sounds like water

My 91 S10 has around 167,000 thousand miles. (rounded off cause I cant remember exactly ) Well everynow and then in the mornings when I have been driving for about 30 mins I will give it gas and it responds fine except that it sounds like water bubbling in the engine. Could it just be that it needs more time to warm up, or is the the start of something worse?


1991 S10 2WD 4.3l

Could it be air in the heater core? I'm just throwing something out there.

That may be, but wouldnt air sound more like a rushing sound? It sounds more like a bubbling sound. Thanks for the help.

Make surwe that your rad is full.
I'm just guessing that you have an air pocket somewhere, somehow

If I were to have an air pocket in there how would it have developed? Also how would I be able to get rid of it. If it is just by filling the rad back up, then wouldnt it still have the air inside there?:confused:

An air pocket can develop by the rad simply running low. The engine basicly drains to the same level as the rad.

They usually work themselves out while the engine is running with a full rad.

I'd make sure your resovoir is up to the right level also

check resivor and radiator at STONE COLD AM temp, is the overflow at the full cold mark? is the radiator full to the cap drooling a little bit? if not, change the delco cap, is the passengers side carpet wet?

I stopped filling rad when i found it stopped leaking here and there. I leave it few inches below filler neck. The bubbling my guess is just from in dash heater core and 2 rubber hoses. I would try removing the highest hose that connects near thermostat top front of engine, pulling off at that point. Hold the end up (with rad cap off) and pour premix coolant in there. this should help totally fill heater core and hoses and let air be forced out hose you holding up.

I stopped filling rad when i found it stopped leaking here and there. I leave it few inches below filler neck. The bubbling my guess is just from in dash heater core and 2 rubber hoses. I would try removing the highest hose that connects near thermostat top front of engine, pulling off at that point. Hold the end up (with rad cap off) and pour premix coolant in there. this should help totally fill heater core and hoses and let air be forced out hose you holding up.

Our trucls are really designed to have the rad filled to the top, without any air space needed. I've seen too many vehicles overheated in the summer filling their cooling system up like you fill yours.

If there is a leak somewhere you mght want to consider fixxing it before the weether starts getting hot.

thanks. but it's been happy for few yrs like this. no more leaks. puts out enough heat in winter and never goes above 110-120 f degress all year, even when 25c outside. city use only. found out eraly on this motor does not like much highway and hill use when it does tend to get lots hotter. i suspect my thermostat may be stuck open sine it is a 160f.

sticking shut if its getting hot

Mine also makes this noise.I notice it when I shut the truck off and it sounds like it is coming from the AC evaporator.

I have a 99 4.3 4x4 and it makes the exact same noise and has the same problems. I wold told by the shop that they never heard of anything like it before. It is not anyhting to do with the coolant. It seems to be coming from the transmission. It sounds like water splashing loudly. Cant figure it out.