4.3 V6 Mercruiser with sheared disributor gear

jhorton

Cadet
Joined
Aug 25, 2003
Messages
7
My local dealer says he has 2000 of these engines out and has never seen it but it's happened. On a friends '89 Sea Ray 4.3L V6 (175 HP), the distibutor gear has some (about 1/3) teeth that are completely worn away, and the others show wear to the point that they are only about half as thick as they are supposed to be. It's hard to see but we also think the Cam gear is also worn (expectedly). This engine only has 200 hours on it and it has been regularly maintained (oil changes etc.).<br />Before we knew why it wouldn't run, I was looking at buying the boat after we got the problem-whatever it was-fixed. <br />So here are the options:<br />1) We remove the engine and put a new one in. Any ideas or recomendations on cost or places to shop for just the engine.<br />2) We remove the engine and go through it completely, for metal fragments, and try to determine why these gears went bad (lack of lubrication for some reason). And then we put it back in.<br />3) I start looking for a new boat, but for some investment in my time I can get this boat very cheap.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,241
Re: 4.3 V6 Mercruiser with sheared disributor gear

Well, My First Guess is,<br />Either the distributer, or the cam are Not original..... <br />There are at Least two different drive/driven gears used on Chevies... I Believe Cast Iron is used on a flat tappet cam,+ a Bronze gear on a roller tappet cam..... There may even be a Steel gear in the mix somewhere.... Your motor is just Mis-matched...<br />Either Way... Don't Give-Up on that motor... Figure out which is your Problem, Then Repair it... Those Few Filings will have been pickup by the oil filters... If All Else checks out, Go ahead and Run it... You'll have No Problem getting Another 1000hrs out of it... Then Rebuild It.....
 

P.V.

Chief Petty Officer
Joined
Mar 14, 2002
Messages
452
Re: 4.3 V6 Mercruiser with sheared disributor gear

Buy a new dist. from Merc. Get on with life. Do more boating! Have more fun!! Don't change the cam!!!!!!!!!
 

airman

Petty Officer 1st Class
Joined
Aug 9, 2003
Messages
332
Re: 4.3 V6 Mercruiser with sheared disributor gear

Bondo's right, the engine's probably fine. But either do all of the work yourself or make sure you're satisfied that the mechanic you choose will stand behind his work until the engine's fixed and running right. Nothing wrecks boating fun like chasing engine problems (and the people who fixed/caused them) all year. If it's cheap enough, you've got little to lose by trying to make that one work right.
 

jhorton

Cadet
Joined
Aug 25, 2003
Messages
7
Re: 4.3 V6 Mercruiser with sheared disributor gear

Well with the advice given here and others we've talked to we are going to put in a new distributor gear and see how it goes. <br />One possible cause, we've been told, is high oil pressure (why it's high we don't know), causing excessive resistance. Bondo, as far as the gears being mismatched my friend bought the boat with about 3 hrs on it, so unless it was changed prior to that (which is entirely possible I guess) it was that origonal.<br />The other thing we got was gas in the oil-presumably from the variance in timing due to the dist-cam gear interface. We have changed the oil so as long as that has no long term effects from it that problem should be solved.<br />So we'll put the new gear in and try it out. We were thinking we would take the dist. out after a few hours (or the end of the season) and see if there is premature wear.<br />Finally what sort of risk am I taking if I buy this boat? It seems small from the feedback I am getting, but if there is a chance of a new engine needed soon down the road I want to take that into account in my negotiations.
 

Northern Eclipse

Senior Chief Petty Officer
Joined
Jun 24, 2003
Messages
665
Re: 4.3 V6 Mercruiser with sheared disributor gear

jhorton have you checked the distributer shaft for play at the housing for a worn bushing or possibly even a slightly bent/warped shaft,any one of these conditions will promote uneven wear of cam gear, I had a delco distributer shaft bushing go bad in a merc 3.0 liter 140hp, causing some side to side play in the shaft, ended up replacing the entire distributer and yes cam gear was chewed up a bit..but not a total failure such as yours...just another note when this happend I had about 260hrs on that boat.
 

jhorton

Cadet
Joined
Aug 25, 2003
Messages
7
Re: 4.3 V6 Mercruiser with sheared disributor gear

Northern Eclipse, that's a good point. We will visually inspect the dist parts before we reinstall them. It's hard to see the cam gear very well but I think (and hope) it's similar to your situation-just a little worn. Have you had any problems with either gear since replacing the dist? How many hours out are you now?
 

Northern Eclipse

Senior Chief Petty Officer
Joined
Jun 24, 2003
Messages
665
Re: 4.3 V6 Mercruiser with sheared disributor gear

Jhorton I did pull the camshaft from that motor amd the gear was fine. its harder that the distributer gear, I just dropped in a complete distributer at that time complete with points and cap that was back in 1990 I sold the boat in 1997 with about 1100hrs No problems, but then again I used a mallory distributer as a replacement.
 

jhorton

Cadet
Joined
Aug 25, 2003
Messages
7
Re: 4.3 V6 Mercruiser with sheared disributor gear

After cranking the engine to rotate the cam gear for a visual inpsection, it seems the cam gear is worn more severly in some places than others, so it looks like we'll be pulling the engine to get that out.<br />But our biggest problem is we still haven't found the cause;<br />-Mismatched gears? Doubtful the boat was essentially bought brand new (3 hrs on engine)<br />-High oil pressure? We can spin the oil pump easily by hand so there doesn't seem to be excessive resistance there<br />-Bent/warped shaft/bad bushing? Everything looks ok there too
 

Northern Eclipse

Senior Chief Petty Officer
Joined
Jun 24, 2003
Messages
665
Re: 4.3 V6 Mercruiser with sheared disributor gear

I am stumped...The only thing I could think of and is a long shot at this point ..is it possible the camshaft itself is walking back and forth ever so slightly. You can't pull cam with engine in the boat??
 

P.V.

Chief Petty Officer
Joined
Mar 14, 2002
Messages
452
Re: 4.3 V6 Mercruiser with sheared disributor gear

See my earlier post!!
 

jhorton

Cadet
Joined
Aug 25, 2003
Messages
7
Re: 4.3 V6 Mercruiser with sheared disributor gear

Northern Eclipse, that seems to be one of our last causes. And no we cant take the cam out unless we remove the engine from the boat. :( This weekend we plan on putting a new dist gear on (this ones for you PV), and giving it a try. After we run it for a little while we will take it out and see if there is any damage. If so it looks like we'll be spending some of the winter pulling an engine-in a heated garage thank goodness.
 

kenimpzoom

Rear Admiral
Joined
Jul 13, 2002
Messages
4,807
Re: 4.3 V6 Mercruiser with sheared disributor gear

Have you determined what type of cam it is and what type of distributor gear it was?<br /><br />Roller cams use a bronze gear if my memory os correct, but dont quote me on it.<br /><br />Find out if you had the right gear for the cam. That will tell you something.<br /><br />Ken
 

Northern Eclipse

Senior Chief Petty Officer
Joined
Jun 24, 2003
Messages
665
Re: 4.3 V6 Mercruiser with sheared disributor gear

Well hopefully just a new gear will end the issue for you.Let us know how you make out....
 

jhorton

Cadet
Joined
Aug 25, 2003
Messages
7
Re: 4.3 V6 Mercruiser with sheared disributor gear

NEW INFORMATION :) <br /><br />We replaced the dist gear this weekend and took the boat out for a ride.<br />1) The oil pressure DOES seem to be high (which we were told could be one cause of wearing out the gear). It is 35 psi at idle (about 700rpm) and 75psi at WOT (about 4600 rpm). 80 psi is the top end of the gauge. I spoke to someone that has a V8 and he says his runs at a much lower psi.<br /><br />2) Still couldn't quite get a good look at the cam gear to see if it was worn. I'm trying to figure out what to assume on the cam gear. I have heard it is harder then the dist gear and the chances of it being worn heavily are slim any thoughts?<br /><br />So it runs now, but the high oil pressure is a major concern. What is causing it and how do I fix it?
 

Wellcraft 89

Petty Officer 2nd Class
Joined
Aug 5, 2002
Messages
158
Re: 4.3 V6 Mercruiser with sheared disributor gear

I've got a 89 4.3 that runs the same oil pressure ,you are talking about.Its been that way since it was new.Not had any problems you describe.<br />What weight oil are you running?<br />does this boat have a remote oil filter ?<br />If I remember when I added my remote filter the pressure increased slightly.<br /><br />If and when you take this engine apart,measure the end play or runout at the front timing chain.<br /><br />Do you know the entire history of this boat? <br /><br />You used lots of engine assembly grease on the new gear,we hope<br /><br />Rich<br />Does this boat stay in the water all the time?
 

P.V.

Chief Petty Officer
Joined
Mar 14, 2002
Messages
452
Re: 4.3 V6 Mercruiser with sheared disributor gear

Not the gear that's at fault, it's the bushings in the dist hsg! There's no support for the dist shaft!The bushings are supposed to be round, I suspect that they are oval/egg'd shape. You can often "see" the "out of round" condition by visually looking at the lower opening of the dist housing! If you can push the rotot/top of the dist shaft sideways AT ALL (away from the cam), Replace the dist. complete!!! I've had two this year alone!! Oh, well!
 
Top