Coolant Bubbles Source

[JerrySab]

Hey gang,
Sought help in a previous post, trying to solve a creeping thermostat. When burping coolant, noticed bubbles when warm in the overflow funnel. Which sucks. It does seem to be exhaust, as indicated by RELD test.

finally pulled it back into garage and did a compression test, but got really consistent numbers . Each cylinder hit 115-120 in first compression stroke, and each hit 180 by 5th. The rate of pressure build was the same in each one. I was expecting to find a smoking gun, or cylinder.

I did the test cold (not wanting to run the engine hot and risk damage).

also, the #5 spark plug was filthy and the threads were full of crud.

I’m stumped; and in my limited knowledge, not sure if exhaust/bubbles can enter coolant by any way other than cracked head or failed gasket. The exhaust manifolds are super leaky, I plan on tackling those, but thought I had a head gasket job to do at the same time.

should I run the engine up to temp and repeat? Or could I have dodged a bullet here?

 

[sgtsandman]

Bubbles in the coolant reservoir only happen if there is a gasket leak or a cracked head as far as I know. I can't think of anything else that would cause it.

 

[RonD]

None of the spark plugs looked "cleaner" than the others?

Do the glove test that's pretty definitive
Get a latex glove or balloon or even a condom
Remove rad cap
Remove overflow hose and plug that port, vacuum cap or gum or putty

Put Glove or balloon or condom over cap opening, use rubber band or ziptie to seal the glove to opening
System is now "air tight"
Disable spark, unplug coil so no start

Crank engine over and watch the glove
It will bounce if a cylinder is injecting air into cooling system from a blown gasket or cracked head
If it just lays there then no cylinder leak

If it bounced then remove 1 spark plug at a time and crank engine again
When it stops bouncing the last spark plug removed is the cylinder that is leaking


No, there really is no other way exhaust can get into the cooling system

 

[JerrySab]

THANK YOU GENTS

I’ll have a closer look at the plugs. Really only noticed #5 looking way more crummy than the others.

Ok dumb question:
- Does thermostat need to be open or removed for glove test?
- in the off chance it just lays there, does that mean my heads aren’t cracked but the gasket is toast?

lookin for any easy way out but I don’t think I’ll be finding one

 

[sgtsandman]

Result will be the same regardless of the source of the gasses in the coolant. The thermostat has a weep hole in it to allow air to pass through, so you shouldn’t need to worry about whether it’s open or closed.

 

[RonD]

+1 ^^^

Glove test, or pressure test, sees if some a cylinder's 150psi pressure is coming into the cooling system
Cooling system is open at the lower radiator hose

 

[Snoranger]

I have had the glove test fail me once. It was a cracked head that only opened up when the engine was above 150 degrees or so and I tested it cold.

 

[JerrySab]

I have had the glove test fail me once. It was a cracked head that only opened up when the engine was above 150 degrees or so and I tested it cold.

This is what I suspect. Compression test was suspiciously good, I feel like it'll pass glove test cold. But coolant is slowly disappearing, and the thermostat continues to behave like there's air pockets in the line, no matter how thoroughly I burp it. Also, STEPPING ON THE GAS MAKES BUBBLES. DANGIT

thanks y'all

 

[RonD]

Remove either heater hose at the firewall
Fill system at rad cap opening until coolant/water comes out hose and core port, put them back together, all the air is now gone from engine side of thermostat
No burping needed

 

[Cees Klumper]

I replaced my heads a few years ago due to coolant loss. The new heads including new valves, springs etc all installed were only a bit over $500 delivered. Add the new head bolts and gasket which as I recall was maybe $130 and it not only fixed my coolant leak but also increased horsepower quite noticeably.
I tried to get away with only replacing the head gasket first but it wasn't the problem so I ended up doing all the work twice. If I had to do it again I would spring for the heads first time.

 

[JerrySab]

Great advice. Who supplied the heads?

 

[kodogtwh]

This is exactly what my truck did when it blew it's head gaskets. I have a special case with my turbo truck, but they blew from corrosion through the coolant passages, not boost. So it should still apply. Small, consistent bubbles in the radiator, dirtied the coolant, smelled of fuel/exhaust/combustion, and I smelled coolant on the drive home. No oil mixing. Since the heads are so small on these engines, and you're already gonna have the exh manifolds off, I'd do them. On mine, because it ran so good, I didn't have them machined, and no issues in doing so, but since you have a stock truck that's probably been left alone for a long time, I'd get them cut flat and crack checked anyway.

If you decide to do them, quick rundown on specs so you don't have to dig:

• Cyl head bolts: Replace. TTY. Torque sequence is 22ftlb, 55ftlb, 90Deg.
• Lifter preload: adjust to zero lash, new lifters get one turn of preload, used/loud lifters get two turns.
• Lower intake manifold gets 30ish ftlb, tighten like it's a cylinder head. Very prone to leaking if installed improperly.

 

[JerrySab]

This is exactly what my truck did when it blew it's head gaskets. I have a special case with my turbo truck, but they blew from corrosion through the coolant passages, not boost. So it should still apply. Small, consistent bubbles in the radiator, dirtied the coolant, smelled of fuel/exhaust/combustion, and I smelled coolant on the drive home. No oil mixing. Since the heads are so small on these engines, and you're already gonna have the exh manifolds off, I'd do them. On mine, because it ran so good, I didn't have them machined, and no issues in doing so, but since you have a stock truck that's probably been left alone for a long time, I'd get them cut flat and crack checked anyway.

If you decide to do them, quick rundown on specs so you don't have to dig:

• Cyl head bolts: Replace. TTY. Torque sequence is 22ftlb, 55ftlb, 90Deg.
• Lifter preload: adjust to zero lash, new lifters get one turn of preload, used/loud lifters get two turns.
• Lower intake manifold gets 30ish ftlb, tighten like it's a cylinder head. Very prone to leaking if installed improperly.

amazing thank you for all of this. going to replace the heads. I was told they were new when I got the truck, but I my suspicion is they were either reman or old casting #. OR I screwed in up somehow by f'ing around and finding out. I really love working on this truck and appreciate the community here so much.

For lower intake manifold, do you mean tighten like a head, in the sense that the bolts torque to yield? I haven't read that anywhere, but definitely hear your caution and could see how it would make problems.

 

[kodogtwh]

For lower intake manifold, do you mean tighten like a head, in the sense that the bolts torque to yield? I haven't read that anywhere, but definitely hear your caution and could see how it would make problems.

I mean tighten them in a sequence from inside to outside, in steps. The bolts are regular metric stuff, you can reuse them. Don't just ram them in with an impact in a random order, cuz it can shift a lot.

 

[JerrySab]

perfect thank you