Pressure in cooling system (4 Viewers)

[Carp]

The last few times I've driven the 60 I've noticed a wet spot under truck for several days after parking it. Under further inspection, it was leaking from the hose connecting to the heater valve. Once I tightened that, the leak moved to the t- stat neck. That's when I opened the radiator cap and was met with a gusher of pressurized water. Tonight I cranked it up and the expansion hose was just constantly dripping. Video below.

I did check the oil before cranking and it looks good, no chocolate milk. Tested the oil on the manifold and no steam, so I don't that the oil and water are mixing. The truck didn't overheat pulling the camper the last few times I drove it ether.

I'm pretty sure that I know the answer to this, but figured that it was a good idea to get few other opinions before I sideline the truck for the summer.

Am I looking at a head gasket or could it be something else?

 

[Spook50]

If you're not seeing any coolant in the oil or oil in the coolant, your head gasket is likely fine. First thing I would do is replace the radiator cap with a new one. They can go bad and cause the system to over pressurize. They're designed to open and let coolant into the overflow when the system reaches 13 PSI and let it freely suck up coolant from the tank as the engine cools. My money's on your cap being bad.

Edit: Noticed you have an aftermarket radiator. Make sure your replacement cap is set to open at 13 PSI since that's what the system is designed for.

 

[g-man]

Exhaust pressurizing your coolant system could be from a cracked head. Is your coolant pushing out when you open the radiator cap with the engine cold? If so, take the valve cover off and look for coolant puddled up on top of the head.

 

[Carp]

@Spook50 I ran the truck with the cap off from cold start, in case it might need to burp some air out. Instead it kept pushing water up over the rim of the fill neck. When I put the cap back on, it went to the expansion tank. Thinking it's not the cap, but I still have the OE cap, so I could try that.

@g-man I'll give that a look and see, hopefully tonight.

 

[rrv333]

x2 with Spook's hypothesis

 

[g-man]

my head was cracked. signs included:
1. cold coolant pushing out the top of the radiator with the motor off or cold.
2. coolant sitting on top of the head.
3. missing coolant. I filled it about 1 qt/month Even though no leaks were detected the coolant was going somewhere ...maybe out the exhaust?

I did not notice milky oil on my dip stick. The oil levels did not overfill (from coolant). I didn't have a lot of white smoke coming out the exhaust. Maybe a little steam at start up.
No loss of power.
I did not have coolant pushing into the overflow jug, in fact the coolant in the over flow jug would slowly work its way into the motor and the coolant jug stayed empty even after 1/2 filling it many times.

 

[g-man]

I also had a mis aligned gasket on top of the t-stat. This caused my truck to run cold. It is important to note that as the motor warms the air/steam in the cooling passages expand and pressurize the coolant. If your t-stat is not holding tight when cold this can cause cold coolant in the radiator to be pushed. I guess it's possible that a bad water pump could do the same. How is your temp gauge reading?

 

[g-man]

When the t'stat opens at operating temps coolant flows into the radiator from the engine, at the same time the water pump should be keeping up by pushing water back into the motor. One or the other may be off. I suppose a clogged radiator could affect flow.

 

[g-man]

If you took the old radiator off because it was clogged and didn't clean the engine, the rust and sediment flowing from a dirty engine can clog a new radiator. Water pumps get clogged too. Although either of these would be indicated by a hot reading of the temp gauge.

More likely it's a slipped gasket on the t'stat or the t'stat is stuck open. A slipped gasket and the temp gauge would read cold always ...unless you overheat. I'm not sure if exhaust coming from a cracked head would be powerful enough to dislodge the t'stat gasket.

if the t'stat is stuck open and not a total bypass of the t'stat from a slipped gasket, then i assume engine temps would take longer to get warm.

 

[Spike Strip]

Easiest 1st step to check for Hydrocarbon gas in the Coolant. You can take to a shop or buy one of these Combustion Leak detectors, which will prolly cost you less than a shop visit. If you have high HC in the coolant, it's prolly a HG.

Amazon product ASIN B0007ZDRUI

 

[NeverGiveUpYota]

This thread confuses me, are folks not seeing the appearance of the OP-ers res hose and the fluid? It looks way too dirty to not have oil in it? Or am I way off base?
@Carp what have you done so far since you began this thread?

 

[Carp]

In all honesty, since the last post, I haven't had any time to dive further into this issue. My buddy has the tool that @Spike Strip suggested, so I should be able to get it soon to see if I have HCs in the coolant.

Let me go a little further in the history maybe clarify some points and see if there are any other pointers.

• The truck has 247k miles on the original motor. Not sure the head's ever been off, but I've only had it the last 40k miles.
• A few years ago, the OE radiator had a bit of a leak to it and in several instances of bad judgement, I used tap water to keep it full. BAD IDEA, as there was plenty of rust forming in the cooling system. Between the degrading coolant bottle and the rusty water, I think that is why the reservoir tube looks so bad @NeverGiveUpYota . When I was able to replace the radiator (Q4 2017), I also replaced the water pump, thermostat and treated the truck to several coolant flushing cycles, using a chemical flush, back flush, etc until the water ran clean. Then installed an inline filter that I clean periodically. The coolant still maintains a slightly brownish color, but the filter is clean (last checked about 5 weeks ago).
• Since the cooling system upgrade, the engine temperatures have always been lower than they were with the metal radiator, but I attributed that to the increased thermal efficiency of the aluminum radiator. As @g-man mentioned, the thermostat could be stuck open, causing the cooler than normal temps. However, it's been like this for over a year and a half without any issue.
• The truck hasn't run hot since the cooling system overhaul. In fact, I'm not sure it's ever run hot. I did pull our 3000lb camper home a few weeks ago and the temp gauge creeped up to mid-gauge, but never saw higher than that. Kept the RPMs less than 3500 at all times. But after that trip is when I started to notice the constant drip until I would release pressure with the radiator cap.
• The video above was taken about 3 minutes after a cold start. I'm certain that if the thermostat is working properly (and positioned properly) it wasn't open at the time of the video (the gauges are also an indicator). Additionally, I started the truck with the radiator cap off, and with the cold engine the coolant was oozing (best description, wasn't bubbling or rolling over the top) over the top of the neck. When I put the radiator cap on, the pressure was directed to the overflow jug. @spook I think this would indicate that the radiator cap is working properly, no?

One thing that kinda confuses me is that if I am able to get pressure into the cooling system during running, why am I not able to get pressure out of it once the truck is turned off? If there is a way to get pressure in to the cooling system, wouldn't that make a pathway to get the pressure out? Likely could indicate a cracked head as the head expands under temp as @g-man said? I'll keep updating this thread as I get a chance to investigate.

Thank you everyone who has replied and offered ideas. I really appreciate the help. Hoping to keep the old 2F running until I can gather parts/funds for a LS Swap.

 

[NeverGiveUpYota]

That inlet filter, is it on the top rad hose? I did notice you’ve got hose clamps holding a smaller section of hose there but thought maybe it was for a temp sensor.
A few times I’ve noticed coolant gushed out from the res and onto the frame and ground. It happened when the truck was shut off after driving. Never thought too much of it, till now.
I rented a pressure tester for my rad today at Napa. Annoyingly the smallest plug fit in w/ a bit of a jiggle and the o-ring that is meant to seal it was too big to push down into the neck snugly.
I’m having some issues. Making a list of all the cons that are significant of a bad head gasket. I think mine is leaking just slightly. Trying to really think all this through before just pulling the head off as it was only off two years ago for a top end.
Reading, thinking, pissing and moaning basically.
Thanks for your concise response.

 

[Willard]

I had this same problem.
Did the @Spike Strip suggestion (found that elsewhere) and all was good.
I knew something was up and figured a thermostat was bad.
I tore the entire cooling system apart. I planned to redo the hoses so this was a no brainier.
New water pump
New Thermostat
New hoses
New Rad cap
All back together.
Did the squeeze the top hose deal and let it over flow until it was stable and not trying to go out of the engine.
Made sure I could see fluid.
Drove it 50 miles and got home. Let it cool and issue was now gone.

In the end it was either the thermostat (it was not happy) or a bubble in the system.
Moral of the story is troubleshoot this from the get go and start with the Hydrocarbon test if you are concerned with a head gasket.

Here is basically how it works.

Block Tester® Instructions - How to use your Block Tester;

Instructions on how to use your Block Tester

www.blocktester.com

 

[Big Timber]

When I replaced my thermostat the old one didn’t have the rubber o ring on top of it. I think that’s why my temp never came up. All is together now and working well. Do you remember installing the rubber o ring on top of the thermo?

 

[g-man]

A correctly working thermostat will open up very quickly when it the engine coolant gets to the right temps. If you have your hand on the top of the radiator it will go from cool to burn your hand hot quickly. If it just stays warm forever w/out the quick change over.. you prob have a misplaced top gasket on your thermostat or your stat is stuck open.

 

[2mountainfish]

I was having a problem with coolant migrating to the overflow bottle and overfilling it after shutdown. I would come out and find coolant on the ground. Truck never ran hot or leaked anywhere else. I replaced my radiator cap and it stopped. Before I replaced the cap I used a pressure tester to eliminate the chance that a blown HG or cracked head was over pressurizing the system. As others have said, test as much as you can before you tear into it.

 

[Carp]

Great hints and tips guys. I'll tear into full diagnostic mode next week. Work sent me away this weekend to Expo West, so I'll have to suffer through without my 60