I went offroading up in the local hills, and noticed once I was up there the temp came up, so I turned on the heater and it came down, but kept fluctuating up and down. I decided to start on my way home at that point, and at one point it started boiling over, so I stopped to let it cool off a bit. Then continued on my way home, at this point the temp was normal, and the heater wasnt working (no heat was coming out the vents), so I dont think there was any coolant left, I put the water I had in some bottles in, but it wasnt enough. It got to the point where it started to ping, so I pulled over and called AAA and got the truck towed home. After putting a new radiator in (the old one was old and the neck broke), taking the thermostat out, and filling it up, the engine wasnt circulating, so I filled it from the back of the engine at the heater hose, and it started circulating, so I guess it had an air bubble. Anyways, now it is circulating like normal, but there are tiny little air bubbles at the radiator fill cap when it is running, and when you give it gas they increase. So im thinking I may have the start of a blown head gasket. My neighbor who is a mechanic swears by K&W stop leak, and says since it is in the beginning stage, it will fix it, and I wont have to worry about it. Its either that or pull the heads, and if I am going to have to pull them eventually, id rather do it now and know its going to be reliable. This is on a 3.4 V6 with only about 37k on it. What do you guys think?

 

don't go tearing off your heads just yet, i would do a compression test first with all the cylinders, and are u sure u put the thermostat back on there good with sealer and all and all your hoses are on there good and tight? does it leak coolant any where, does it smoke out the tailpipe any? theres a few test u should do first before u go pouring that stop leak ▓▓▓▓ in there, my buddy did that and it just looked like solid chunks just floating around it there a while after he did it.

 

Does the oil have a milkshake consistency to it? Thats a very well known effect of a blown HG.

 

I know the usual signs of a blow HG, and mine doesnt have them. No milkshake oil or coolant, no coolant leaking, no water through the exhaust. The only thing im seeing is the little bubbles in the radiator. I will do a compression test and see what I come up with.

 

take it to a radiator shop and have em check it for co and co2 in the coolant

 

Ok I did a compression test... The results are good...

1- 140
2- 150
3- 155
4- 140
5- 140
6- 140

I checked the oil at the dipstick and it is perfectly fine, no evidence of water. No evidence of oil in the coolant. There is no anti-freeze in the coolant right now, just straight water, dunno if that has something to do with it. Like I said, the motor got really hot, and now there are little bubbles at the radiator fill cap that increase if you give it more throttle. Im going to look into the thing to test the gases coming out of the radiator...

 

man with only 37k miles you over heated?? what was the initial cause of the over heating??? thats too young

 

The thermostat stuck, causing it to get hot. After getting hot it started to boil over and broke through the weak upper radiator hose neck on my radiator (original 3.0 radiator) and I lost my coolant. This is in a 3.4 swapped 1990 truck.

 

when i checked compression on my 98 3.4 with 127k miles - they all came in around 185-190 psi. your 140 psi seems low to me. Maybe others will chime in on that.

 

Unfortunatly, you'll be lucky if you didn't crack both the heads. Look for steam in the exhaust after it warms up. You can still have good compression with a crack going through to the exhaust port. Take it to a shop and have the cooling system "block tested" for exhaust containation in the cooling system. That's the chemical test you mention. It will show blown head gaskets, and warped or cracked cylinder heads. Or if you know a smog tech he can put the sniffer over the radiator neck, but the block test is more reliable.

Motors that have aluminum 4-valve heads are not durable at all when it comes to overheating. I see you're in Rancho too, I can take a look at it for you if you want, I'm a professional mechanic.

 

Hey all,
I have a similar situation with the 3vz 6 cyl in a 93 toy PU. About a year and a half ago i had the head gasket replaced, at 230000, now at 245,000 looks like the same problem again, with coolant in oil, i'd say thats a pretty positive sign. Just wanted others opinions, it this point it's probably not a good idea to replace the gasket again, but to get a long block and replace the engine, right? any ideas on the best price I can expect to pay? I know here near Los Angeles, they have numerous places in the recycler that advertize engine rebuilds for approx $1200.00, anyone ever try those? (usually in pomona)
Thanks

 

Once the head gasket begins to go on the 3VZ they almost always continue to get worse and eventually blow head gaskets more often unless you machine the block and the head to a surface finish of 30 micro inches or better and then use a copper head gasket to keep compression stock and resist the massive shear forces created from the different rates of expansion. It is the same on a 5VZ to a lesser extent (since the head gasket was improved to reduce the chance of this happening), but the problem is still there nonetheless.

 

It is low but all the numbers are veyr close to each other and that is the good thing. Much below 120 on any one of the cylinders means bad things. I think the rings are starting to go on that motor or something is wrong with the testing.

 

It is often hard to get the compression tester screwed in tight due to the recessed spark plug holes on the 5VZ so it's quite possible that the "real" compression numbers are actually much better. As you mentioned, the true indicator is that they are all within about 10% of one another with no big anomalies.

 

Bummer Steve, here's Jamie's related thread:
http://www.ultimateyota.com/index.ph...6&topic=2241.0