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New B&S 15.5HP 28N707 has arrived - some ?s


Paul78zephyr's Avatar
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11-30-05, 06:48 PM   #1  
New B&S 15.5HP 28N707 has arrived - some ?s

Hi to all,
I hope everyone had a great Thanksgiving!

Well my new B&S 15.5HP 28N707 engine arrived (actually Monday) and I finally have got around to un-crating it. Just in case you did not follow my earlier threads I am the guy whose 9 year old 28N707 siezed, was un-siezed, got a new head gasket, then spit out its connecting rod - in three pieces! I bought this new engine via the internet from Willards Small Engines.

So my old engine was a 28N707 Type 0173-01 built 8/30/96 (Code 960830ZD). My 'new' engine is a 28N707 Type 1026-E1 built 11/02/99 (code 991102ZE). So if am to interpret the date code correctly my 'new' engine seems to been sitting awaiting a home for over 6 years! Anyway it looks brand new and it came with the factory 2 year warranty. The large label on the red sheet metal blower housing says 'Diamond I/C' where my old engine just said 'I/C', Im not sure the difference there. The new engine has a stamped 'honeycomb' steel blower screen that appears to be mounted such that you dont need to remove it to remove the red blower housing. My old engine has a molded plastic blower screen that needed to be removed before the blower housing could be removed. Seems like just a minor design update. Everything else seems the same. I will need to reuse my old (original) muffler.

Right now after looking the new engine over my main concern is with the 4 mounting holes in the lower crankcase that the engine mounts to the tractor frame with. These holes are not threaded. My old engine is mounted with bolts that come up thru the tractor frame and either go into threaded holes in lower crankcase or these bolts are self threading. I looked up the part number for the bolts used in my tractor (Sears/AYP 17490620) and the description comes up as 'Bolt, 3/8-16, Thread Rolling'. I measured the inside diameter of the holes provided in the new engine and they check .344 -.348. I know the proper tap drill size for a 3/8-16 UNC thread is 5/16 (.312), so the holes are too big to be tapped and still get a full thread. So should I reuse the existing 3/8-16 'thread rolling' bolts - how much force will it take to drive them in? Should I try to tap the holes with a 3/8-16 tap? Should I use 5/16-18 bolts and nuts in the existing holes? Should I try to drill the holes out to accept 3/8-16 bolts and nuts? Other?

Once the engine is mounted and set up is there anything about getting it 'well lubed' prior to initial startup, especially since it seems to have been sitting for so long? Should I fill the engine with oil and crank it over a bit with the sparkplug removed, etc?

Cheese, your input would be especially appreciated as the issues I ask about are probably uncommon and are best answered by someone with firsthand experience.

Thanks to all,
Paul

ps I haven't got around to posting the pics of my old engine with its new 'crankcase inspection window' and '5 piece connecting rod' but I have taken the pics and just need to get them developed and put on CD.

 
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v8driver's Avatar
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11-30-05, 10:10 PM   #2  
no, the engine was put together with assembly lube, just add oil and start it. follow break in procedures..... for the bolts to mount the engine, you can use bolts long enough to put nuts on the ends to hold it down, i'd use a little bit of thread locker.

 
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12-01-05, 12:25 AM   #3  
Hello Paul!

I always use the old bolts to self-tap the holes when they are installed. They seem to stay tighter this way, since the bolt has tapped the hole to itself. I use a 1/2" drive impact gun, but be careful not to tighten them so tight that they strip or you'll have to put through bolts in it with nuts on the end. You can install them easily enough with a 1/2" drive ratchet. Get them tight or the engine will eventually get loose.

The diamond I/C is no different from the regular I/C. The only difference would be the height of the cooling fins on the flywheel (to allow for the screen to be below the shroud rather than above it). I've seen no benefit to one over the other.

I usually don't do anything about pre-lubing the engine, but you can put a quart in it just before installing it on the mower and slosh it around in such a way that it oils the cylinder and other moving parts if you want to.

Another thing you can do now that may save you some trouble in the future is to put anti-sieze on the exhaust bolts and the crankshaft where the pulley slips over it.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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12-07-05, 07:20 PM   #4  
Hi guys,
Thanks for the input and sorry for the delay in posting.

I have the new engine all mounted and ready to go but have not tried to start it yet due to the very cold temps right now here in eastern MA.

I used my impact wrench to remove the tractor mounting bolts from the old engine. I needed to jack up the front of the tractor with my floor jack to make room for the impact wrench and required extension. Once the bolts were out and everything else disconnected I went to lift the old engine off the tractor just to have the double pulley on the output shaft hang up on a belt guide that I did not notice the pulley would not clear. Another bolt/nut and the guide came off and then I was able to lift the engine off. I layed it on its side on a milk crate and used my impact wrench to remove the pulley bolt from the crankshaft and the pulley slid right off. I put the new engine on its side too on another milk crate and put the pulley and bolt on, running the bolt tight with the impact wrench. I also decided that I would pre-thread the bolts into the engine as there is a little room under the tractor frame an I wanted to be absolutely sure the bolts threaded in correctly. I started each bolt by hand with a socket, extension, and ratchet wrench and once sure the threads were engaging straight and clean drove them in all the way with the impact wrench at reduced power and in small bursts - as you suggested Cheese. I also put a bit of anti-sieze lube on the threads as well before running them in. I then removed them with the impact wrench (what would I do without my impact wrench!!!). These bolts make nice threads as I was able to put each bolt back in by hand after that. With the mounting holes now threaded and pulley installed the engine dropped right in and I threaded the bolts in from underneath, tightning them securely, but by hand, with a socket, extension, and breaker bar.

My old engine had a short length of threaded pipe and a 90 degree fitting with a plug on the end for the oil drain. The new engine only had a pipe plug right on the engine. Without the extension pipe the oil would drain out all over the tractor frame so I needed to swap the drain pipe to the new engine. I guess I assumed the new engine would have no oil in the crankcase but when I removed the drain plug a lot of oil came out (and drained out all over the tractor frame, and a bit on the garage floor!). But I was going to put fresh 5W30 in it anyway.

So I am just waiting until the temps get a bit higher before first startup. Considereing this 'new' engine has sat for 6+ years it can wait a few more days. I will update when it runs.

Thanks again,
Paul

 
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12-08-05, 01:53 PM   #5  
since you have 5w-30 in it now, its ok to run it in the cold.

 
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12-17-05, 07:22 PM   #6  
Hi all,
Well I finally got around to starting the 'new' engine. I drained all the [6 year old] factory oil and added 1-1/2 quarts of fresh Castrol HD 30W. I used 30W as I not planning to use the tractor again before spring. I used to plow snow with the tractor but I just bought a brand new Toro 1128 OXE Power Max Snowthrower with the 11HP Techumseh Snow King engine (OH318SA). We just got 16 inches of snow last week and the snowthrower was great. So I wont need to use the tractor to plow anymore.

Anyway I reconnected the battery, removed the spark plug and just cranked the new engine for 30 seconds or so before putting the plug in and trying to start it. Fresh gas in the tank, a little choke and she started right up no problem. I let it run for about 20 minutes and even took it for a little ride before shutting it down. I probably wont start it agin until spring. So all in all getting the new engine and installing it was not a big deal and the $450 that the new engine cost was alot less than the $1200 to $1400 to replace the tractor I have. I'm also getting an hour meter for it so I can accurately stay on top of the maintenance and I have made a promise to myself to check the oil level and keep it correctly filled all the time.

I still cant get over the fact that the engine has an ALUMINUM connecting rod. Even the lowlyest of auto engines use forged steel connecting rods. As I understand it no other part of an internal combustion engine takes more mechanical stress/abuse than the connecting rod. I undestand that one of the most common engine failure modes of these type of small engines (at least B&S) is connecting rod failure.

I can't remember where now (Ive read so much about these engines in the last 2 months) but I read somewhere that the head gasket on the B&S OHV engines should be changed every 100 hours of operation. Perhaps if I had done this I would have found my original problem before I let my 'fix' destroy my engine. Has anyone else seen this? Also the original engine maintainance schedule that came with the tractor (the Craftman manual that covered the entire tractor) called for the first oil change after the first two hours of operation and then every 25 hours (or seasonally) thereafter. That made sense to me. The new B&S manual that came with the new engine calls for the first oil change after the first 5 hours of operation and then every 50 hours after that. That seems a bit too long and I plan to e-mail B&S concerning that.

Finally what do you all thing about an engine friction reduction treatment such as Slick 50. I used to think the stuff was a good product and worthwhile and treated many a car engine with it. But now, a bit older and a bit...well a bit older, Im not so sure. Any thoughts?

Thanks again to all that gave input and advise,
Merry Christmas
Paul

 
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12-17-05, 08:55 PM   #7  
actually its not more for briggs connecting rods to fail, tecumsehs have more of a tendency, briggs connecting rods are very strong, still though, they don't put up with the forces delt with in a car, they run 3600 rpm all the time, max, very strong rod, heck even tried to blow a briggs 3.5 up removing the governor....didn't work ....... and that was running a 22inch deck, dull blade through foot tall weeds. does the new engine have a oil filter? then i'd use the 25 hour regimen, 50 hours is good, oil's have improved alot since the old oil change regimen....they even recommend syns. use mobil one myself.... plus you'd adjust for dirty conditions, as for slick 50....... its not good stuff, they were sued for false claims i beleive......the teflon did nothing but clog oil passages and clog the crosshatch in the bores....beleive briggs did a study on that as well, one engine treated, other not. one that wasn't had less wear. you can search more on that, as for the head gasket, never heard of changing it every 100 hours...... now when problems arise..... then check it.

as for craftsmans deal on oil changes.....didn't even recommend changing the oil after the 5 hour breakin......of course it had the new 18.5 hp intek avs, oil filter caught the break in metals...

 
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12-17-05, 10:03 PM   #8  
The aluminum rod doesn't seem to be a problem in small engines. Most rod failures are a result of damage caused in some other way (mostly from running low on oil, as you've seen firsthand). Steer clear of slick50 and most all oil additives. A good synthetic alone is far better than any additive.

There is no scheduled maintainence on the head gasket to my knowledge. If there's a problem with it, change it, but not necessary until then. Some of these engines run until they're completely worn out without ever having a problem with the head gasket.

50 hr oil changes are fine with a good oil, especially with synthetic. In fact, you could probably go longer with synthetic as long as it's still clean. Once the engine gets a few years under it's belt and begins to dirty the oil more quickly, then change it as often as needed.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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12-17-05, 10:47 PM   #9  
yes synthetic oils are far better then using any oil additive though as for slick 50 they are owned by quaker state, good oil, bad additive.... owned by sopus, shell oil products u.s., again, good oil, bad additive....
http://www.evergreenamerica.com/dura-lube_slick50.htm more on everything...
only oil treatment that i would use would be the valvoline synpower oil treatment, just because its not damaging, and just adds more of the additives already found in oil's today. as for your engine, if you want to go the syn route....break it in good on conventional, syn will just be a waste draining it early getting wear metals out.

 
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