Head Gasket

[tlava]

Had a mechanic check the HC--he did a pressure test, and claims that the HC is OK--but coolant has dropped significantly in the reserve tank--must be going somewhere, right? Should I drive confidently or might the HC still be weak and not show up with only a pressure test?

Hate to get on the road with 2 dogs and 2 cats and have a breakdown... I already told my wife to fly...

[WME]

Did you replace the headgasket, thermostat, hoses, radiater lately?

If you did you may just be burping out the remaining air in the system.

[5Toyota]

might check the water pump is this a four cylinder so you can see the water pump

[fred heath]

An easy test to tell if coolant is getting in the oil.

With the engine at normal operating temperature pull the dipstick and let a few drops of oil fall on the exhaust manifold. If it smokes your fine. If it sizzles there's water mixed with the oil.

Feel the carpet on the passenger side of the cab. Is it wet?

The coolant has to be going somewhere.

[tlava]

Hi All--

radiator and water pump etc are new and yes the system was burped and no water in oil, but I assume it is the exhaust side that could be weak--I was just wondering how fool proof the pressure test is, as compared to the chemical test; no one around here seems to have a gas analyzer anymore....

[WME]

NAPA auto has diy chem test for checking coolant, under $20

[85Diesel]

If the timing chain is old and stretched it can wear a groove into one of the coolant passages, simulating a h.g. failure. Fairly common on older four cylinders.

[MontanaChinook]

Usually when the chain wears a hole through the wall it's a catastrophic failure. Coolant dumps into the oil. You'd know.

If the water pump job was not long ago, you may just not have enough coolant in the system yet. So it seemed full, but now that it's been driven around and circulated completely through the system, you're seeing that it's not completely full. Usually when I drain my coolant and refill, I need to top off the reservoir two or three times before it finally stays at full.

Also, check the reservoir when warm (right?). Because when everything gets hot and expands, that's when the fluid goes into the reservoir. When it cools off, some of the coolant in the reservoir gets sucked back into the radiator.

But yes, also make sure your heater core isn't leaking coolant into the cab.

[5Toyota]

shops will often have a cooling system pressure tester it is a little hand pump that you screw on to the radiator. it has a gauge on it can show head gasket leaks rad leaks hose leaks. heater core is a good one another good one is the water valve under the hood that controls the water going to the heater. did they take the spark plugs out for the pressure test when i did a 20 r antifreeze shot out of the plug holes.hose fittings can leak and dry up from the eng heat and be hard to find. at times you may smell them or see white crud from leaks.

[Skydancer2992]

In your situation, look for the leak immediately after engine shutdown. Check your heater hoses and use your nose to sniff for the "sweetish smell" of coolant. You can sometimes smell it in the exhaust as well (only one sniff). Change your oil yourself and check the old oil for signs of coolant.

I have had disappearing coolant occur in two different vehicles.

Each time, the coolant loss would occur right after engine shutdown, when the engine cooks internally without the benefit of active cooling. The pressure in the coolant system seems to spike.

The first instance was the tip of a heater hose was starting to split. The mechanic showed me where the leak was and cut off the tip of the hose, clamped it back in place and told me be on my way, no charge (as I was a college student at the time, I was eternally grateful).

The second instance is still with me on my 96 4Runner. After shutdown, a few drops of coolant leak on my crossover pipe and provide a distinctive stench. This happened in 2006 and I just wanted the 4Runner to last another year or two since it was getting close to the 250K mark on the odometer. I worried about it for the first year.

I now have over 350K and the problem is still present. I add a cup of coolant each month.

If the problem becomes worse, I will probably do a combined valve job, timing belt change and head gasket change.

Between my Warrior and 4Runner, I have 600K miles. I've put another 500K on several other Toyotas in the past. I've learned over time not to let the small mechanical issues reduce my enjoyment of the vehicles. The Toyotas have not been my main source of car repair knowledge. They are just too reliable. The vehicles of friends and relatives are the ones that help me appreciate how well the Toyotas are designed.

[mason]

I've learned over time not to let the small mechanical issues reduce my enjoyment of the vehicles."

That takes a lots of understanding not to panic over little problems in life.

[Boots]

Hi all,

For Your Information, Toyota has a secret warranty on certain engines which are prone to failure. Specifically if the engine is a V6, and has a head gasket failure, Toyota will reimburse you for the cost of repair, replacement of the engine-if you qualify. This is applicable to 1988 to 1995 models. The reason is (was) that during this time, asbestos was banned in the manufacture of head gaskets and Toyota switched to a metal composite, and they proved to be flawed. So if you are experiencing mechanical problems relating to head gaskets, contact Toyota and ask them if you qualify; they will check your VIN number and other related information, and will base their decision on that. I experienced a head gasket failure and arranged to repair it, the cost was approximately 3300.00. During the time the engine was being repaired, I surfed the internet and found about the warranty from a US site. When the engine was rebuilt, I drove it home, went to my local Toyota dealer, they confirmed that I was eligible for the warranty and ten days later handed me a cheque for the whole amount. I was at first skeptical, because we live in Canada and thought the warranty coverage was in the US, but it turns out the truck frame was sent to the US from the Japan and the RV was built on top of the "Japanese" frame.

Another handy piece of information is if you have a computer failure, and can get the associated information (model, serial number VIN and transmission type) you can get a genuine rebuilt replacement computer, from a company in Florida. They are called Auto Computer Exchange.com and I bought mine from them about three years ago at a very reasonable price. If you return your (broken) computer to them, they will give you a great warranty. They also provide computers for other makes and models.

Boots

[MontanaChinook]

Oh boy...

[tlava]

interesting discussion and suggestions. Curious--were is this water valve, exactly, and should it be full open?

[MontanaChinook]

Where are you getting water valve from? Give us a frame of reference.

[MontanaChinook]

Ah, I found it.

The "water valve" he's talking about is either open, closed, or somewhere in-between, depending on the temp setting you have in the cab. It controls how much engine coolant is allowed to come into the heater core in the cab of your truck. So when your heater dial is all the way over to red, you're getting the maximum amount of coolant into the heater core, and the most heat on you. As you move the dial/lever towards blue, you're closing that valve and allowing less coolant, and therefore heat, into the cab.

That valve will be right up against the firewall that divides the engine compartment from the back of the dashboard, up at the top. A small diameter coolant hose will be going into it.

Often when people notice that they loose a little coolant, and also have a wet carpet, it's from the heater core leaking, or one of the hoses attached to the heater core. And of course the valve you're asking about is connected to the inlet hose letting coolant into the heater core.

[5Toyota]

and at times those valves will leak coolant