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Discussion Starter #1
There are so many questions.......
- is it a cracked intake and bad rings that lead to the coolant getting into the cylinder?
- could the oil cooler lines have cracked inside radiator?
- block cracked?
- head gasket gave out?


I know i have a bad ring or 2 on my aluminum heads, the #8 blew oil out past the plug threads and about 1/2 quart of fluid in the cylinder after i removed the plug...... of course i got white smoke comin' out my exhaust.


So where would you start without spending too much time and money searching for the culprit here? :spank::confused:
 

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You have bad rings on your aluminum cylinder head ?

Suggesting that you tear it down quickly and get the coolant out of the areas it is not supposed to be in.
 

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There are so many questions.......
- is it a cracked intake and bad rings that lead to the coolant getting into the cylinder?
- could the oil cooler lines have cracked inside radiator?
- block cracked?
- head gasket gave out?


I know i have a bad ring or 2 on my aluminum heads, the #8 blew oil out past the plug threads and about 1/2 quart of fluid in the cylinder after i removed the plug...... of course i got white smoke comin' out my exhaust.


So where would you start without spending too much time and money searching for the culprit here? :spank::confused:
Bad rings - huh?

Coolant can get into a cylinder several ways, cracked bock, cracked cylinder head, leaky headgasket. Oil cooler, intake or intake gasket will lead to coolant in the oil , but not in the cyinder. There is a remote possibility that the intake could crack in such a manner that the coolant could get into the intake runner and wind up in the cylinder, but HIGHLY unlikey.

Best next move, remove heads, evacuate cylinder. Be very careful pf the head gasket during removal so as to examine it.

Usually, repeat usually, when a head gasket leaks, you will get compression in the cooling system when the engine is running and then the cylinder will fill up when the engine is shut off. The exception to this is with forced induction applications where you have become too aggressive with the timing in boost and the head will 'lift' momentarily. The mild result is coolant in the cylinder and a bent rod, the non-mild result in block ventilation - this isn't real common though and again usually only occurs with forced induction.
 

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This will pretty much come down to cracks in the heads or a leaky or blown head gasket. Some times a leak between the intake to head gasket between the coolant return and the adjacent intake port.

Ported heads often crack in the ports because the material has been cut too thin so it fails after exposure to heating and cooling cycles.

Head gasket failure is common on aluminum heads usually a problem with insufficient or inconsistent head bolt torque values. Along with that can be a lack of sufficient bolt thread sealing that allows coolant to leak up the bolt threads, that can be a source along with transfer passage leakage. The most common head gasket leakage problems are between the center cylinders, but not exclusive to this area.

Piston rings are not a coolant leakage cause unless they break and jam into the cylinder wall cracking the wall, this happens especially with some form of supercharge or laughing gas applications but is rare.

Engines that use O rings that seal a flat copper head gasket can fail and blow a hole between them and a coolant passage but this is territory of extreme out put engines. But while on the subject of copper gaskets these sometimes show up on engines without the O ring around the cylinder bore thus a good candidate for leaking coolant or compression.

No matter the cause at this point the top end has to come off and you have to look for possible causes as you go. Typically disassembly damages gaskets as you go so you often have to look for other evidence of leakage paths. The heads and block will have to be checked for mating surface quality as well as cracks. This takes some expertise and tools more given to shops than hobby engine assemblers so expect this in whole or part will be going to a shop for inspection at the least or correction to replacement at the most.

Bogie
 

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Discussion Starter #6
good info thank you sir!

I think you are eluding to just pulling the head of one side where its had coolant in the system or both? In order to evac. the motor of all coolant must i keep flushing it with some cheap motor oil till its all out or mostly all out of the system? Still unsure where to start. Its a carb'd 350 btw
 

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Discussion Starter #7
This will pretty much come down to cracks in the heads or a leaky or blown head gasket. Some times a leak between the intake to head gasket between the coolant return and the adjacent intake port.

Ported heads often crack in the ports because the material has been cut too thin so it fails after exposure to heating and cooling cycles.

Head gasket failure is common on aluminum heads usually a problem with insufficient or inconsistent head bolt torque values. Along with that can be a lack of sufficient bolt thread sealing that allows coolant to leak up the bolt threads, that can be a source along with transfer passage leakage. The most common head gasket leakage problems are between the center cylinders, but not exclusive to this area.

Piston rings are not a coolant leakage cause unless they break and jam into the cylinder wall cracking the wall, this happens especially with some form of supercharge or laughing gas applications but is rare.

Engines that use O rings that seal a flat copper head gasket can fail and blow a hole between them and a coolant passage but this is territory of extreme out put engines. But while on the subject of copper gaskets these sometimes show up on engines without the O ring around the cylinder bore thus a good candidate for leaking coolant or compression.

No matter the cause at this point the top end has to come off and you have to look for possible causes as you go. Typically disassembly damages gaskets as you go so you often have to look for other evidence of leakage paths. The heads and block will have to be checked for mating surface quality as well as cracks. This takes some expertise and tools more given to shops than hobby engine assemblers so expect this in whole or part will be going to a shop for inspection at the least or correction to replacement at the most.

Bogie
Bogie,

I get that it would be damaging gaskets and difficult during disassembly to pinpoint the culprit of the leak.
Besides visual evidence to find the leak..... what would you do? Im thinking disasemble, inspect then have the heads checked because its hard for a novice like me to see where the leak would be other than the dark areas around the cylinders after removing the head gasket (if i dont see a crack(s)).


BigChevy
 

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Bogie,

I get that it would be damaging gaskets and difficult during disassembly to pinpoint the culprit of the leak.
Besides visual evidence to find the leak..... what would you do? Im thinking disasemble, inspect then have the heads checked because its hard for a novice like me to see where the leak would be other than the dark areas around the cylinders after removing the head gasket (if i dont see a crack(s)).


BigChevy
Yes, if you don't obviously spot a bad intake gasket or a blown head gasket during your tear-down, and cannot see any obvious cracks in anything, the next step would be to have a machine shop pressure test the heads for you.

A blown head gasket could be the fault of the gasket, the fault of an engine overheated, or it could be a result of the heads being warped, ...so the heads should also be checked for flatness. They may have to be re-surfaced before you install new gaskets or you may be doing the job all over again a few thousand miles later.
 

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Bogie,

I get that it would be damaging gaskets and difficult during disassembly to pinpoint the culprit of the leak.
Besides visual evidence to find the leak..... what would you do? Im thinking disasemble, inspect then have the heads checked because its hard for a novice like me to see where the leak would be other than the dark areas around the cylinders after removing the head gasket (if i dont see a crack(s)).


BigChevy
It's hard when your not a novice, it's just after a few of these you get a feel for what to expect but there's always surprises.

I'd pull both heads and get them checked if one failed the reasons for it's failure might exist on the other side but just hasn't presented itself yet. So if it's an issue with uneven head bolt torque, a lack of the hardened washers that should go between head bolts and aluminum heads, or bolts that are too short which is common as properly done with hardened washers there are head bolts that are a few threads longer than stock to insure there is enough thread engagement.

Gasket failure is common to inadequate or inconsistent bolt torque this can come again from too short of a bolt, or missing hardened washers that increase the screwing in torque without properly stretching the bolt because the hard steel galls the softer aluminum giving a higher torque reading than is actually being achieved in the threads. Another big problem is damaged, dirty, or warped block decks and the same for the head mating surface. These surfaces cannot sufficiently nor equally compress the gasket to prevent leaks.

Typically with aluminum heads you need a composition gasket as the coefficient of expansion is quite different and larger for aluminum than iron. To accommodate this generally gaskets for these sandwiches are compositions of layers that allow differential casting movement without loosing the seal. Most used are about .050 in thickness some can be had at about .028 inch. Steel shim gaskets typical of all iron build ups have trouble holding a seal in these aluminum to steel combinations.

Then there are the usual casting cracks which can vary by inadequate bolt torque, to warped or uneven surfaces, to overheating the engine, or ports that have been ported or heads to even blocks that are excessively milled resulting in metal thicknesses that are no longer strong enough for the imposed stress and strain. Cracks are not always visible the shop will use magnetic or dye inspection or iron and steel parts, and dye inspection on aluminum parts to detect cracks that are there but not visible. Another thing to be inspected is the integrity of the valve seats, these are some sort of high and hard alloy steel pressed into the aluminum; not an item you want to crack or come loose in a running engine.

Whose aluminum heads are you using?

Bogie
 

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Discussion Starter #10
-I purchased the truck with claimed ZZ4 heads and the chevy performance intake so FIRST ill remove the valve covers and confirm via stamp they are true ZZ4 heads, they are definately aluminum but those came on motors back in the 80's so confirmation is what i need (chime in on that)......

I have NEVER overheated the motor only a dozen or so times it clocked @205-210 deg.

Ill definitely remove both heads as you suggested and have them checked for cracks, warping, matting etc. However, I dont have a way of taking the block out of the truck and transporting it at the moment.
 

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-I purchased the truck with claimed ZZ4 heads and the chevy performance intake so FIRST ill remove the valve covers and confirm via stamp they are true ZZ4 heads, they are definately aluminum but those came on motors back in the 80's so confirmation is what i need (chime in on that)......

I have NEVER overheated the motor only a dozen or so times it clocked @205-210 deg.

Ill definitely remove both heads as you suggested and have them checked for cracks, warping, matting etc. However, I dont have a way of taking the block out of the truck and transporting it at the moment.
The ZZ4 head is the mid 1980 to early 90's L98 engine from the Z28 Camaro and Corvettes in aluminum and the SS Impala in cast iron and Mercruiser 350 marine engine. They were obsoleted for Gen I engines by the much copied L31 Vortec head of 1996 to about 2000 production. The iron L31 head with all stock components will out power the L98 head in aluminum or iron be an easy 25 horsepower. The bigger the cam you stuff in the engine and the more head work you do on L31s the bigger that number gets for comparable cam and work done on the L98s. Full out porting and valve train mods to both will net the L31s outgunning the L98s by about 60 horsepower all other things being equal. So while the L98 head was a great improvement over the first generation SMOG heads they are in present day terms, no big deal.

The L31 Vortec head is also available in aluminum from GMPP known as the Fast Burn, never used on production engines only available over the counter. The L31 also spawned a flood of aftermarket heads in iron and aluminum,import and domestic, inexpensive as heads go to unbelievably costly.

The GM versions take a unique bolt pattern intake while the aftermarket supply their heads with both the pre 1987 bolt pattern and the post 1995 Vortec pattern. The L98 uses a variation of the pre 87 pattern that is unique to 1987 through 1995 production where the angle the center pair of bolts is changed. You need to watch this when ordering intakes for these heads.

Inside this time period from 92 through 97 is the Gen II, LT1 and LT4, the basic block and head castings do not interchange with Gen I engines largely because the coolant is routed to the heads first in the Gen II engine and there are major changes to the coolant pump and distributor as well. Except for crank, cam, and valve train there isn't much that will interchange to Gen I engines. Then the Gen III LS comes along as a totally new SBC having nothing in common with the earlier SBCs.

So the L98 isn't a bad head, performance wise it's rather a return to the 1960's double quench heads, but the L31 Vortec draws a line in the sand that nothing before can get across without so much modification it's insanely not economical to even try and even then you probably won't get there.

Bogie
 

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Discussion Starter #12
GREAT INFO on head comparison

yup, all great info bogie.

I know they are the l98 heads or the zz4 head because im not on spider ls fuel hook up and these heads are angle plug port heads.

Ill let ya know what i find out, I MIGHT end up buying another set of heads that are close to these because they are a good street and off road set up for the truck.
 
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