Well new to me D4 pony threw a rod cap 3 weeks back. So i tore into it polished crank turned new main bearing on lathe. Replaced bad rod. New bearings and seals rings etc. Hined bores with 80 grit and gapped rings lapped valves. I budengines army shop so not new to this. Set valve clearance carb was redone. It fores right.up but I'm somehow losing oil andthere is some super bad blowby.. When I checked rings I shone a light from behind and saw nothing so assumes they would seal well. Plugs are tan. I also cut the slots in the manifold gasket ..
Might run it some and see if the rings break in.. I.am.running Lucas 30 weight break in oil hoping it gets better :/
Not that I know anything about this, but you've got a picture there of the manifold gasket on a diesel engine, but you say the carb was done and the plugs are tan. So gas motor or diesel ? Joe H
It mentions starting engine so I'd say a gas pony starting engine.
So what's the manifold gasket info have to do with it?
Last paragraph says pics. are of starting engines manifold gaskets.
Check top pic: it says starting engine, the lower gasket is for the main engine. Its gas -
not sure if that has sth to do with the blowby - i doubt it but just confirmed that I did follow the updated design. far as i could tell all that seals is crank gas basically - should not have anything to do with blowby but maybe i missed something.
DIESEL engines,
joe i think the document is specifying the STARTING engines ON those diesel models as there is no model number on the starting engines no. Read the 1st sentence - it states "starting engine con rod failure". Besides that upper gasket is IDENTICAL to the starting engine manifold gasket -
I understood what you were saying from start. Thinking rings are not broken in yet. Too much oil in the crankcase , what oil weight are you using ?
lucas 30 weight break in just cos i have it lying around - man i build alot of engines this is nuts. i thought maybe sth in the vent system was weird- rings did seem a little dodge but overall they went in fine and i gapped them chamfered the edges bla bla bla. This thing was CLAPPED out and ran fairly well before it threw the rod cap out 180 degrees..
there is also a whine in motor and i think there is maybe not enough lash between the ignition unit gears- might have to pull intake manifold which means pulling motor cos i dont think you can get a good seal against main engine without tilting the pony back to slip seal in- should have bench ran this b4 dropping it on. luckily all the hard work is done and it shouldnt be too hard disassembling- ill do a comp test today- as mentioned i did shine a flash light behind rings and didnt see anything past ring and bore surface so figured it shd be ok- ring quality was very below average- anyway it had 80 grit hone job pretty rough sure those rings should have started breaking in- ill do a few more runs and see if it starts improving otherwise ill yank and recheck and order other rings.
How many hours since this overhaul? I'd be guessing the rings are all worn down due to that rough road in the cylinders. . Curious, why the lost rod cap? Bolts not tight?
oh i ran it yesterday for the first time- rings that came out were pretty bad (see pic) but it actually still kind ran ok- less blow by than now! dam this thing is spitting oil out the top. I might have over filled so will check later when i get down to the shop. one cylinder had zero valve clearance. i thought spec was 12 thou but after setting to 12 (well that involves grinding the valve stem!) found online docs that spec it at 8 thou.. oh well little less compression. I guess i can reweld with 7018 / oil quench and polish back down for 8 thou if i have to go back in. . the split pin came out and nut backed off is my guess. it got toasted. I blue loctited mine and put in all new split pins so they not going any where.. it was carnage this was the ring gap b4 tear down- rod cap looks completely redesigned-
Both pics. are for starting engine gaskets as per the last paragraph. One for 4 1/4" bore 6 cylinder engines and the other for D17000 engines. I don't get all the confusion?? It's pretty clear 1940 english to me.
Split pin ? Do you mean a cotter pin, AKA cotter key, other pins that are split are roll pins. I'm a nomenclature person.
well the darn mag shaft snapped today not good!! might have to visit a machinist friend to try xome up with a plan.
Mag shaft breakage is usually caused by too much end play in crank usually caused by locating pin problems in front main bearing. There are alternatives to end play control discussed on ACMOC requiring machining.
I machined a new crank bearing on the pulley side and reused the flywheel bearing as it was ok.. I added material to take up the end play it's down to about 15 thou now.. I'm thinking the combination of tighter tolerances stacked up paired with possibly a ightly thinner manifold gasket (unconfirmed) led to too much gear load.. mag did slide in but teethhad almost not play so after heating up it probably tightened up and fatigued the shaft.
Can anyone confirm if the mag shaft key ways are inline going to attempt to machine a new shaft if welding doesn't work out well..
How long did you run it? Did you have the drive engaged so the main engine was turning? If the main isn’t turning you don’t have water flow for cooling.
i was running the main to gdt it going almost fired up- i do keep an eye on head temps and the pony has been fine otherwise..
Good deal. Just makin sure.
I work on all.kinds if marine engines at my shop so always have to keep an eye on everything..
Mag gear must have some back lash or shaft breakage can occur. may require gasket thickness change to get the required clearance.
old magnet agreed- noticed it was pretty tight but thought hmm its timing so maybe its ok- mag went in easy without hassle. flywheel might have off round wear or as i suspect tightening up the crank endplay moved flywheel to fresher part of the mag gear (tighter). i might double up a gasket and will def check it upon reinstallation.
well the intake gasket got delivered today - its significantly thicked than mine, but both are thicker than this guys rtv he had in there before. I beveled welded and turned it back down on the lathe got to within a thou run out which is not bad for my junky sb9- will see how it holds up. excuse the nasty welds, it was the alum housing throwing sparks everywhere. someone borrowed my welding helmet and set the brightness so i high i got eye arced and couldnt see jack. anyway turned most of that down. I had to reverse engineer the timing using the points opening as a firing reference and eye balling the gear a few degrees BTDC. Real hack but anyway will see how it runs once i get it back together.
Only shows 1 pic. and looks like it got magnetized. Hopefully it works OK.
yeah initially i tried a butt weld and the aluminum spattered around- cut it, bevelled it and rewelded it - so thats not going to affect anything. just looks plain ugly. The main bearing on the pulley side came out perfect and I added 50 thou into it to take up end play (i took measurements before disassembly)
80grit seems mighty coarse to hone with
yeah its all i had just took it easy- i use flex hones. either way hopefully the rings will break in soon with that- i did have some light scoring on one cylinder so it certainly helped speed up the cleaning process-
I know you are not out of the woods yet, @CamaroMan , but it looks like you do nice work. Thanks for posting it up.
those are the magneto magnets- real mess when machining! picking those bits off by hand is a real chore. started wrapping it with tape but they tend to stick everywhere.
Impressive work on a small Southbend. I still have our little SB that my dad taught me on many moons ago. Even though I don't use it for really anything anymore, I can't get rid of it. Too many memories.
Tx well it actually worked. Pony fired up and ran great I actually managed to get main engine going for the first time in 30 years- I do have an oil leak and suspecting ignition issues after it’s ran a while maybe coil is heat soaking or something.. after a while it wont restart. If it fires up cold there’s def an issue there I need to investigate- in my experience points can and will stop firing when hot- not sure if it’s the condenser or points themselves- I’ve always deemed condensers to not really fail. I do have more advance than before but Its running fine can always find a rec mark and hook up a timing light