How to tell a cracked block from a blown head gasket

[robisonservice]

In years past I've written several articles on block failure, and how we fix those motors with the flanged liners. In this most recent article I show how we diagnose a cracked block through examination of the evidence seen when the heads are removed. I'd be interested if any of you have seen similar signs, or have thoughts to add

John Robison

Article link: http://robisonservice.blogspot.com/2014/02/blown-head-gaskets-on-land-rover-v8.html

 

[SGaynor]

Great write up. Thanks, John.

Some questions -

Why do you think these cracked blocks are becoming more prevalent?

Is the cost of repairing the cracks worth it vs. R&R the engine? Considering...

Do you think cracks would form elsewhere in the block, thus causing another faillure?

 

[p m]

I wish I read this article when I had my engine apart...

 

[seventyfive]

Is the cost of repairing the cracks worth it vs. R&R the engine?

fwiw, figure the labor to remove the engine, strip the block, machine shop costs to remove liners, inspect, etc, then boring the cylinders, installing new sleeves, deck the block, install new cam bearings and line bore, then new bearings, rings, gaskets, etc, then install the lump. don't forget machine shop costs for a head job.
parts, labor, tax, etc would be steep. depending on your location machine shop costs may vary though, labor rates, etc.

i should have filled out an invoice for the gems i just swapped into my spare '03. but guestimating it would have been well over $5000. which is why most paying customers usually just find a tall block on ebay or a salvage yard and roll the dice.

 

[SGaynor]

Yeah, that's what I figured.

So then back to the question of why the increasing incidence of cracked blocks? All 4.6? just break down of the aluminum (which means were all doomed...)? How to prevent it?

 

[singingcamel]

I'm thinking the cracked block in the article could be coming from the head bolt itself. Look were its located. To close of tolerance between the bolt and the cylinder wall .

 

[robisonservice]

For those of you who have asked if the cracks spread from the head bolt holes or the cylinder bores, the answer is . . . BOTH The cracks extend from the bolt holes into the cylinder bores, as shown in this earlier story. Certainly - as one of you suggested - the bolt holes are
too close as evidenced by the cracks. Yet they are no closer than the head bolt holes in many other engines, and older LR engines did not crack.

We think the problem is grounded in the metallurgy of the late series LR blocks, and the tension stress imposed by the late series stretch head bolts.

http://robisonservice.blogspot.com/2010/04/last-word-on-land-rover-liner-failures.html

We address that by welding the cracks, and in some cases by fitting studs in place of the bolts

 

[seventyfive]

Yet they are no closer than the head bolt holes in many other engines, and older LR engines did not crack.

We think the problem is grounded in the metallurgy of the late series LR blocks, and the tension stress imposed by the late series stretch head bolts.

http://robisonservice.blogspot.com/2010/04/last-word-on-land-rover-liner-failures.html

We address that by welding the cracks, and in some cases by fitting studs in place of the bolts

this is what a handful of us have come to the conclusion. the manufacturing changed hands, for the bosch engine management engines, and the quality was terrible. then add the stress intoduced by torque to yield bolts, add poor maintenance and numerous heat cycles....

we use studs here, and suggest cometic head gaskets at the shop, but the experts here will tell you studs are the reason the blocks fail. starts quite the pissing match!

 

[SGaynor]

Thanks.