Head gasket problem but without all the symptoms

[pat garaffa]

I have a 2004 4-runner SR5 and most of the symptoms of a leaking head gasket but without the overheating problem.

The problem started when the check engine light came on. I immediately looked at the oil and temp gauge and both were normal. I pulled over and had steam coming from the radiator and the overflow tube had popped off the radiator. It was obviously running very hot yet the temperature gauge never moved form it's normal position (just under the halfway point.)

I removed the radiator cap and the system was empty. I added the full amount (about 2 gallons) and drove it home and then to the mechanic the next day. They found leaks in the system and replaced the radiator and the hoses. They didn't think the thermostat was a problem so they left it alone.

They said the hoses seemed overly firm after the repair and that indicated excessive pressure. The anti-freeze probably had a place to leak prior to the repair and that pressure is probably what caused the overflow tube to pop off. But now the system is all new and the pressure has no where to go and the hoses are firm.

The temperature gauge is also much lower than it was before and it seems like it takes much longer to get the temp up and the heat working properly.

Here is what I am experiencing now:

1. The car runs extremely rough for the first minute or two and then it's fine. The longer it sits, the more likely I will experience this problem.

2. It sometimes bucks as I drive. That is also very intermittent and just started.

3. I have also experienced very low power in the first mile or so and then it returns to normal.

4. The CEL indicates misfire on cyl 2 and 4. (PO302 & P0304). I also have a random cylinder misfire (P0300) and also a coolant level/temperature/thermostat error (P0128).

5. The CEL sometimes blinks for a while and then goes solid. I also have those other two lights that seem to pop up every time. VSC track and something else.

6. I'm still leaking anti-freeze. That was happening prior to replacing the radiator and hoses but its still coming out somewhere. It leaked about a quart over a 2 week period of very light driving.

7. I popped the cap on the radiator after the car had sat idle for 6 hours. The engine was cold but the cap opened like a carbonated beverage (pop!) so there was a lot of pressure in there and that doesn't seem right.

8. My mechanic said that I should top off the anti-freeze and start/run the car with the radiator cap off. If the head gasket was a problem then the anti-freeze would bubble over (mild problem) or act like a volcano (big problem). It didn't do that at all but there was a tiny bit of anti-freeze flowing out of the opened cap and that may have been a result of me overfilling the system. Or also indicative of a small problem that may get worse.

9. The thermostat on the dash normally sits around 40% (just below half.) The thermostat rarely makes it to 20% now and that started after the radiator was replaced. If anything, could it be running cooler now?

10. The interior heat is inconsistent and not very warm. The vents on the driver side dash produce much more warm air than on the passenger side and the volume is about the same. When I switch it to the floor, the volume and heat is heavier on the passenger side. If I switch to defrosters, its seems about the same. I can't fathom how that can be related? It may be a totally separate problem.

11. There is a high pitched whining noise that seems to be coming from the left side of the engine towards the front. It's hard to be sure of the location. The whine increases in pitch as I accelerate.

Were all scratching our heads here and I don't want to spend $3000 to find out my problem was something unrelated to a head gasket.

I bought the 4-runner used about 3 years ago with 118K. It's about 140K now.

You've read all the blogs. Any thoughts on this?

 

[NJshadow93]

A couple things I would do is to first figure out where it's leaking. If it's dripping onto the ground then that shouldn't be too hard to locate where it's coming from. If it's leaking internally somewhere, that's a little more difficult obviously, but if it is a headgasket issue then it likely ends up in the oil. Do you see a puff of white smoke or steam out of the tailpipe when starting the engine cold?

Another thing I would do without a second thought is to replace the thermostat and gasket! It's such a cheap part and good insurance that the thermostat itself is functioning properly. Get the Toyota part and don't waste your time on the aftermarket thermostats.

Also, the heat issue in the car is almost certainly related to all the cooling system issues. The cooling system flows through the engine, radiator, and heater core (which is a miniature radiator inside the cabin which is responsible for your heat). It sounds to me that the shop who installed your radiator did not fill the coolant properly or didn't bother to bleed the air from the system. There are likely lots of air pockets blocking the coolant from flowing freely and into your heater core.

On a related note, this is probably why your engine temperature gauge on the dash is showing low, the coolant may not even be passing the sensor if it is blocked by air. Overall, if there's air in your cooling system and it's not flowing properly, it'll make the truck do some wacky things.


While the head gasket is a valid culprit, you should not jump to this conclusion until all the other issues with your cooling system are resolved (including the leaks).

To recap, find and fix the coolant leak, replace the thermostat (and radiator cap too while you're at it) and find a shop who can properly flush and bleed your coolant. Good luck, hope to see some updates on this

 

[macgyver_ga]

Go ahead and replace the t-stat and gasket as recommended. Also go ahead and replace the radiator cap. They're cheap. The high pressure in the hoses leads me to believe that either the t-stat isn't opening properly, your radiator cap isn't functioning properly, or you have some sort of blockage in your system.

To burp the air out of your system, park your vehicle on an incline (facing uphill) with the radiator cap being the highest point in the system. remove the cap and let the car run (preferably after it has already warmed up to operating temp (this means the t-stat will be open allowing coolant to flow). Keep the car running & keep topping off the coolant until the burping stops. If it doesn't stop bubbling, you might have a bad headgasket/warped head(s).


Check/change your plugs (they're cheap anyways) and make sure they aren't fouled it. If they are fouled, you probably have a leaky headgasket allowing coolant into the combustion chamber.