VH4D Head cracked?

TimWafer · May 12, 2011

Have a Wisconsin VH4D engine in my old skid steer. Rebuilt it a couple winters ago w/ new pistons & bearings & all. It’s been running super, far better than anytime since I owned it.
Last night however, I was using it and a strange hissing sound started. At first I thought it was a manifold exhaust leak somewhere, but on closer examination it appears one of the heads has a hairline crack across it just below the sparkplug. Haven’t removed the head yet but just wondering what the likely causes of this might be? I torque the heads to the specs and sequence in the manual.
Hadn’t used it that long or hard last night when it started.
Tim

Bob · May 12, 2011

They do that sometimes, perhaps without a specific reason.

Some things to look for are correct ignition timing and distributor orientation, if this is an "odd-firing" engine (I can never remember which Wisconsins are), as well as checking for debris in the cooling are shrouding.

teddy52food · May 12, 2011

VH4D is an even fireing engine.

JOCCO · May 12, 2011

Never had hat happen, have had blown head gasket stripped out plug. Lots of parts for them show up on evil bay.

Crem · May 12, 2011

On our old 610 Bobcat we had a chunk blow out of the aluminum head right by the spark plug a couple of years ago. I found a used one from a local guy and along with a new head gasket it is still running. I thought that maybe someone used starting fluid or something to cause that but I never did figure out what caused it. The darned thing likes to run hot though even though I cleaned all of the air passages.

Jon Hagen · May 12, 2011

Make sure the distributor advance weight setup is not rusted solid. I have worked on two different Bobcat loaders with V4 Wisconsin engines that would split the aluminum heads.

In both cases, the distributor was rusted up from storing the machine in damp cattle barns.

The odd thing is that a Wisconsin V4 with the distributor advance stuck in the full advance position, will start and run normally, but under heavy load at low rpm, will spark knock bad enough to crack those aluminum heads right between two cooling fins.

A quick test for a sticky / stuck advance, is to grab the distributor rotor and twist it in the direction of normal rotation. You should be able to twist it about 15 degrees against light spring pressure, and should snap back to the original position when released.
If it won't do this, the distributor advance is sticky / stuck. Remember to put a few drops of motor oil per year on the felt pad in the end of the hollow rotor shaft to keep it lubed.

This is where the most advance sticking happens because no one remembers to oil that little felt oil wick.

TimWafer · May 14, 2011

(quoted from post at 10:22:12 05/13/11) Make sure the distributor advance weight setup is not rusted solid. I have worked on two different Bobcat loaders with V4 Wisconsin engines that would split the aluminum heads.

In both cases, the distributor was rusted up from storing the machine in damp cattle barns.

The odd thing is that a Wisconsin V4 with the distributor advance stuck in the full advance position, will start and run normally, but under heavy load at low rpm, will spark knock bad enough to crack those aluminum heads right between two cooling fins.

A quick test for a sticky / stuck advance, is to grab the distributor rotor and twist it in the direction of normal rotation. You should be able to twist it about 15 degrees against light spring pressure, and should snap back to the original position when released.
If it won't do this, the distributor advance is sticky / stuck. Remember to put a few drops of motor oil per year on the felt pad in the end of the hollow rotor shaft to keep it lubed.

This is where the most advance sticking happens because no one remembers to oil that little felt oil wick.

I think you’re on to something there Jon. I had thought that I noticed a pinging sound like spark knock the last couple times I used it. I wonder if the timing slipped somehow. I had installed a Pertronix ignition a while ago to replace the points & condenser. Just checked the condition of the spark advance and it might be a little sticky. At any rate I think the cracked head is related to the ignition timing. It cracked in a U right around the plughole. Piston & cylinder still look fine. Going to make sure the spark advance is truly working well and adjust the timing again once I get the new head on.
Thanks!
Tim

VH4D Head cracked?

TimWafer

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Bob

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teddy52food

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JOCCO

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Crem

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Jon Hagen

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TimWafer

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