more pics

 

Coolant all along the rear valve cover seam but still not sure where the leak is ...
There are small puddles down in the valley also ...

 

That is a bad leak and it looks like the coolant valley pan leaking or cracked. Recommend getting it resealed with Toyota FIPG sealant along with new thermostat and associated o rings. Change the hose as well and knock sensor sub harness since they do get brittle. Also the coolant block off plate above the oil filter can also leak.

 

Is there a coolant valley pan on the 04 Sienna? (3MZ)
I'll replace the water bypass hose for sure under the IM with new clamps and the intake gaskets. The van has NO OTHER PROBLEM beside the coolant leak. The coolant plug by the filter is bone dry. Thermostat / housing / connections bone dry. Also added more pics. Thanks.

 

bone dry valley, still need to take out the water outlet
does it look like an intake gasket leak? front ones just dirty with oil crud, rear ones you can see coolant around the flange...

 

Have you possibly missed a few bolts when tightening in a sequence? Or a bypass hose got cut near the throttle body?

 

Can't be since it's the first time the intake being removed. I'll be changing the 2 intake gaskets for sure. The rear one seems to be leaking based on the coolant on flange and gasket pictures.

Would you happen to know the torque spec for the intake and sequence? The bolts were easy to remove so I guess no more than 10 ft/lb.

Bypass hose is bone dry but I'll replace that too with new spring.

I was wrong about dry valley. I do see dried coolant down there at the top left. Pic attached.

So far I have a "valley plate" leak and a rear intake gasket leak.

Is "valley plate" the actual term for it? Would you happen to know its part number?

So far I'll be doing:
"valley plate" gasket
1 top air box / intake orange / pink rubber gasket
2 metal intake manifold gasket
1 bypass hose w/ new clamps
2 valve cover gaskets
probably thermostat, housing, gasket/seal since everything is out.
spark plugs are new, wires good

Anything else you would recommend? Thanks a lot.

 

Don't quite understand how coolant got on the valve cover on the back...

 

Probably from the hose running to the throttle body. When you're driving you have all sorts of wind moving around in the engine compartment, drops are not going to fall straight down to the earth. Most likely the profile causes the air to move from the driver's side towards the middle of the engine bay.

 

Hello

Thanks for letting me join!


Need some help here. I pulled the intake to replace the knock sensors on my 2004 sienna. I found a lot of coolant residue and stop leak? residue under the intake. The bypass hose and gaskets look good, it looks like it is coming from the "valley pan". I haven't pulled it off yet, is there a gasket underneath? Cant find a part # either. I'd like to fix this problem before I start putting it back together. Any help will be greatly appreciated!


Thanks,
Dan

 

Thanks for letting me join!

Need some help here. I pulled the intake to replace the knock sensors on my 2004 sienna. I found a lot of coolant residue and stop leak? residue under the intake. The bypass hose and gaskets look good, it looks like it is coming from the "valley pan". I haven't pulled it off yet, is there a gasket underneath? Cant find a part # either. I'd like to fix this problem before I start putting it back together. Any help will be greatly appreciated!

Thanks,
Dan

My original problem was a torn hose which squirted coolant everywhere and made it appear to be leaking from else where. I'd done a pressure check first from now on before anything else. Anyways.

Check your hoses, especially those cross/junction types with small clamps. They are easily rubbed/ripped by the clamps. These is a gasket under the valley pan but it's not a pre made one. It's a black paste out of a squeeze tube.

Toyota Seal Packing 103 (FIPG) P/N 00295-00103

Scrape the old gasket with razor, clean mating surfaces, make the gasket, mount within 15 min, okay to start in 1-2 hr, completely hardens in 15-16 hr.

 

Hoping this gives you a few pieces of useful info.

2004 Toyota sienna 3.5L Engine Torque Specs| Toyota Specs

sienna 3.5L engine bolt torque specs, common problems and repairs. Cylinder Head Torque specs, timing chain installation, manifolds torque specs, engine assembly.

toyota-specs.com