another pony issue

You do't need special toll and you could check in same time the camshaft or its could be the piston ring are broken and I dismantled many poney
and never see a broken valve spring .

I took the top cover off today, and two springs are broken, both on the same side. The broken spring was'nt really the problem because the breaks are pretty close to the end. The problem was the valve was stuck in the guide. The spring was compressed and this let the whole assembley move back and forth in the casting, making me think it was a broken spring. I figure while I'm in here I should replace the springs, one of them however is rusted to the block and trying to free it I broke the guide. I think now I will cut the spring to remove the valve and then I will be able to drive out the rest of the seat.

Both areas that house the valve springs dont appear to be getting any oil. They are rusty. I know that some oil is supposed to get in there through the gaps in the gaskets but maybe because this is a marine application and the engine is not sitting flat, this is'nt happening. I think a good solution would to to drill and tap a hole in each area so that I could periodically squirt some oil in these areas to keep this problem from happening again. Anyone have any thoughts on this idea?

Last year I dismantled a d6 poney from 318cat. and was stop for 20 years
and when I removed the top cover(manifold) surprise it was like brand new and make sure your manifold has no crack on that side.

Hi Bruce,
I believe the following article may have a possible answer for your problem, it is from the Sept 13 1945 Service Magazine on oil levels for Marine Starting Engines, albeit, for the D3400-4400 and 4600 series engines, the same theory will hold true.
As stated in the article the Marine Engine OMI's explain how to do this for both the Pony and the Main Engines-(if needed)
At the Dealer we used to have to re-calibrate the dip sticks on Some re-powered truck engines as well as Any Marine Applications.
I believe that the pony's on the later engines are similar enough that this should work for you or give you somewhere to start from.
Perhaps with the top manifold/cover off you could check the actual oil level at your front-highest-conrod and adjust the level accordingly to suit as per the attached diagram and then re-mark your dip stick.
Hope this helps.
Cheers,
Eddie B.

edb, thanks for that info, it makes perfect sense. I am going to the boat this morning to cut out the valve with the broken guide and I will check and see if the dip stick has been re-marked of not.

I still like the idea of drilling and tapping two holes in the block so that I can occassionally squirt some oil on the valve stems, and would like to hear anyones thoughts on this.

Also I have noticed that some of the later ponys had a crankcase ventilator. Mine does not, and on a boat there is alot of moisture in the air. Especially a wooden boat. There is always some water in the bilge.

Hi again Bruce,
the pony breather is on the manifold/top cover and is a part of the air cleaner piping system. It sits between the carby and the air cleaner, it is below the air cleaner pipe and helps support the pipe.
Also to the left center of the flywheel in the rear face of the top cover is a breather for the pony drive geartrain housing. It is only a flat disc of felt with a perforated steel disc held in with a circlip. It may be broken off as it is made of diecast pot metal and is very fragile. They also block quickly as there is little effective area to filter with. If it is broken off all you will see is about a 3/16" hole through the stub of the breather tube thread which is only a 1/8" npt thread.
As for the oil addition to the valve chests via holes strategically drilled into the block sides would not hurt if it can be done, are there any water passages up this high in this area? This area is normally lubed via the cut outs in the top cover gasket and therefore is just a mist that then drains out the slits? in the bottom, If I Recall Correctly, been awhile since I did one of these jiggers. Perhaps if your oil level is not correct then this problem will be addressed with the level correction. As gemdozer said they normally do not break springs and these areas are not normally rusty. Way back in early days there was a SM article to cover making those slits in the gaskets and I'm sure that was for the 4 1/4" bore engines.
Hope this helps and not confuse you.
Cheers,
Eddie B.

Edb, that crankcase breather is not there, just a rusty plugged hole where it used to be. I'll try cleaning it out. There are no passages in the side of the block where I am contemplating drilling the holes, and it is only about a 1/4" thick.
Those slots that are cut in the top cover gasket does not look like an effective way to get some oil on the valve stems. Also consider the engine is sitting at an angle and a boat is almost always listing a little to one side. Add to this the fact that the air in an old wooden boat is laden with moisture, no wonder the valves get stuck. Cat knew this was a problem because the operators manual said the pony should be run every week and if it was'nt, to remove the spark plugs and add 1/8 pint of oil. I like the idea of removing a couple of pipe plugs and squirting in a little oil directly on the stems much better, given the fact that the valves angle downward.

Hi edb,
That little 1/8 in. pipe pancake breather is not a gear housing or crankcase vent.....it actually ties into the bottom (side) of the intake runner.....never see mention of it in the literature but I believe it is a raw gas drain from the bottom of the runner in case of carburetor flooding. Also amounts to a vacuum leak (small orifice) if it isn't already plugged. Not a good feature for a marine engine so I would hope that it is plugged off. All the more reason to be sure and shut off the gas when pony isn't being run.

D318 Marine,
Check to see if your pony has the copper drain tubes and fittings (2 sets) that drain the valve chambers. These are provided to route drainage to a low windage pressure location in the crankcase. May not be the reason for your situation though as missing tubes usually cause excess oil to accumulate in the valve chambers at the expense of the main sump level.

[quote="Old Magnet"]Hi edb,
That little 1/8 in. pipe pancake breather is not a gear housing or crankcase vent.....it actually ties into the bottom (side) of the intake runner.....never see mention of it in the literature but I believe it is a raw gas drain from the bottom of the runner in case of carburetor flooding. Also amounts to a vacuum leak (small orifice) if it isn't already plugged. Not a good feature for a marine engine so I would hope that it is plugged off. All the more reason to be sure and shut off the gas when pony isn't being run.

D318 Marine,
Check to see if your pony has the copper drain tubes and fittings (2 sets) that drain the valve chambers. These are provided to route drainage to a low windage pressure location in the crankcase. May not be the reason for your situation though as missing tubes usually cause excess oil to accumulate in the valve chambers at the expense of the main sump level.[/quote]

Old Magnet, after looking at my parts book again, it appears that the earlier marine d318's like mine are supposed to have a tube going from the top cover to a little can under the closest cylinder head. Maybe I'll just leave it plugged.
The drain tubes are there, but on the side that had broken springs, it was clogged.