New from Wisconsin.
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New from Wisconsin. Hello all:
New to this site. Site recommended by some Techs at Summit. Please forgive if I am not posting this correctly. (quite lengthy)
I have what I believe a cooling system dilemma after an engine rebuild which has confused several mechanics, both certified and shadetree. Wondering if anyone could provide any additional insight or has seen anything similar. Summit Racing recommended I throw a post out in this forum.
Engine is 5.3 from a 2000 Chev Silverado truck. 5.3 from what I understand is a descendent of the LS1 or along the same line. Pulled the motor out after discovering I had a chipped cam lobe. Originally thought it was just a bad lifter but then found the true problem (chipped cam). Wanted to make sure didn't get any metal in the bearings, etc so had the motor completely gone thru and freshened.
Had the engine rebuilt by a local rebuild shop, valve job, the works. Had the radiator flushed, back flushed, chemical cleaned and pressure tested. Put it all back together and in the truck with a rebuilt waterpump, new hoses, fan clutch, and new thermostat along with multiple other parts too numerous to list.
Started engine, performed break in procedures for new cam, lifters, etc. Once the engine got warm (up to operating temp) a noise started to develop from the cooling system and water pump. Sounded like cavitation noise and possibly the impeller was hitting the case. Seems to build a lot of pressure in the cooling system.
Had a couple other guys listen to it and determined must be the rebuilt water pump. Pulled it off, put a brand new waterpump on it. Same thing when engine gets warm.
Noticed lower radiator hose stays cold, upper one gets hot. Good heat through heater core. Motor does not overheat. Talked to a GM tech at a local dealer. Recommended another thermostat and if that didn't solve it must be the radiator. He didn't think we were getting adequate flow in the cooling system.
Tried both. No difference.
Searched the internet for possible options. Seen several blogs regarding combusion leaks into the cooling system. Invested in a combustion leak test kit but am unable to get an accurate test result due to the excessive pressure in my cooling system. Antifreeze keeps contaminating the test fluid. Test calls for coolant to be 2-3 inches below rad. cap. I had at least 4-6 below the cap.
Did some more searching on the net and am now thinking the head gaskets were installed backwards by the machine shop causing my problems.
Finally, for my question: Anyone ever see or hear of anything similar? Want to get some other opinions before I pull the heads. Again.
Thanks
New to this site. Site recommended by some Techs at Summit. Please forgive if I am not posting this correctly. (quite lengthy)
I have what I believe a cooling system dilemma after an engine rebuild which has confused several mechanics, both certified and shadetree. Wondering if anyone could provide any additional insight or has seen anything similar. Summit Racing recommended I throw a post out in this forum.
Engine is 5.3 from a 2000 Chev Silverado truck. 5.3 from what I understand is a descendent of the LS1 or along the same line. Pulled the motor out after discovering I had a chipped cam lobe. Originally thought it was just a bad lifter but then found the true problem (chipped cam). Wanted to make sure didn't get any metal in the bearings, etc so had the motor completely gone thru and freshened.
Had the engine rebuilt by a local rebuild shop, valve job, the works. Had the radiator flushed, back flushed, chemical cleaned and pressure tested. Put it all back together and in the truck with a rebuilt waterpump, new hoses, fan clutch, and new thermostat along with multiple other parts too numerous to list.
Started engine, performed break in procedures for new cam, lifters, etc. Once the engine got warm (up to operating temp) a noise started to develop from the cooling system and water pump. Sounded like cavitation noise and possibly the impeller was hitting the case. Seems to build a lot of pressure in the cooling system.
Had a couple other guys listen to it and determined must be the rebuilt water pump. Pulled it off, put a brand new waterpump on it. Same thing when engine gets warm.
Noticed lower radiator hose stays cold, upper one gets hot. Good heat through heater core. Motor does not overheat. Talked to a GM tech at a local dealer. Recommended another thermostat and if that didn't solve it must be the radiator. He didn't think we were getting adequate flow in the cooling system.
Tried both. No difference.
Searched the internet for possible options. Seen several blogs regarding combusion leaks into the cooling system. Invested in a combustion leak test kit but am unable to get an accurate test result due to the excessive pressure in my cooling system. Antifreeze keeps contaminating the test fluid. Test calls for coolant to be 2-3 inches below rad. cap. I had at least 4-6 below the cap.
Did some more searching on the net and am now thinking the head gaskets were installed backwards by the machine shop causing my problems.
Finally, for my question: Anyone ever see or hear of anything similar? Want to get some other opinions before I pull the heads. Again.
Thanks
Welcome to LS1tech. Sorry to hear of your problems.
From LS1howto.com: "If you got the 97-01 graphite style head gaskets, each headgasket will say "This side up" and will also say "FRONT", make sure the "this side up" is up, and the "front" part is to the front......the two gaskets are unique, so make sure you do this part right! If you got the new 02+ style head gaskets, they are identical so just make sure you have the right side facing up. The gaskets will line up with the dowels discussed above."
If the HGs were installed wrong, I believe this would block some of the coolant passages. I would contact the rebuild shop and have a heart to heart discussion and find out which type of gasket was used and how sure they are about them being on there correctly.
Unfortunately, regardless of what they say, it sounds like it's time to remove the heads and verify correctness of the head gaskets.
I hope you get it figured out.
From LS1howto.com: "If you got the 97-01 graphite style head gaskets, each headgasket will say "This side up" and will also say "FRONT", make sure the "this side up" is up, and the "front" part is to the front......the two gaskets are unique, so make sure you do this part right! If you got the new 02+ style head gaskets, they are identical so just make sure you have the right side facing up. The gaskets will line up with the dowels discussed above."
If the HGs were installed wrong, I believe this would block some of the coolant passages. I would contact the rebuild shop and have a heart to heart discussion and find out which type of gasket was used and how sure they are about them being on there correctly.
Unfortunately, regardless of what they say, it sounds like it's time to remove the heads and verify correctness of the head gaskets.
I hope you get it figured out.
