Engine Coolant Leak

Is there an acceptable limit for how much the pressure can drop during a 12 hour test?

 

pressure test



block test



thermostat and water pump supposedly easy to replace and typically due by now on any other vehicle.
You might tear into that area anyway to replace worn accessory drive belt, pulleys, and tensioner.
Wouldn't even be able to see where coolant sprays out of during pressure test (if it leaks) with that engine cover and skid plates blocking view to the engine

 

That I do not know.

 

Me either. Anyone feel free to correct me. I would call the pressure test of the cooling system you did as passed.

How did the radiator cap look? If the rubber part is deformed or mushy, replace it. If your pressure tester has the adapters, you can also test the cap.

 

There's no standard for how much its allowed to lose overnight. Usually if it doesn't lose any pressure over an hour our two its considered a pass for the cooling system.

For testing a blown head gasket you should do a dynamic test. Run the engine with the gauge attached and see if it builds pressure as you rev it or if pressure spikes after the thermostat opens up.

My engine would also pass a basic static pressure test.

Check the radiator cap.

Thermostat is easy to swap but water pump you have to pull everything from the front, fan, belt, pullies.

 

Considering it’s an 06 and this happened to mine when the head gasket started to fail I’m gonna go with that

 

I also realized that the temperature fluctuations outside likely had an effect on the drop in pressure. I attached the gauge at night when it was still warm out and I read it in the morning when it was a bit colder. I left it on and it rose slightly above 16 when it was super warm out. I think it held pretty dang close to where it should be.

The cap looked worn and definitely needs to be replaced for how cheap they run. I'm going to do the water pump and thermostat just to be done with it.

I also developed a hell of a squeak somewhere in the belt system. I think may be from all the fluid that got on the belt and the pulleys. Not sure if a bad water pump would squeak like this.

 

I sure hope it's not a sign of a failing head gasket. Most things seem to point to the thermostat as of right now. I've read a lot of 05 and 06 models have this issue, but not every single one fails and I hope I'm in that group.

I JUST installed a brand new AC system, ARB front bumper, wheels, tires, full OME lift kit, and rack and pinion - I'm heavily invested at this point lol. If it is a head gasket I'm going to become a Tacoma expert almost replacing everything on the dang thing. Doing the Clock Sping/Spiral Cable this weekend!

 

I see that you are replacing your head gasket right now! I haven't read anything about starting the engine while it's connected to the tester and monitoring the pressure. Wouldn't the pressure automatically increase from coolant expansion as the vehicle warms up? I understand the underlying idea if combustion gases exist the pressure should increase if started.

Curious how you identified your blown gasket!

 

A slow steady rise in pressure is expected a sharp rise or fluctuation in pressure indicates a headgasket failure.

First I had coolant coming out of the overflow when driving the truck harder than just around town. Then noticed a couple bubbles coming from the coolant tank. Minor like a one or two every couple minutes after the engine was warmed up.

As I said the leak was very minor, passed the block test and no change in oil color. Would even hold pressure when the engine was off.

An oil analysis confirmed my suspicions. They said there was a small amount of coolant detected in the oil but it was minor enough to be managed through regular oil changes. Since I use my truck to camp and hunt I don't want the headgasket to let go when I'm in the middle of nowhere.

Honestly it only sounds like a bad radiator cap or headgasket not a thermostat. Also a stuck thermostat is very easy to check for, run the engine without the radiator cap and watch when the coolant starts to flow, also the thermostat on these trucks are not known for going out.

 

Put the pressure adapter on the radiator and start the engine. Watch the pressure and see if it spikes or rises steadily

 

I don’t want anyone’s to go on here just like I didn’t want mine, but to my understanding Toyota changed the head gasket for 07+ since they originally used a faulty material or something like that

 

got to this point with the build and right after the head gasket blew, motor mount and ripped the frame and fell into the frame

 

Sometime halfway through 06 is when they changed the design.

I'm debating pre-emptively reinforcing the motor mounts on mine.

 

If it’s in the funds I’d do it… even if I had a later year

 

Just to be safe

 

Just put the pressure adapter on the truck and started it up! It was a slow and steady gradual climb in pressure as the truck heated up, absolutely no quick spikes. One thing that was interesting was it climbed over 27 PSI - Would this be cause for concern? It looks like the radiator caps are rated for 16lbs. This is probably something that I misunderstand about the system.

 

The radiator cap's job is to keep the system under pressure to prevent the coolant from boiling under normal operating temperatures but yet relieve the pressure if it gets too high to prevent damage, it's other function is to allow coolant that escapes into the expansion tank during normal operation to be drawn back into the system when it cools.

 

I don't off road any more, but still recently added the DMZ engine mount gussets. Easy enough even with a TIG welder. Any shop with a MIG welder and lift could knock it out easier than lying on the garage floor on your back.

Site prep took the longest time.

 

seems high in a short period of time.
check the sparkplugs, If they are all black or brown and one is super clean. There is water in there.
Also maybe run the engine without the oil cap while hot and check for steam.

and yes my head gasket went at 200,000 miles. It was consuming small amounts of water for a long time until one day I forgot to check and it overheated and boiled over thru the reservoir.
I did a low budget gasket job with FelPro aftermarket gaskets and took the heads to the machine shop for valve job and check for cracks and so far its gone 50,000 more with no issues

best of luck.