Bad headgasket..good compression??.. stumped!

[ianfromdaygo]

Hi, this is my first post here so let me give you guys a little run down. Ive had a few toyotas previously. Not my first toyota truck but my first 4runner, i bought it about a month ago from a local seller. It currently has 230k miles. It is a 95 4x4 5spd 3.0l v6. The first week i brought it home and started driving it, the leaky valve covers started leaking bad and onto the manifold so it was smoking like crazy. Ive changed the driver side (easy side) but havent got to the passenger side yet. The passenger side isnt as bad. Well the first time i tried to take it on a long trip (300miles) it started to run hot with the a/c on going up hills only. I quickly noticed and i could return the temperature back to normal operating temp by turning the heater on. The next week i had to make another 150 mile trip and again on hills with no a/c on this time it started running hot again. When i got to my destination i figured id try to change the thermostat before i headed home. As soon as i hit the freeway on my way home the first incline it started running hot again. Everytime it ran hot i could bring the temp back down with the heater.

Well i made it home so i decided i better test the new thermostat. It passed the test so i went ahead and bought a brand new radiator. Filled up the radiator and burped it properly. I decided to take it for a test drive, about 40 mile round trip. It was kind of hot outside around 90 degrees so i decided it would be a good test to see if the truck would over heat. I also had the a/c on so if it was going to heat up i would know quickly. Well it didnt overheat at all, not even on inclines, but it didnt run so well. Real rough idle and the engine is missing almost like a bad plug or bad plug wire. I get home let the engine cool off, check the radiator, and its empty. Hmm, thats weird. I sniff the radiator and i can smell fuel, or combustion. Seems like bhg symptoms. So i decide to check my oil. Level is perfect. I recently chagned it so its still brand new golden color. I take my oil cap off and i see this:

I just did a compression test and every cylinder hit 150 psi with cranking it and hearing the motor turn over 4 times each cylinder. Good compression? 150 across the boards seems awesome to me. So now im stumped. I was going to attempt to change the headgaskets on my own but after doing the compression test i dont know what to do. I dont want to rip the engine apart if the compression is perfect. But why is my oil cap milky and where did the water go from my radiator? The plugs are brand new, nothing about them looks abnormal. Maybe someone can help me out. Thanks
Ian

[Dave's]

Ever see a head gasket? Of course there are openings for the cylinders but there are also holes for cooling, oil and the bolt passages. If the gasket fails between a cylinder hole and anything else you should see a compression loss. If it's between a cylinder and oil you can lose oil (black smoke) and even contaminate the oil with fuel and exhaust. Cylinder and cooling and you can blow coolant out the exhaust (white smoke) and/or super heat the coolant. But if an engine overheats and the head warps (or whatever the cause) it is possible to have a leak only between just an oil and a coolant passage. In which case whichever has the most pressure will contaminate the other while compression remains good because the cylinders are still sealed. A leak can occur between any passage and the outer edge of the gasket as well. Keep in mind it is possible a crack in the block or some other failure could be the source of your problem. But a near total loss of coolant without smoke pouring from the engine compartment plus the smell of fuel/exhaust certainly does sound like a head gasket failure between a coolant passage and a cylinder. And the filler cap looks like coolant has made it into the oil as well although that could be from bypassing the piston rings to the oil pan. Just my two cents though. Hope someone else can provide better info.

[ianfromdaygo]

Thanks for the input. I see what you're saying. I'm def gonna troubleshoot around a little more before I tear the heads off. I'm gonna try to check out the oil cooler tomorrow. Maybe change the oil and fill the radiator back up with water and see what happens.

[ianfromdaygo]

So since my compression is still good, can I get away with pulling the heads and just replacing the gaskets and then slapping the heads back on? Or should I still take them to the machine shop to get milled and pressure checked...

[ricksrunner]

It would be good to at least check to see that they are not warped with a good straight edge. The repair manual has the specs on this 40.10mm or .0039in for 3vze. Best to take to machine shop to magnaflux for crack.

[Zembonez]

Very common for a head gasket to "blow" between water and oil passages while not losing compression. Once the engine has been run hot (and especially at your mileage) it would be best to have the heads checked by a good machine shop so you don't end up with the same problem after you do the big head gasket job. THAT would be a bummer.

[flying07]

Originally Posted by ianfromdaygo

Hi, this is my first post here so let me give you guys a little run down. Ive had a few toyotas previously. Not my first toyota truck but my first 4runner, i bought it about a month ago from a local seller. It currently has 230k miles. It is a 95 4x4 5spd 3.0l v6. The first week i brought it home and started driving it, the leaky valve covers started leaking bad and onto the manifold so it was smoking like crazy. Ive changed the driver side (easy side) but havent got to the passenger side yet. The passenger side isnt as bad. Well the first time i tried to take it on a long trip (300miles) it started to run hot with the a/c on going up hills only. I quickly noticed and i could return the temperature back to normal operating temp by turning the heater on. The next week i had to make another 150 mile trip and again on hills with no a/c on this time it started running hot again. When i got to my destination i figured id try to change the thermostat before i headed home. As soon as i hit the freeway on my way home the first incline it started running hot again. Everytime it ran hot i could bring the temp back down with the heater.

Well i made it home so i decided i better test the new thermostat. It passed the test so i went ahead and bought a brand new radiator. Filled up the radiator and burped it properly. I decided to take it for a test drive, about 40 mile round trip. It was kind of hot outside around 90 degrees so i decided it would be a good test to see if the truck would over heat. I also had the a/c on so if it was going to heat up i would know quickly. Well it didnt overheat at all, not even on inclines, but it didnt run so well. Real rough idle and the engine is missing almost like a bad plug or bad plug wire. I get home let the engine cool off, check the radiator, and its empty. Hmm, thats weird. I sniff the radiator and i can smell fuel, or combustion. Seems like bhg symptoms. So i decide to check my oil. Level is perfect. I recently chagned it so its still brand new golden color. I take my oil cap off and i see this:

I just did a compression test and every cylinder hit 150 psi with cranking it and hearing the motor turn over 4 times each cylinder. Good compression? 150 across the boards seems awesome to me. So now im stumped. I was going to attempt to change the headgaskets on my own but after doing the compression test i dont know what to do. I dont want to rip the engine apart if the compression is perfect. But why is my oil cap milky and where did the water go from my radiator? The plugs are brand new, nothing about them looks abnormal. Maybe someone can help me out. Thanks
Ian

Ianfromdaygo,

I have a 94 4 runner and Toyota sent me a recall for the head gaskets. I've heard that the head gaskets were defective, and I've heard that the Toyota factory installed the head gaskets upside down from the factory. I don't if that is true or not but it is food for thought. Now, you might want to call your Toyota Dealer and ask them to check your VIN # to see if they have been replaced by Toyota. Keep in mind that my 4 runner is a 94 so I don't know if the recall applies to 95 4 runners. Hope this helps and good luck.