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Dist gear failure


Well-known member
I`m running a 455 Buick,been running fine for 5 years other than when I tried running cheap gas. Took it out tonite and it was running normal,all of a sudden it poped twice and died.brought it home and check it out and the gear on the dist was chewed up and took the gear on the cam out. What causes this? Never had a problem till tonite. The boat sat for a month,but I started it and ran it for a little while in the yard,no problems till I went out.
Only thing I can think of is the usual...... BAD LUCK, hope it gets fixed soon.
Thanks fish,but it`s gunna cost about 700.00,so it will wait till my 4wheeler sells :cry: So much for my 150 getting done anytime soon

I love them Buicks but they have one drawback. They have a weak oiling system. We never saw the failure you described but everything we sold was DD. Seems the oilers can cope with it DD but when ya speed it up the oill system especially in the heads needs improvement.

There was a book out back then "Hot Rodding The Buick" that had great oil passage solutions. Im concerned with this failure you may have an oil gallery in the block plugged up. Fortunately its easy the way the front accessory housing works on the buick to get in there and check it out. I would pass sopme keroscene through the oil galleries to clean them before you put the new gear and cam back in.

When you pull the cam, make sure none of the cam bearings have rotated and the oil holes no longer lign up. Im just thinking out loud here and it may be none of this, it could be s simple material failure, but I never saw it in any of our engines. There is a spec somewhere about vertical travel in the distributor shaft, if there is wear in the distributor and the shaft has enough travel then the gear on the end can possibly climb on top of the can gear leading to disaster. Same for the fiber washers under the distributor or a lose hold down clamp. Not saying this is what happened to you but its things to double check as you get into it.

Biggest Buick problem we had was folks couldnt leave their timing alone once we set it. Seen a bunch of good pistons converted to ashtrays like this.

If ya want a second set of eyes to look at that as ya pull it apart, let me know. Always willing to help where I can.

Scotty,I appreciate your insite.I`ll check all the things you mentioned.I have all the oiling mods done on this motor trying not to have oiling failures.I have it set to not go above 4500 rpm,and there suppose to be fine to 5000 rpm with out oil mods.Is it possible the oil bypass stuck putting to much load on the gear? The rigging is to high for my engine hoist or I`d pull it today.Have to wait till next saturday for my buddy to make arrangements to use a fork lift.I`ll call ya and maybe we can get together and pull it down. Thanks

Do you know how to check the mesh on the two gears when ya put it back together?

Its fairly important you not be running on either end of the gear or at the edge of the teeth.

If ya wanna mess with it today, call me and well take that distributir down on the back porch and inspect all the little goodies inside and see if you got wear in there.

Scotty,I went to my property after that post to mow the grass,tractor had a flat so went to have a few beers :lol: I pulled the dist back out and tryed to look it over,looks good to me but I`ve never pulled it apart.I would be grateful if you would check it.After looking at it more today it looks like the to gears got to far apart and ate each other :? Somethings up this don`t happen for no reason,and I damn sure don`t want it happening again rite after I put it back together.If it does it mite find it`s self with a case of sledge hammer idus :lol:
Whats your schedule Monday man?

Bring it over and well find what happening. Well take the shaft out and check the bore with a light and then well check the shaft, and then well check side and end play. Then Ill show ya how to check the gear mesh when your ready to drop it back in the engine. You likely already know most of this and just dont realize you do. Its far simpler than it sounds.

Scotty :wink:
One thing myou mentioned and I forgot to talk about was the oil pump. Now that the distributor is out, take a long screwdriver and try to spin it. If it turns easy then try a long whatever in the drill and spin up some oil pressure and see if it spins easy for 2-3 minutes.

Looking at the gear, the wear is not symetrical all the way around there is a spot where the teeth are worn all the way through and the rest of it is about 2/3 worn through. Makes me think something is loading the shaft in one direction or the shaft isn't true. I'll know more about that tomorrow. All of the wear all the way around the gear seems to be about even placement from top to bottom. Not running high or low, seems about centered. When you can check and see what the cam shaft end play looks like too.

Ok Ill check more on it tomorrow.

Is this thing belt or gear reduction or is it DD??????

Its gear reducted. The oil pump was free,I spun it for about three min.with a screw driver and it turned free,other than the drag of the oil.I pulled the pump off tonite and slowly disassembled it,The relief plunger was stuck bad.Could that be the problem?Causing too much load on the gear at higher rpms? Them oil pumps are out infront of the timming chain.
I have never seen one stick, but in my mind if its stuck it could at someRPM put a sure nuff load on it. Enough to cause a catastrophic failure, I'm just not sure.

Maybe Waterthunder can chime in here and lend some expertise about the bypass being plugged. I'll call my boy in a sec and see if he has seen it as well.

Talked to the kid and he says to spin up the oil pump with a drill motor and see what your oil pressure reads with the drill running wide open.

He also said to pull the spring and see if the ball is still stuck, thats a really heavy spring. He further said check the cam real close because the cam gear is hardened and may not be hurt even though it ate the distributor gear. Gotta check it to know.

It was stuck bad enough that I had to use a screw driver in the slot to rock it back and Fourth to get it out :shock:

Heres some fuzzy cell phone pix of the shaft and odds and ends today. note the Marlboro Box.... there is a Queen Fireant I found inside the distributir. This may be your BUG ! LOL

You can see the scoring on the shaft at the lower bushing, and the pitted rust area above that. Neither are good but neither will keep it from working, there is not any excess play end to end or side to side. There is a shot of the full length shaft and the gear sitting to one sied. The pix of the hold down part and the single "E" clip is how it came apart. There are now 2 E-clips there and not shown is the missing snap ring under the reluctor. Just for everyone elses info, this was a new-rebuilt distributor a few years ago. New and missing parts, hows that folks for rebuilders.

Note the wear spot from a heavy load on the side of the oil pump drive. A little shine here is normal but I see pressure wear there. Nothing that will harm the distributir or oil pump but its more than I have ever seen right there.

Was going to comment on something else. Oh yes ! The shot of the end of the casing shows no real vertical wear or pressure at the washers above the gear. No hard wear in the bushing or around it. All is snug, but the scarring on the shaft matches inside the busing inside.

The rotor button nose was bent from a hit with the distributor cap at some point in its life, I stuck a new cap from another distributor I had here on it. Its never been run in an engine, I got it new for the distributor for some experiments I was doing a couple years ago. Just ran the distributor with my battery powered drill. The button is new, though not yesterday LOL.

This distributor should run fine with a new gear, I see nothing to kill it. Just a bunch of little stuff thats more of a curiosity than damaging.

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