Head gasket?

Starting when I got this 2000 tundra 3.4L, I've always had to add coolant because there was a leak.. Since the new radiator last year there's been no more external leak, now at 208,000 miles, 20kmiles later and I've still had to add coolant ever since I've owned it but there's never been any white smoke or any coolant in the oil etc. I'm asking now because a month ago the crankshaft position sensor was bad and the garage had a hard time figuring it out because the sensor they ordered was bad. luckily I had ordered one that came the day they figured out it must've been faulty. When I dropped it off and it did work they added at least a half gallon of antifreeze before I took it home which I said it really isn't anything new, I always have to add some. it was smoking white, heavy and constant for a few days, I assumed" from all the cranking it was burning stuff off. Since then though the coolant is always low and it seems like while it sits is when it's draining the most and the white smoke is heavy for the first minute or more the longer it sits. The only constant code is P0441 vacuum etc, which I just got a new gas cap to see if it'll clear itself. I am going to get a head gasket test tomorrow and see but I'm wondering what else it could be because It doesn't have any symptoms, no overheating and no coolant has ever been in the oil. There is white gunk under the oil cap which I read about could be because the pcv valve which was gunky and I changed that last week

 

You're obviously burning the coolant (given the white smoke). So a head gasket or cracked head is absolutely your culprit. A compression test would likely indicate what cylinder(s) are compromised.

Sometimes you can nurse these things along by adding coolant (as you've been doing), but eventually its going to get much worse and totally fail (usually quite suddenly).

Might be worth looking around for a junkyard motor to just swap in. Just finished doing that with my buddy and his '98 Tacoma (with the same 3.4L motor). Scored a motor with ~170k miles for $400, and was probably less labor than a head gasket repair. We plan to rebuild his original motor here soon to have a spare sitting around.

 

On the 5VZ cylinder 3 is often the one being leaked into (middle passenger plug). Pull it and see if it isn't nice and shiny clean.

Has it overheated - these engines tolerate very little in the way of overheating - I've seen 217 doom them. Otherwise its is one of Toyotas top 3 engines ever in my opinion.

 

It's never once over heated which is why I've been weary about the head gasket. It is seeming to be the only explanation though. But I just took a ride and this time no smoke, sometimes it does sometimes it doesn't. Sometimes the coolant is low and it does smoke, then other times it's fine and it doesn't smoke..It also had a big crack in exhaust manifold passenger side which I just j.b welded and drove after curing now the 3rd time

 

The sometimes smoke sometimes not is because of how the luck of the draw ends - if valves happen to end up closed when off then no leaking into cylinder.

 

Which valve though? That would seem to make more sense the way it happens

 

I did the liquid gasket test today and it stayed blue thankfully! out of 4 quick trips today it smoked once after I was in the store about 15 minutes. Since I welded the manifold I had a good drip from the exhaust today that I realized I haven't seen in a long time. So maybe it's tight and burning stuff off the way it should now.. It still leaves me to question where the coolant is going but I'll try to stop worrying and see how it runs this week

 

To help confirm, remove plugs and use a borescope camera to look inside the cylinders. Look at the piston tops and the valves. When you see one cylinder appears extraordinarily different from the others you will be able to confirm a head gasket leak. That one will be steam cleaned. You might even see a drip and or a puddle of coolant if you take your time and analyze closely. Good luck!

 

You need to post in the first gen section instead of the general discussion and you'll get more help from the first gen guys.

 

Sounds like a cracked head or head gasket to me.

That said, you might get away with nursing it along for a good while. Is this your primary vehicle, or just a truck for when you need a truck?

My previous truck (1997 Dodge) had 2 cracked heads (cylinders 7 and 8). It would burn white smoke whenever I started it up, but would stop after a few minutes. I would just keep an eye on the coolant levels and add some whenever it got close to the bottom of the reservoir. I drove it a little over 9 years like that, problem never got any worse for me. I figured a new engine was in my future though. It wasn't my daily driver, I would drive it when I needed to drive off paved roads (farm land, crossing creeks, etc) or when I needed to haul something.

Eventually the rest of the truck started to fall apart (rust, water in the cab, etc) and I needed a truck with a bigger rear seat and rear doors so I sold it and bought the Tundra instead.

 

Agree - post in FGT section. A lot more 4.7 owners but we have a few V-6 guys. Another cause of smoke is a failed vacuum valve on the power steering pump. Also look carefully at the coolant crossover pipes and weep hole of water pump. Post pics over there as well.