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Hi yall, I recently rebuilt my chevelle motor and am having some (a lot of) cooling system issues. I drove the car for LESS THAN A MILE today and it got to 230 (210 on the EFI sensor). Everything is brand new and still overheats. 78 degrees outside, Socal. Should be no problem.
LQ4 block, stock crank, Frankenstein CNC LS3 heads, 11.5:1 pistons, etc, Terminator EFI, 4 row Champion radiator, champion shroud with dual 14" fans, Motion Raceworks 4 corner steam vent kit, no thermostat, holley water pump, etc. etc...My coolant temp sensor for the EFI (driver side front) reads 20-40 degrees cooler than the sensor for my Dakota Digital dash (left side rear). There are no leaks anywhere (somehow).
My thoughts:
-Fans turn the correct direction, did the ribbon test
-Thermostat stuck closed-its gone, removed.
-Too small of radiator, replaced it with 4 row champion (replaced a 2 row cold case and it now runs a few minutes longer before getting to 220 @ idle)
-Steam vents or improper bleeding, but I have the Motion Raceworks kit and all 4 corners go to below the filler neck as they should, and bleeding is kind of self explanatory...
-Bad/insufficient flowing water pump, its turning the correct direction for my setup (maybe holley one isn't cutting it and I should go to a high flow Mezeire electric unit?)
OR
-i bought and installed 2 LEFT SIDE cylinder head gaskets and theres zero coolant flow on the right side because the main port is blocked (waiting on Summit Racing to tell me if the gaskets I ordered are side specific, pictures everywhere online indicate no buuut...)
What am I missing here? Any ideas? Beating my head against the wall hasn't helped and I don't want to start cheese-grading my forehead if I don't have to :3
UPDATE: For t*ts and pickles, I ran the car for a few minutes today WITHOUT the serpentine belt on and observed the temp readings....Car heated up at basically the same rate but the temperature difference between the front left and right rear sensors was only ~10 degrees...will be going on craigslist for a cheapy used one to find out exactly instead of buying a new one......
I also did some detective work and found I installed the head gaskets CORRECTLY. Theres a nub of the gasket that hangs past the edge of the block-head contact, that nub is between cylinders 2/4 or 1/3 and indicates the "FRONT" of the gasket, so I installed it correctly (main water pump inlet ports are open on the front and rear of the gaskets I used so they aren't bank specific, but there are 2 bypass holes that are supposed to be at the REAR of the bank)
UPDATE 2: Started the car and let it idle with the heater hoses going to a bucket of water. There was ZERO water movement out of either hose. Put my loop bypass back on, filled the radiator and let it run with the cap off for a bit to see if there was any water flow in the upper hose: there was zero water flow, the the only water movement was through the steam vent outlet. Anyone have ideas as to what that means? No flow from either upper nor lower, but plenty through the steam vents. Is my head gasket indeed the culprit?
Sometimes that big azz radiator can be the issue.
Are you sure your getting enough flow across that radiator to cool things down?
wp spinning the correct direction?
It had the same issues with the smaller radiator, and I used the smaller one for 6500 miles without issues before the latest engine rebuild.
WP was spinning the right direction (counter clockwise), (no over/underdrive balancer or anything),
There was nothing coming out of the upper hose when i ran it today (ran with hose ON and looked through the filler, also ran the car with the hose OFF and it didn't move any water either. No thermostat mind you), nor was there anything coming from the heater hoses when I had those go to a bucket. Will be getting a cheap bottom tier pump from an auto parts store tomorrow to see if i can get some water flow.
I used my borescope to look in the block outlets to make sure I oriented the gasket correctly that checked out right.
When I initially filled the block yes I filled it through the upper hose. When that was full i connected it to the radiator, filled the radiator then filled the rest of the engine through the steam vent hose, all before starting up. Start the car, run for a little then fill, revv a little then fill, etc etc. Upper hose connects just below the radiator cap, lower/upper on the same side, thats how I was looking at water flow (in this case, lack of water flow) All the while the car was running and cooling system bleeding, car was jacked up as high as the jackstands extend such that the radiator is the highest point.
UPDATE: High flow water pump did nothing. Brought myself to pull the heads and check head gasket orientation, it was indeed OK but I found that they are LS2 head gaskets......Is using LS2 gasket with LS3 heads a no-no? 4.00 bore so that's not even on my mind, is there a difference in the cooling passage holes in the gasket? This is the very last thing there is on the list of possible issues.
You should see flow if there is no thermostat, try another radiator if you have one sitting around, that one may be clogged or something going on there. When you pull that one out lightly add water in one side and see if it comes out the other.
And by the way running without a thermostat will cause one to over heat. And over heat fast. Tried that once and quickly learned it doesn't work out well.
But that doesn't explain you seeing no water flow with the thermostat out.
Wait you also said your radiator hoses connect on the same side of the radiator?? You wouldn't see flow in that case because it would just flow top to bottom and not through, unless you have some wild *** radiator I've never seen that is sectioned off in between the hoses/spit down the middle of the radiator.
Out of the steam vent was the ONLY flow I was seeing with 2 different radiators (both with less than 5000 miles on each) and 2 water pumps (both brand new). And my head gaskets were installed oriented correctly. I'm completely at a loss. Coolant passages in the heads are different from the LS1 heads I have sitting around, but I asked Martin from CPR Engines in Gardena (they ported the heads) and they've never had cooling issues with the Frankenstein heads.
Turning correct direction, yes. I found after close inspection that some holes in the gasket don't 100% line up with the holes in the head. Will be doing research as to the correct gasket I should use.
PUTTING THIS THREAD TO REST: FIGURED OUT MY ISSUE. I did some digging and found some guys were weary about buying aftermarket heads cast from Liberty Castings, they do Frankenstein M311 and MAST Black Label. Thought nothing of it initially. Well, the main water jacket that goes directly to the water pump was COMPLETELY plugged, both sides and around the pass-through for the head bolt. Absolute garbage casting job. Can't see too well in the photos, but BOTH SIDES are completely plugged with casting flash with the exception of maybe a pencil lead size hole (lots of resistance when I blew thru the hole). Could try and open them up with a dremel but one side is inaccessible and I don't trust them at this point, I have better self esteem and better things to do than to try and work them to no avail and have to disassemble again. Also, what's to say the rest of the inside of the cylinder head doesn't look like the same way? THANK YOU TO ALL RESPONSES!!!!
Ported area was done by me to open it up to gasket opening size, as-cast opening was WAY smaller than the LS1 heads I had sitting around.
Last edited by kimbalmlq4; 07-04-2020 at 07:12 PM.
Reason: important details!!
Liberty Castings should be put out of business for crappy products/QA like this. It should never gone out their door.
LIBERTY CASTINGS, ARE YOU READING THIS???
Well...I don’t have any LS3’s for sale but I must say that the issues with these castings were the last thing I expected you’d find. Very interesting indeed.
06-27-2020, 06:59 PM
Cooling issues 
