I want to know if it is possible to have a cracked or warped block but not have any oil in the water or vice versa. check my sig, everything I have is there. I had some pretty bad overheating problems before I put the new heads on, but it got even worse now, I cant drive it more than about 10 minutes before its getting hot. I hooked up my scan tool, it showed 220 while my dash showed 240, we then hooked up a mechanical guage and it showed the same thing. anyway, Ive got a pretty long post on the cooling board called "serious cooling problems, need help" but I wanted to see what anyone thought about the block.

 

The only way I know of to have an over heating problem and not have a leak, or contamination would be if there was some serious blockage in the coolant passages. Not uncommon at all on high mileage engines. Especially if you fill it with city water. You can get lots of mineral deposits.

 

why don't you put a preasure tester on it and see if the system holds preasure or not?

 

it was filled with water off a well with a water conditioner, so shouldnt be too much mineral deposits. as far as high mileage, there are only about 50K miles on the engine, and about 20K on the radiator, everything else is either brand new or was replaced in the last two months. plus, we flushed the entire system about 3 times thinking maybe there was some serious buildup.

we already have the engine torn down so we cant pressure test it. I know its atleast holding some pressure because Ive got a pressure release radiator cap, and as soon as you pull the lever, there is a rush of coolant into the overflow tank. only question is whether or not its the correct pressure. should be, the cap isnt but about 6 months old, I cant see a radiator cap going bad that soon.

 

Are you measuring temps at idle or on the highway? The car should still be able to idle relatively cool. On the highway if it runs hot you need to check your air dam and make sure it's still on there.

 

Yes u can have a cracked block without water in the oil been there done that .

Check out your radiator my dads truck was heating up for 1.5 years he changed everything from water pump, thermastat ect
it turned out to be the air cod and radiator was cloged with years of bugs and debrie took a power washer cleaned it never had a nother problem
my .02

 

Yes, thats entirely possible. It'll hold water just fine, it wont show up under a leak test, there wont be measureable coolant in the oil, and it'll run hot. Been there, done that. Cracked in the lifter valley area.

Make sure you have addressed all other potential problems first (clogged radiator, debris in front of the radiator, stuck or bad thermostat, collapsing lower radiator hose, bad water pump, bad radiator cap, no air dam, bad state of tune) and then you can start pointing at the block.

 

well, I pulled the heads back off last night, and we have checked absolutely everything else, I mean we are completely confused as to what it is. brand new heads, brand new gaskets, 1 month old thermostat and water pump, both of which have been checked, hoses are Goodyear wire bound ones that dont collapse, radiator is clean with no buildup on the inside, no a/c condensor, fan is wired on at all times, turns the right direction. we checked the block last night, flat as could be, no warpage or anything, no obvious cracks on the deck, will check the valley tonight. but how would a crack there effect the temperatures?

 

I couldnt tell you. Increased friction? Anyway, I replaced the block, cooling problem went away. At one time, I had the block out and had it decked and honed, and it looked ok to me and the machinist, so I reused it. Turns out that was a mistake. Who knew?

 

hmm.....if nothing else works then I'll keep that in mind. Ive wanted a 4-bolt main 'vette block anyway, maybe I'll be able to get one now. I just didnt want it to be out of necessity.

 

I have the same prob. texaslt1. Mine will run up to 230 on the interstate pretty quick, but will drop fast also with foot off of the gas! I have been following you're post in cooling it down. Everything is new on mine. It is a 87 GTA, has new: waterpump, 2 sets dual fans( one set pushing in front of ac condenser, and one set pulling in stock location, all come on with ign) new airdam, new 180 thermostat, new aluminum 1 3/8ths radiator, second temp gauge to verify stock gauge, new hoses all the way around, new rad. cap. Timing is set a 6 degrees. My 88 G.M. shop manual says something about a blockage in the head at this point. Is there a way to check this without tearing it all down? Also, i tried this, to see what kinda flow i had out of the pump: I took thermostat out, rehooked up rad. hose to thermo housing, and disconected the other end from rad. I put garden hose in filler, and started car. Had a lot of flow at idle, but when i gave it some throttle, i would get a ton of flow for a couple of seconds, then almost none for a couple of seconds,ton of flow for a couple of seconds, then almost none for a couple of seconds,ton of flow for a couple of seconds, then almost none for a couple of seconds,ect. This dosen't seem normal! Only thin i can think of that could be left is a blockage in the motor it's self? Any way to remedy this without completelly tearing it down? Input PLEASE guys! Thanks!

 

I would think the pulsing would be caused by the water hose not being able to keep up with the water pump. But I don't know what to tell you. Sounds like you did like we did and started replacing stuff in order to try and find the problem. I guess the only advice I can give you is to just follow the shop manual and see where it gets you.

I feel like a jackass for mine. We never considered the problem to be the radiator because it was only a few months old. But what happened was when we replaced the radiator, there was still stopleak and other crap in the engine block from when I blew a head gasket. All that crap quickly clogged nearly the entire bottom 1/2 of the radiator. We took it to a shop here in town, had it rodded out, put it back in, and it cools so well now it barely gets above the thermostat temp.

 

I would check to see if you have the correct LT1 impeller in the water pump. The impeller is different because of ther reverse flow cooling. I recall reading a post redarding this about a month ago detailing the same problem.

After the correct pump was installed it cooled the car down to normal temp. Not sure why the wrong impeller was on the pump. Perhaps a careless manufacturer.

 

hey i dunno but after reading everything, i was thinkin is there any chance the computer or something threw the timing off and retarded it and caused it to run hot? becuz ur all sayin after uve replaced the blocks the car ran great, im not sayin its not the block , maybe it is but what if it was the timing? just an idea