Smoking, Low Comp - Reason Found

So I finally got a chance to remove the #2 piston from the engine which was pulled in August. The #2 was suspect due to very low compression in that cylinder and lots of blue smoke being generated. When I removed the piston, the top 2 rings fell out - each had broken in half. The expander rail is fine. So, looks like this would be the source of the smoking, yes?

I will post pics tomorrow whe my wife returns from a GS camping trip with my 'good' camera. I want to get an opinion on the bearings. They SEEM okay, but I am not sure how to tell if they are worn or not.

I am seriously considering just getting new rings and putting it all back together again. Don't have a lot of spare cash at the moment for a full rebuild, and I really want to try and get some driving in before the snow flies!

Dan S

Have the engine checked - damaged rings may have damaged the bore, in which case the new rings wont last too long and it may still smoke..

yes i agree with simon have the bores checked to see if they are in spec. if not a over bore and hone along with oversize pistons will be needed

Dan,

Some folks will object to what I am going to suggest but trust me, you CAN save some bucks and have that thing back together pronto with just a few things done and get very considerable service out of it.

Pull all of the lifters out of their bores and either label them or put them in some sort of wooden jig to hold them in their original order and keep the push rods tagged and matched to them.

Pull the oil pump, disassemble it and clean it well. When you put if back together pack the rotor and shafts with petroleum jelly. Make sure that the strainer is clean and free of gum and varnish. A can or two of carb leaner will do the trick there. Stick it in a big baggie until you are ready to put it back in.

Pull all the pistons and remove the rings. Clean the ring lands completely, first using the end edge of a broken compression ring and then a stiff bristle bush followed by some judicious use of carb cleaner. Clean, Clean, CLEAN!

Then remove the rod bearing inserts if you haven't already and clean the whole assemblies again with carb cleaner followed by hot soapy water. Blow dry well and let them sit for an hour or two to air dry.

While you are waiting set out individual sets of Deves rings of the correct bore and skim over the literature that came with them.

Now insert each ring set as directed, and set each assembly aside with the pistons in a large baggie.

Wrap each rod journal with a couple of rounds of masking tape and drape each one with a clean shop towel.

Hand scrape the block deck and the head face with several single edge razor blades until all traces of the old head gasket are gone.

Now use a dingle berry hone of the appropriate diameter and fine tooth in a hand held drill set at a relatively moderate speed and run it up and down the bore several times.

Pull the hone and wipe the bore with a clean cloth dampened with some solvent to have a look at the hone pattern. What you want to see is a pronounced cross hatch spread evenly all around and up and down. You also want to look for a ridge at the top of the bore. If it is pronounced, as in you can definitely feel it with your finger nail, beg borrow or steal a ridge reamer and cut that sucker away until you can't feel a step.

Once the ridge is removed go back and do your hone thing again, keeping mind to keep the whole operation washed down well with a mix of K1 kerosene and ATF.

Remove your hone often and recheck for complete coverage of the cross hatch pattern. Stop honing once you get the pattern every where and move on to the next hole.

Once all of the bores are prepared bring on the clean solvent and wash the whole block down as best you can over a big tub and let it drain well.

Follow that with a good bath of hot soapy water, Tide does well, and follow that up with as much rinsing as you can stand.

Use a CLEAN white terry cloth to wipe each bore down and inspect the cloth for dirt or discoloration. Repeat the cleaning and rinsing process until you end up with a CLEAN cloth. That will mean that all of the carborundum material from the hone has been removed and won't be in there causing early failure of the working surfaces.

Once you have it as clean as you think that you can get it, do it one more time for good measure and blow it all as dry and as clean as you can get it. Don't' forget to blow out any open stud or bolt bosses and any oil line that you can find.

Slather LOTS of engine oil onto the piston and rings sets, you can just dunk them in a pan full of engine oil and that will get lots of lube to the wrist pins too, and stuff them in their original bores making sure that the rod squirt holes are AWAY from the cam. It is a good idea to turn the crank each time so that the journal for that rod is at BDC.

After you get each set down in the bore remove the masking tape from the journal and wipe it down well with a clean cloth soaked in carb cleaner. The idea of course is to get all of the adhesive off.

Proceed with the usual pulling down of the rods and insertion of the bearing inserts. Remember to use either clean engine oil or engine assembly lube on all of the bearing surfaces. DO NOT USE STP or any sort of common grease.

Turn the crank through a complete revolution by hand after each rod hook-up to make sure that there hasn't been any mistake that would cause binding.

Repeat all of this for each cylinder until all are tidied up.

Next, install your cleaned up oil pump.

Follow that with a finger swipe of assembly lube on each cam lobe and stuff some into the distributor drive spindle gears.

Now put the pan back on. Remember, the Lord decreeth that you shall use NO BLUE GOO!

Now go clean each lifter WELL inside and out, one at a time and return them to their wooden home.

After the lifters are super clean and dry put a dab of assembly lube on each face and on their bore sides and insert them in their original holes.

Install the head and finish up with the insertion of your cleaned up push rods back where they came from and the rest of the usual engine assembly stuff.

BTW: You can probably benefit by a quick back yard valve job too.

Don't sweat the guides. Just remove the valves and rocker assembly, keeping each valve marked for re-installation in it's original home.

When everything is apart use one of those gnarly short stiff wire bushes in your drill to clean off as much carbon and top soil from the combustion chambers and ports as you can. Follow that with a good leaning with what ever you can manage, the best case of course being solvents followed by hot soapy water.

Once you have it all reasonably clean use a dab of valve grinding past, medium grit to begin with, and a hand held wooden lapping tool to lap each valve to it's seat. There is a technique that works best and if you don't know it ask and I or someone else will explain it in detail. Anyway pull the valve occasionally and wipe it's mating surface and the seat surface to see how evenly the seat is being ground. You want a seat on the valve to be about a 16th" wide and positioned so that it shows up about a 32nd" inboard of the outer rim of the valve face. Once done with the medium grit stuff move on to the finer paste for a final finish. Understand that we are doing a back yard refresh here so don't expect all of the surfaces to be exact or to even match perfectly one valve to another, but if you can get somewhere near to this you will be all right.

Anyway, when you are satisfied that the valves are going to seal lay all of them aside for a good cleaning and go back again and wash down the head well. Be sure to get ALL of the valve grinding paste out, and finish off with the usual hot soapy bath followed by a good drying out and a wash down with engine oil.

All tolled this little effort should only cost the price of some solvents, a set of rod bearings, a set of Deves rings and some gaskets on top of your time and patience but it will as I say produce a decent running motor that will get you by for at least several seasons.

Best of luck, Jack

Very nice detail Jack!!

Jack, thanks for that info. I will digest it for a day or two and see if I have any questions!

Thx, Dan D

I didn't mean for that to sound like a detailed lecture. I just wanted folks to realize that sometimes magnafluxing and working to a ten thou tolerance isn't needed or necessary.

It sounds a lot more complicated than it actually is. Just use your intuition and keep everything CLEAN. All you are trying to do is squash some air and gasoline without having it leak out before the spark plug ignites it and then have the working surfaces not trash themselves within the first ten minutes.

I have been reading a book on Chevy drag and distance engines and the guy goes into ultrasonic measurement of the darned cylinder wall castings to a ten thou tolerance but his basic premise and rule is to just use your head and keep stuff clean. The usual basics are the root and all the other stuff is just piled on whipped cream and cherries. The toppings really do taste good but they cost tons more money. If you've got it to spare that's a good thing but sometimes it isn't necessary.

Jack

Old School.

Jack-that is a brilliant posting. I am going to print it and use it. Thank you.

I do have a couple questions:

No blue goo? Does that mean you don't use gasket adhesive on the oil pan?

You said, "And stuff them in their original bores making sure that the rod squirt holes are AWAY from the cam."

I don't understand that...my conn rods are at the mecca getting new piston/rings put on them, so maybe it would make more sense if I had them in hand.

Can you explain that as well?

Many thanks

Matt

Ok, here are a couple of pictures -


Broken Rings


So what do worn bearings look like? Here are the rod and main bearings from cylinder #2 -

Rod Bearings




Main Bearing


Thx, Dan D

Broken rings have often been the culprit, especially when a car's performance sags or smoke comes billowing out the rear suddenly (well, relatively suddenly). Glad you found your problem. Follow Jack's outline and you should be good to go for less money and less time spent in the process. His process is just what I did to my old Datsun 510 I mentioned that had the collapsed oil control rings expander. That old beast soldiered on from 80K miles (fix) with no smoke or other issues until our family lost track of it at about 180K miles.

But why did the rings break in the first place? Both compression rings on one piston? I would suspect that the ring lands have been worn to the point that there is too much motion for the rings causing them break. I would at least check that before assembling it.

Those rod bearings look pretty bad.

Matt Ruch Wrote:

scottydawg Wrote:

I too used Jack's method with success when I was a poor hippy back in the 70's. One little thing to add about the oil pump. The end cap will have wear marks in it and this increases the end float and thus clearance. You can sand that on a piece of glass until the marks are gone. Turn it 90 degrees every 10 strokes or so to help keep it sanding flat. Start with 220 and end up with 400 grit or finer. Clean it real good before reassembly.