5.0 cobra belts and pulleys

Steveo666

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Hi, I could do with some help with my 5.0 ho OMC Cobra (1993) I was out yesterday for few few hours and all was running well. Good power. Good temp. Boat has been running great all season. Then on returning home up on the plane the engine died. I investigated and found a belt had gone ( no problem I thought as I always carry spares ) On investigation the top pulley assembly had split open and this is why the belt had been destroyed. On further investigation it looks like the lower pulley assembly is now out of line with the others. So I'm guessing the pulley split open and the belt slipped in, got jammed gave the lower pulley a yank. Needless to say I had a tow back to the dock. I'm wondering if this will have damaged the engine? The temp gauge went up after the engine stopped ( as expected ) At the very least I'm going to need some new pulleys and belts, but should I expect any other problems? Any help or advice would be very useful Thanks Steve
 
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bruceb58

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The crankshaft pulley is a harmonic balancer so it sounds like the rubber may have failed.
 

jerryjerry05

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Try taking off the pulley's and turn the motor over or even start for a bit.
Look at the balancer and see if it's running true?
 

Steveo666

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The lower pulley is not running true at all. It is visibly on an angle and the top pulley is split in two. Can anyone suggest where to get a replacement pulley set.? Haven't been able to start since this happened. ( only tried once just after I lost the belts )
 

Bondo

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The lower pulley is not running true at all. It is visibly on an angle and the top pulley is split in two. Can anyone suggest where to get a replacement pulley set.? Haven't been able to start since this happened. ( only tried once just after I lost the belts )

Ayuh,.... It's a 5.0l, but Chevy or Ford,..??
 

Steveo666

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Hi Bondo

Its a Ford. this is the engine number 502APRJVB

Ive included a photo of the split pulley wheel.
(You can just see the lower crankshaft / harmonic balancer pulley wheel which is now out of true)
 

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SpitAndDirt

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This is what I will be getting for my motor when I install it back in my boat.

http://www.cvfracing.com/Ford-Small-...p/sbfe2kit.htm

Now, you say that the pulleys don't run true. Are you talking about the pulley or the harmonic balancer which is what the crank pulley bolts to? The picture below is Dayco part number PB1203N which is a 3 bolt style. If you look inside your crank pulley you should have 3 bolts holding it on. RockAuto.com has it for $114 Beats trying to find a OMC part that probably will cost 3x as much if this actually is your problem. I've heard of Harmonic Balancers separating at the vulcanized rubber before, but never on a boat. This would be a first for me.

If you check out my resto thread, I have pretty good pictures of my motor. I assume that yours looks very similar, unless yours is fuel injected.

By the way, trying to locate factory OMC pulleys is probably best done on Ebay as the original ones are either no longer available or prohibitively expensive or BOTH.

Uploading more detailed pictures of your problem would really help!
 

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Steveo666

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It's The crankshaft pulley that is now out of alignment. I will be taking the boat out of the water over the weekend so will have a better look and take some more photos. Judging by the way the top pulley has split open I think would be a good idea to replace them all. Those alloy ones look ideal to me. Thanks spitanddirt
 

Redrig

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wow, I didnt realize you could have catastrophic failure like that on a balancer.

At worst I thought it could just walk a few degrees on the rubber and thrown your timing off over time. Learn something every day , good luck with the fix!
 

Bondo

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REDRIG;n8665283[B said:
]wow, I didnt realize you could have catastrophic failure like that on a balancer.[/B]

At worst I thought it could just walk a few degrees on the rubber and thrown your timing off over time. Learn something every day , good luck with the fix!

Ayuh,.... It Ain't the harmonic balancer,.... It's the Pulleys, which bolt to the harmonic balancer,....
 

SpitAndDirt

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Just to add to my original post, I have already purchased this pulley for my power steering pump. I opted to go with this seller's design because it has the steel hub. The original "deep dish" steel pulley puts a lot of stress on the hub if it's not a solid press fit. I don't have any pictures available of my installation, but I can tell you that it fits perfectly, excellent craftsmanship. I feel I definitely got my $115 worth. The power steering pump used on our engine is used by both Ford and Chevy. So don't be fooled by the description.

http://www.ebay.com/itm/BILLET-ALUM...UISER-CHEVY-/160371742411?hash=item2556e696cb
 

Steveo666

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So... the boat is out of the water and Ive been able to have a good look at the pulleys.


Thanks SpitAndDirt for your help and advice. I took a look at your build thread and my motor is almost identical to yours

(Just more rusty! Ford engine number 502APRJVB)

I have ordered a replacement pulley set and power steering pulley (from your links above) so that's on its way and I will get them fitted as soon as I can.

The water pump pulley has completely split open but most concerning to me is the lower pulley (crank) which is now on a odd angle.

I have tried to photograph it but its tight for space in the engine compartment.


The pulley is totally out of alignment with the other pulleys and the photos don't show it too well.


The pulley is tightly bolted onto the Harmonic balancer and doesnt look bent or deformed, but the whole assembly - pulley and harmonic balancer is on an angle


Could the harmonic balancer failing cause this? Or am I looking at something more serious?


Can I just get a replacement and bolt on when I do the pulleys? where would I get one from?
 

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Lou C

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That looks like either a salt water boat, or there was a water leak for a very long time on the front water pump. I've never seen one of those pulleys rust through, even in salt water use unless there was a leak right on that area for a long time.. It looks like the pulley split, put side force on the pulley on the harmonic balancer and pulled the outer end of it out of alignment. You need to replace the harmonic balancer. It takes a special tool (remover and installer) to do it.
On some engines the harmonic balancers just seem to fail at a certain age and mileage. I had to replace the one on our 4.0 liter Jeep a few years ago. The rubber layer in between the 2 halves of the balancer fails and starts to come out that allows the outer half to slide outward or inward. It can rub against a timing cover and wear a groove in it or even damage a radiator in an automotive application. The balancer is most likely not marine specific but a Ford part.
 
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Steveo666

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It's a salt water boat.

And I think it's also possible that some water has been leaking onto that pulley. ( All the pulleys are rusted on one side - so it could be storage related )

So it's time for new pulleys and also a harmonic balancer.

I have found the remover / installation tool. Just need to source a harmonic balancer.

It looks like I'm going to have to remove the seat so that I can get to work on the pulleys and the balancer.
 

SpitAndDirt

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The Harmonic Balancer I told you about in post #8 should be a perfect replacement, if indeed your outer ring has separated. You may have to do some visual comparisons to verify.
 

Silvertip

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Grasp the crankshaft pulley/harmonic balancer and wiggle it. If the balancer moves side to side you have a broken snout on the front end of the crankshaft. That is not a good thing. I say that only because it does happen, and loss of the belt should not have killed the engine. A broken crankshaft would have. That would make the harmonic damper run crooked for just a very short time causing the belt to break the upper pulley. I think you have more going on here than everyone thinks. But then I've been wrong before ------- once I think!
 

Steveo666

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Thanks again SpitAndDirt. Not sure how I missed all the info in post #8

I'm hoping it's nothing more serious.

I will see if I get any movement on the crank pulley.

I'm not sure I'm going to have time to get this repaired before it needs winterizing. Might have to skip the fogging oil this year.
 

Steveo666

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I got some time today and whilst waiting for the pulleys and harmonic balancer to arrive.
I thought I would try and get the engine and sterndrive drained of water just in case we get a cold snap.


I got a good grip on the lower pulley and tried to move the crank pulley......Nothing. No wobble. No movement.
I had wanted to pull the spark plugs and try again. But I ran out of daylight.

I think I'm going to have to pull the engine to get this sorted.

I will update this thread as things progress
 
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Steveo666

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Engine is out.

Looks like slightly more of a problem than some pulleys and a harmonic balancer!!

Crankshaft is busted. And have a hole in the case

Engine is more rust and less metal.

Time for a new engine?

Also have saltwater damage to the Gimbal housing and shift hose.
 

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