You ever seen this?

[75starflight]

Finally got a break from all the rain today and got phoenix fired up for the first time this year.

Found that the one common part between Phoenix's old 120 and her fresh 140 caused the camshaft damage last year. The distributor cam gear roll pin was cracked almost the full length of the pin causing it to move and throw off the timing. New roll pin is installed and timing is set. Now I just need to run her for 5 hours change the oil filter, then run another 5 hours and then do a full service.

[dorelse]

glad you found the source of your issues!

[Hyperacme]

A small $1 part caused all that grief ...
WoW !

Guess it's always the little things that bite ya in the rear end !
 

[Jerry]

I don't think that was the problem. The Dist. gear couldn't move as long as the pin was in one piece. Somebody's feeding you a line I'm afraid. Look for something else.

[Plugcheck]

I changed my dizzy drive gear when I put the new bumpstick in, there can be metal compatibility issues between this gear and the cam.  I would be skeptical believing this pin failure would be the culprit.  Have had these shear off before, but the engine dies immediately which is good since you now lost oil pressure.  If I remember correctly your camshaft gear walked off?  Typically hydraulic grinds are self centering, rollers require end play.  When you get it back together, take some time with the timing light and notice if the timing hunts around.  Even small end play issues can cause significant timing change.  Maybe you, me, and Tim could have a test and tune before Rathbun?

[75starflight]

I don't think that was the problem. The Dist. gear couldn't move as long as the pin was in one piece. Somebody's feeding you a line I'm afraid. Look for something else.

Thank you Jerry, but here is my thoughts.

When I removed that pin from the gear it only took two wacks with a punch and hammer to remove it. Then I put the cracked end of the pin back in the distributor and it pretty much dropped back into the gear up to the line on the dark end. I really believe that the roll pin was pushed out by centrifugal force when I would go to WOT. It would also explain the difficulty i had adjusting the timing on the 140 at the end of last season when the camshaft timing gear pressed part way off the end of the cam shaft.

Plus, when I tore down Phoenix's old Mercruiser 120 (back in January) I could find absolutely nothing wrong with that engine. I tore it all the way down to the bare rotating assembly and could find nothing wrong. Timing gears are all in good shape, valves are all in good shape. The only explanation I could come up with for the timing getting as far off as it did (enough to allow exhaust to come back through the intake side of the manifold) is that roll pin working its way out.

Additionally, what brought me to that conclusion is the distributor is the only common part used between the old Mercruiser 120 and the 140 that is currently in Phoenix.

[Jerry]

Whatever I've only been a Journeyman Mechanic for 50 years.

[75starflight]

I changed my dizzy drive gear when I put the new bumpstick in, there can be metal compatibility issues between this gear and the cam.  I would be skeptical believing this pin failure would be the culprit.  Have had these shear off before, but the engine dies immediately which is good since you now lost oil pressure.  If I remember correctly your camshaft gear walked off?  Typically hydraulic grinds are self centering, rollers require end play.  When you get it back together, take some time with the timing light and notice if the timing hunts around.  Even small end play issues can cause significant timing change.  Maybe you, me, and Tim could have a test and tune before Rathbun?

Honestly I thought it was a shear off before I got the pin out since the engine died right on the spot after putting it in WOT and would not restart. I was dumb founded to have the pin come out in one piece. I came to my conclusion of the pin working its way out when I saw the crack 75% of the length of the pin and then placing that end in the cam gear and it slid in the length of the crack with out a hammer.

I will be checking my timing over the next few nights (when it isn't raining) I plan in putting 10 hours on the engine and doing a few filter changes to make sure all the metal from the camshaft issue is removed.

[75starflight]

Whatever I've only been a Journeyman Mechanic for 50 years.

Jerry, I know you know what you are talking about and you have helped me several times. All the information is get from every member of this group is valuable since this 140 is my first engine build.

But, I am the type of person that starts with the simplest and cheapest solution first and then works my way from there. If this issue pops up again I will be replacing the distributor with a new one to see if that will solve the issue. This engine would have gotten a new distributor when I built it, but I ran out of budget when I had to buy a different cylinder head and a different manifold during the build.

[Jerry]

Check the end play of the cam. there should be a plate that keeps it from moving back and forth.

[75starflight]

Check the end play of the cam. there should be a plate that keeps it from moving back and forth.

yep did that when I put the new camshaft in last fall. it meets the spec of my service manual.

[75starflight]

Check the end play of the cam. there should be a plate that keeps it from moving back and forth.

yep did that when I put the new camshaft in last fall. it meets the spec of my service manual.

But i do have that thought in the back of my mind.

[Plugcheck]

Your engine has a direct drive helical gear set, which could account for your cam gear walking off.  On vw engines, that I know well, we used bolt on cam gears and full can thrust bearings.  I am not intimately familiar with setting or adjusting the cam end play in a merc 140, never had my 140 apart, but you will need to understand it well.  I wonder if any resistance to the valve train that would cause the cam gear to walk off.  As for any metal parts in the pan, the only way to be sure is pull the pan, but a strong speaker magnet on the bottom of the pan could help.  They also make magnets for the oil filter, but this is after the pump.  Keep us apprised, and good luck Brandon.

[75starflight]

OK, I want to get these great minds thinking. One question keeps popping up in my head on the roll pin.

If it wasn't the roll pin causing my problem, what would have caused the distributor to rotate hard when I went to reset the timing during trouble shooting last august.

edit:  just food for thought when the distributor was turning hard is when the timing gear pressed off.

[Plugcheck]

Not certain what you mean by the dizzy turning hard.  As in the shaft turns hard when off the engine, or the body is hard to turn when running when you are setting the timing.  I'm curious to know if the roll pin would come out far enough to bind the camshaft?  I would guess the pin would show damage.  Hard turning and bad roll pin would have me disassembling the dizzy right now, its possible that something is binding the shaft up which could account for your issues.  Heck, the roll pin removal is the worst part of dizzy disassembly

[Jerry]

The cam was pushing against the dist. base.

[Plugcheck]

Could the dizzy from the 120 not be compatible with the 140 engine. Brandon, I would be doing some research and checking.

[75starflight]

Nope same dizzy

[Plugcheck]

I assume your running a drop in electronic ignition module, so the shaft should turn easy with no binding.  I would look closely at the gears that drive the dizzy and oil pump.  Does the oil pump turn without binding?  I would check by driving it with a drill, in the same way you ore oil an engine.  With the dizzy and plugs out, does the rotating assembly turn over smoothly?  Sounds like your in the hunt, just have to troubleshoot.

[75starflight]

Nope running points set I removed the electronic module. Oil pump turns by hand. And the distributor gear shows no excessive wear. And the engine turns by hand as it should.