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Cooling System Problems I Think


SenorNoob

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I have what sounds kinda like an engine knock sometimes and sometimes like very large air bubbles from boiling water going on most of the time when I cut the engine off. I've never noticed anything while driving.

Kinda sounds like the problem described in the Coolant By-Pass Kit TSB.

Also after stopping if I turn the key back to on so that gauges work the temperature gauge goes to the top of the normal range. Never past to the hot area and never while driving. It usually stays cool while driving sometimes so cool the heater just about goes out when it's really cold (like below 15F) outside.

I've also noticed that the coolant level checks fine when cold but if I check it immediately after stopping it's low. Add any coolant at this time and it just ends up in the reservoir.

I've recently replaced the thermostat with a Motorcraft part. New lower intake gasket. Also a junkyard replacement radiator that was completely stopped up when I got it. (Could turn it sideways and pour water in one side and none would make it to the other.) I thought we got all of the crap out but now I'm not so sure.

BTW, the reason the radiator and lower gasket were replaced was leaks.

I didn't have the problem before the work.

Sorry about the long post but wanted to give all relevant details.
Thanks.
 


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RonD

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Couple of things.

First you can't clean out an old radiator, you can get it to have some flow, but it just doesn't pass enough coolant.
If you want to test a rad after "cleaning" do the Flip Test
With rad out of vehicle
Put cap on
Place rad so tubes are up and down
Put hand over lower rad hose outlet
Fill rad using upper rad hose outlet

After rad is full stop filling
Remove lower hand
Rad should empty quickly, there is no air "trap" because hose outlets are the same size
After rad is empty, tilt it a bit to get rest of water out of lower rad

Now the test
Flip rad upside down
If ANY water comes out it could ONLY come from blocked tubes.


I don't think that's your problem though.
"......coolant level checks fine when cold but if I check it immediately after stopping it's low"
How can you check coolant level in rad when engine is warm?
It should have 14-18PSI of pressure in rad, that keeps coolant or water from forming bubbles. i.e. boiling above 212deg

If you are able to open the rad cap when engine is warm then that would be your problem, either rad cap is bad or you still have a leak.
 

SenorNoob

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There is definitely not pressure in the radiator then. If anything it's a vacuum by the sound of it when I pull the cap.

No leaks, coolant stays in the system once added. Just not in the radiator. It ends up in the plastic tank on the fender.

Best I remember the radiator passed that "flip test". I've been very busy so I'm not for sure.

Wouldn't it be leaking if the cap is bad? I've had that. Cheap O'Reilly's cap.
 

SenorNoob

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This was bugging me so I went and did something stupid. I warmed the truck up and opened the radiator cap engine still running. For about 2 seconds I could see halfway down the radiator.:icon_surprised: Then it starts puking coolant like what you'd expect in the first place.

I'm certain there are no external leaks on the engine.

I guess it's either a heater core (although heat works and doesn't fog the windshield) or I have a bad head gasket/head/block. Most likely the latter. That would explain why the coolant always checks fine when cold wouldn't it? The air stays in the block when it's cold?
 

cp2295

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Did you burp the cooling system when changing all this? Air bubbles could be stuck in there causing that random high temp when you turn the key back on. If you don't see white smoke billowing out the tail pipe you probably don't have a leak in the block/head/gasket. Id just do a compression test if I was you
 

RonD

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The glove test is free and easy to do to see if cylinder(head) gasket has failed.

Cold engine
Remove rad cap
Remove overflow hose and block opening
Disable coil, you want a no start
Put latex glove over rad cap opening and seal with rubber band, or use a balloon or even seen a condom used, lol
Cooling system is now sealed

Crank engine and watch glove
If it bounces then you have a cylinder leaking compression into cooling system, head gasket or cracked head issue.

If it just lays there you are good.

If it does bounce then remove one spark plug at a time and crank engine, when bouncing stops then last spark plug removed was the leaking cylinder.
Put spark plug back in to confirm.
Finding the leaking cylinder can be helpful if head gasket looks OK after disassembly, could be cracked head and no uses paying for two pressure tests.
 
Last edited:

SenorNoob

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Well, now I'm extra confuzzled. It passes the glove test. If anything were clogged I'd think it would overheat. Same for the pump not working like it's supposed to. If there is a leak it's VERY slight. I've currently marked the level in the reservoir to check that after work tomorrow.

There is zero air in the system right now. I even pulled the temperature sender to check behind the thermostat. Full there, in the radiator, and at the tee fitting in my heater hose. Unless the air is in the other side of the radiator or the bottom of the block?

Am I just hearing things? (BTW, rhetorical question. PLZ don't answer that.)

Thanks experts for your help.
 

SenorNoob

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I'm fairly sure it was the radiator cap. Stopped by advance for a Stant yesterday after work. Put it on right then and haven't had the boiling since. I still have no pressure on the radiator after stopping but it's been like 5-10F every time I've driven it since then.

Also the heater is very consistent now. No more cold when I pull up to the stop signs.:yahoo:

I still have to see how it does when things warm up around here.

Edit: I still can't believe 2 NEW radiator caps were bad. Especially with the one being a Motorcraft. Quality really has gone downhill.
 


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