Well is time to shop for engine parts now. As my rig approaches 300k miles it has served me well, taken a couple 20 hour road trips and always gets me to work. The other day my engine light came on because my breather hose had split causing a more than decent air leak, this is not a big deal it's a 20 year old hose, upon replacement I had noticed oil in the metal pipe and going into the intake tube. This can only mean one thing, excessive "blow by", more compression going past the piston rings than the PCV can handle. I first found a good parts supplier, seeing as the local parts stores general sell off brand crap, my next consideration is whether or not to change the pistons. Seeing as this motor will have 300k once rebuilt I will replace them, my dilemma is whether or not to change from a dished piston(which it OE) or buy a set of flat top pistons(because I have no intention of doing any sort of forced induction). Has anyone here done this? seems like a more cost effective way to add some ponies to a 5vz, vs adding forced induction.

Toytayoda, slow down for minute buddy. 300k is just broke in for a 5VZ. Since your speaking of dropping $$ for a rebuild whats the maintenence history. Its normal to have oil gunk buildup in thottle body if you haven't cleaned it regularly,
40-60k miles, more often if you want the most from 5VZ. Along with PCV valve clogged can cause what you describe. If it was me compression leak down test first thing on the list to do IMHO. Money spent on mods is better than a rebuild if you don't need it.

Dude I've seen <20K Chevy cars have oil in the intake and they end up going a fair amount even when the owners have terrible maintenance, and this hog is a YOTA. If the oil bothers you that much do a search on catch cans some folks on here run. I personally don't, but some guys swear by them.

^^^^agree with a compression and leak down test as well. That's the end all-be all for an engine's breathability and sealability.

One more thing: You said you weren't surprised by a 20 year old hose splitting, but having that same 20 year old hose with 20 years of minor oil blow-by DOES surprise you? I'm not attacking, it's just a bit of a leap of your up on maintenance.

Remember: you can't say overreact without saying ovary. (Goddamnit is that gonna get me banned? I mean it jokingly come on!)

On my 96 365k miles going strong, have owned it 17 yrs.
Just purchased 01 198k miles had been neglected some was nasty, compression leak down test was fine.
If the engine has some pep to it, gets decent mpg's 15-20 thats with 33's & 4.30 gears what I get on my 96. IMO your good.

Not hijacking op post
4reak, it's early in Cali have cup of coffee your sounding ovary.
(if I don't pick on you I don't like you)
We good.

Random thoughts

These engines are STOUT - they are really well designed and built. Unless you know you have a dead cylinder I would not open the engine.

The piston profile/dish may exist to accommodate valve travel.

Changing compression ratio is going to make a lot of changes to engine performance, not all of them good. Detonation may occur. Valve and ignition timing should probably be changed for optimal performance. The ECM will need to adapt. So many variables.

It's easier to add and remove a blower than swap pistons. Plus if age of pistons is a concern, then age of everything including bearings is a concern too too. These engines go for 400K+ miles when treated right, probably more.

Maybe it's been done and there's a formula for this, but I'm not sure it's worth it.

I would do a leak down and compression test to make sure it is all good and go from there. I would not rebuilt I would just get a JDM motor from a good supplier. Slot cheaper and I feel a way better deal then a rebuild


Sent from my iPhone using Tapatalk Pro

Not sure what you consider excessive, but I think it's normal dude. Mine has had oil in the intake where that hose comes in since I've owned it, even after replacing the PCV. Although the throttle body seems to stays clean.

My goal it just a few more powers and torques in the low to mid end, I'm not a fan of forced induction of a daily driver, so I was thinking that a bit of extra compression would be the ticket. Fully understanding I should probably consider cam timings, and injector adjustments to keep it nice to drive daily. Also worth mentioning, not the common weekend warrior here, I turn wrenches for a living, the 5VZ is a solid engine but by no means complicated. And even though they will run forever like all others they are susceptible to compression loss from worn piston rings. Not pulling the thing out tonight, probably be around this time next year, the rings, bearings and gaskets only run about $400, so the real expense is pistons and cylinder head work.
Anyway I was wondering if anyone had taken on building a 5VZ, a build will happen, Ill post the simplicity as it happens.

Any rebuilt toyota engine will run good for about 100K miles.

If you want to get good compression, do a head job. Get all the valves seated correctly. This makes a big improvement and this it the only thing needed for a toyota until you hit about 400K miles.