TRCVIP3R

Hey guys so @dlayne is my dad and I am helping him out with trying to figure this out.

The vette was actually mine before he bought it from me (2008 Z06). I never had any issues with the car's performance. The car has lots of aftermarket parts, professionally tuned, etc. Here are the mods pertaining to the engine/performance:

Ls7 Cylinder Heads done by West Coast Cylinder Heads
ARP Head Studs
CNC Stage II Port & Polish for optimal flow
Mulit-Angle Valve Job
Milled .037 to bring static compression ratio to 11.8:1
Replaced Stock Exhaust Valves with solid Stainless Steel Valves
C.H.E. Rocker Arm Upgrade
C.H.E. Manganese Bronze Valve Guides
Tumble Polished Stock Titanium Intake Valves
Ragin Racing LS7 Camshaft
Stalker Crane Cam Specs 224/246 .660/.660 Lift 115 LSA
5 degrees of overlap
Comp Cams Custom Length Push Rods for Proper Preload
Marley High Performance Duel .700 Lift Valve Springs w/ Titanium Retainers
Lg Motorsports Exhaust
Stainless Steel Long Tube Headers 1 3/4 inch Primaries
Stainless Steel High Flow Catted X Pipe
Corsa Exhaust w/ Black Tips
Halltech MF103 Beehive Cold Air Intake System
FAST LXR 102 Intake Manifold Painted Silver
Holley Fuel Rail
Nick Williams 102mm Throttle Body
Elite Engineering Oil Catch Can
Lingenfelter 160 Degree Thermostat
NGK TR6 Spark Plugs
High Temp Plug Wires
TMOD Customs upgraded box and 5% shifter with poly bushings
Norris Motorsports
Professional Engine Assembly and Degreeing of Camshaft
Straightline Performance
Custom Dyno Tune


-We believe the issues started with a blown head gasket, causing car overheating, etc, and from there things kind of spiraled downward with more issues:

-Replacement head gaskets (stock LS7 gaskets) Before, the gaskets were beefier/aftermarket gaskets with arp studs, etc, unsure exactly what they were.

-New water pump, many coolant flushes and changes, many oil changes

-Replacement thermostat was a stock thermostat that opens at 205 degrees, the prior was a lingenfelter 160 degree thermostat. Went through 2 stock thermostats with car overheating before finally installing the Lingenfelter 160.

-Cylinder heads were professionally resurfaced, cylinder 7 exhaust valve was replaced (it was slightly bent, likely due to gasket failure, and by slightly I mean very slightly). Mechanic pressure tested cylinders and everything looked good, all pressures were solid.

-Car continued to overheat, coolant consumption, coolant in exhaust until the latest work which was the FelPro Head Gaskets 1161 R-053 and the Lingenfelter 160 Degree Thermostat. Since this was done the car has not overheated. Highest temp has been 195, averages around 185. It is 95+ degrees in Alabama so those are good looking temps. Ensured there was not air/air pocket in coolant system.

-After this, still smoke in exhaust, coolant is being consumed. So then replaced all the intake manifold gaskets and I believe checked the manifold for any cracks/issues.

-After this, still smoke in exhaust, coolant is being consumed.


So at this point we are puzzled...
Mechanic thinks it needs to have an engine block pressure test/check. This would be at a different shop, he does not have capability.
Possibilities: Head still has problem? Head Gasket is not working properly? Crack in engine block?

Your guys thoughts on what could be causing this?

Also, the car is in Auburn AL, there is a lack of performance shops there, likely have to go to Atlanta. Who knows of excellent performance shops in Atlanta that could figure this out?

Thanks everyone!

Sub8

Cracked liner is a possible cause.

Have you pressure checked the coolant circuit? PEPboys etc usually have this kit available for hire.

G8Pumpkin

Couple of possibilities for you, you might have a cracked cylinder liner and or the head gaskets can still be weeping a bit. On the head gasket you can drill out the rivets except for one in a corner so you can fan out all the layers like a deck of cards and coat all sides of all layers with Permatex hi tack which will pretty well guarantee they will not weep. On my car I have been chasing a small leak about 1 cup of coolant each time I drive it so I pressurized the cooling system to 25 psi and left it over night to find a small pin hole leak on the bottom side of the surge tank cross hose that goes over to the heater core the leak was a pin hole on the bottom side where it crosses over the drivers side rad hose and the new hose is upgraded in that area with an expanded mesh over it so I guess it was a common problem. That part is discontinued but there are 9 hose left showing in various dealers stock but no stock in GM warehouses so you need to ask your parts man to tell you which dealers have it in stock. The rad hose would not explain the coolant in the exhaust though only head gasket would. If there is no water in the oil it would suggest not a cracked liner. If the heads are pulled again check the flatness of the block with a feeler gauge and straight edge, same for the heads, also what pistons are in this and why did it blow a head gasket in the first place.

Hib Halverson

Before I'd do anything more, I'd find a service facility which can pressure check the cooling system. A cooling system pressure check will help identify the specific problem.

My guesses are:

Faulty head gasket or head gasket(s) not sealing due to warped head or block deck caused by coolant overtemp
Cracked head.
Cracked liner.

I would absolutely not take the suggestion to split the head gasket layers to coat them with Permatex High Tack. Doing that will create new problems with head gasket thickness consistency and head gasket clamping pressure.

Unreal

Very likely that a cylinder is cracked. Probably was from the beginning.

RGT

My guess is a cracked cylinder liner in the #7 hole. Happened to me and a lot of other guys.

dlayne

In the very beginning, when the cylinders were compression tested, the #7 cylinder read 140 psi when all the rest were around 180. Also, the exhaust valve for this cylinder needed replacing. What was the solution for your situation? Thank you.

Uncle Meat

Just as an FYI and as a fellow Alabamian there is a decent speed shop in Alabaster which specializes in LS based performance. Calibrated Speed & Performance is the name. I doubt they have the ability to pressure test your block for you, but for general performance upgrades they are not too far from you if you need any work in the future.

U.M.

TRCVIP3R

Thanks for the info so far. If it is a cracked sleeve, I've read that Darton makes good replacement sleeves for the LS7? Also, sleeve is another name for liner, correct?

TRCVIP3R

And yes, shop recommendations in AL and Atlanta area would be a huge help! Thanks!

Mordeth

If you cracked a cylinder liner and intend to re-use your LS7 block then one of the few places that can be trusted to sleeve it correctly is Steve at R.E.D. (Race Engine Development)

http://www.raceenginedevelopment.com/blocks/gm-ls7/

Compression and leak down will give info. As will a pressure test on the coolant system. You can also try a cheap block tester kit like found here:
These are all very simple, straight forward tests that anyone with two hands and the appropriate tools can perform to help assess the situation, including block integrity, cylinder/piston health etc.

But I think that engine is coming out.

Unreal

What Mordeth said. Steve@RED is one of maybe 2-3 places that should be touching a sleeve setup. Maybe TSP and Livernois can be added to the list, but anyone local probably can't do it properly. I would only trust RED to do it, as he is the industry leader, developed the system, and has the proper equipment to do it. Not many places have the correct parts to do it.

dlayne

Recommended part for sleeve replacement?

TRCVIP3R

So very late update here, and something new with the car
What originally started this whole thing was Cylinder 7 Exhaust Valve dropped/failed, cracked cylinder sleeve, yuck.
That has all been sorted out and repaired!

Just now, Cylinder 8 Intake Valve dropped. No damage to cylinder sleeve or piston head for cylinder 8 (Praise God)
Apparently what caused it to drop was the valve retainer (titanium I believe) failed/broke.

Curious, because the LS7 in this car already has:
Multi Angle Valve Job
Replaced stock exhaust valves with Solid Stainless Exhaust Valves
CHE Rocker Arm Upgrade
CHE Manganese Bronze Valve Guides
Tumble Polished Stock Titanium Intake Valves

Do we replace ALL the intake valves and retainers? To be totally on safe side? Or is that unnecessary? New Exhaust valves and retainers all the way around as well?

We are just puzzled as to what might have caused this to happen. Anyone have any idea on cause?

Cheers!

Dale1990

The bent one looks like an intake valve and it appears the valve tip broke off. Were the lash caps all installed properly?

Unreal

Could be install issue, or wrong locks. I've seen big name shops on this forum use the wrong valve locks for the valves, not even knowing there were different types. Many people piece parts together without taking stuff like that into account.

You should at least pull them all, verify they are the correct type and style of locks, and all properly installed.

Also what person above said, looks like intake valve, which if no lash cap, would cause the same thing as it wears through the valve. Check for all the lash caps and that part being setup properly.

TRCVIP3R

Clarification, the INTAKE valve on cylinder 8 was bent!

Treadhead

Coolant consumption still a problem? I just had my engine rebuilt for the same issue. Pressure testing revealed a very small leak inside of one of the head stud holes in the block between a thread. VERY tiny, but enough to leak coolant into the combustion chamber and everywhere else in the engine. It was a mess. The idea is that there was a metallurgical thing going on that caused erosion and a tiny pinhole to form and leak coolant from one of the water jackets. Took forever to find the leak, it was so small. Sealed it up and its now GTG, even more so with a bigger cam. E85 is my friend!

TRCVIP3R

@Treadhead coolant leak is all settled, cracked cylinder sleeve fixed, no leaks, all good there.

TRCVIP3R

Thoughts are:
Replace all the exhaust and all the intake valves and all retainers.
Brand recommendations? Metal types? Anyone use Inconel?