Urgh, this god damn car...

A few weeks ago i got a hole in my champion 3 core rad so i pulled it and put my stock radiator back in, which is like new so its all good. Ive been on a long trip in it and it never missed a beat, stayed cool, even in slow traffic and it was a really hot weekend too. My dual fans are on a switch

Ive been out in the car tonight, its raining, its cool outside, a mix of motorway driving going about 50-60 then onto the slower roads coming home. I noticed the temp gauge kept going up even with the fans on so as soon as i got home i popped the hood and my coolant level was off the scale, it wasnt bubbling but just very very high in the bottle



I could however hear a bubbling / gargling coming from the top hose ???? which was hot as you would expect, so i know the thermostat is good. the whole cooling system is new, new water pump, new hoses, thermostat, rad, distilled water and fresh coolant 50 50 mix.

This is the 2nd time the car has done this where if ive been driving around a while then slow down the temp jumps up

after around 10 minutes the coolant level had dropped to just under the hot mark on the expansion bottle though

 

Radiator cap maybe.

 

I reused the cap from my champion rad saying as its less than 7 months old. Theres no leak or anything around the cap area

 

Is it a 16psi cap?

 

How long has it been since the radiator swap? Trapped air, perhaps?

Regardless of the coolant level in the reservoir, was the engine actually overheating?

 

I think this cap said 19lb, i will have to double check. What happened was my champion 3 core rad got a hole in it but luckily i had my stock rad stored in the garage which is only 2 years old anyway.

My car was never overheating as such it was just running hotter than i liked after swapping in a 5.7 and fitting headers and a big stainless exhaust etc etc etc.

I bled the system twice the night before going away for a weekend which was a 3 hour drive and the car stayed nice and cool, even in slow traffic with the fans on it was spot on. Its just the past couple of times ive driven it, if ive been going fast for a while and then get onto slow roads, by time i pull up outside my house the temp is creeping up even with the fans on and the coolant level in the bottle is rising, and the gurgling noise can be heard coming from the top hose and intake area. It happened again tonight.

But is that classed as overheating ? coolant wasnt spewing out and it wasnt even bubbling in the overflow tank

 

Gurgling without it bubbling into the overflow makes me suspect there's still air trapped in the system, but you did say you bled it twice...

 

I did yeah. Kept squeezing the top hose to get as much air out first then ran the engine upto temp until the bubbles had pretty much all gone. I let it cool down for a few hours then i done the same process again and there were no bubbles aftee a short period. I dont get how air would be in the system now as it hasnt been touched.

 

Did you run it with the radiator cap on or off? You don't really have to squeeze anything when bleeding the cooling system (unless you get bored).

I refill the cooling system and run the engine at idle with the radiator cap off, heater temp all the way hot and let the thermostat open 2 or 3 times. Yes, it'll spit some coolant out when the thermostat opens but I just top it up when the thermostat closes again.

After 2-3 thermostat cycles, I top off the radiator and cap it and fill the reservoir.

I fill the reservoir half way between the hot and cold marks, shut off the engine. Sometimes I drive it, sometimes I don't. The next day, I adjust the reservoir level as needed and I keep checking/adjusting every few days while the level stabilizes.

 

I've thought about getting one of those spill-free funnels with the radiator attachment for this very reason. Just haven't gotten around to it since I haven't cracked the cooling system in a while.

 

the air self purges after a couple of heating cycles- that's why the temp gauge might swing erratically when it warms up then stabilize after a little run time after you work on something that causes you to have to refill the coolant.

if it's getting air in it after the initial heat cycle, then you have other problems. a cracked head or blown head gasket allowing combustion gasses into the cooling system is the most likely culprit- you can get a kit at a parts store to check the coolant for hydrocarbons. it might not show up on a pressure test with a coolant system checker, but the crack opens up when the engine gets warm and it does it.

it might also be a bad seal on the radiator cap that is sucking air back in when it cools down or even a crack in the hose from the radiator to the overflow, but that air would get purged out once it gets up to temp.

honestly, i think you hurt something when the coolant was low from the leaky radiator. all it takes is one localized hot spot in the head and it's cracked. but check the easy and cheap stuff first- replace the overflow hose and the radiator cap. make sure all the hoses are tight. after eliminating that, move onto the bigger stuff.

 

Nah the hole in my radiator was tiny, it was spraying a very fine jet of coolant when hot, the cooling system was still pretty much full when it happened as i noticed drips under my car when putting it in the garage. my engine was stripped and rebuilt with all new gaskets and the heads were tested and skimmed, i know the engine is fine.

all my hoses were replaced when i put the 5.7 in too. I might change the champion cap for another stant locking one and see what happens. I might even try bleeding the system again just incase.

I noticed after the last time it done it though, i was in the garage with the hood open and in the space of 10 minutes of the car being off the coolant level returned to just under the hot mark on the expansion bottle ?

 

Maybe, coincidentally your having water pump issues....? Or Maybe a mouse or something build a home in your radiator.

 

I think im all good now. I bled the system again and i got a few little bubbles as expected then a couple of bigger ones when the thermostat opened, handily i had my vacuum pump to suck up the coolant so it didnt go everwhere when it starts pouring out when the thermostat opens.

I took it for a drive and when i got home i let it idle with the fans on and the temp came down nicely i will just keep an eye on it but if it stays like that then its all good