I just attempted to fill my cooling system to run the engine for a while. I am using an LT-1 radiator and I filled it to the top of the radiator cap and filled the overflow tank. Here's the problem. I've read on several threads on this forum that the lower hose on the water pump housing is the inlet to the water pump. This does not appear to be the case. I took the thermostat out and saw that the opening is completely blocked until the thermostat opens. My coolant guage got up to 210 degrees and I immediately shut it off. I don't think there was any coolant being puleld into the system on the inlet side (right side) because the radiator is not above the engine at that point. It must not have been pulling any water in from the lower hose either since it would have to have been blocked off. Do you think any damage occurred? The heads were too hot to touch, I don't know if that is normal. On my LT-1 radiator, the hose on the right (facing the engine from outside) is at the high point, and the hose on the left is at the lowest point (which is the point I thought was the inlet to the cooling system but now realize is the outlet from the thermostat). How am i supposed to get coolant into the system? The inlet hose is level with the radiator. If the inlet is on the right side, doesnt the radiator need to be higher than the engine? Was my water pump running all that time without any coolant

 

I went outside and poured coolant directly into the block through the REAL inlet to the water pump (the right side). The temperature only went up to 180 degrees this time, the thermostat opened and coolant came through the radiator as it should. Can anyone please tell me if there is a remote chance that any damage happened to my engine as my coolant gauge read 210 degrees? Keep in mind there was no coolant in the damn block, so I don't know what that water temp gauge was reading. Also, what are the odds that I hurt my water pump, this was running 10 minutes? I'm kind of angry that this happened, I really hope i didnt damage anything. I took such extreme measures against overheating and runnign my engine without coolant. I had only started it once before and ran it for less than 5 seconds. Now I end up running it for 10 minutes without coolant. I feel sick.

~Bob

 

no it's just air bubbles you should be alright man is the motor making any weird noises if not your fine

 

What air bubbles? The block was completely bone dry until I poured the coolant in the second time I ran it. If there was at least some coolant in there, I might not be worried, but there was nothing in there.

 

I literally had nightmares about this last night. If the gauge was showing 210 degrees without any coolant, does that mean the actual block and head temperature was much higher?

 

My LS1 got to about that temp on my Autometer gauge (I had the same issue, and the same fill technique). I wouldn't worry too much, I've not had any issues with mine, and the actual block temp wouldn't have been much more, as the heat passes right through the metal to the sender, so your block temp was likely pretty close to that 210* which is WELL within tolerances (hell, a stock F-Body runs that hot).

 

this is an ls1 i thought with a lt1 radiator.

 

Phew, that's a relief to hear. I am still going to do a compression test when the car is all buttoned up and on the road. Nevertheless, I still wish it never happened, it was stupid of me to let it run up to 210 and not stop it immediately at 180 when warm water didn't cycle through the radiator.

 

Yes, it is. I don't understand what that changes though? The fill technique? Please explain.

~Bob

 

Just because you don't understand how the system works doesn't mean previous posts explaining how to hook it up are incorrect; they are not. Your info on the other hand IS incorrect.

The LS1 thermostat housing IS the water pump inlet. The other nipple on the pump is the return.

The LS1 circulates water internally until the thermostat temperature is reached. Then the 'stat opens allowing some cool water to be drawn IN to the pump, from the radiator. This cycle repeats to maintain the desired temperature.

The proper way to fill an LS1 (or LT1 for that matter) is to fill it thru the upper-most port to get the most coolant into the ENGINE, not the radiator. On an LS1 you fill it thru the RETURN port until full.

You finally figured that out, so since you poured coolant IN the return port, that makes it the "REAL inlet to the water pump" ??? Interesting, but wrong.

You just have to think about what is more important when pouring coolant; filling a $50 radiator, or a $5000 engine.

 

The LT1's were reverse flow meaning they sucked from the left side of the radiator and expelled to the right. The coolant flows through the heads, then block then back to the radiator.

The LS1's are not reverse flow. The coolant comes in through the thermostat from the right side of the radiator and out the top near the throttle body to the left.

When I first did my conversion, my heater core blew and the water pump pumped my entire radiator full of 200 degree water right onto my feet. I was only a mile or so from home and the temp gauge pegged high. Not reall sure how hot it got. I waited a few days to fill the engine to make sure I didn't shock the block and heads by adding cold water making them crack. You know, brittle fracture and all. Anyway, I did a compression test and everything was dead on. Filled up the system and everything ran fine. These engines can take a beating and still be just fine.

 

I see. Thanks for explaining. Well the reason I assumed the upper hose was the inlet is because the water pump seemed to be pulling the water in through that port, but pulling nothing through the lower water pump port. I read through at least 15 posts and searched for a few hours. I could not find any that said to put coolant into the block first. When I read that the lower pump hose was the inlet, the common sense assumption would be that the pump would draw water from that location. It was definately not obvious to me, even knowing that the water pump was a reverse flow configuration. Reverse flow didn't automatically trigger "internal circulation until thermostat opens" in my mind.

I don't think that I have "to think about what is more important". Obviously I value my engine over my radiator, and I was trying to take every precaution against damage. It sounds like you are an authoritative source to tell me whether or not running the engine for 10 minutes with no coolant was harmful. Do you think it was?

~Bob

 

Oh Okay, well that was news to me about the LS1 not being reverse flow. I think I will just stop posting anything informational entirely so I stop spreading misinformation.