CK5
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1989 Diesel Jimmy. What do we have here hmmmm
- Thread starter blazinzuk
- Start date
I can't see any issue with the mains but it seems to really look you have to pull the caps. Which I guess is no biggie.
I might have to anyway I have a new rear main gasket in my rebuild kit. So I'm gonna replace that.
Anyway up to this point I think there might be one crack in the heads. But it was very hard to see.
The precombustion chambers are oval.
No biggie. I have a 93 6.5 sitting in the garage I could pull the heads and see if they have the diamonds. But is it really worth the trouble?
You looked at the shape stamped on the head not the opening shape right? Almost all of those heads are cracked between the valves. You can have them fixed with the valve guide trick or just run them. The 93s won't be diamonds unless they have been replaced. Not a huge deal I just wondered for when you get it together.
. You know I am old, everything in my mind is $30 from Napa, starters, alternators....
That's my problem lol. Every time I go in for something I think it should be about half what they want for it
Just remember, you don't want to make what you did when things were that price. My buddy has built high end race engines and doesn't like the fluiddamper dampers, he uses stock or ATI. I am just going to have a new stock balancer and pulley with my 6.5 crank and flywheel when he balances it all.
So if the heads are cracked I have to run them. I'm struggling to get where I am with it.
If it runs fine should l start looking for heads? Or ignore the cracks?
What's the eventuality of cracked heads?
If it runs fine should l start looking for heads? Or ignore the cracks?
What's the eventuality of cracked heads?
If they're dry (i.e.: not into the water jacket) run 'em, and keep your engine cool (below 210°F...max...ever). I run a 195° stat and keep my eye on a good aftermarket temp gauge.
If you bought new heads, they too would crack within 50,000 miles - I'd bet money on it. It's inherent in the design. Time has shown, however, that it's not that big of a deal.
If you have a machine shop that's familiar with these engines, they can install sleeves in the coolant passage that runs between the valve seats (the valve guide trick @80' 427 mentioned). That will guarantee that the cracks stay dry.
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So one fix is to remove the freeze plug in the head to access the cooling passage that goes between the valve seats. You then drill it larger and press in a valve guide so even if it cracks to water there is a "sleeve" that still prevents water leaks. Otherwise you run them as is till they leak, if they ever do. Almost all of them are cracked. Despite the fact that I have read a lot, I am far from an expert on these. Most guys get the valve guide fix but some have run cracked heads for 1000s of miles with out a problem. I would have the seats touched up on the heads either way but I am one of those guys. I have a hard time not assembling the most perfect engine I can.
Just open your wallet and follow this article. I haven't read it all but looks good. I used to get MaxxTorque magazine and it had some good info for GM diesel guys. http://www.maxxtorque.com/2008/10/the-best-ever-65-chevy-diesel-rebuild.html
Another good article http://www.enginebuildermag.com/2007/06/the-optimizer-6500/
Mine is a newer improved block, I have no intentions of doing anything different to the block with exception of head studs. I see main girdles as band aid over an ax wound. If it made it this far with no cracks, it should keeps on living. Maybe bevel all the edges to lower stress points.
Boy, this thread took an expensive turn! 
Though that article was fun to read.
I wouldn't worry about the precombustion chambers. You're going to be wanting those 6.5 heads down the road, right? I'd just run what you have.
Have you pulled the old engine apart yet to see what it looks like? It may have a different combination of cracked hardware.
Though that article was fun to read.
I wouldn't worry about the precombustion chambers. You're going to be wanting those 6.5 heads down the road, right? I'd just run what you have.
Have you pulled the old engine apart yet to see what it looks like? It may have a different combination of cracked hardware.
You can buy improved casting heads that won't crack.
The only cracks I can see are in-between the valves but they aren't fully cleaned yet.
If I was gonna rebuild a motor for this its gonna be the 5.3 I have.
But reading everything I guess I just expected everything to be cracked like EVERYTHING.
Hence the title change to crack a lackin.
I.E. lacking of cracks
The only cracks I can see are in-between the valves but they aren't fully cleaned yet.
If I was gonna rebuild a motor for this its gonna be the 5.3 I have.
But reading everything I guess I just expected everything to be cracked like EVERYTHING.
Hence the title change to crack a lackin.
I.E. lacking of cracks
^^^ turible
@80' 427
It literally kills me not to do some at least honing and new rings. I'm not even gonna pull my snap gauges outto measure the bore. I will get to point where I convince myself it has to be rebuilt.
But this is our second car. It has sucked being down to one car.
But I am gonna go pull my valve spring compressor out and lap the valves.
Another thing that kind of sucks up here no engine machine shop. Closest good one is 2 hours away
It literally kills me not to do some at least honing and new rings. I'm not even gonna pull my snap gauges outto measure the bore. I will get to point where I convince myself it has to be rebuilt.
But this is our second car. It has sucked being down to one car.
But I am gonna go pull my valve spring compressor out and lap the valves.
Another thing that kind of sucks up here no engine machine shop. Closest good one is 2 hours away
