Over heating

[jacob1963]

Recently had an over heating issue and coolant boiling over. 1971 17O in-line 6. I have re filled radiator and tried to burp it of any air bubbles, but once it reaches about 190 it starts steaming and bubbling over. Not sure why the coolant was low to begin with but have seen a lil rust at the bottom so may have small leak. The coolant is measuring over 200 degrees. What could be my issue? Thermostat, bad water pump or that much air in the system?. If it was a blown head gasket would I see bubbles right away?
Thanks

 

[DirtDonk]

Wow, I think it's been awhile since we've had a good overheating discussion!
Sorry you have to go through it though.

Sounds fishy in a couple of ways. You gauge may not be telling you the whole truth, because just water doesn't even boil until it reaches what, 212° is it? With anti-freeze it should be slightly higher I think.
With a properly working pressure cap, it should be a LOT higher still.
So if nothing else, you may have a defective cap. But that's assuming the gauge was even remotely close.

If the coolant was low enough (how low was it by the way?) the temp sending units don't have direct contact with the liquid to give an accurate indicator. At least in the V8 engines. Not sure where the sending unit is in your engine. If it's high enough though, maybe that was really the only issue. Your engine was running hot from the coolant being low, and the gauge did not indicate it correctly until the boil-over.
Did you happen to notice a rise in temperature on the gauge after it boiled out a little? Or right before?

Yes, you usually see funny stuff with a blown head gasket, but if it's a small breach you don't always seen symptoms all the time.

Did you do anything prior to this happening? Any service of any kind?
Have you been driving it extensively otherwise, without any trouble?
If so, I would simply re-fill it and drive it around a bit with your eye on the gauge. Then check the coolant level every chance you get for the first few days.

Just use water at this point too, unless you're in the freezers right now. If you do have a leak you're just wasting anti-freeze. But if you're in the cold, you've got to do it. Better safe than sorry, at least as far as the engine is concerned.

Good luck.

Paul

 

[jacob1963]

So I have refilled it twice, Drive to or from work and it overflows and steams out of the overflow hose. 5-7min Drive
I was trying to make sure all the air was out when it starts to bubble a spray out, my temp measures may be off because I didn’t wanna get to closed. I really see no fluctuations in fluid until this happens. Oil isn’t milky, coolant not foamy and no white smoke. Just this splashing of coolant everywhere

 

[DirtDonk]

Well some of those are good signs perhaps, but the fact that you can't drive very far before this happens is bad news it sounds like.

This is precisely when I used to do a full service. Flush and clean the system, replace the thermostat and run around on water until I was sure the problem was fixed.
I don't like that quick overheating though. But a sticking, or partially sticking thermostat can indeed cause this I would think.

The sure-thing test for a head gasket though, would be to have the coolant tested for combustion gasses. They don't always show up as oil in the water. All depends on where the gasket has failed.

What about ignition timing? Could it have slipped somehow and be running extra retarded and causing the overheating?

Worth a look at this point I would say.

Paul

 

[DirtDonk]

You can also test a thermostat in a pan of water on the stove. So there's that while you're deciding if a new one is warranted.

Paul

 

[jacob1963]

Crazy thing ran find this am to work, ran hot on way home. The interior gauge isn’t even hitting the H, that’s why I’m confused about the steam and over flow

 

[DirtDonk]

If the coolant is getting a reading to the gauge, and it's not showing hot even though it's "boiling over" then you may very well have a bum head gasket after all.

But here's where one of those cool infrared thermometer gun thingies will come in real handy. Be nice to have something to verify the gauge is reading correctly.
It's harder to test if it does not do it's thing when just idling in the driveway. But if it does run hot eventually after idling, you can verify the temps at that point too. You can even run it without the cap to see what's going on.

Trapped air pockets will do it, but those seem unlikely at this point.
A steam pocket will build up and do this too, but a steam pocket means trouble somewhere. How old is the water pump?

Paul

 

[jacob1963]

Thermostat inexpensive may just replace.

 

[jacob1963]

Water pump orginal.

 

[jacob1963]

It will idle 20-30 mins in driveway before the bubbles start.

 

[jacob1963]

Prior to this going to work I barely would get to 180.

 

[DirtDonk]

Water pump impellers do wear out sometimes. I've seen them worn to just bare nubs. Shadows of their former impeller blade shapes. They still pumped by some miracle too!
But as you can imagine, they didn't pump very efficiently.

We know how many years, but how many miles on your engine? Even with the bearings and seals good, it's possible the pump just is not working at it's best.
But that's also a lot of work on just a hunch.

On my Bronco I can look down inside the open filler neck with the engine running and see coolant flowing out of all the tubes that are visible from that vantage.
Not everyone has the same (I use a high-volume pump) but you should see at least some action going on inside there. If nothing more than the coolant level lowering as the engine speed increases.
Not sure where the liquid goes at higher rpm levels though, as it's supposed to always be flowing through all the areas. It's not like engine oil that has to drain back into the pan. Seems like the visible level should remain the same. But it doesn't.

Check that out and see if you see at least something that indicates the pump is still working.

Paul

 

[jacob1963]

Imma start with flushing and thermostat today.and see if I can see anything with water pump. I kinda missed spoke about the over heating it definitely over heats, just not to the point where I have to immediately pull over, if I went another couple of miles yes. So, that was another question even with thermostat closed it should still circulate through heater etc... is it possible that the thermostat is just opening and closing intermittently causing my fluids to do this. The engine would have close to 150 miles I would guess, up until today I have driven it daily to work

 

[B RON CO]

Hi, a lot of bubbles in the coolant is a bad sign.
You know you need some room at the top of the radiator for expansion of the coolant, maybe that is why it bubbles over.
If the upper hose does not get hot the thermostat is not opening. Either feel it by hand ( you will not get burned) or use a point and shoot temp gun.
A compression test may show a blown head gasket, that is unusual, but can happen.
The head gasket may be sealing when cold, but expand when hot.
Good luck

 

[jacob1963]

thanks for all the information guys I will tackle this when I get home. I’m not thinking or at least hoping it’s not a head gasket problem. I will flush the system and change out the thermostat first. Then go from there. Any ideas what the radiator should heat up to at the top (guess depends on the thermostat used) and what the temp should be at the bottom after cooling down. I have an infrared thermometer so can get some of these measurements.

 

[jacob1963]

So system flushed new thermostat put on, idles fine, once drive it a while it over heats. When I turn engine off I can hear my water boiling at the input tube of the radiator. The tube and thermostat housing measure 220-235 with infrared thermometer. Any thoughts bad water pump, poor out flow of the radiator maybe? Or is it blown head gasket.
Thanks

 

[72Sport]

AutoZone has a kit you can borrow that you pressure test your cooling system. It has been awhile since i used one. You pay for it and get a refund when you bring it back. I believe it had a hand pump, special radiator cap with pressure gauge. You pump up the system with the hand pump and see if the pressure in the cooling system drops. It should hold pressure overnight. I believe the kit had instructions with it.

 

[pipeline010]

Compression test is both annoying and stressful (mentally) when you're seeking an issue, but really it's not that much time to rule something out. When I had my engine issues in September (bad idle vent on carb) I stressed the cylinders for weeks til I finally ran the compression and it came back perfect.

Wish I had just done the compression test earlier, would have saved a lot of grief.

 

[B RON CO]

Hi, check the radiator for cold spots either by hand or with the thermometer.
The top of the radiator should be @200* and the lower area @140*
Very cold spots are clogged.
Good luck

 

[Skytrooper15]

It will idle 20-30 mins in driveway before the bubbles start.

From what I have seen around my cousins radiator shop when they refill a radiator they let the engine run without the cap on and when it starts to bubble it means the thermostat just opened.I go along with your comment about replacing the thermostat and if you haven't replaced the radiator cap in the last 10 years I would replace it also.