1FZ-F coolant leak help. (2 Viewers)

[thebill]

Hello!

My upper radiator hose popped off and dumped coolant. Engine temp needle went to about 1/4” from the lower edge of red on the gauge for about 30-60sec before I cut the engine off.

Engine has run fine since - for about 10 days since losing coolant - but developed a coolant leak (no evidence of oil & coolant mixing) with the strongest flow while cooling down. It would leave a small puddle about 6” across over the course of 20-30minutes after turning the engine off.

I tracked the leak to the second to last lower intake manifold bolt so I pulled the manifold today expecting to see a crack in the head but it’s not showing anything that would produce a leak, at least not on the mating surface or in the #5 or 6 intake chambers. The port cap just below and ahead of this bolt is soft and not leaking.

Could there be a crack at the bottom of the bolt hole?

After the leak started, I made sure all the manifold bolts/nuts are torqued correctly and they all were but the leak persisted.

Before I go forward with pulling the head to have it looked at, any guesses as to where else to look?

Thanks for taking the time!

 

[Fj80oregon]

I would try replacing the hose and cap with new hose and new clamps and see if that was the leak. The 1fzfe do not leak from the head itself, you could have over heated and lost the Head gasket. I have seen them fail in the back of the head but never from that location.

 

[Fj80oregon]

You could also do a combustion gas test, the kits are cheep and will tell you if the head gasket is leaking combustion gasses into the coolant system. You test it at the radiator with the kit. Might not be necessary leaking into the engine and could be just an external leak from the head gasket failing around the water jacket.

 

[thebill]

You could also do a combustion gas test, the kits are cheep and will tell you if the head gasket is leaking combustion gasses into the coolant system. You test it at the radiator with the kit. Might not be necessary leaking into the engine and could be just an external leak from the head gasket failing around the water jacket.

Thanks.
The radiator, cap and all hoses are a couple years old.
Wouldn’t a HG failure be below this bolt though?

 

[JuanJ]

Hello,

The upper radiator hose is close to the manifold but the cooling circuit goes to the water pump and through the cylinder head. See the image below.

The 1FZ engine tolerates excess heat and low coolant more than it looks, enough to go back home or to make it to the shop.

Remember that these trucks ran for too long with water instead of coolant. It takes a while for the coolant to replace whatever fluid the previous owner used.

I would take the chance to replace the water outlet hose and pipe. If I wanted peace of mind, I would change the gaskets as well.

Hope this helps.





Juan

 

[thebill]

Hello,

The upper radiator hose is close to the manifold but the water circuit goes to the water pump. See the image below.

View attachment 3786174

The 1FZ engine tolerates excess heat and low coolant more than it looks, enough to go back home or to make it to the shop.

I would take the chance to replace the water outlet hose and pipe. And the gaskets, of course.

Hope this helps.





Juan

Thanks @JuanJ
Hoses are all relatively new, except for the one that goes through the firewall to the heater which I may replace now that the manifold is off. Water pump was replaced at the same time.
When you say gaskets, do you mean the head gasket?

 

[JuanJ]

Thanks @JuanJ
Hoses are all relatively new, except for the one that goes through the firewall to the heater which I may replace now that the manifold is off. Water pump was replaced at the same time.
When you say gaskets, do you mean the head gasket?

Hello,

Yes, the head gasket. There should be a gasket where the hose connects to the head.






Juan

 

[Fj80oregon]

That’s not a head gasket he is referring to, if you look at his diagram he provided it’s labeled water outlet hose(it’s actually a cast aluminum part) and has a gasket there. It’s a possibility also if you could not see exactly where the leaks was.

 

[thebill]

That’s not a head gasket he is referring to, if you look at his diagram he provided it’s labeled water outlet hose(it’s actually a cast aluminum part) and has a gasket there. It’s a possibility also if you could not see exactly where the leaks was.

Understood @Fj80oregon. The leak I saw was gathering & dripping on that bolt (cyl #5) and coming straight down, collecting on the ridge at the bottom of the block then onto the ground. Truck was on flat ground and stationary. I know tracing leaks can be tricky but this one didn’t appear to be coming from anywhere but this spot. Since I’m 1/3 of the way into it I may just pull the head and have it checked.

 

[Fj80oregon]

If you have the capability (sounds like you do) then yah yank the head have it machined and rebuilt and slap on a new head gasket. If your going that far it’s a good time to insure your new investment with a full cooling system refresh and add a external coolant sensor somewhere so you can monitor engine temps and avoid overheating in the future!

 

[JuanJ]

Understood @Fj80oregon. The leak I saw was gathering & dripping on that bolt (cyl #5) and coming straight down, collecting on the ridge at the bottom of the block then onto the ground. Truck was on flat ground and stationary. I know tracing leaks can be tricky but this one didn’t appear to be coming from anywhere but this spot. Since I’m 1/3 of the way into it I may just pull the head and have it checked.

Hello,

Considering that you are in the neighborhood, so to speak, this is a diagram with all the gaskets you may consider replacing.

And this is the head gasket schematic.

Chances are there is a lot of sludge to clean in there. I would do the cleaning and I would replace parts/gaskets as needed.

By the way, the air connector is a pain to remove. Those two bolts have a nasty habit of seizing. Ask me how I know.




Juan

 

[Fj80oregon]

If you buy an engine gasket kit it will come with 95% of the gaskets you need about $280 on partsouq.

 

[thebill]

@JuanJ @Fj80oregon Thanks for the speedy and continued support!
The air connector is already off and gasket kit 04111-66047 is in my cart. I just need to add all new hardware and I think I'm on my way. I've wanted to replace my distributor O-ring for a while so this is rather convenient

 

[OGBeno]

@JuanJ @Fj80oregon Thanks for the speedy and continued support!
The air connector is already off and gasket kit 04111-66047 is in my cart. I just need to add all new hardware and I think I'm on my way. I've wanted to replace my distributor O-ring for a while so this is rather convenient

That’s the engine gasket kit part number.

You want 04112 prefixed number.

 

[thebill]

That’s the engine gasket kit part number.

You want 04112 prefixed number.

Thanks @OGBeno an engine gasket kit is what I’m after.
Is 0411266027 the one, then?

 

[OGBeno]

Thanks @OGBeno an engine gasket kit is what I’m after.
Is 0411266027 the one, then?

Oh. Well disregard then.

 

[cruiserdan]

This is suspect. That port is for the water line to the throttle body on an EFI truck. That cap is old and the clamp has been moved around on the cap. I'd pressurize the cooling system and watch that cap.

Cap, 90339-07001
Clamp, 90467-13001

 

[RHINO]

I'd just pull it out, tap the hole and plug it for real.