Challenge: Engine Diagnosis

[Jesse]

Wait, I just had a thought, the altrnator just might turn at two to one and access to it would be easier than engine internals and easier to remedy with no damage. A bolt through the pulley could stop engine rotation at nearly 180degrees.

[Celestialsailor]

Originally Posted by Jesse

Wait, I just had a thought, the altrnator just might turn at two to one and access to it would be easier than engine internals and easier to remedy with no damage. A bolt through the pulley could stop engine rotation at nearly 180degrees.

The belt is loose to alleviate the pulley's...sorry.

[DeepFrz]

JohnL, the camshaft has a 1:2 ratio to the crankshaft. It takes 2 revolutions of the crankshaft for 1 revolution of the camshaft.

[Cheechako]

Oh, we're gonna loose some sleep on this one... PS:You can have the head off that engine in about 1/2 hour +.....

[Celestialsailor]

Originally Posted by Cheechako

Oh, we're gonna loose some sleep on this one... PS:You can have the head off that engine in about 1/2 hour +.....

The head will be the last thing to come off a almost $200 for a head gasket. I will remove the rocker assembly and injectors first.

[Captain Bill]

It seems to me that all we really know is that the crank will move through 180 degrees. We don't really know if the is from TDC to BDC on two cylinders and BDC to TDC on the other two. It could be a broken rod or wrist pin with a piston jammed in the cylinder half way down. In that case the crank would move approximately 180 degrees before the rod jammed against the piston again. I doubt this is any kind of hydraulic lock. Piston rings are not that good and any fluid would have drained into the oil pan over time.

[SkiprJohn]

Thanks DeepFrz,
Yes, you are obviously right. Just grasping at the ridiculous and realized it after I posted.
Good luck Martin.
kind regards,

[Celestialsailor]

Thanx John...I will pull it out in a week or so and take pictures. I'll let everone know what I find. I'm trying to I.D. the engine cross-over to Mitsubishi, in hopes of buying parts cheaper than Westerbeke. They must be taking lessons from Volvo.

Captain Bill...You're thinking but hey...think good, easy and cheap thoughts...he he he

[Celestialsailor]

I was back at it this last Saturday. I thought maybe the water pump">raw water pump but alas...not. I had another sailor/motorhead look at it while go clunk one way, then clunk the other way. We marked the Crank pully and the rotation is 140 degrees and never moving a hair off the marks. One thing we did conclude or at least suspect is that the clunk seems to be coming from the rear of the engine. So maybe the flywheel area. Next Saturday will be dismantling all connections and pulling the engine later in the week. I will look at it on the ground instaed of hauling it home in hopes that it is something simple like a bolt too long in the bellhousing or something like that. I'm trying to think positive and simple...

[Cheechako]

I assume this is pretty hard to turn right? Can you get the tranny off to check inside the aft end?

[sww914]

You just need to take some time off of work to pull the engine, it's rude of you to make us wait.
I still stick to my first 2 guesses, a broken rod or a bolt on the flywheel that has backed out.

[Celestialsailor]

Originally Posted by sww914

You just need to take some time off of work to pull the engine, it's rude of you to make us wait.
I still stick to my first 2 guesses, a broken rod or a bolt on the flywheel that has backed out.

A broken rod probably would not cluck in the exact same place every time. I looked at a drawing of the bell-housing area and saw that it has a dampening plate with 5 springs in it that is bolted to the flywheel via 6 bolts. Also there are dowel pins on the engine block backing plate. Lets hope it's in there.
Thanks for your help on Saturday. I should offer $10 to the person with the right guess...

[SkiprJohn]

My fingers are crossed that it's the flywheel or dampening plate. Pretty easy fixes.
A bolt could have worked loose if the people who did the last work there didn't put the little metal keepers on the bolts holding on the flywheel.
kind regards,

[Kapena]

I'm with the guys suggesting a connecting rod...but if you want a scenario of what if's then....

It can't be the flywheel, a bolt too long, or dampening plate. It would cause friction the entire rotation. Same for starter and transmission. Valve train would be 360 degrees, so that's left out.

Best bet is liquid in one of the cyclinders...you can't compress a liquid. So somebody took the hydraulic oil out of the steering and put it into one of the cylinders. That's what you will find...if it isn't a connecting rod.

[sww914]

I still maintain that it could be a rod because I have seen a broken rod, broken near the top, laying against a web near the side of the block. As the engine rotated the end of the rod became stuck under another web running perpendicular to the first along the side of the block. I've also seen a broken pressure plate bolt (this engine doesn't have a pressure plate but the equivalent bolt exists) back out and hit the webbing inside of the transmission bell housing and stop the car. It was a racecar with 12" slicks going 125. It broke some other stuff too, like all the gear teeth on 4th gear and the pinion shaft. It was exciting.
That same car had another pressure plate bolt back out and replicate the exact symptoms that we're discussing here. The bolt head was hitting the webbing on either side of the bell housing. The engine would rotate about the same 140 degrees as Celestial Sailor's engine and made the same sound as his.
Whatever it is, we'll be able to see it for sure.