[MTL_4runner]

That's actually could be a bad thing at 140K miles. You may be leaking just enough water to steam clean the cylinders.

While in theory you could be right the chances of that happening in every cylinder equally is almost nil.  I am going to just do a head gasket anyway to be sure it's all done right because breaking down up here in winter really sucks.  I know of at least a few other trucks that have survived a dance with the temp redline and still been ok (even Johnny from sea2sky tuning had it happen on his Tacoma), but I'm the more conservative type so I'd rather do the work and have the piece of mind that everything was done right.

[BennyTRD]

I hope you get your issues dealt with Jamie. I think this post has made my mind up about changing the t-belt, t-stat, pump, and tensioners next time I have a few days off. A little preventative maintenence goes along way. Let me know how sourcing the head gasket goes, might aswell do the whole works while I have it apart. Good luck.

[MTL_4runner]

I hope you get your issues dealt with Jamie. I think this post has made my mind up about changing the t-belt, t-stat, pump, and tensioners next time I have a few days off. A little preventative maintenance goes along way. Let me know how sourcing the head gasket goes, might as well do the whole works while I have it apart. Good luck.

Wise choice.....much better safe than sorry as you can see clearly in my case (sucks being the guinea pig).
I'm still not sure I'd call my WP failure normal though.

[MTL_4runner]

Looks like the only items needed to do the entire HG job are:
Intake and exhaust manifold gaskets
Throttle body gasket
Head Gaskets
Head bolt set

So, I've been looking at head gasket options....

1) New MLS Head Gaskets from the dealer (@ $35.20 per side or about $70 for a full set)
www.toyotapartsales.com

2) Cometic brand MLS head gaskets (@ $82.50 per side or about $165 for a full set)
http://www.mr2.com/forums/sea2sky-tuning/Toyota-MR2-20121-sea2sky-tuning-offer-cometic-mls-headgaskets.html
http://www.cometic.com/gaskethome.aspx

3) Victor Reinz MLS head gaskets  (@ $45 per side or about $90 for a full set)
http://carquestgaskets.ca/solutions/SS-VR-I-02.pdf

There are tons of rebuild sets on eBay, but from what I gather (from people who work on the 5VZ-FE quite a bit) they are 99% junk and I don't plan on doing this job twice so I won't be trying any of them.

One other place had been mentioned to get full rebuild kits for the 3.4L engine:
http://www.rpmrons.com/Toykits.html

[mkgarrison5]

i would go with a toyota one then jamie. like you said you dont want to be doing it twice.. so you are please with the synpower huh? its BOGO here in the states at advance auto.. just bought 24 qts of it and only paid for 12 shhhhh :-) dont tell anyone

[MTL_4runner]

i would go with a toyota one then jamie. like you said you dont want to be doing it twice.. so you are please with the synpower huh? its BOGO here in the states at advance auto.. just bought 24 qts of it and only paid for 12 shhhhh :-) dont tell anyone

I'm pretty pleased because I'm sure it saved my butt from killing the motor during the overheat.  If all I did was lose a HG, then I'd consider that pretty lucky.  I haven't torn the heads off yet so I can't say for sure there's no more damage, but my fingers are crossed.

[mkgarrison5]

keep us informed and take plenty of pics!! hopefully you lucked out. 140k miles is too young. thats like dying at 30.

[mkgarrison5]

any word on the culprit yet jamie?

[MTL_4runner]

Not yet.  I want to pressurize my cooling system up to 15 psi and see if I get any visible leaks before I go ripping the heads off it.  I cleared out my garage and made space to do the head gaskets if I need to but I was debating if it might be easier to just rip the entire engine out of the vehicle and give it a good overhaul at the same time (or maybe even just getting a used motor with some miles on it and doing up a full rebuild while the other motor is still in the truck, but I'm not sure that would make good financial sense).  I also wanted to order the head gaskets just in case so I have the parts on hand and it takes a bit of time to get snail mail to deliver north of the Border.  I promise I'll have pics when I start tearing it down and I plan to have it fixed before the weather gets too cold (luckily in this case global warming is on my side.  )

[mkgarrison5]

how bad did it overheat? i have overheated many cars and never had HG issues till lots of miles down the road and all were a gradual HG decend.. is it running like crap? or are you just trying to be cautious as possible?

[MTL_4runner]

The first time it redlined pretty badly and it's hard to say how long it was like that since when you're driving long distances time seems to blend together.  The second time it overheated after about 50 minutes of driving (so that would tend to tell me that something let go along the way....HG?.....not sure at this point), but once I let off the gas the engine temps started coming back down (again this would indicate a HG failure).  There is definately something wrong because the other night I was able to get the truck up to normal operating temp on the coolant even though the thermostat was completely removed from the engine.  I don't think there's any way around it, I'm going to have to at least tear the heads off and see what's going on inside this motor that would cause it to heat up excessively like that.

This 3.4L motor and especially it's cousin the 3.0L are very succeptable to an overheat partly because it is an iron block and aluminum heads but I think the design of the motor itself also comes into play because I've overheated cast iron chevy 350 blocks with aluminum heads and not had it blow the head gasket or crack a head.  This aspect still does not diminish the fact that to me the 5VZ-FE is still one of the most durable motors out there in terms of the mileage you can put on one before a rebuild.  My truck did suffer what I would call a severe overheat and clearly some damage was done......now I just need to find out what happened and fix it.

[MTL_4runner]

I finally started tearing it down today but only got as far as getting off the intake and clearing out all the electrical wiring (some of those are a pain to get at).  Hopefully tomorrow I'll have the heads off the motor and I can get a good idea of what the heck is going on with this engine.  If I still don't see anything obvious I may just go ahead and pull the entire motor out and set it on an engine stand for a complete inspection.

The ace up my sleeve is that I can always get a used 3.4L for about $1000 and be up and running quick.   


Here's some pics of before I started.....

[MTL_4runner]

Made some good progress today but I couldn't take the heads off because I forgot that I needed service bolts for the cams (and I didn't know you need to take the cams out to get at the head bolts).  The engine is still in very good condition all things considered and when I pulled off the heads it didn't appear to have much sludging at all under the valve covers.  One thing to note is that the knock sensor wires are very easy to pull out (one wire pulled right out of it's connector) so make sure you OHM them out before you install everything or you may need to do it all over again to fix a bad connection.

[MTL_4runner]

Here's where I stopped for the night....







You can see my shiny new $1000 water pump in the pics too. 

[mkgarrison5]

i am assuming you are going to go ahead do some HG work since you have torn this one down just about? cant wait for the pics of your valves and etc. it will be nice to see what a overheat and lifelong dino use looks like..my fingers are crossed jaimie