I'm at my Wit's end with coolant problem, need some advice...

I am at my wits end. I am to the point where I'm about to just replace everything again, water pump, shroud, over flow tank, hoses, thermostat, etc..

- 4-5 months ago after about 100 miles on the interstate the water pump went out, coolant everywhere
- when I took the water pump off it looked fine, blades looked good, no play in it, spins just like new
- it looked like the seal just blew
- I had an OEM brand new water pump in my shop, been in the box for a couple of years, but brand new
- I replaced the water pump and put new hoses
- I burped the system and got all the air out
- It seemed like everything was running ok, but just did a little local driving
- Then about a month ago I took a trip about 150 miles on the interstate
- Ran fine
- When I parked and turned the engine off the temp started to rise
- I popped the hood and the over flow was boiling and I could tell a bunch of coolant had flowed out of the release valve at the bottom
- Once it cooled off, the over flow was still full and I added about a half a jug of coolant to top of the radiator
- So I put in a new OEM thermostat and put a new radiator cap.
- Now the coolant is being pushed into the over flow and not being pulled back into the radiator
- Once it cools the over flow tank stays full and the lower radiator hose collapses
- Then when I open the over flow jug or the radiator cap a bunch of pressure is released
- If I run on the interstate at about 2700 RPMs for 40-50 miles enough coolant is pushed out to where the coolant temp will get to 200, then I stop and have to add coolant.
- So I am thinking, great another head gasket
- I have delt with several head gasket issues on 1GR-FE's
- I ran the test for exhaust in the coolant, nothing
- no moisture in the exhaust
- Scoped the cylinders, no signs of head gasket issues
- Pressure tested cylinders, no issues
- It can idle all day long and coolant temp stays at about 187 with A/C on
- when it does run hot, if I put a spill proof funnel on it while it is running the coolant starts to push into the funnel, no bubbles though. Once I turn the engine off the coolant will fall back into the radiator, then I have to add more coolant to replace the coolant that went into the over flow.

Throughout the whole ordeal the coolant has always looked like brand new. I installed a new OEM radiator about 4 years ago. It still looks new, no leaks I can see

I am running out of ideas? It is like the coolant is being pushed through the radiator, but not returning to the radiator? The high side is holding positive pressure and the low side is like a vacuum collapsing the hose? I notice that the old radiator cap looks like it was missing a piece of the gasket or something, do you guys think maybe a piece of the old radiator cap broke off and is lodged in the radiator?

any ideas?


--- edit ----
the bubbles in the tube are from me pumping it, not gas being pushed through

 

Drain the radiator. Remove lower hose from radiator and fill radiator with water. Water should come out of the lower hose fitting. If it doesn't out barely comes out then you got a blockage. I would start with that.

 

The symptoms sure sound like a potential headgasket failure, checking for combustion gas at the overflow bottle isn't gona be very accurate.
My method is to put a spillproof funnel on the radiator, put a plastic bag over it with a rubber band, cut a small slit in the bag for the tester, then let the engine run for awhile before testing but if you say it wants to push coolant out that won't work.

Seems like something is blocking the coolant from going back from the overflow bottle to the radiator.
Did you check the overflow bottle port and radiator port for blockages or junk floating around?

 

This ^^^^.

I used one on those testers like you have posted above. Said my twin turbo rotary engine was fine. I had a blown seals though. You could see water inside the engine if you left it over night and took out the spark plugs.


another test is to use those giant funnels that attache to your radiator to burb the air out out of the coolant. sometimes it will be obvious water will be gushing out. other times it's a little more difficult.

If you have access to leak down tester this test works really good. take off your radiator cap then do a leak down test.
https://www.youtube.com/watch?v=QOHMtUm4JYY

 

I saw you replaced the thermostat with a new OEM, but it may only be opening partially?

 

I’m thinking along with what dm93 said.

I’ve never heard of an overflow tank having pressure. Something isn’t right there. Overflow tanks usually have 2 hoses, one going to the radiator and one vented to atmosphere. Or the cap has sort of a spout. Maybe the vented portion is clogged. If you have a pressure tester, it might have a cap tester with it. You could confirm the cap is good.

 

Make sure the expansion tank hose is free and clear of sludge. But it does sound like a headgasket

 

Headgasket is what sounds most like to me as well. However, I did encounter vapor lock once. There is a small hose that takes a u-turn. It is parallel to the ground, and near the upper radiator hose.

I pulled that to evacuate the air pocket, then when coolant came out, I pushed it back on. Problem solved on that rare case.

 

The hose that goes to the over flow tank or a diffrent hose?

 

I'll try this this afternoon, thanks!

 

I'll try running it without the thermostat also.

Thanks!

 

I scoped the cylinders, no steam cleaned cylinders or seapage I could see. Also, no matter how small of a head gasket leak i have seen there has always been some moisture in the exhaust.

 

The one attached to this barbed fitting.

 

You can test the thermostat by boiling it to ensure it opens

 

Gotcha! Thanks!

 

The "not pulling fluid back into the radiator" part really sounds like you've got the wrong radiator cap.

 

Make a list of all theses suggestions, easy at the top, more difficult at the bottom. Start at the top, work your way down.

 

I printed the thread and have it with me in the shop

Thanks guys, I'll keep you posted

 

updates....

Hoping I didn't cause more issues by pressure testing to 17psi....


- 08/01/23
- Pressure Test up to 16psi, drops to 13-14 after about an hour
- Started truck and let ir warm up
- at 190 deg upper hose hard, burn your hand hot
- lower radiator hose softer and very warm
- Let engine cool
- pressure tested up to 16psi and let it settle a few times to 13-14psi
- left system pressurized
- scoped cyliders 2-4-6

-08/02/23
- Engine cold, Radiator cap on, thermostat installed, ran water through the top radiator hose, no water came through the engine
- Removed the Radiator cap, ran water through the top radiator hose and water flows out of the the radiator fill hole
- Radiator cap on, disconected the lower radiator hose, ran water through the top radiator hose and water flowed out of the bottom af radiator fine,no radiator blockage detected
- Removed radiator hoses and thermostat, ran water through the engine until water was clear, no blockages detected, cleaned over flow tank
- Reconnected Radiator hoses, left the thermostat removed
- filled the system with water and burped the system
- Took a few short trip during the day, temp stayed below 183 all day
- Took the truck on the interstate for a few miles and temp started rising to 190
- Stopped at gas station and turned truck off, temp shot up to above 200
- popped the hood, reserve was about 80% full
- noticed water under the truck
- water appeared to be coming from the radiator drain plug, so I tightened it about a 3/4 turn, "seemed" to help stop leaking
- added about half a jug of 50/50 coolant.
- temp dropped wuickly to about 183
- pulled back on the interstate and in about 1/4 mile CEL came on.
- pulled over, with truck running check and Scan Gauge read "Left Bank Running too Lean"
- reset codes, CEL went off
- Continued on the interstate at normal speeds for 20 or so miles at about 70-ish keeping RPM's pretty low, temp stayed low, under 180deg
- Went home
- let truck cool down for several hours
- 08/03/2023 (late night)
- with truck cold, pressure tested up to 17psi, seemed to start dropping pretty quick...
- Noticed water leaking from left fron of truck, when I checked it, couldnt tell if the drain was leaking or radiator leaking see pic???
- hoping I didn't cause a new problem by pressurizing to 17 psi !!!
- removed the pressure tester called it a night for now....

My better cam quit working, sorry cylinder pics are not the best...

I don't think if the initial issue was a leak at the bottom left corner of the radiator would have been the original cause for all of this? still stumped

 

cylinder 6