1HDT Coolant into Overflow - What am I missing? (2 Viewers)

[Bama4door]

We have verified that 2 of them continue to bubble when the engine has been shut off for a couple minutes, suggesting that head gaskets or block compression leakage is not a likely culprit.

My truck also bubbles after the engine has been shutoff. How does this rule out a bad HG?

I've also noticed my lower radiator hose never gets hot. I drove it for around an hour today on the interstate, getting into boost, going uphill etc. Temp gauge reads normal around ~1/2 on the stock water gauge. I ordered a new Toyota thermostat and gasket to rule that out.

 

[perrobravo]

HOLY COW

thats a keeper image thanks !

where did u dig this up ?

always a new day of learning new and exciting things here on MUD !

@ToyotaMatt ...you asked for it!

Here are a few more pictures from the Toyota Commemorative Museum of Industry and Technology that I took myself when visiting a few years ago. Awesome place.

The 1HD-T in all sliced up and on display

Who knew the Toyota Reflex Burn combustion chamber is where all our power comes from?

I found this picture especially helpful when trying to put the injection pump and lines back together

If I remember correctly, that little motor on the bottom left slowly turned the engine over in the display

Close up of the same engine in frame pic I posted earlier

Waiting for a turbo conversion

I think, not sure, this is a picture of @Onur

And for no reason, a random pic from Tokyo

 

[ToyotaMatt]

@ToyotaMatt ...you asked for it!

Here are a few more pictures from the Toyota Commemorative Museum of Industry and Technology that I took myself when visiting a few years ago. Awesome place.

The 1HD-T in all sliced up and on display

Who knew the Toyota Reflex Burn combustion chamber is where all our power comes from?

I found this picture especially helpful when trying to put the injection pump and lines back together

If I remember correctly, that little motor on the bottom left slowly turned the engine over in the display

Close up of the same engine in frame pic I posted earlier

Waiting for a turbo conversion

I think, not sure, this is a picture of @Onur

And for no reason, a random pic from Tokyo

i am dizzy now , and need to go to the ALMA COLORADO Oxygen bar @ 14k feet

 

[Cruisin']

I’ve got one in my shop at the moment that’s got the same symptoms.

I installed an aftermarket coolant temp gauge. It tops out at about 195f on sustained hills.
I did the test for combustion gases in the coolant, and that came back negative.
I used a laser thermometer to check the rad and block for hot/cool spots indicating potential blockage or something. Then compared to another rig with no issues. Temps were very consistent between the same places on the two trucks.

The engine was recently rebuilt (less than 15,000km) and is otherwise running very well. It has ARP head studs and proper tightening procedures were used.

I’m hoping someone has had this issue and successfully solved it and can shed some light on what the problem is. It doesn’t appear to be the obvious things.

 

[Loober]

What a frustrating deal, I am dealing with my own gremlin of this sort, not the same problem, but similar where its an obvious problem with a very unobvious cause. Whoever finds the cause of this is going to make a lot of people happy.

 

[chelo]

I've been chasing this issue for a while now. I have a 1hd-t and it also pushes the coolant the the overflow tank on long trips or when I get on it.
Just got back from L.A and let it sit overnight. I just went outside and the tank was almost full and I slowly undid the radiator cap. You can here the pressure release when I fully loosened the cap.
I've done the radiator recently and hoses. I haven't changed the water pump nor the thermostat. It seems like it is common on these engines but not sure what is causing it. It doesn't overheat and it runs fine.
Any other theory of what could be causing this?

 

[Bama4door]

I've been chasing this issue for a while now. I have a 1hd-t and it also pushes the coolant the the overflow tank on long trips or when I get on it.
Just got back from L.A and let it sit overnight. I just went outside and the tank was almost full and I slowly undid the radiator cap. You can here the pressure release when I fully loosened the cap.
I've done the radiator recently and hoses. I haven't changed the water pump nor the thermostat. It seems like it is common on these engines but not sure what is causing it. It doesn't overheat and it runs fine.
Any other theory of what could be causing this?

Surprised it didn’t suck the coolant back in overnight.

 

[chelo]

Surprised it didn’t suck the coolant back in overnight.

Me too!! It had more than enough time.

 

[nickolai]

There is a lot of chatter on the Australian facebook pages about this issue. Seems to be appearing after rebuild/head job.

Take it with a grain of salt, but the 'fix' seems to be running distilled water instead of coolant after a rebuild/gasket change. Apparently this helps HG sealing.

Not sure if this is actually true but lots of people seem to be recommending it. I'm watching with interest as mine is using coolant but not pressurizing, and also has the oil leak at 5&6 as described in this thread.

 

[Bama4door]

There is a lot of chatter on the Australian facebook pages about this issue. Seems to be appearing after rebuild/head job.

Take it with a grain of salt, but the 'fix' seems to be running distilled water instead of coolant after a rebuild/gasket change. Apparently this helps HG sealing.

Not sure if this is actually true but lots of people seem to be recommending it. I'm watching with interest as mine is using coolant but not pressurizing, and also has the oil leak at 5&6 as described in this thread.

This just seems really hard to believe, but I don’t know…

 

[Beach80]

Looking for help solving a new problem with my 1HDT. After replacing the head gasket for unrelated reasons, the truck consistently pushes coolant into the overflow when driven under load. I've read every burping thread, searched extensively for ideas, have tried a dozen things, and have run out of ideas. Any help would be appreciated!

Observations:

Truck starts immediately, runs great, and pulls very well through the rev range
No unexpected smoke from the exhaust (just a puff of black on startup)
Engine temps (measured by factory gauge) normal, never budge once up to temp
EGTs in check, never exceed 1200F (most of the time far lower), reasonable AFR through rev range
No visible water or oil leaks
~320k on the odometer
New GTurbo green wheel (boost set to max ~23)
Injectors and injection pump rebuilt (timing set to factory spec)
PDI front mount intercooler
Torfab airbox and aneroid pin
EGTs in check, has never exceeded 1200F, reasonable AFR through rev range

Problem:

Under load (i.e. uphill, high speed, pushing a bit harder than just driving to the local dealer to buy more coolant), coolant is pushed into overflow and doesn't get drawn back into the radiator when the engine cools. A couple times, the overflow overflowed and dumped coolant onto the ground. Most often it simply fills the overflow, but I haven't been pushing it to avoid making the problem worse.

Tests completed:

Checked for bubbling of coolant in radiator...none other than usual flow of water once thermostat opens
Oil and coolant appear clean visually (no milkiness or other bad signs)
Oil tested by Blackstone (no indication of coolant making its way into the oil...I specifically asked them to look)
No sign of compression gases in coolant (using 2 different test kits in both overflow and radiator)
Cooling system holds pressure (tested to 16psi)
Compression at sea level (on cold engine) 510-525psi (maybe a bit high, but could be my cheap gauge isn't as accurate as it should be)

Work done recently:

Head resurfaced, tested for cracks (none)
Valves cleaned up, new OEM stem seals, lash set to factory spec
New OEM head gasket (the right one based on the number of tabs on original)
New OEM head bolts torqued per FSM instructions
New OEM radiator and radiator cap (0.9bar)
Coolant drained and flushed (including block and heater core...which seemed very clean)
Rear heater deleted
New 50/50 mix of Toyota red coolant
New OEM thermostat (installed with the jiggle thing at the top per the FSM)
Used Venturi compressed air/vacuum coolant fill tool with front end on ramps, truck on an inclined driveway, heater on

I'm hoping this is simply an air pocket somewhere in the engine, but I've tried multiple times to burp the system and haven't read too many stories of people struggling with this on this engine. I don't want it to be something I screwed up when replacing the head gasket, but also don't know what else to test to confirm/deny this. I wouldn't love doing the head gasket work again, but would IF I was confident doing so would fix the problem.

Anyone have ideas? I know there are quite a few folks here deep into 1HDT engines, so maybe some specific tips or something I'm missing? @Onur @SNLC @torfab @Loober ?

And a picture, just because

I had similar issue, my coolant overflow bottle cap was on backwards. I flipped the cap 180 degrees reattached the line from the radiator, never had the problem again.

 

[chelo]

I had similar issue, my coolant overflow bottle cap was on backwards. I flipped the cap 180 degrees reattached the line from the radiator, never had the problem again.

Not sure why that would happen. I'll take a look.

 

[nickolai]

This just seems really hard to believe, but I don’t know…

I thought the same, pushed the issue a couple of times and the consensus was definitely that distilled water first instead of coolant was more strongly correlated with a successful rebuild and a good HG seal etc. I have no idea why that would be the case but that's what the posts are showing.

Search on this group: 1hz, 1hd/t/ft/fte modification's & upgrades - https://www.facebook.com/groups/1745801785659911/

And there's multiple sad stories, seems to be three common themes - pump timing, not decking the block and running coolant instead of water.

 

[SNLC]

sure you can.

does the book say you can? No. But it can be done

It does say so on the bottom end yup. You need to measure them though to make sure they are within limits of stretch.

1HDx engines are known to “lift heads” under higher boost without ARPs.

Matt is right about block decks, I have seen a number out. Last one a 1FZ out by a thousand. That is nothing really but it was enough for me to get the block decked. Toyota takes their specs to tens and hundreds thousands which is crazy but to them it was important.

Cheers

 

[michaelb]

Maybe you are overfilling it. Ive noticed on the 1HZ's they don't stay full in the top tank and are usually about 1/2 an inch above the core. Radiators tend to find their own level if everything is working ok. Ive gone 18 months without topping them up , even in hot weather.

I've noticed since getting a shop to rebuild/replace my head + gasket + water pump + fan clutch + hoses, it kept pushing out coolant,
I kept filling radiator back up when cold to full, and overflow to full, though it would easily fill up the over flow and extra after a drive getting the engine warm, I kept repeating the cycle of correcting "full" levels but think I may have been over filling.
When left alone it seems to do its thing of releasing under pressure and drawing in on vaccumm but its now always in back of my head that it's pushing out coolant, prior to any work, I seldom glanced at the over flow bottle

 

[67azcruizr]

correct head gaskets on engines with replacements?

I'm not saying that OP's engine overheated during his ownership, but an engine that has overheated and requires a new head gasket/deck and head resurfaced, is a ticking time bomb

 

[SNLC]

Seems one we worked on turned out to have cracks in the cylinder walls. That hasn’t been verified by a machine shop but after the head came off it’s the only thing that makes sense.

Cheers

 

[duece71]

Could coolant expansion be a factor here? I don’t know which is why I ask.

 

[perrobravo]

Still haven't determined the root cause, but I have collected all the bits I need to pull the head (again) and see what I find.

-ARP head studs in the hopes they will better hold the head down under load/boost
-3 and 5 notch Toyota head gaskets (3 notch currently, but will measure, then likely use the 5 notch version as I think @SNLC recommended somewhere)
-A bunch of other OEM bits: injector o-rings, various gaskets, seals, FIPG, etc.
-Proper straight edge to confirm mating surfaces are within spec (fingers crossed)
-Even more coolant, though I'll run distilled water only at first in case that helps

Will dig into this as soon as I get into my bigger shop space, hopefully within a few weeks...don't want to disable the truck since it is much easier to move a running, albeit coolant sucking, Land Cruiser.

And a gratuitous picture because...pictures.