Rocker shaft broke, possible negligence, where to find parts?

[Celestialsailor]

Originally Posted by Lepke

Any decent machine shop can make a new rocker shaft, it's not that complicated.

Being a Toolmaker I am going to have to disagree with you about the complexity. Special steel turned, then heat treated, then drawn, then ground +/- .0005" (that's 5 tenths of one thousands of an inch or less). He will have to find a new one or maybe a used one in good shape.

[sinnerman]

Originally Posted by Scubaseas

You're not going to want to hear this but who ever put the head back on the block is responsible for assembling it properly. I wouldn't look to the machine shop to torque the rockers with the heads off the engine. It's also up to the assembler to lube the valve stems on assembly. The machine shop would correctly assume the head bolts need to be torqued prior to putting the rocker arms on it. Having said that if the springs were changed or the new seats installed past the point of interference, i.e. the spring binds when fully open then yes the machine shop screwed up. But that is also up to the assembler to verify it's correct before starting the motor. Just my opinion as a retired master mechanic and repair shop owner of over 50 years.

Ditto. You would install the head and torque the head bolts with the rocker assy removed, THEN install the tappets/lift rods/rocker assy and adjust the valce clearance. IMHO.

[Cadence]

My guess is, they left the bolts for the cam not pulled down so you could easily remove them in order to torque the head bolts?

[Bill Seal]

With the open valves keeping the head up, how could you have ascertained it was seating properly on the locating dowels and things like that? If you had looked a any UTube video on head installation, you would have seen that they ALWAS do it with the rockers removed.

[sailingunity]

Originally Posted by Cadence

My guess is, they left the bolts for the cam not pulled down so you could easily remove them in order to torque the head bolts?

Maybe, but like I said I followed the Westerbeke service manual to the T which made no mention of removing or re-installing the rocker assembly.

[Cadence]

Originally Posted by sailingunity

Maybe, but like I said I followed the Westerbeke service manual to the T which made no mention of removing or re-installing the rocker assembly.

I was just going from what you had said.
I hope all works out well.

[Lepke]

The engine was also used in tractors. Try tractor junk yards here and abroad.
Also try:
https://www.ebay.co.uk
https://www.ebay.com.au

[sailingunity]

FYI I found the rocker shaft assembly from Trans Atlantic Diesel. Will install this weekend and see how it runs.

[Cadence]

Originally Posted by sailingunity

FYI I found the rocker shaft assembly from Trans Atlantic Diesel. Will install this weekend and see how it runs.

Great!

[sailingunity]

Got the new shaft installed and surprisingly, it fired right up, actually rather quickly (the last few times I've started it took 4 or 5 seconds to start it). My temperature probe shows even temps across the exhaust ports, and it's not missing.

I ran it up to temp and will take the valve cover off again later to check up on things, but it seems as if I've dodged a bullet on this one.

Any thing else I should look for before taking off on the next leg of our trip? I'm guessing the fact it fired up quickly is a good sign that I have good compression.

[Scubaseas]

Originally Posted by sailingunity

Got the new shaft installed and surprisingly, it fired right up, actually rather quickly (the last few times I've started it took 4 or 5 seconds to start it). My temperature probe shows even temps across the exhaust ports, and it's not missing.

I ran it up to temp and will take the valve cover off again later to check up on things, but it seems as if I've dodged a bullet on this one.

Any thing else I should look for before taking off on the next leg of our trip? I'm guessing the fact it fired up quickly is a good sign that I have good compression.

Check the service manual but retorqing the head and more importantly checking the valve clearances is pretty standard. I would check the valve clearance after about 10 hours no matter what the service manual says (or does not say) about it. But that's just me.

I wouldn't be concerned about any loss of compression .

[Celestialsailor]

Originally Posted by Scubaseas

Check the service manual but retorqing the head and more importantly checking the valve clearances is pretty standard. I would check the valve clearance after about 10 hours no matter what the service manual says (or does not say) about it. But that's just me.

I wouldn't be concerned about any loss of compression .

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
What he said. Wait until the engine is "stone cold", then torque the head to specs and then adjust the tappids for the correct clearance.

[Scubaseas]

If you retorque the head bolts/ buts do it with a cold engine, loosen 1/4 turn then tighten to spec. Do one bolt at a time and in the order specified in your manual. This is usually from center out. Do not loosen all then tighten all bolts. Check valve clearances after retorque. They shouldn't have changed but hey. You're right there.

Easy way to adjust valves is put a crank on TDC and you will see both valves rocking on one cylinder (either #1 or #4) when you rotate the crankshaft +/- 5*. Once you have two valves on one cylinder rocking adjust the valves on the opposite cylinder. IE if #1 is on TDC and rocking adjust #4 valves. If #2 is at TDC and valves rocking adjust valves on #3. #2 and #3 will be rocking at BDC. I'm theory you can adjust all valves in two crank revolutions.

[Carl-T705]

Originally Posted by sailingunity

The section of my engine service manual for removing and reinstalling the cylinder head make no mention of needing to torque the rocker arm pedestals after the head is torqued down, nor of needing to remove it at all. I actually found the antique spanner adapter on eBay so I wouldn't have to remove the rocker arm assembly.

Question for the mechanics out there, what is happening to the fuel that was still getting injected into the cylinder with both of the valves closed?

That's when fuel gets injected into the engine when the valves are closed, the piston comes up on the compression stroke and compression in ignites the fuel in the cylinder and boom power!! . Air comes in and out through the valves not fuel... On a diesel

[Carl-T705]

Originally Posted by Scubaseas

If you retorque the head bolts/ buts do it with a cold engine, loosen 1/4 turn then tighten to spec. Do one bolt at a time and in the order specified in your manual. This is usually from center out. Do not loosen all then tighten all bolts. Check valve clearances after retorque. They shouldn't have changed but hey. You're right there.

Easy way to adjust valves is put a crank on TDC and you will see both valves rocking on one cylinder (either #1 or #4) when you rotate the crankshaft +/- 5*. Once you have two valves on one cylinder rocking adjust the valves on the opposite cylinder. IE if #1 is on TDC and rocking adjust #4 valves. If #2 is at TDC and valves rocking adjust valves on #3. #2 and #3 will be rocking at BDC. I'm theory you can adjust all valves in two crank revolutions.

I never heard of backing off on head bolts and retorquing them. There absolutely no reason to retorgue head bolts, What you may do is check the torque on the head bolts. I would never back off head bolts after the engine assembled and the gasket had been compressed, you would be asking for problems. Unless you are running a copper head gasket I wouldn't waste the time unless you question your workmanship.