Bubbling from radiator, maybe overheating after turned off. (1 Viewer)

[MikePL]

So I have a weird (overheating?) issue.

- Truck drives fine on flat surface. Temp needle in the middle (no temp needle mod yet)
- Truck drives fine uphill.
- When truck idles after going uphill all is good.
- When truck is turned off after going uphill, there is bubbling heard from the radiator and a lot of coolant goes to the overflow tank.
- When ignition turned on (engine off) the needle is close to red but goes down once engine is turned on.

So literally the truck overheats after it is turned off. What the heck? It looks like the block somehow produces heat which has nowhere to go after there is no circulation and the coolant boils and starts bubbling. But these are only my assumptions.

Bad cap? Clogged radiator? Bad engine, should I hang myself? Bad thermostat?

Coolant is clean, no white smoke, no bubbling when engine is running and radiator cap is removed so it doesn't look like HG

 

[bj70bc]

You need to check if it bubbles into the overflow while running, possible headgasket....
but time for a complete cooling system checkup, fluid levels, trapped air, flush the rad with a hose inside and out, cap etc

 

[robnicko]

you may also want to inspect the water pump for cavitation around the impeller reducing its ability to pump coolant through the system

 

[Kernal]

@MikePL : what year/model are you driving?

Does the radiator overflow tank get filled to the top or overflow itself?
Does the coolant get sucked back into the radiator after the engine cools down?
Is the radiator/cooling system full with a cold engine?
Any recent PM (flushing?) done on the cooling system?
Is the concentration of anti-freeze/coolant correct, newish Toyota Tstat and Toyota radiator cap??
Check also that the cap and tube on the overflow tank are flowing freely

IME here's one easy method you could try to get more accurate Temperature data:

If your model is OBD 2 you could buy any cheapo scan tool (Wally marts sells a $39 tool) that shows Live Data, plug it into the OBD port with the key to ON, then start the engine, click the tool to Live Data while watching the ECT values (engine coolant temperature).

FWIW

 

[ChaseTruck]

So I have a weird (overheating?) issue.

- Truck drives fine on flat surface. Temp needle in the middle (no temp needle mod yet)
- Truck drives fine uphill.
- When truck idles after going uphill all is good.
- When truck is turned off after going uphill, there is bubbling heard from the radiator and a lot of coolant goes to the overflow tank.
- When ignition turned on (engine off) the needle is close to red but goes down once engine is turned on.

So literally the truck overheats after it is turned off. What the heck? It looks like the block somehow produces heat which has nowhere to go after there is no circulation and the coolant boils and starts bubbling. But these are only my assumptions.

Bad cap? Clogged radiator? Bad engine, should I hang myself? Bad thermostat?

Coolant is clean, no white smoke, no bubbling when engine is running and radiator cap is removed so it doesn't look like HG

Nothing produces heat when the motor is off. The engine, which is a large mass of dense metal storing a lot of heat, is simply hotter than the coolant, and the heat is no longer transported away by the coolant to be dissipated at the radiator. That is why 80s make excellent garage heaters.

Agreed on a cooling system overhaul - that is never a bad idea - but: I’d start with a new radiator cap.
We had something similar happen driving up Beartooth Highway in Montana. Coming to a snow-based road closure (in June, no less), we pull around and stop for a few pix; coolant is boiling over to the overflow tank, and some out the top of that. Turned the motor on, temp drops within a few minutes, added some water, nursed the truck to Cody, Wyoming, via Chief Joseph Highway, bought all the radiatior caps for an 80 they had in store, one worked, problem solved. That cap is still on there…

In the spirit of full disclosure, the truck got a new head gasket three years later - didn’t want to do valve seals in the truck, truck had 225k anyways, and found the head gasket still intact but only by a hair, so, just about to go. No idea whether that episode in Montana contributed.

 

[MikePL]

We recently cleaned up the entire cooling system. There was some sludge in it so we flushed it some 6 times or more and then filled with coolant. Also deleted the rear heater to simplify the circuit. I will start with the cheapest option (the cap) and work my way up from there. Engine has under 100k miles so the HG is probably not gone yet. My son actually drives it so he is also looking at aluminum radiators. Not too expensive but maybe will help and add bling (that what he's mainly interested in, hahaa). Then, if problem persists we will get a new fan clutch etc.

But anyway it seems weird that the engine gets warmer and not colder after being turned off.

 

[bj70bc]

it doesnt get warmer, it boils the now not moving coolant from the retained heat in the metal, which means it's bastard hot while driving somewhere in there.....
i wouldnt continue driving it like that or you definitely will be doing a head gasket.... or more

 

[robnicko]

when cleaning & flushing the system did you remove the WPump to make sure the impeller is not clogged up?
its a simple thing to do, can reuse the gasket for testing purposes and if the impeller is clogged in any way will stop the coolant flowing as is required

 

[ajax1]

I wouldn’t buy a cheap aluminum rad. I would stick with oem, or if you wanna be cheaper the tyc is good.
Side note more than a few with aluminum rad have had them get eaten by the fan when off-roading