I took my 05 silverado in for service today because of a loud tap during cold startup. Lasts about 30 seconds then goes away. Also loss of about 1/2 gallon of water every 1k miles. No water in oil. Mechanic says i may have the silverado cracked head. He said this is common. Any thoughts would be great. He said he will check the part number on the head with the tsp report he has.

 

Never heard of that being common. I would suggest he run a compression check to verify it. It does sound like its leaking from the exhaust. You may be loosing coolant through the exhaust.

 

I never heard of it either. They had an issue with intake gaskets in earlier models. Let us know what they find.

 

so he got back to me today. he said that the casting number on my heads coencide with the tsp reports he has. he took off the valve covers to get the casting numbers and he said there are visible signs of water. he said if the casting numbers didnt coencide with the tsp report he would just say its the head gaskets but because they do he say most likely the heads are cracked. looks to be a 3500 dollar bill.

 

$3500 to replace a couple heads?!?!?!?! I am in the wrong business!!!!

 

What i would do check water pump for leakage hoses ect. Before i let anybody change head i would get compression test and i would watch. The loud tapping maybe lifter where it is cold thick oil . Also if it is head they make some great stuff to pour in stop leaks even fix cracked heads they guarantee it with a great warranty .I used some fixed mine. Like Shamrock said 3500 . For 3500 i could have whole engine rebuilt.
OH DOES IT PUT ALOT OF WHITE SMOKE OUT OF EXHAUST. IT WILL NORMALLY ON COLD MORNINGS , AFTER IT GETS WARMED UP GOOD. ALSO SHOULD SMELL ANTIFREEZE IN EXHAUST.

 

i dont believe it smokes (white) when driving, i will check today. your right for 3500 i can find a used motor with less miles for less than that. when you mention the oil being thick because its cold. the tap only occurs in the morining and temps about 35. yesterday i let it sit for 4 hrs after getting it home. i then started it and no tap. either way i am going to see what the auto parts store has for anything like this.

 

The cold tap is normal. I have had a dozen or so newer GM trucks that do it. GM says it's piston slap till the motor warms up and won't do any harm. I was skeptical about the harm thing till I put well over 200K miles on one that was doing it since about 80K. I would just worry about the coolant loss. Have someone with a pressure tester pump up the system and see where it is going.

 

Check this stuff out works http://www.steelseal.com/?gclid=CLe5...FYNI7AodEW-YGg

 

Just did a motor swap last weekend due to a set of cracked heads. Had a slow coolant leak and I changed and checked everything and found a bulletin online about the castec heads. The motor had 176k on it w a brand new GM tranny and the truck still being mint , a motor w 60k was bought for$ 550. With the valve covers off there was visible orange coolant sitting in the head bolt seat as suspected. 05 silverado 4.8l