulling the head. That much rust will just cause you headaches when scowered in between the Piston rings and cylinder walls.

11-17-2018, 08:51 PM
Yeah, pull the head. Lots of penetrating oil on head stud nuts. Twisting off a stud is an aw-pooh. A blown head gasket way back when could have let water into the top of the engine.

Shop vac out all the crud, use penetrating oil/brake or hydraulic fluid 50/50 mix to loosen things up before you try to turn it.

Slow is good here. Let us know what you find , pictures are always good.

Good luck.

11-17-2018, 09:04 PM
Hope is good, thanks guys.... slow is no problem, also putting finishing touches on 63 Buick Wildcat. Thanks again.

11-17-2018, 10:59 PM
I'd like to see the Wildcat. I like to see other cars that aren't Chevelles and Mustangs. A side project I have clogging up the drive way is a '65 Fairlane 500. The engine was stuck, but now turns with descent compression. Only problem now is all of the teeth on the flywheel are worn to nubs. When the starter is engaged, it turns an eighth of a revolution then the starter grinds.

11-18-2018, 05:30 AM
Oh so true about chevelles and mustangs. Vettes and camaros also. Donít even look at them anymore at shows.

11-18-2018, 11:05 AM
I had a '68 Dodge Coronet. It was not close to a show winner, but very drivable. I have had a soft spot for the executive muscle cars. Anyone can build a Camaro or Mustang.

11-18-2018, 02:03 PM
I love my Cat! Executive muscle car, I like that... also known as gentlemen’s muscle car. She’s pretty quick for a big girl.

11-18-2018, 08:50 PM
I had read that the Buicks were the executive muscle car, and the Monte Carlos were the gentleman's cruiser. I liked the fit and finish of the Buicks and Oldsmobiles. Even the Chryslers were good rides.

12-04-2018, 07:22 PM
Hey guys, I hope you still tell me thereís hope... just pulled the head, it came off without even a nudge. Same with the bolts.That is the only good news in my book. But my book doesnít have a lot of pages. Have you EVER seen a mess like this? Check out these pictures! This is gross! Still hope??? Forge ahead with the cleanup and the mystery oil? Or is it motor rebuild time?

12-04-2018, 07:25 PM
Here is the second pic I wanted to send

12-04-2018, 09:27 PM
That, my friend is ugly. The first shot from the hip would be to start figuring on a rebuild, and to be ready for a cracked block. Now, the optimistic side wants to dig deeper before condemning the engine.

First, vacuum out all that crud so you can see better what you have beneath. Drain the engine oil to see if the engine is full of water, instead of oil. Next, if no major issues are found, soak everything down with marvel mystery oil, transmission fluid, and any old cheap oil you can find to soak. This process will take the most patience. After soaking a while, attempt to wiggle the crank shaft with a socket and breaker bar. If there is still a build up of rust in the cylinders, use a dingle ball hone to clean up the cylinder walls. If no cracks or deep gouges are found, then there is still hope even if the Pistons are still stuck. I say hope, but by this time, if the engine shows no signs of budging, then it will be time to start a rebuild.

12-05-2018, 07:53 AM
visual inspection not enough, need measurments, and dimensions from qualified person to measure bore, lot of metal there and hope is not lost, believe me first thing is to vacume all of it out, then got to strip the block down to bare metal, all the way

12-05-2018, 11:29 PM
As pelago says, you need some measurements and if you don't have the right equip for that then you need a good machine shop. The worst hole needs to be cleaned, honed and measured to know that it is still within tolerances. It is not only the cylinders but also valves, valve seats, rods, and mains. it's all steel and can be rebuilt, just how deep you want to go into your pocket vs finding a replacement cost.

12-06-2018, 07:45 AM
I've looked at the pictures and yeah - ugly, but as I look at them I have to wonder where all of that stuff came from. It had to have fallen off of the head. How rusty is the head?

Does it have a lot of carbon deposits?

Can that stuff be carbon deposits that have fallen off the head - and not really rust? My curious self just can't see that much metal turning to rust in such big chinks.

12-06-2018, 12:56 PM
It appears that the engine has spent time underwater. Whether the rust came from the exhaust system, and filtered up into the engine? Is it rust or mud deposits? It isn't impossible, but highly unlikely that the head has flaked off that much, unless it was in salt water, in a warm climate. After going back and re-reading the post, he said that the head studs and head came off easily. If that was rust accumulated in the cylinders, then more than likely, the head would be fused to the studs. Even the head gasket is in decent shape, and the block surface doesn't look that bad.

12-06-2018, 06:11 PM
Vacum the bugger and send more pictures, blast it out with air compressor also,, and do as the man suggested breaker bar and socket and lots and lots and lots of marvel mystery oil

12-10-2018, 09:53 PM
I think the top half of this engine was a rodent motel for decades... lower half seems okay, oil was normal, green antifreeze still in there. 3 or 4 valves seem rusted to the block. In no hurry at all to try and move anything. Just soaking the pistons in mystery oil and keeping the valves wet with penetrating oil. Still dismantling the rest of it down to the frame and now playing with the Buick.

12-10-2018, 10:21 PM
It's a lot more promising than I expected. The block looks darned near perfect under the valve guides. Spray them down, smack the open valves with a rubber hammer. Looks like you may get away with a new set of valves/valve guides, and new valve seats. This visual assessment doesn't figure in to the cylinder wear, but having good coolant and full of oil is a great sign.

12-11-2018, 09:54 AM
you know, oil and heat do a lot of things,,, loosen things up, apply some heat with a propane torch, then some oil, then a block of wood and a 16oz ball peen/machine hammer and tap it some, not heavy but some taps with block of wood on metal... might see some stuff start to move and that helps in dismantle. been there and done it

12-13-2018, 06:03 AM
Thank you Pelago and gmwillys. You clearly have done this before and you both give me hope. I’ve been diligently and gently scraping, cleaning, oiling, and massaging that top half while I pick away to get it down to frame. I’m in no rush at all as I tend to the Buick also. I get my engine hoist back from being loaned out in January and I’ve sourced a reputable engine rebuild shop. Gonna wait till after the holidays to try and move the pistons. Keeping busy, staying warm, and picking away... a rather perfect winter, I’d say. I’ll let you know how it goes... Thanks again.... Tom

12-13-2018, 07:19 AM

Patience is the name of the game. Jeeps are simple machines, but they are a lot more quirky then your Buick in comparison. A GM corporate engine is more forgiving, and will run/perform descent even when everything is not perfect. For an example, I had a neighbor that purchased a '70 Olds 442 W30. He was a body guy by trade, but mechanicals scared him. I watched him do a long smoky burnout down the block, but I could hear a bit of a miss at the higher RPM, at the exhaust. We checked the plugs and found that two cylinders on the right bank were not burning consistent to the others. I checked the valve lash and found to exhaust valves were loose. When adjusting the lash, the two that were loose needed to be tightened much farther than they should have been necessary. Upon further inspection, one exhaust push rod was bent, and the other was a temporary adjustable push rod used to measure correct length for ordering the proper length after a cam change. The push rod was never meant to be used for running the engine. The neighbor then decided that he would have his buddy the drag racer rebuild the engine for him. That went alright until the next summer when he would cruise around town. He started consuming a quart of oil every time he went to town. After looking at the build sheet that the drag racer put together, I found out that he used single ring light weight pistons. The pistons were designed for low miles, (a 1/4 mile at a time). This is why it would consume so much crude while driving around.

In my opinion, when looking at a machine shop, I would look at one where there is at least one guy who is in their mid to late 60s or older. These guys understand flat heads and cast iron. On the M38A1 that I did the body work on, the engine was sent out by the owner. The machine shop was recommended by the local military vehicle club. When the owner tried to start it for the first time, it was hard to start and ran like crap. When it did start, it leaked all over. The cam was not in time with the crank, so the timing was way off. Half of the gaskets were either torn or the surface wasn't prepped for a good seal. Whatever the shop had charged, it was too much for what they did. Due diligence is important to ensure you have a good result. Do your home work on the reviews of the shop, plus talk to anyone who was dealt with them.

12-13-2018, 12:36 PM
read and heed!!
rebuild is first dismantle, then measure, then repair and finally re assemble. for strict dollars and sense you reassemble, you be present when machine shop measures, you decide on new pistons and what size (oversize pistons readily available). you be there when crank measured and inspected, you decide on how much crank metal to remove (bearings all sizes readily available) putting one of these back together is not all that hard. only thing i would do is to align engine for cyl one to fire and mark the timing gears with a punch and photgraph it for re assemble. hell if old retired infantry guy like me can do it,,,,,,,,,,,,,,,,,,,,,,???