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99 - 00 Block worth?

If it was n/a it may have the squirters blocked. As with any 6.5 block, check for cracks in the main webs around head bolts ,rear cylinder walls and between the valves on the heads. Wash those areas with carb cleaner and wipe with paper towels. The cracks,if any, will weep black diesel oil.
 
The guy selling it is asking $50 for it. It is just the long block with the heads. He says it blew head gasket and he hasn't got time to mess with it and he wants it off the shop floor. I am going to go take a look at it, $50 is a heck of a deal... maybe to good to be true.
 
It's worth more than that for scrap. I've paid over $100 for blown 6.5s just for the useable parts. They are worth over $100 for scrap right now.
 
Well, I bought and picked it up. Its date stamp is F219, and it is the 506 for sure. It is a non-turbo and the heads look decent, but I bought it for the bottom end. No apparent cracks on the outside. Ill have to get my tools out and open it up to see the inside. From all appearances it looks to be a great motor. The auto shop that had it didn't want to mess with it being diesel and wanted tool money instead.
 
zielinski.family said:
Well, I bought and picked it up. Its date stamp is F219, and it is the 506 for sure. It is a non-turbo and the heads look decent, but I bought it for the bottom end. No apparent cracks on the outside. Ill have to get my tools out and open it up to see the inside. From all appearances it looks to be a great motor. The auto shop that had it didn't want to mess with it being diesel and wanted tool money instead.
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F = month - June

21 = day of the month

9 = last number of the year. In this case 1999 since you know it's not 2009.

Check the main webs at the bolt holes and cap registers closely for cracking. Also look very closely at the #8 cylinder walls for cracking. This is the block design that has a bad reputation for these particular issues.....
 
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Well, opened it up and found..... the first cylinder on the pass side had the valve break half its head off and implanted all the tiny pieces in the top of the piston. Will look further to see any cracks. Got some cleaning to do. The head are non turbo, so I hadn't planned to use them. So it still a good possibility to build off the bottom end.
 
The heads upon further inspection are cracked in a few places. I noticed this head has the diamond cups in it. What is so significant about these cups? And has anybody heard of these cups cracking? There is one bad head where the valve came apart and there is one other spot on the last cylinder where there appears to be a crack between the valves. (there is a line across there, and not on all the others, so I take it that would be a crack) Again, had no plans to use these heads, but just the bottom end. Tomorrow Ill take the bottom end apart and look it over.
 
zielinski.family said:
The heads upon further inspection are cracked in a few places. I noticed this head has the diamond cups in it. What is so significant about these cups? And has anybody heard of these cups cracking? There is one bad head where the valve came apart and there is one other spot on the last cylinder where there appears to be a crack between the valves. (there is a line across there, and not on all the others, so I take it that would be a crack) Again, had no plans to use these heads, but just the bottom end. Tomorrow Ill take the bottom end apart and look it over.
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"diamond" precombustion chambers are supposedly the best balance between power producing potential and fuel economy. I do believe they are the largest chambers (opening) available but don't quote me on that.

They are fairly prone to cracking at the "mouth". It has to do with the hardness of the metal they are made of (inconel IIRC) and the heat cycling/pressure wave environment they are exposed to.

GMC has a tolerance for cracks in the chambers and it's quite large (something like 3/16, but don't take that as gospel).

Personally, I would just toss them if they're cracked. Esspecially if you're doing a fresh rebuild.

From my understanding, they can be had for around 8 bucks a piece. Again, don't quote me on that, I've never bought a set myself.

Cracks running across teh valve seats is also another common place. If cracked deep enough, it hits water in the head water jackets.....
 
I have been wondering about the difference in the 599 and 506. From what I have heard the 599 is stronger. This is what is currently in my truck. But my question to whoever can answer is: What role do the oil squirters play, and how much difference is there between these two blocks besides the strength of the 599?
 
zielinski.family said:
I have been wondering about the difference in the 599 and 506. From what I have heard the 599 is stronger. This is what is currently in my truck. But my question to whoever can answer is: What role do the oil squirters play, and how much difference is there between these two blocks besides the strength of the 599?
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The oil "squirters" are jets of oil directed at teh underside of the piston crown.

Thier role is to assist in cooling the pistons.

It's a common cooling scheme and virtually all high performance motocycle engines use it.

The 599 block is assumed to have a higher nickle content which makes the block stronger. It is also rumored to be "thicker" in certain areas due to being a common block with the earlier 6.2 blocks.

A 599 also does not have the oiler holes. Many main web cracks have been supposed to have started in the oiler holes.

Another issue/theory put forth is that the tooling for the oiler holes nicked the block in the machining process of #8 cylinder which caused a stress riser and made them more prone to cracking.

If you've got a crack free 506, I wouldn't worry too much about rebuilding it and returning it to normal service. If it's lasted this long without cracking, it's probably not subject to the "usual" 506 weaknesses....some good castings had to come out of the factory in a production run.

Difference in strength?

bit of a roll the dice thing there.

There's lots of 506 blocks still running around out the and lots of cracked 599's have gon to that great big smelting furnace in the sky......
 
You mean like this ?
I put them back on with new gaskets and it's been fine. Of course I wasn't too concerned about the longevity of this truck or motor anyway which it why it will last another 100k...:D
 

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I put my 929 back in service with these big old cracks got 30,000km on it right and now already over heated it twice lol both heads had cracks the same as yours

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