Once all the head bolts have been removed it's time to pull the head. I mentioned in an earlier post that the Thomas school buses have very little headroom at the rear of the engine.
Originally we used to pull the engine front crossmember and engine mount allowing us to lower the front of the engine providing enough clearance to remove the rear pushrods. That took a lot of time so eventually we thought of a better idea.
Using tie straps we suspended the last 5 pushrods in the head so when the head was lifted high enough, the bottoms of the pushrods would clear the block.
The picture above demonstrates this technique saving hours of labour compared to the old front crossmember technique. The exhaust manifold has been left on giving the head a bit of a tilt providing more clearance for the pushrods.
There you have it, the head and engine block can now be cleaned up and inspected. Look for cracks and unusual wear on both machined surfaces of the cylinder head and engine block. If uncertain it's advisable to send the cylinder head out to a machine shop who specializes in heavy duty diesel engines.
The top of the block and cylinder head can be checked with a straight edge to find any uneven surfaces. Check for pitting especially where the failure in the head gasket occurred.
In this case there was a coolant leak from the rear of the head gasket that allowed coolant to run down the back of the engine which we eventually spotted. We've done a number of leaking head gasket repairs on the Cummins 8.3 but usually after extended running time and mileage.
To be continued....
No comments :
Post a Comment