I took my 87 IROC out for a first ride with the 92LT-1 engine. It ran fine and sounded good, BUT the temp varied up and down from around 195 (on dash guage) to 230 or so. The fan was running when i got back to the garage.....the car has the original 87 Radiator ( new) and I have the hose from the thermostat to the lower right of the radiator and the other hose to the top left of the radiator..........it has plenty of coolant in it, but I can't help but think there is air in the system, or I have the radiator hoses backwards..........I did bleed the air out of the top of the thermostat housing.............does anyone have any ideas? Thanks Pat

 

Do you have the chin spoiler on the car still?

 

Add some Water Wetter. it works.

 

yeah the chin spoiler is on there , and it was actually pretty cool out last night...........50's...............I think I must have some air in the system, so II wil try to vent it out today. I was more concerned that I had the hoses wrong onto the radiator..........does anybody else use a 3rd gen radiator with a 4th gen engine? SOunds like a silly question, but I don't know the iin's and outs of the reverse flow cooling..........

 

Can't help you on that, it's one of the main reasons I went ahead and ran the 4th gen radiator/fan setup. Mine stayed at 175-190 while driving and would heat up while idling until the fans kicked in

 

3rd gen radiator here. I've tried the hoses both ways. As long as the air is out of the system, either way works, strangely enough. Just have to make sure its full of coolant. Check and make sure you got all the air out.

Also, you have the steam line connected to the back of the heads, right?

 

I think you are right. I took the cap off the radiator after it cooled down and topped it off...........it ran as I would have expected it today............slowly warm up and then stay there.........not bounce back and forth........I think the radiator HAS to be completely full , other wise the water pump suction sucks wind- along with SOME coolant............if the radiator is completely full, it has no choice but to suck coolant...........I am glad to have heard from somebody who tried the hoses both ways.........now I won't bother.............Thanks again to all who offered advice.........without sites like this, i don't think I would have tried to put an LT-1 in my 87..............but I am glad I did!

 

your radiator should ALWAYS be full of water. I never go on any long drive without making sure I've got a little extra coolant in the overflow tank.


also, if the hoses are connected correctly, it will pull the water from the bottom hose and return it through the top one.

 

I always keep it full with about a quart or 2 in the overflow tank. The problem with having the pump pull from the bottom with this setup is that the lt1 water pump has the outlets "pointed" in the wrong direction to easily have it that way. The radiator has the lower connection on the right side and the upper on the left. Is it the same on the 4th gen radiator's? I wouldn't be opposed to changing the radiator to a 4th gen if it makes a difference....As for now, it seems to be running as coll as anything else I drive............

 

The 4th gen radiators have the inlet and outlets almost directly in the middle of the tanks, then has a connection at the top where the fillerneck is at for the return from the heads, then the overflow. Now at the very bottom on the drivers side, it has a place for the oil cooler to circulate from but if you don't have an oil cooler, you connect the little heater hose from the driver side of the waterpump to it.

 

After I posted that I couldn't remember which way they pointed as I know there was some confusion about that when I did my swap.

 

Thanks for the info on the 4th gen radiator. I am going to run the car for awhile and see how it performs. I'm planning on taking it to Watkins glen this sunday for a driving school.........ie hours of flat out driving till it runs out of gas................