bubbling overflow when stopped (1 Viewer)

[dirtaddicted]

Ive got a 1994 that has generally lived as a mall crawler. 147k miles. Recently I chased down a hesitation problem to the air meter, which has been replaced. The rig runs and wheels great.

Ive had no overheating issues, but I do hear bubbling from the overflow after I stop. usually its when Im wheeling. I dont get this around town.

There is no carbon in the coolant to indicate head gasket. I did the funnel test on a warm motor with no bubbles. Could it simply be a weak radiator cap or something else?

I'm planning a leak down some time this week.

Any advice appreciated.

 

[zapatius]

Have you installed a temperature gauge to see what actual temperatures are? Have you block test kit for your head gasket?

 

[TriaxialBulls]

When was the last time you did an oil change? Unless it was really recently, I'd do one now and send a sample out to get analysed. If there are any traces of coolant, it's going to be either your oil cooler (unlikely) or your head gasket (very likely)

 

[OffGridOverland]

I'd get a leakdown down, And then also do a coolant system pressure test.
Report back those results.

 

[mudgudgeon]

Could be radiator cap. I had a bad cap on my old hdj81, it would occasionally drop a bit off water out the overflow tube.
Low dollar item, easy to replace and check.

 

[elhombre]

I agree with above, it could easily be a weak cap or the rubber is going bad under the one you have. Get a Toyota one. They are cheap and will fit correctly. After market ones sometimes aren't the right size and won't seal on the radiator very well.

 

[leonard_nemoy]

When was the last time you changed or added coolant?

I have had my overflow tank bubble and even spill over on my old 91 when the rig was hot and I was offroading in strange angles. It would always happen once or twice after a drain and fill. I always figured it was because I added to much coolant and the high temps from crawling and crazy angles forced the extra "overflow" out into the bottle.

 

[retrofive]

x2 on simple things. New rad cap and pressure test the coolant system.

 

[z531519]

Stop as in killing the engine? The coolant temp shoots up once you stop the engine and may likely cause the cap to release pressure. In my truck, i can see it go up to 210 when it's really heat soaked.

 

[ChaseTruck]

Happened to us in the '93 last summer, trying to drive up a ways on Beartooth Highway (the pass was closed due to snow). New radiator cap from Autozone in Cody, WY, solved the issue. And Toyota radiator caps are good for Toyota radiators, but perhaps not best for aftermarket radiators like the TYC that's currently in that truck.

 

[Michael Hanson]

Hi, Let it cool, park facing uphill,remove radiator cap ,idle engine and add coolant as needed until full. Probably air in system . Is radiator cap a Toyota .9 ? Mike

 

[dirtaddicted]

Thanks you for the input here.

Have you installed a temperature gauge to see what actual temperatures are? Have you block test kit for your head gasket?

I have not. I need to look into options here. Will research "block test kit". Thats new to me thanks!

When was the last time you did an oil change? Unless it was really recently, I'd do one now and send a sample out to get analysed. If there are any traces of coolant, it's going to be either your oil cooler (unlikely) or your head gasket (very likely)

Its been a year at least. Good idea. Im hooping its not the gasket. The PO did mention the PHH blowing on the freeway in San Francisco but said he got off right away. Hopefully he did not warp anything. Ambient temps in the city tend to be low.

I'd get a leakdown down, And then also do a coolant system pressure test.
Report back those results.

Ive got tools for the leakdown but not the coolant system pressure test. Thanks

Could be radiator cap. I had a bad cap on my old hdj81, it would occasionally drop a bit off water out the overflow tube.
Low dollar item, easy to replace and check.

my thought too. It only happens really when wheeling. Last weekend I was at 4000ft and ambient temps were high 80s. At high desert 95 Ive had the AC cut off until I downshift and wheel at higher rpms.

I agree with above, it could easily be a weak cap or the rubber is going bad under the one you have. Get a Toyota one. They are cheap and will fit correctly. After market ones sometimes aren't the right size and won't seal on the radiator very well.

It is an aftermarket radiator. Its got a .9 on it that looks a bit old.

Stop as in killing the engine? The coolant temp shoots up once you stop the engine and may likely cause the cap to release pressure. In my truck, i can see it go up to 210 when it's really heat soaked.

Never killed the engine. What you are describing ive experienced. Sometimes Ill stop and it wont start bubbling until a minute after it has stopped.

Happened to us in the '93 last summer, trying to drive up a ways on Beartooth Highway (the pass was closed due to snow). New radiator cap from Autozone in Cody, WY, solved the issue. And Toyota radiator caps are good for Toyota radiators, but perhaps not best for aftermarket radiators like the TYC that's currently in that truck.

Definately on my list. Thanks!

Hi, Let it cool, park facing uphill,remove radiator cap ,idle engine and add coolant as needed until full. Probably air in system . Is radiator cap a Toyota .9 ? Mike

Ill do this today. Thanks. The PO is a friend from work. He ended up using green coolant when he changed out the PHH and radiator. Im debating going back to red. From what I read here, cooling seems to be the same.

 

[dirtaddicted]

Heres the rig btw.

 

[TriaxialBulls]

The PO is a friend from work. He ended up using green coolant when he changed out the PHH and radiator. Im debating going back to red. From what I read here, cooling seems to be the same.

I made a looooong post a while back about coolant after I did a ton of research. Basically my conclusions were that I wouldn't recommend using Prestone Coolant, but Valvoline Zerex is pretty good. I would go with the green Zerex, it's cheap and you can get it in the 1-gallon concentrate jugs.

 

[Toofless916]

block test it

 

[brockdeck]

Please please please, first bleed the system and replace your cap.

Then...... worry about HG.

Mud Mania

 

[bajaphile]

Yep, I had this exact problem on my truck. New radiator cap fixed it.

 

[saraujo]

Jumping in on this thread too, to note, I've been experiencing, noticed this bubbling in my cooling system. Notice it overflows only out of my overflow tank, which just happened when traveling to Carmel Valley and back home. I just ordered a new OEM radiator cap, thermostat and thermostat gasket. Will try the radiator cap first and see where that gets me. I've replaced every coolant related hose over the last year and a half, including that PHH, which is a PITA.

I'll update on how things go once I replace the radiator cap. FWIW - I have a TRAD radiator and San Kei radiator cap.

Additionally, if anyone has any experience with best way to clean the engine without causing issues with wiring, etc, please let me know. Thanks!

Thanks! @dirtaddicted

 

[BILT4ME]

Jumping in on this thread too, to note, I've been experiencing, noticed this bubbling in my cooling system. Notice it overflows only out of my overflow tank, which just happened when traveling to Carmel Valley and back home. I just ordered a new OEM radiator cap, thermostat and thermostat gasket. Will try the radiator cap first and see where that gets me. I've replaced every coolant related hose over the last year and a half, including that PHH, which is a PITA.

I'll update on how things go once I replace the radiator cap. FWIW - I have a TRAD radiator and San Kei radiator cap.

Additionally, if anyone has any experience with best way to clean the engine without causing issues with wiring, etc, please let me know. Thanks!

Thanks! @dirtaddicted

View attachment 2545530

TRad is the factory OEM replacement radiator.

Definitely get an OEM cap and that will help. May even do that and wait ion the T-Stat. It may solve the problem.

 

[ZackR]

Also don't overfill the expansion tank. When the engine is cold fill it above the low mark but not by much, so there's room for expansion.