New guy, blown head gaskets

[Newguy1998]

Nice. What precups do they have in them? Just curious.

The diamond kind?

 

[Newguy1998]

The old cracked casting # is 10137567
The new one is 10137657.

Will this be an issue?

 

[Husker6.5]

The old cracked casting # is 10137567
The new one is 10137657.

Will this be an issue?

Nope. Truck heads are truck heads, as long as you don't have van or Hummer heads, everything bolts right in. Those new to you heads have diamond pre cups in them, or at least the one in the photo does.

 

[Newguy1998]

Nope. Truck heads are truck heads, as long as you don't have van or Hummer heads, everything bolts right in. Those new to you heads have diamond pre cups in them, or at least the one in the photo does.

Are the diamond ones good? Don't forget I'm new to this...

 

[Husker6.5]

Yeah, not sure how I missed that. I have a spare block with a broken crank. Going to be pulling the heads off it here today. Hopefully I have something that will work.

A "spare block" with a broken crank means you have a 900lb paper weight or boat anchor. Ask @chevyCowboy what happens to your block when you break a crank, or @6.5L , as both are dealing with the aftermath of detonated blocks following crank failures.

 

[Husker6.5]

Diamond cups were the latest GM designed cup. Very good to have.

 

[n8in8or]

You were lucky to score those - apparently crack-free and with diamond precups. Nice.

 

[Newguy1998]

A "spare block" with a broken crank means you have a 900lb paper weight or boat anchor. Ask @chevyCowboy what happens to your block when you break a crank, or @6.5L , as both are dealing with the aftermath of detonated blocks following crank failures.

I haven't confirmed a broken crank, just shows signs. I bought it as a parts truck, hoping to get it running and flip it, found the CP had waaay to much play. Didn't think a crank breaking could damage heads...

 

[Newguy1998]

You were lucky to score those - apparently crack-free and with diamond precups. Nice.

The shop had rebuilt them, waited 4 years for the guy to come get them... Can't believe my luck today. Picked up 2 GMX turbos today for $100 too

 

[WarWagon]

The shop had rebuilt them, waited 4 years for the guy to come get them... Can't believe my luck today. Picked up 2 GMX turbos today for $100 too

I'd call that bad luck! Quick see if you can get at least 1/2 your money back on the turbo's! Seriously you going twin turbo? Otherwise IMO the Asthma Attack GMx is almost scrap metal.

You will have to pull the other head as the precups must match for the engine to run properly. The Diamonds are the best precups to have.

 

[Will L.]

So from here, pull the other head, examine the block thoroughly. New head bolts or arp studs, felpro headgaskets and intake gasket. New rocker buttons.
Examine the pushrods and rocker arms for damage.

The right stuff for valve covers, thermostat crossover, rear head crossover blocknoff plates.

This is if you are throwing together on the cheap. If you know for sure you want to make it last a while without problems, plan on tearing into the lower end.
Rings, bearings, timing gears (forget the chain- they suck) fluidamper balancer, front and rear main seals, etc. etc. etc.

 

[Newguy1998]

I'd call that bad luck! Quick see if you can get at least 1/2 your money back on the turbo's! Seriously you going twin turbo? Otherwise IMO the Asthma Attack GMx is almost scrap metal.

You will have to pull the other head as the precups must match for the engine to run properly. The Diamonds are the best precups to have.

Remember early when I said my old turbo was warn out?

 

[Newguy1998]

So from here, pull the other head, examine the block thoroughly. New head bolts or arp studs, felpro headgaskets and intake gasket. New rocker buttons.
Examine the pushrods and rocker arms for damage.

The right stuff for valve covers, thermostat crossover, rear head crossover blocknoff plates.

This is if you are throwing together on the cheap. If you know for sure you want to make it last a while without problems, plan on tearing into the lower end.
Rings, bearings, timing gears (forget the chain- they suck) fluidamper balancer, front and rear main seals, etc. etc. etc.

I seriously need to change both heads? How will it run of I don't?

 

[EWC]

Probably run but with the different size in the precups one side of the engine may not balance with the opposite side with respect to power output .

 

[n8in8or]

I seriously need to change both heads? How will it run of I don't?

And.........you probably have the same problems in the other head that you had in the passenger side head, so you may just be delaying the inevitable if you don't open it up now. Yes, you could get away with not doing it now, you're probably going to be tearing it down again at some point either when the gasket blows or when the cracks in the head get to a point of failure. Hopefully you're close to home when that happens.

 

[Jaryd]

X2 on what Nate said

You would be better off doing it now because like Nate said the other side is going to do the same thing. Them diamonds will be a noticeable difference in power. I went from diamonds to squares and noticed a slight difference in mine.

 

[Husker6.5]

FAR better to just do both heads now while you have the top torn down, than to do just one, have the other old one fail, and have to tear everything back down and replace both heads the second time around. Remember what I said earlier in the post about thermal stress to the driver's side head from the passenger side failure? When you dumped coolant, air got into the system and the FIRST thing it does is create air pockets in the head passages of both heads. Inevitable, can't be prevented, just part of the design. Those air pockets create hot spots within the head which stress the cast iron. When you pull the driver's side head you may not see any cracks between the seats, even under magnification, yet - but the stress is there on the molecular level and will appear the next time there is thermal shock to that head, which could even be on initial fire-up, with the same results you're dealing with now.

Replacing both heads is just a good preventative maintenance measure, unless you enjoy the idea of becoming really good at tearing down and rebuilding the top end several times (I think not).

 

[Newguy1998]

Ok, I'll do both.

 

[WarWagon]

Remember early when I said my old turbo was warn out?

IMO the GMx turbos are fuel wasting scrap metal. There are far better performing turbo's out there above and beyond the large turbo I run. A start is the article below and many other discussions of other turbos abound on here.
http://www.maxxtorque.com/2012/07/the-65l-diesel-factory-equipped-asthma.html

FYI Pre-cups are almost a forgotten black art. Different precups will make the engine run like it needs a tune up: severe bolt loosening vibration that may be bad enough to break the crankshaft. Precups control the flame entering the combustion chamber as far as speed, when peak pressure happens, fuel limits, economy, emissions, etc. Different precups would be like firing one side of the engine several degrees off the other side and this would vary by load and throttle. The smaller precups can even hit their limits with fuel blowing so fast they centrifugally separate the air fuel charge: thus you have half the engine making more power while the other half smokes black. (I doubt you are pushing that much fuel w/o a turbo upgrade.)

You absolutely got lucky with getting a pair of diamond precup heads.

 

[6.5L]

Actually Husker65, crank failure was not an issue at all, crank held strong with no problems. I just updated my carnage thread accordingly to reflect my thoughts, so as not to complicate this thread