Bizarre Radiator Coolant Issue

Do not h have any collapsing hoses, nor are the (main) hoses hard from excessive pressure.

I would like to connect a rad pressure tester and test my system as you describe. I've never used one, and considering renting one and doing this test while driving around a little bit.

TB

 

Maybe if you use a bunch of zipties, you can. But there may be a hood clearance issue. Not a good idea.

 

I wanted to give an update on this issue.

1. Replaced the radiator cap with OEM cap, no difference.
2. Used a "Spill Proof Radiator Coolant Filling Funnel Kit" to purge out any bubbles in system, that made no difference. (read below)
3. Verified that my thermostat "jiggle valve" is at 12:00 (always was)

What's interesting is this. When using the funnel kit, I was getting intermittent bubbles coming from radiator. Some big, some small, always intermittent, (several every 30-40 seconds, sometimes longer). No consistency at all. I let the engine run for about 15 minutes, heater set to max, temp was in the 180's when I called it done. Not real sure if I waited long enough.

I have not run my engine in two days. I go out today, slowly loosen radiator cap and a significant amount of pressure came out of the radiator into the reservoir. If I had a head gasket leak, would I still have pressure in my cooling system 2 days later? This is the part that's baffling me!

I have not done a cooling system pressure test, what's the point when I already know it's holding pressure?

I can still try a OEM thermostat, but if something is pressurizing my cooling system, changing the thermostat would not affect that.

Still not ruling out a leaky head gasket, but if it was bad, why does my cooling system hold a significant amount of pressure for several days? And if it was leaking, wouldn't I get a steady flow of bubbles when using the cooling funnel kit?

Thanks in advance for any replies

TB2

 

I had a similar issue recently and it was the head gasket, the truck never overheated but i kept an eye on the coolant and topped it off every day and emptied out the overflowing reservoir. Mine was most noticeable after driving on the hwy for a while, you can pull over after a hwy cruise and you should see bubbles coming up in the bottom of the overflow reservoir. Mine started slow and would also hold pressure for a while, so i wouldnt be surprised if yours was doing the same

 

There is only ONE component in the cooling system that manages system pressure. If you had a bad head gasket or cracked head, cooling system pressure would "bleed off" through the crack or gasket. You might also find coolant in the crankcase. Since that doesn't appear to be the case, I would locate a radiator shop and have them do two tests: pressure test your "new" cap, do a combustion leak test.

 

Thanks for the reply. I'm not loosing any coolant though, well, at least not yet.

TB

 

Yea, I think I'll have the compression test done. As a side note, the OEM cap holds a lot more pressure than the non-OEM cap (new)

 

I'm in agreement with this opinion.

I have heard of shops misdiagnosing a bad head gasket due to performing the test incorrectly. You could buy one and do the test yourself.

Why is it holding pressure for days? Puzzling, which is why testing the new cap is a good idea. Also, the cap should fit the radiator correctly, no dented radiator neck, if it's a metal radiator. A plastic neck won't dent of course.

Pressure testing a cooling system will help locate a leak. Also, you'll be able to see if it holds pressure. If you pump it up to 15 psi, it should stay at 15. If not, start looking for a leak. If no leak is found, that pressure is pushing coolant somewhere. I'd try this, keep pumping it up, don't go too high, 15 is good. Keep pumping it up repeatedly. If you have access to a boroscope, you could look into each spark plug hole to see if you can see coolant seeping in. Or, put the cap back on, start it up, if you see a bunch of steam come out of the tail pipe, you know it's leaking into the combustion chamber. Drain the oil, if it looks milky or you see coolant mixed in with the oil, it's leaking into the crank case. Remember oil floats on top of water.

Please don't take this next question wrong. Is there any possibility you left a rag stuffed in the radiator?

I like the bizarre ones like this. An example, I had one nobody could figure out why it was overheating. 2 guys before me got stumped. Turned out the fan was installed backwards. You'd think it wouldn't matter but, the fan is designed to kinda scoop and push air, backwards it didn't work.

 

Well, I could pressure test it, but as I stated before, it has LOTS of positive pressure in it, even if sitting for two days. I could do a pressure test just to see if it bleeds down at all, but the way it's acting, I don't expect it to loose any pressure at all! And this is the third cap. (original, Non-OEM, and now OEM) and they all do the same thing.)

Also, I don't take any question wrong, (irrelevant accusations yes, questions no). No foreign materials (rags) have ever been introduced into my cooling system.

JUST did a oil change, no water in oil. Not loosing any coolant either. It fills the reservoir due to excessive pressure, drain that out to a set point on reservoir, and it fills the radiator. Rinse and repeat. No coolant loss, it's just getting misplaced. LOL!

Liked your fan story!

TB2

 

pressure test gauge on the cooling system then pressurize each cylinder 1 by 1 and see if any increase the pressure in the cooling system

 

I have one time seen a tiny miniscule leak between the layers of a head gasket on a Honda. It never failed a exhaust gas in coolant test.
My understanding of the pressure cap is this.
System is full of coolant at ambient outside temp, as engine heats coolant expands, and builds pressure, when pressure limit of cap is exceeded it allows coolant to bleed in to the recovery reservoir, when engine returns to ambient temperature, coolant contracts, pulls a vacuum and draws the same amount of coolant (+ or -) new ambient temperature.

So if that is true, and I believe it is.
If you have a pressure slightly over what would be exerted by the coolant change in temperature it would push extra out, but not draw the same amount back in. The gasses would maintain a slight positive pressure, even because the system can not equalize based on the change in volume.

Maybe I am off, but I think you have a very very slight head gasket leak.
I have also seen a head with porosity. It was a just a tiny slow leak as well.

I worked as a service advisor for years, so I got to see alot of wierd failures, and I got to deal the upset customers, and frustrated mechanics.

Just adding my opinion and some data points.

Hope it helps.

 

@Jimmyh

I don’t know what to tell this poor dude. Beyond what’s in the first post, he replaced the radiator cap again with oem, 3rd cap, same issue.

 

One thing I would do if it’s an automatic is check the transmission fluid for contamination. And drain out the coolant the let it sit to see if any stratification occurs.

 

When you used the funnel kit was the front end of the car either raised or were you parked on and incline that had the front end the highest point in the cooling system?

The Altima used to take 20-30 minutes to get most the air out.

 

Have you taken the radiator cap off, Started the truck and looked down into the radiator and watched for bubbles yet? Try that if you haven't. That's a sure sign of a Head Gasket issue.

 

IMO You can't rule out a Head Gasket just based on it holding pressure for an extended time. Small leaks tend to only leak when hot and in one direction then seal up tight as soon as it starts to cool down. Based on my experiences... Yours may differ.

You can't keep replacing the radiator cap and expect a different result. That is insanity.

The jiggle valve goes up at 12:00 regardless of what you read on the internet.

If I were going to bet I would put my money on a leaking head gasket.

On your fan clutch, it should not be an issue unless you are overheating, but: https://www.aa1car.com/library/cooling_fan_clutch.htm

CHECKING THE FAN CLUTCH


A good clutch should offer a certain amount of resistance when spun by hand (engine off, of course!). But if the fan spins with little resistance (more than 1 to 1-1/2 turns), the fan clutch is slipping too much and needs to be replaced.

If the fan binds, does not turn or offers a lot of resistance, it has seized and also needs to be replaced.

Fan speed can also be checked with an optical tachometer, by marking one of the fan blades with chalk and using a timing light to observe speed changes, and/or listening for changes in fan noise as engine speed changes.

You should also try to wiggle the fan blades by hand. If there is any wobble in the fan, there is a bad bearing in the fan clutch, or a worn bearing on the water pump shaft. A bad water pump bearing will usually cause the water pump to leak and/or make noise, but not always. Remove the fan clutch and see if the play is in the water pump shaft. If it feels tight (no play or wobble), replace the fan clutch.

 

At this point, take it to a radiator shop. You’re wasting time and money. A shop has the tools and experience to properly diagnose the problem.

 

1. 05 V6
2. 160k
3. Air in coolant

It is the head gasket. 100%. It is a defective design. Toyota fixed it in 06. But your 05 rolled off the line with a defective head gasket that would start leaking at 160k miles.

You don't need to mess with the radiator cap or pressure tests or anything else. You need to change the head gasket.

Here are some notes that can help with the job:

https://www.tacomaworld.com/threads/mk5-build.567028/page-2#post-22362694

Good luck!

 

Not entirely true.
A head gasket can get compression gasses going through a bad spot while not allowing coolant back through.

 

ALL good information! Thanks all! I am NOT trying to rule out a head gasket issue, far from it! I just couldn't wrap my head around why it would leak in one direction and not the other. Thanks to several posts above, I would have to agree with all that is said!

This is not a job I'll undertake, (in my younger years no problem!), and have a shop I trust to do it for me. (WHY can't my neighbors ever be what I need? A/C, Roofer, Engine mechanic... LOL!!!)

Again, I am satisfied with the head gasket being the issue.

TB2