Performance Boats Forum banner

1 - 20 of 33 Posts

·
Sit N' Spin
Joined
·
1,423 Posts
Discussion Starter #1
Was out on the delta Friday and my boat broke down. Started it up, idled fine, motor sounded great. Water temp was about 140* and oil pressure was up at 50psi. Swung it up gradually to 4,000RPM and heard a noise, and the motor instantly died. Got towed in by a friend and as he was towing me, I turned the key, the motor cranked over kinda weak sounding, then it locked up.

On a hunch I pulled the valve covers off, and two of the pushrods are nowhere to be found! Somehow they came out and I'm assuming they ended up in the rotating assembly which is what is locking it up. I checked the oil and there's no water in it, so I doubt the pushrod ever punctured the cylinder walls. I haven't torn the motor apart yet.

What could have caused this to happen?

What are the chances of the rotating assembly being undamaged by the pushrod that is stuck in it?
 

·
steelcomp was here
Joined
·
26,512 Posts
Whatever it is, it's CStraub's fault.

Sorry...couldn't resist. (Inside joke)

This is always hard to diagnose without more info, especially over the internet so pictures would help, but something, for some reason let the pushrod out of the lifter. The lifter came out of the bore, and the pushrod went down through the lifter bore or through the lifter valley floor and disappeared. Yes, this is most likely what's causing the lock-up, but I'm more interested in why the pushrod left the lifter. What does the valve train look like? Any broken rockers or studs? Are any of the valves stuck open?
Something let loose before the pushrod came out of the lifter. That's what you need fo figure out.
 

·
steelcomp was here
Joined
·
26,512 Posts
OK...I re-read this a little more carefully. The pushrods could be laying in the lifter valley (most likely are) and the lock-up is from something else coming apart that in turn caused a valve to hit something, probably bending the p/r and letting it fly. Still need to look at the valve train for valves stuck open on those cylinders. Sounds un-good.
 

·
Angry American
Joined
·
3,103 Posts
Jon,
As I mentioned on the phone, there is a possibility that the push rod guide wore a groove in 1 or more of the rods and at least 1 let loose. I know that one from experience. When mine let loose, it took out the retainer on the top of the lifter which put a bunch of little pieces in the valley. I also found part of the push rod in the valley and the other in the head.
As steel said, there's a lot more info with pics needed to really figure out what happened and how.
 

·
Sit N' Spin
Joined
·
1,423 Posts
Discussion Starter #5
OK...I went out and pulled the intake manifold and discovered that the cam broke. It broke in 2 spots...right at the #8 exhaust lobe and also at the journal that seperates the 7/8 lobes from 5/6. Also some broken lifters were found. Here is a pic of one of them.



 

Attachments

·
Angry American
Joined
·
3,103 Posts
ahhh, good ole #8 exhaust. When I was in the pricess of rebuilding my engine, there were a few people on Hot Boat that had issues with #8 as did I on the engine I was running. I asked a couple of different machinists about it and they said that there were some blocks where that particular lifter boare was tweaked a smidge. It was never really a problem in the cars as they didn't see 5K in rpms very often.
In any case, when my block was done, all the lifter bores were addressed to help avoid problems in that area.
My guess is now the #8 lifter stuck for a split second, tweaked the push rod then broke the lifter. From there, all hell broke loose inside with bits and pieces from the lifter. As I said, just a guess.
Looks like a complete tear down is in the future.
 
Joined
·
1,011 Posts
I guess I got lucky a couple years ago. Going down the track I had an exhaust poli lock back off even with a girdle. When the push rod came out, that caused more pressure on the intake rod than it could take. That caused the intake rod to flex and come out of the cup and push on the folcrum. The rod then bent and opened the guide plate before it broke. I found the exhaust rod unhurt, the lifters, and half of the intake rod in the valley. I have screens over the return holes to keep junk in the valley. I had to replace the guide plate, intake rod and the valve.

Tim
 

·
E-7 Sheepdog (ret)
Joined
·
6,834 Posts
I wanna see broken cam pics !
I suspect you will in a few days. ;)


Looks like if the block survived that the lifter bores definitely need looked at closely on that alignment note.



That really sux Jet.
 

·
Registered
Joined
·
178 Posts
OK...I went out and pulled the intake manifold and discovered that the cam broke. It broke in 2 spots...right at the #8 exhaust lobe and also at the journal that seperates the 7/8 lobes from 5/6. Also some broken lifters were found. Here is a pic of one of them.



Hey at least you can do is circle the problem hil:)
 

·
E-7 Sheepdog (ret)
Joined
·
6,834 Posts
Did you lose a rod into your cam? Ive seen solid cams break or rods smack cams and break them. Good luck.
Seen that one happen myself.
 

·
Sit N' Spin
Joined
·
1,423 Posts
Discussion Starter #15
Not that I could tell. Looking into the lifter galley inspection slots I can see both cylinders 7/8 rods are still attached to the crank.
 

·
Registered
Joined
·
4,115 Posts
Not that I could tell. Looking into the lifter galley inspection slots I can see both cylinders 7/8 rods are still attached to the crank.
Chevrolets have inspection slots? Is that so you can see your broken parts?:D:)hand
 

·
Sit N' Spin
Joined
·
1,423 Posts
Discussion Starter #17
Chevrolets have inspection slots? Is that so you can see your broken parts?:D:)hand
Actually it's for proper oil drainage...something Fords have to be modified with for boat use :D
 

·
Angry American
Joined
·
3,103 Posts
Not that I could tell. Looking into the lifter galley inspection slots I can see both cylinders 7/8 rods are still attached to the crank.
but you can't tell if they're bent or if the caps have been stretched. When the crank comes to an abrupt halt, something is probably gonna give a bit even if it was only spinning using the starter.
 
1 - 20 of 33 Posts
Top