2UZ-FE suspect blown head gasket (UPDATE - 3x pistons stuffed) (4 Viewers)

[joshAUST]

Hi all.
Help diagnosing my issue with my 2003 uZJ100 - petrol 4.7ltr V8 .

I was freeway driving at 110KM/H, listining to music, when I heard a ticking sound.
I reduced volume, realised it was coming from the engine, so I backed of, and it sounded like the car was low on oil.
I also noticed I seemed to be losing power.
So I immediately put it into neutral and rolled to a safe park, and stopped the engine.

I popped the bonnet, and what a mess.
The coolant had leaked out everywhere, the top of the radiator was blowing bubbles and hissing.
There was a large amount of oil, that looks like its coming from around cylinder number 4 ( looking at the front of the car, the left hand side, second one from the front).
This oil has come out with some force - blowing oil up and hitting the bonnet.

Once it had cooled down, I checked the oil level, and, while low, was still just above minimum.
The oil also looked as clean as it ever does.

I tried the engine for a few seconds, but it wouldn't fire.
The mechanic from the road side company that ended up towing me home said it sounded like the engine had no compression.

Obviously, a catastrophic coolant leak was the start of the matter, and I'm guessing, given the oil leak as well, from that location, I can only think that the coolant loss has caused the head gasket fail.

Is there anything else that anyone reading this could think it could be?
If so, I'd appreciate their input.

Assuming it is the head gasket, I guess I'll have to get the head tested for warping, weakness, etc., before replacing the gasket, but is there any other head related parts I should check, and/or service, prior to completing any repairs - such as valve clearance?

Thanks for any advice you can provide.
Josh

 

[TheForger]

The EXACT same thing happened to my rig about 8yrs ago minus the freeway driving, I was going up and down a few steep hills in my neighborhood. Heard and saw all the same symptoms except it was cylinder 5. It was indeed the head gasket since that's the only thing preventing oil & coolant from mixing in the head. Fortunately I didn't have any mechanical issues caused by the blown gasket, but I'd say just put a new one in and make sure everything else is visually in good shape and give it a shot. I had my mechanical replace spark plug tube seals, clean/replace coils/plugs as needed, starter, and a complete timing belt kit including cam/crank seals while he was in there. Overkill? Yes, but that was the first baseline I had done when I bought the truck and it saved me a ton on labor as opposed to stretching out those services.

 

[joshAUST]

The EXACT same thing happened to my rig about 8yrs ago minus the freeway driving, I was going up and down a few steep hills in my neighborhood. Heard and saw all the same symptoms except it was cylinder 5. It was indeed the head gasket since that's the only thing preventing oil & coolant from mixing in the head. Fortunately I didn't have any mechanical issues caused by the blown gasket, but I'd say just put a new one in and make sure everything else is visually in good shape and give it a shot. I had my mechanical replace spark plug tube seals, clean/replace coils/plugs as needed, starter, and a complete timing belt kit including cam/crank seals while he was in there. Overkill? Yes, but that was the first baseline I had done when I bought the truck and it saved me a ton on labor as opposed to stretching out those services.

Thanks TheForger, I appreciate that info.
Yes, I can't think of anything else that could cause the oil leak from that area other than a head gasket.
If that is what it turns out to be, I'll also do a timing belt, water pump and pre-tensioner, etc, as its overdue, at 260,000KM, and no sticker or other evidence it has ever been changed.

I purchased this vehicle second hand a couple of years ago.
It never used oil, transmission fluid or coolant, ever - even after a 4500KM+ round trip from Hobart to Brisbane and back home again.

However, a year ago, the starter motor failed, so I had to replace that.
Ever since, I've noticed some wetness around the thermostat housing, intake port and on the fans...
I replaced the upper radiator hose, replaced the hose clips with stainless steel hose clamps, etc, but haven't yet found the source of the leak.
While hunting the source, I did find that three of the top cover screws were missing - three all next to each other - so either the mechanic who installed the starter failed to install them, or didn't do them up tight enough and they all worked loose....
I don't know.
Interestingly but perhaps not relevant, they were all on the side where the oil leak was from....but the leak is coming from below the inlet manifold gasket... and as far as I'm aware, going from the FSM, there's no oil lines in the inlet manifold...so unless its leaking out of the block, my guess is, and your comments reinforce, it has to be a head gasket... as, if it was leaking out of the bottom end, I'm sure I would have heard it.

After the starter was replaced, I'd just keep topping up the radiator twice a week - but as I generally only do short <30min trips weekdays, I never had any issues - until I took it for a long drive last weekend.
So, on top of a head gasket, I guess I'll have to factor in the TB, WP and Pretensioner, and probably radiator, thermostat, other related hoses, probably replace the drive belt and AC/alternator belts as well....sounds like its going to be expensive.
Thanks for your input.

 

[Nottajeep]

Wow. Head gasket job seems pretty rare on these engines in the US. Wonder if extreme heat plays a factor here

 

[joshAUST]

Hi Jasonbraswell.
I live in Tasmania, Australia, and while its technically 6 days into our summer, the ambient temperature is around 9-15 degrees centigrade.
A loss of coolant, of course, negated that.

The temperature gauge in the dash, from what I've read, and experienced, is notoriously unreliable, and even more so when you're low on coolant.....

I agree a head gasket does seem to be very rare, and not just in the US, here in Aus there's virtually no info about it.

Reading up on the 2UZ-Fe engine, it does seem to be an extremely reliable engine, in the top three best engines of all time, according to some, but only so long as you have enough coolant, it seems, lol.

 

[2001LC]

You may or may not have blown head gasket. Even with badly warped head(s) and blown head gasket they can still run. Here's a blown one that was very badly overheated. You'll see exhaust blowing out heater Tee hose.

The oil looked like milk shake as coolant entered cylinders from head/gasket and drain past the rings into oil pan.

Driving with coolant or any leak is never a good idea. If coolant level get to low, we may get false reading on dash temp gauge. It may show running cool when actually overheating.

Your "bolts" missing are likely to the head cover (valve covers). These loosen over time and oil leaks out. It's not oil under high pressure, so just a leak.

Coolant blowing out radiator as you describe. May indicates a bad radiator cap not releasing pressure, or may be exhaust gasses. The fact you saw it bubbling out, indicate you may have only been a few quarts low. Picture will be very helpful.

The next step is a compression test. If you find compression down to around 40PSI in two cylinder next to each other, then it for sure is blown head gasket.

Next step is to scope those cylinders, to see if they are badly scored or not. It they are, you'l want to find a used engine. If cylinder walls are in good condition, a head job may or may not be best course of action. It really depends on if you can source a good used engine. When doing a head gasket replacement. It is best to do both heads, or just one yield a rough idle.

See The Unicorn for one I did.

 

[2001LC]

BTW Cylinders are numbered:
Front
LH-RH (sitting in driver seat)
1-2
3-4
5-6
7-8

 

[Nottajeep]

Yeah, I was thinking check VC gaskets also.
These engines are fantastic but they don't like to be overheated at all.

Cheap Bluetooth OBDII reader is a life saver for real coolant temps.

 

[joshAUST]

Thanks for your input 2001LC.
Turning the engine over sounds very similar to the one in the video you posted.
From the look of it,there's no obvious sign of coolant in the oil fortunately.
Yes, I'll be getting a compression test done first up.
If it is the head, and the rest looks OK, I will replace the radiator - its in pretty poor shape.

 

[joshAUST]

Thanks also Jasonbraswell.
VC gaskets? - ah, valve cover gaskets, ok.
If I have to do the head, I might as well replace those gaskets while in there.

Yes, I do have a cheap - sub $50 AUD scancode reader, which gives a far more accurate idea of the temps, but I only connect it when diagnosing/troubleshooting, as its clunky, and the cables to short to mount anywhere practicable.
I wish I could find a device that can sit in the dash and have digital temps for the coolant and transmission temps...
I know the Toyota techstream software can monitor both, but haven't yet found a suitable unit.
Thanks again.

 

[Od86]

What cause head gaskets failure in 2UZ?

 

[joshAUST]

What cause head gaskets failure in 2UZ?

Excessive heat I guess - caused by a coolant leak, in this case.
Not helped by a pretty much useless dashboard thermostat guage...

 

[2001LC]

I've heard as others have, of 4.7L 2UZ-fe head gasket failure without overheating. If they do happen without overheating, it supper rare.

Number one cause of HG failure is overheating.
Number one cause of overheating, bad enough to cause damage, is low coolant.

Even if you had a scan gauge hooked up. It may still have given a false low engine temp. What happens is the coolant level drops below the water temperature sending unit. It then reads air temp. It does a poor job of read air temp and air temp will be lower than the coolant itself. So we see a lower than actual reading on the dash or through tech stream.

It's the Achilles Heal of the 2UZ. Many engine for that matter.

When I did compression test on above 4.7L 2UZ-fe VVTi engine. I did with a cold engine and throttle body closed. Not proper procedure, but I just need to see difference.
Bk 1. BK 2.
PSI PSI
1-152. 2-84
3-110. 4-10
5-30. 6-10
7-40. 8-40

I then scope the cylinders to see if scored.
They were scored.

Coolant or water really cleans out the carbon.

 

[2001LC]

Engine got so hot the heads warped. This is evident by compression test and separation of head gasket

Even the block changed color

So hot it melted plastic designed for high heat.

Discolored the pistons, of scored cylinders.

Same engine for comparison

 

[Od86]

Oh boy
Is any have to attach the temp reader ..somehow ... obd II ?

 

[2001LC]

Temperature is read from same place. ECT or Water sending unit which is on water bypass joint.
Reading from a scan gauge plugged into the OBDII port or off the dash makes little difference other than you see exact temp with a scan gauge hook up. Dash gauge is just approximate indicator, that moves very little.

Depending on year (below is 06-07) you may of two sensors on the water bypass joint. In the 03-05 only top one has a wire block attached. In 98-02 both have a wire block attached

You can see this sensor sits high in the engine above the water pump. Just the top of radiator, thermostat and heater tees are higher. ~ 80 to 90% of coolant is below the sensors level.

It's very important to keep coolant system properly service and topped. Also be on the alert for the sweet smell of coolant. A momentary infrequent wift on a hot days is normal and should pass in 1 or 2 seconds. It come from reservoir over flow hole in cap. More often or longer duration is sign of a leak. No leak is a good.

Radiator cap is so often overlooked. If it is to weak it will allow excessive fluid flow from radiator. Stuck close and excessive pressure builds, which is when a weak radiator top or heater tees blows.

I put out and alert on clogged radiator fins. These need washing now and them. But be warned, the drive belt and it's pulley don't like water.

Radiator fins need cleaning! Alert Alert Alert

I've a 06LC w/192K I just bought. In reading history I found PO complained of engine temp raising when both front and rear AC on. Toyota Dealership diagnosed with clogged radiator fins. Recommended new OEM radiator, $600 for the US spec Radaitor plus coolant and labor. They should have added...

forum.ih8mud.com

When a client comes in or I'm doing a restore project. Coolant system service is something I always recommend and do.

It starts with noting level then inspecting for leaks. Next step is cleaning radiator. I like to replace radiator cap and thermostat about ever 90K in a well maintained system. I use only Toyota coolants and in interval recommend for year.

 

[joshAUST]

Thanks again 2001LC.
I hope mine is not as bad on the inside as those pics... but its not looking great.
I should find out early next week re a compression test, etc.

 

[2001LC]

Would be nice if you posted a few high res pictures. I'd like to see the entry engine bay including battery.

 

[Nottajeep]

My LS 430 (3UZ) had a leaking radiator for several days before I realized it. Fan would run very high at low idle which caused me to pop the hood and check. I was between 1 and 2 gallons low on coolant just in the radiator. This engine has 275K miles. Dropped in new radiator and everything runs great. Just wanted to point out these engines may hate heat but they are not fragile either. I think you need to really heat them up to blow the HG.

 

[joshAUST]

Would be nice if you posted a few high res pictures. I'd like to see the entry engine bay including battery.

Hi 2001LC.
I'll try to get some photos on Saturday.
Its currently at a friend's workshop, but he hasn't had a chance to look at it in detail.
He suggested it may have lost a ring...as the compression test he did was causing oil to pump out the dipstick...
However, I suggested that could be still the head gasket, as, if there's a hole in the gasket between a cylinder and a oil channel/whatchyamacallit/, then the compression test would leak air into the sump, pressurizing it...causing the same symptoms.
From what I've read, the bottom of the engine is generally considered one of the most reliable engines around... so I hope I'm right in my diagnosis... fingers crossed.