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5VZ-FE Possible Head Gasket

Stingray

Toyota Junkie
CAL4
Joined
May 19, 2020
Member Number
235
Messages
1,186
Loc
So. Cal.
2001 4 Runner just clicked off 300K and has started to run warm, I found a broken radiator cap initially and replaced it, This did not solve the problem.

When I say warm I've driven this truck about 80K miles and it has never ran more than 205, and lives around 201 always. (Reading off the OBD2 port off of the torque app)

Also hot is it will idle in the driveway for 30 mins. and ride at 190* when I take it out for a drive it slowly climbs to about 215* within the 10 mile around town loop.

So far I have a new Aisin fan clutch, replaced a missing lower radiator shroud section, replaced thermostat with a factory Toyota (installed correctly), and a lower radiator hose because I was there.

Ran a compression test, Plugs all look good, compression was 180 across the board.

Did a radiator pressure test and it held 15 psi long enough for me to get bored waiting. ( probably 20 mins.)

I have not done a leak down test yet, I don't have a tester, and can't find one local to rent.

The thing leading me towards a head gasket is it has started to drink coolant, It seems to empty the overflow bottle in about 5-8 days of around town driving.

(I did check the bottle for leaks, It has none) My commute is less than 5 miles so I'm still able to hobble around town in it and keep it under temps.

One other thing, About 20K ago it got a timing belt set, water pump, thermostat, radiator. At that time it did not over heat, the water pump just started leaking, and has run fine from then to now.

I have a new water pump sitting on the bench on the bench.

:homer::homer::homer:

Cliffs.

300k 5VZ-FE runs hot, may need head gaskets.

Have not done a leak down yet, should I?
 
Easy test would be to get the car up to temp without a radiator cap on. Then put the coolant pressure tester on it and let it sit overnight with pressure on it. Then check the cylinders for coolant intrusion.
 
Bummer the new water pump is leaking.

If it's only running 215 from 205, I'm not sure I'd jump right to HG.

Maybe the leaking water pump is the cause of loosing coolant?
 
Easy test would be to get the car up to temp without a radiator cap on. Then put the coolant pressure tester on it and let it sit overnight with pressure on it. Then check the cylinders for coolant intrusion.
What's the purpose of that vs just pimping it up to pressure with the tester? Getting things to expand and be more likely to leak?
 
Bummer the new water pump is leaking.

If it's only running 215 from 205, I'm not sure I'd jump right to HG.

Maybe the leaking water pump is the cause of loosing coolant?
Sorry for the confusion, the new pump is not leaking, I bought a new one thinking it was a flow issue, I have not installed it yet, and the one from 20k ago is not leaking


I also did the exhaust fluid tester deal in the radiator, where it changes from blue to yellow, that tested negative. no exhaust gas in the radiator.


I haven't let it get above 215, so I have no idea where it will go, I just know where it normally has run, and have not been willing to let it climb above that.

The climb is very slow, just a degree at a time over a 5-8 mile stop and go loop.
 
Easy test would be to get the car up to temp without a radiator cap on. Then put the coolant pressure tester on it and let it sit overnight with pressure on it. Then check the cylinders for coolant intrusion.
Hot vs Cold,
would pumping it up cold do the same?
honest question
 
Gotcha, the water pump leak is what made you change everything.

No idea on anything else. We had a little Honda do something similar years ago. Would slowly use coolant and if you didn't top it off, like day 3 it would overheat.

It had no oil/coolant mix and no white smoke. But did have small bubbles in the radiator and it would build pressure before it was warm.
 
Gotcha, the water pump leak is what made you change everything.

No idea on anything else. We had a little Honda do something similar years ago. Would slowly use coolant and if you didn't top it off, like day 3 it would overheat.

It had no oil/coolant mix and no white smoke. But did have small bubbles in the radiator and it would build pressure before it was warm.
ya, It went 20K no issues after timing belt/ water pump, now I have a slow water temp creep, and after a week or so of driving coolant is missing from the overflow bottle,

Like as it cools it draws water into a cylinder, and the sealed system sucks it out of the overflow. Like a syphon.

Am I missing something simple?
 
This is so timely.

My Tacoma has always run a tad warm on the stock gauge. Timing/pump done about 15k ago. Coolant disappearing.

I believe mine is water pump leak… but I’m going to watch this thread for other ideas.
 
This is so timely.

My Tacoma has always run a tad warm on the stock gauge. Timing/pump done about 15k ago. Coolant disappearing.

I believe mine is water pump leak… but I’m going to watch this thread for other ideas.
I think you can pull the cam cover off and see the water pump.

Is the radiator itself low, or does it draw water out of the overflow bottle, and keep the radiator full?

As long as I keep the overflow bottle topped off the radiator will stay full, but it will steadily draw coolant from the bottle a little bit every day.

I rented the pressure tester to hold pressure and check for leaks.

My next option is a cylinder leak down test.
 
I think you can pull the cam cover off and see the water pump.

Is the radiator itself low, or does it draw water out of the overflow bottle, and keep the radiator full?

As long as I keep the overflow bottle topped off the radiator will stay full, but it will steadily draw coolant from the bottle a little bit every day.

I rented the pressure tester to hold pressure and check for leaks.

My next option is a cylinder leak down test.

rad is low, sucking from overflow. I just yanked skid plates...will create new thread as to not hijack this
 
rad is low, sucking from overflow. I just yanked skid plates...will create new thread as to not hijack this
I've been busy as shit, And not wanting to tear into mine, it's good as long as I keep it close to home 10 miles or less per trip.

And I keep an eye on the overflow bottle. I've got 6 days off coming up soon, and my son just got his motor back for the Land Cruiser, That's another thing, He is driving it to work, ( 3 miles one way) So we are limping it along.


It's been a great second/third backup car around the house, I hate to lose it.

I'll follow you, to see if you figure something I don't.
 
Ok, so just checked the overflow bottle, The truck is using about a quart a week from the overflow, it's getting driven about 50 miles a week, probably 3-4 miles at a time, just enough to start to get at about 200*.

As soon as my sons LC is up and running I'll dive into it, right now It just needs to get him to and from work.


Son's Build
 
If its not leaking, it burning it. Another tell tell sigh of water consumption is very clean spark plugs. usually there will be only one cylinder consuming water in a blown HG, so one plug will sometimes stand out being cleaner and less carbon build up on it.
 
If you have no visible leaks it is going into the cylinder/s. One other thing to check, I think you have an auto, if you are routing your tranny line through the cooler that is sometimes built into the lower radiator tank, make sure your trans isn't taking on water. I have heard of this happening where the line going through the lower tank corrodes and lets water into the transmission line. I wouldn't think this would cause overheating though unless you were letting your radiator get low.
 
If you have no visible leaks it is going into the cylinder/s. One other thing to check, I think you have an auto, if you are routing your tranny line through the cooler that is sometimes built into the lower radiator tank, make sure your trans isn't taking on water. I have heard of this happening where the line going through the lower tank corrodes and lets water into the transmission line. I wouldn't think this would cause overheating though unless you were letting your radiator get low.
"Pink Milkshake"

Usually, And I say usually, (anything is possible) it pumps trans fluid into the radiator, just because the trans is higher pressure than the radiator.

But I have not looked at the trans level, tonight that will happen, Thanks.
And yes the cooler is still in the radiator, I have not moved it out yet. Trans runs around 190*

I replaced the radiator about 20k ago when I did the timing belt/water pump/thermostat. I had a brand new (Zero Miles) one laying around from another project.

Right now It is a back burner deal, My son is driving it as we wrap up his engine project, (it's good for about 10 miles before it creeps above what I'm comfortable with) I need to do a cylinder leakdown, and throw the radiator pressure tester on it one more time, I'm hoping to get that done over the weekend, if all of that comes back ok, I have a new Toyota waterpump sitting on the bench, I just didn't want to start that just to find it needs a headgasket.
 
"Pink Milkshake"

Usually, And I say usually, (anything is possible) it pumps trans fluid into the radiator, just because the trans is higher pressure than the radiator.
That makes sense but, if you shut the engine off and that line losses pressure it is possible that the radiator pressure could be higher.....just a theory. I'm no mechanic.....just a DIY hack.
 
That makes sense but, if you shut the engine off and that line losses pressure it is possible that the radiator pressure could be higher.....just a theory. I'm no mechanic.....just a DIY hack.
Join the club, aren't we all to some extent:lmao::lmao::lmao:

This is going to sound crazy, but I am chasing a difference of about 20 degrees, and I won't drive it once it gets above that.

Chasing it on the OBD2 factory sensors, through the Torque app.

I even bought two new Toyota water temp sensors, but have not installed them yet.
once the LC is running I'll dive into it. this has been a "backup car" but its nice to have.
 
20210726_140433.jpg


I'm a glutton for punishment:lmao:
 
Join the club, aren't we all to some extent:lmao::lmao::lmao:

This is going to sound crazy, but I am chasing a difference of about 20 degrees, and I won't drive it once it gets above that.

Chasing it on the OBD2 factory sensors, through the Torque app.

I even bought two new Toyota water temp sensors, but have not installed them yet.
once the LC is running I'll dive into it. this has been a "backup car" but its nice to have.
That was going to be my next question. new sensores, and verify you have the same reading at the sensor and the PCM connector. but considering it is losing water, I dont think its a sensor issue.
 
I had a slow leak over time on my 99 taco 3.4 and I wound up noticing a water stain on the back of the motor and top of the trans. Had a knock sensor code at same time. Pulled the intake and the valley between the heads was full of water from a failing heater hose. Replaced the heater hose, knock sensors and wiring harness. This happened with 220k on the rig. At 240k now and so far good to go.
Take a look at the top of the trans where it meets the motor for water stains.
 
When replacing the water pump, did the thermostat also get removed or replaced? If it was replaced, which orientation is the jiggle valve? Apparently it makes a difference at 6 vs 12 o’clock..
 
When replacing the water pump, did the thermostat also get removed or replaced? If it was replaced, which orientation is the jiggle valve? Apparently it makes a difference at 6 vs 12 o’clock..
I did the waterpump, timing belt, idlers, thermostat,radiator all at the same time, and yes it was installed proper, and has gone about 20k without issue.
I can't tear into it now, As soon as I get the LC running I'll have more time.
 
I have seen new Aisin fan clutches low on fluid. Your symptoms could be fan clutch. I would run all the fan clutch tests and then consider ordering a bottle of the fluid from Toyota to top it off.
 
I have seen new Aisin fan clutches low on fluid. Your symptoms could be fan clutch. I would run all the fan clutch tests and then consider ordering a bottle of the fluid from Toyota to top it off.
Replaced it with a new one when all this started, the one I replaced was probably factory original though.
my son did buy fluid and refilled his on his land cruiser
 
Replaced it with a new one when all this started, the one I replaced was probably factory original though.
my son did buy fluid and refilled his on his land cruiser
Like I said, I have received new Toyota fan clutches that were low on fluid.
 
Every headgasket failure (or head failure) on these engines that I've seen has started off with coolant leaking into a cylinder after shutting it off hot and letting it sit overnight. Pressure is going to typically rise until the cap vents as the engine heat soaks into the coolant after a hot shutdown. Usually there is a bit of a misfire on the next cold startup.
 
Every headgasket failure (or head failure) on these engines that I've seen has started off with coolant leaking into a cylinder after shutting it off hot and letting it sit overnight. Pressure is going to typically rise until the cap vents as the engine heat soaks into the coolant after a hot shutdown. Usually there is a bit of a misfire on the next cold startup.
So far none of that yet, Just a slow rise in temps the longer I drive. So far I haven't driven it long enough to see where it stops. I've blown a head gasket on one of these trusting the factory gauge. so far I haven't let it get over 220* ( Reading off the OBD2 port using the torque app)

For reference since I've owned it over the last 80K miles it sat right at 199/205* max. 20K ago it got a timing belt set and water pump/thermostat and continued right back at the 199/205 pattern.

Also it is loosing about a quart of coolant every two weeks or so driving it 3/5 miles a trip, lowering the overflow bottle no leaks in the bottle.( My son is using it to get to work until we get his cruiser finished)

Things are busy so we are nursing it along, knowing the limits, and working inside of that for now.

Thanks for the input.
 
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