What should I do next with my 3.4L engine?

Hello all,

This one of my first posts so excuse me please for it being kind of long.

I purchased an 04 Tacoma Double Cab Off Road 4x4 in July. She had a good amount of miles at 175K but is cosmetically excellent. I felt really good I made a good purchase.


When I've had the time, I'm going through the truck and fixing any issues and changing fluids.

This weekend I started changing the timing belt. Glad I did, the crank shaft bolt came off very easily. Must not have been torqued to spec by the prior mechanic.
The water pump is in pretty bad shape. There was big pile of coolant crust at the bottom too.


No biggy I had a new water pump with the timing belt kit.

But here is what really has me worried. Evidently some rock pebbles had made there way into the air box. These pebbles were down at the bottom and were keeping the air filter from sealing properly. The amount grit through out the intake system look like it has been this way for a long time.



And the worst discovery. This head gasket leak is near the #4 cylinder. I'm so bummed.
I just sold an 89 Toyota PU 4x4 with the 3.0L. I was not expecting this on the 3.4L



The spark plugs show a lot of electrode wear but are almost completely clean. Almost no deposits. Could it be that all the cylinder are leaking coolant or does this engine run very clean?

I really wish I had checked the oil pressure and compression before I had take the engine so far apart. The engine runs great. No loose bearing knock or blue smoke out the tail pipe. It passed Cali smog so I'm guessing the bottom end is okay and the compression is good.

Since this ugly discovery I have been doing a lot of reading. I understand that these motor have tendency to have cracked heads.

I would like to ask the engine builders out there what is your opinion of this engine? Is it likely toast? Is it worth spending $80 on a leak down tester before pulling the heads?

All I have left to do is remove the lower intake manifold, exhaust manifolds and cams before the heads come off.

Any advice is appreciated.

Barry

 

Excellent pics and write up. Sorry I cant help but there is a vast amount of knowledgeable people on here that should have some great suggestions. Nice looking truck and good luck.

 

My 3.4 has been doing that for close to 100,000 miles and still runs perfect. Looks like the same exact place too. As long as your oil looks good and you can do a compression check and if the numbers are good then it's nothing to worry about it's just leaking out. I have to add a little coolant about every 3 months and that's only about 8oz so very little probably normal amount for evaporation. If I clean it off after a few weeks it gets the crust again and that's it. I wouldn't worry about it.

 

This is good to hear. A guy I worked with said the same thing. I like to hear the same opinion a few times before I tend to believe things.
It looks like we go wheeling in the same area. If the truck wasn't down I would have done Red Rock Canyon with TTORA last weekend.
Would you have any reservation about taking your truck full length of the Mojave Trail or some gnarly trail near Big Bear.

 

The 3.4l is a very stout motor, arguably the best V6 Toyota has ever made (the 4.0l is tried and true as well). Cracked heads and blown gaskets plagued the 3.4l's predecessor, the 3.0l V6 of the late 80's/early to mid 90's. That was probably the worst motor Toyota has made, lol. They learned their lesson with the 3.4l and it's not really a motor you ever have to worry about if it's been well taken care of.

I'd get a compression check done like mentioned above to be sure everything is working as it should

 

i would try to torch the bolts on the valve cover gaskets that'll tighten the head down on the gasket it fixed my coolant leak when i had 270k on original gaskets

 

I wouldn't even worry about that dried accumulation honestly. It doesn't even appear to be wet. I have a very similar dried residue pile near the thermostat housing which doesn't seem to leak or have any other issues. If it were constantly wet/ leaking into the cyl/ out the side of the block then that would be something to address. Are you saying that you already have the engine torn down to do the work?

 

I have no reservation taking my truck anywhere. Have been to Moab several times and ran the harder trails like Behind the Rocks and Golden spike and most of the local harder trails like Nightmare Gultch after a rain when it was still open with no problems. These trucks will go just about anywhere they just flat out work even when stock and you don't have to worry about breaking down.

 

Like your truck - wish mine was a 4 door.

Just drive it. That sounds simplistic but it's a legendary engine and if it's running smooth and cool just drive it. Either that or go ahead and bite the bullet and do the heads for peace of mind. I replace plenty of stuff for peace of mind. I know of no tendency for 3.4's to have cracked heads - you may be thinking about the 3.0 which preceded it. Mine has 180K on it, is sludged (that's a thing) and was neglected by the PO, and it still runs like a scalded dog. I just take care of it and don't worry about it.

 

Thanks everybody for the great replies. Yes, I do have a strong tendency to replace things for piece of mind but this case I'll resist. I'll buy a leak down tester and if everything checks okay I'll leave the HG alone.

What's your opinion of the spark plugs from this engine. They look very clean to me. But since they are all pretty much the same I'm not thinking it is a coolant stream cleaning issue. Would you guys say they look normal?


Another question about spark plugs is I understand that Toyota went with these duel electrode spark plugs because this engine design has a wasted spark (the plugs spark every stoke instead of just at the power stroke). So the duel plugs would give longer life. But now with the long life of iridium plugs could they be used? Has anyone had good experience with iridium plugs?

 

Those plugs look great, very new. Throw them back in and get another 50k out of them. 90% of people on here will recommend you the factory spark plugs because they seem to work just fine without Boost. They're not expensive either.

 

id say replace your front shocks with 5100's

 

If I had zoomed into one of the plugs closely you can see a fair amount electrode erosion so I think they have quite a few miles on them. That why I'm surprised there so clean.

I had 5100's on a 89 Toyota Xtra Cab 4wd and they were awesome. The truck floated over the rough stuff and all the gear stayed in the bed. I just had the ICONs revalved so I hope there as good as the Bilstein's. Just have to get the truck mobile again.

 

Iridium plugs should really only be used on forced induction applications (i.e. if you're running the TRD supercharger). The 3.4l motor was designed to run on copper plugs so I would stick with those.

 

what?

 

I agree that the OEM plugs are the way to go. I would like to know if the lack of deposits on my plugs are normal. I usually see a light brown deposit on plugs but this engine is new to me.

+1

 

I'm not that well-versed in spark plug health by the looks of them but hopefully this chart helps

edit: just realized it's hard to read the screenshot, here's the link to the page it's from...

http://3.bp.blogspot.com/-5aOlZoHEn...niUCG_5I/s1600/check_spark_plug_condition.jpg

 

Kind of hard to see the pic you posted of your's but based on what I can see versus the chart above, they look like they've worn normally

 

Yea their nothing like in the chart (I think that chart is a Clymer Manual staple). The plugs are just very clean like the engine is running lean. When I get it all back together if there's no ping then I figure all is good.
Thanks

 

You put a torch on your valve cover bolts...to stop a leak...

...of coolant.