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Cylinder heads damaged; urgently need new ones


PVerspeek
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All, my 2004 SS currently has 230.000 Km, and both cilinderheads are damaged, little cracks causing water lose. Problem has been identified, but now we are desparately looking for a solution.

 

Because of LPG-installation I need further alterations to the engine room, because of higher burning temperatures, dryer burning process, ...

 

This has already been changed 100.000 km's ago, but again there is a problem. For example the valve rings (I don't know the correct word, but the things that are between the block and the valve, to close properly, have already been replaced by hardened ones, but after 100K they look appareil to the previous bad ones (original factory ones).

 

We have found an Italian company who specialez in hardened valves.

 

But we do need 2 brand new cilinder heads. Any ideas or tips please.

 

If I find further information, I will post it here.

 

thanks

 

Pascal

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The things between the block and cylinder heads is a head gasket. so is it the head gasket that is leaking causing you to lose collant or is the head cracked for sure? you can also lose coolant/water from a blow head gasket.its kind of hard to make sense of what you have stated. is this a stock engine or a built engine?

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stock engine, only addition of extra fuel system, by LPG (Liquid Petrol Gas)... The gaskets are fine, the head itself, the aluminium has cracks. Left cilinder is leaking, right cilinder is about to.

 

we understood hardened or special heads exist, to stand higher temp. Also, does a 5.3 fits a 6.0?

 

P.

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Are you sure its not the LPG?, I have been on this forum a while and I dont think I ever heard anyone talk about cracks in stock or built motors/heads.

I would have to say that you mod might be causing the issue.

 

Sent from my DROID BIONIC using Tapatalk 2

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stock engine, only addition of extra fuel system, by LPG (Liquid Petrol Gas)... The gaskets are fine, the head itself, the aluminium has cracks. Left cilinder is leaking, right cilinder is about to.

 

we understood hardened or special heads exist, to stand higher temp. Also, does a 5.3 fits a 6.0?

 

P.

 

 

P

Can you give us any more info on this fuel set up? You said it burns hotter, how much? Does it effect the compression ratio of the motor? Do you know what the stoch AFR is? does it have an octane rating? How was the truck tuned for this? How did you determine the heads are cracked?

 

Otherwise to hopefully answer some of your questions, are you asking about harder valves or valve guides, because the grades of the aluminum castings in the heads are going to be about the same. Aftermarket heads like trick flow, afr, or dart offer their own castings that MAY use a different alloy and that MAY help you. You would have to look into this. As far as valves, if your running a high heat situation you may want to look into using inconel valves to resist the heat better, as far as guides go you would have to ask an after market company like the ones above. Hard to think you wore the springs out....possibly a nitrided spring will help you with life, but consult a company like PAC to check on that.

 

The 5.3l heads do fit our lq9 6.0 but they raise your compression by a large amount. Our stock 317 heads are a 71 cc head the 5.3l heads are 61cc, this would raise your cr about 1.28 so it would be around 11.43:1.

 

Should you need a head that will take more abuse, 99-00 lq4 6.0l heads, 873 casting number, are steel heads. As far as i know, they are the same specs as the 317 heads so tuning should be minimal. I'm not really sure i know how you cracked a head when we run superchargers and turbos on them with extreme heat and pressures.....but its an option for you.

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Most likely the issue that caused the cracking that you see is an overheating condition. Since the truck is an LPG vehicle I would recomend raising the compression on it to help to get the efficiency of the burn up. A 5.3L cylinder head would be a very good choice in getting the compression up and replacing what you have. You would be best doing them and spending a few hundred dollars/euro's on having a 2"/50.8mm intake valve installed in them to help retain the flow of the 317 casting you removed. If the extra funds are there though I would highly recomend doing the Trick Flow 205cc heads. These are going to flow much better than your stock heads as well as having a 58cc combustion chamber which will raise your compression to almost 12:1 (off the top of my head without calculating it out). With the small gain in flow and huge gain in compression you should see a nice improvement in the burn rate of the LPG as well as gain the stronger deck surface and combustion area.

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P

Can you give us any more info on this fuel set up? You said it burns hotter, how much? Does it effect the compression ratio of the motor? Do you know what the stoch AFR is? does it have an octane rating? How was the truck tuned for this? How did you determine the heads are cracked?

 

LPG has an octane rate of 108-110. I don't know the exact temperature LPG is burning at, but it is a bit higher then petrol. I don't think the compression ratio has been changed, because it is just another kind of fuel that we use, as petrol is becoming quite expensive, and always was overhere (1 Liter of 95 Octane petrol will set you back at € 1,5, = $ 1,98 per liter, where a gallon = 3,78 Liters, so we pay $ 7,48 per gallon...)

 

The truck has no tune, it is completely stock. Heads show a little crack. It is tiny, but it is there, and I lost a gallon of cooling fluid in a week.

 

Otherwise to hopefully answer some of your questions, are you asking about harder valves or valve guides, because the grades of the aluminum castings in the heads are going to be about the same. Aftermarket heads like trick flow, afr, or dart offer their own castings that MAY use a different alloy and that MAY help you. You would have to look into this. As far as valves, if your running a high heat situation you may want to look into using inconel valves to resist the heat better, as far as guides go you would have to ask an after market company like the ones above. Hard to think you wore the springs out....possibly a nitrided spring will help you with life, but consult a company like PAC to check on that.

 

I still don't know the english word, but Google pics shows me this: https://www.google.be/search?q=klepzittingen&hl=nl&tbo=d&source=lnms&tbm=isch&sa=X&ei=SD7fUK_CG8LDhAe-3YH4BQ&ved=0CAcQ_AUoAA&biw=1280&bih=675

 

They were already replaced with harder ones 100K ago, but they show similar problems. This is a known problem, and almost every car running on LPG will get this problem.

 

The 5.3l heads do fit our lq9 6.0 but they raise your compression by a large amount. Our stock 317 heads are a 71 cc head the 5.3l heads are 61cc, this would raise your cr about 1.28 so it would be around 11.43:1.

 

Should you need a head that will take more abuse, 99-00 lq4 6.0l heads, 873 casting number, are steel heads. As far as i know, they are the same specs as the 317 heads so tuning should be minimal. I'm not really sure i know how you cracked a head when we run superchargers and turbos on them with extreme heat and pressures.....but its an option for you.

 

Good to know it fits, that's already something. I also like Zippy's comments above. I will inform my technician to look into this.

 

Thanks guys!

 

enjoy the last days of the year.. At least those Maya's were wrong.. :)

 

P.

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P

 

Is that German or Dutch? My wife was in about 8 years of German and her parents were born there.....and they have no idea what that translates to, lol.

 

I think the words your looking for are valve seat.

 

Zippy is a professional and very well respected tuner over here so he can answer this better, but if the truck isn't tuned for this fuel.....I have no idea how it evens runs on it. The stoich ratio must be off and the timing advance must be very slow for a fuel with that high of an octane. Or was this truck sold over there and meant to run lpg?

 

Sent from my SAMSUNG-SGH-I747 using Tapatalk 2

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P

 

The truck needs to be tuned for that fuel anyways, but if you add the compression with the 5.3 heads it should really be tuned or monitored at the very least to make sure you don't have any issues.

 

Sent from my SAMSUNG-SGH-I747 using Tapatalk 2

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