The Stovebolt Site Forums The Shop Area Engine Shop Hole in Engine Block

A big hole blew in my block at the poker run today. I guess I was pushing it pretty hard on the highway. I thought the valves were clattering louder and louder but in hindsight it was somthing more serious.

What do you suppose would cause this? It we be good to know so I don't destroy the next engine.

Hole in block

Busted rod bearing

Saying OUCH just doesn't seem sufficient!

Stove, seems you've "stoved" you're Stovebolt.

I'd guess the rod broke at the wrist pin and swung around busting the side of the block.
Or the rod bolts broke, cap came off and crank left the rod and most of a revolution later smacked into the side of the rod pushing it out the side of the block. This might be more likely?

Excessively high RPM probably the cause, what was it running? Or what gear ratio, tire size, and MPH to then calculate the RPM?

Grigg has some possibilities. One major problem with the 216 was the rod bearings. Poured babbit bearings have wear problems. This can be from grit in the oil, prolonged operation at high RPM, lugging the engine (low RPM under load). Those are the big ones. Another is operation without enough oil (2 or so quarts low).

One common fix was to replace the engine with a 235, which has insert bearings, which have a steel shell with a layer of babbit inside. Another solution, if you want to replace with a 216, is to have the rod ends machined to accept the insert bearings.

I've seen worse. Threw a rod in a GMC 478 V6. Picked up a piece of the block larger than my size XL hand.

Improper maintenance is a likely cause of this catastrophe. The rod bearings are serviceable. The standard maintenance procedure is to drop the pan, remove the rod caps, pull one shim at a time from each until the slack is taken up, yet not dragging.
Another possible cause would be intentional abuse to a worn out 216 in order to convince the wife to allow the purchase of that sweet 235 you have been dreaming about...
Time to come clean, Stove. The truth will set you free.
Carl

My fault, should've dropped the pan but I was busy changing the water pump and axle.

The gears are 4:11 and the tires are 16" and I would guess I was travelling 65 mph. If my math is correct that is 5600 rpm. Of course the engine blew up!

Even at 55 mph that is 4800 rpm which also seems high to me.

I am in the lucky or unlucky position of having no wife other than an old truck. The good news is a found a 235 that has reportedly been rebuilt. The "wife" should be rolling again shortly!

Wanted. Wife with a Boat. Please send pictures of Boat. Yeah, these engines do not like more than 3500 rpm and I would not push mine above 3k. I would address gear ratios and try to get that rpm number down. Good luck!

How are you figuring that RPM Stove?

Dennis

Ouch......
Looks like at that rpm the oilers can't get enough oil to the rod bearings.

You must be using those tires you took off the low-rider!

65 mph with 7.00-16 tires (29" diameter) and 4.11 gears is 3095 rpm.

Your numbers work out too a 16" diameter tire, which means you gave the wheel diameter instead tire diameter. To determine the tire diameter with bias-ply tires.

Using 7.00-16 as an example.
Tire height X 2 (7.00 x 2 = 14) + wheel dia. (16) - 1" (the flat portion at the bottom) = tire dia.
So 7.00" X 2 + 16" - 1" = 29"

I used to be able to calculate the metric sizes, but I would have to take off my boots.

That makes more sense 3095 rpm.

The engine was beginning to knock after about 100 miles, and blew out about 1/2 mile after coming out of the valley. I left a long streak of oil and probably a few parts all over the highway.

Also, the blowout caused a fire near the fuel pump which was beginning to get out of hand on the side of the road. A good reason to carry a fire extinguisher.

Before buying a 235 first look for a 261.
Years ago when I was searching for a new engine for my truck nobody told me about the 261 and I had no idea they even existed (pre Stovebolt page for me).

Had I known I sure would have used a 261 instead.

Hi Stove, Yup, try to find a 261. Check the yards for Canadian Pontiacs. That was the standard six cylinder engine after 1955
I found a extra engine for my two trucks but you cant have it.
It will run circles around a 216, If you find a truck version newer than 1958 it will have a full flow oil filter.

Keep searching. Howie

Yeah, that one is toast.
Your dilithium crystals weren't properly aligned.

After sleeping on this, I believe the primary cause of engine failure was low oil. The engine was full first thing, but after going through the valley the first time the engine was 2 liters / quarts low. This engine leaked ALOT of oil.

So when the engine was pulling hard up the hill, number 1 rod bearing was not oiled properly and weakened. Coming back through the valley a couple hours later, the rod had cooled and then heated again. And then failed.

The sad thing is an oil seal and oil pan gasket kit are sitting on my workbench. The water pump and rear axle superceded the gaskets.