Used engine or new heads?

I have a 5VZ with bad compression (see below) after my fan bracket bearing went bad and caused the engine to jump timing. I drove it with a bad misfire to the mechanic, and now after changing the timing belt and water pump, it won’t start due to low compression, according to the mechanic.

People have been pushing me towards a junkyard engine, but I already have at least a grand into this one, and how do I know the used engine wouldn’t also need a new timing belt, not to mention bad seals, etc. My engine also has new OEM knock sensors and fairly new valve cover gaskets, although it did leak a bit from the rear main/oil pan etc.

Do I source new heads, or just throw a used engine in there and hope for the best?

Also, what could have caused a non interference 3.4 to lose compression like that? Warped heads maybe?

 

I got my new heads for $400 a piece online for my v6. If you’re price gauging.

 

Yea I saw some for that price at CHI. I was almost suspicious at how cheap they were though.

 

Prices from February of this year.
I went with Clear Water heads, CHI had no cores at the time.
Junkyard/cheap used option not included.
Probably add $1000+ for labor, more if you move to a bigger shop than the guy you're at.

 

Toyota 3.4 V6L Remanufactured Cylinder Head - 8/94-9/04 5VZFE - Powertrain Products

Toyota 3.4 V6L Remanufactured Cylinder Head - 8/94-9/04 5VZFE - Powertrain Products


https://shop.powertrainproducts.net/product/8-94-8-04-5vzf-e/


long blocks differ by the oil cooling

 

I will say be careful putting new heads on a high mileage engine, often times if you do that they will start burning oil.

 

Wouldn’t it be getting new valve stem seals though?

I suppose a junkyard/JDM engine could just as easily burn oil as well..

 

Depends on block miles......and got to go inside the engine.

IF its immaculate and no sludge......and hone is still good...

all this you'd need borescope and maybe drop the pan.....see if it was taken care of.....or beat to death

 

I am in a similar boat. I called and spoke with a fellow at metricmotorsusa, nice guy. They sell JDM motors but they pull the pan and valve covers, do leak down and compression testing. He told me 6 month warranty on the block and head. $3600+500 shipping to me in VA. I have not found any other JDM sellers that do this so far but dang that's a lot of bread. His opinion was to avoid east coast JDM resellers because of the saltier conditions. Does anybody have a JDM/used supplier they have dealt with and recommend?

 

A cheap bore scope would be a good investment here. One that can turn 90 and look up at the valves as well as the bore. If the cylinders still have good crosshatch I may go with just heads. But a used JDM engine is a great option, not sure of the market on those though.

 

Is the low compression being caused by
Heads….failed leak down test
Or
Block…..failed compression test
???

heads(if no catastrophic damage/cracks) can be RM’d buy reputable machine shop for $400-$750….depending on condition

 

Not sure, the mechanic just told me the compression was bad. I asked about leak down but I didn’t get a response.

 

were those heads from Yota1 ?

 

https://www.tacomaworld.com/threads/was-trouble-installing-cams-now-restarting-hg-job.787833/page-5

No. Got them from a shop out in Texas. The link is in post #94 in this thread. The link isn’t working for me right now, maybe it will for you.

 

From my experience JDM motors are almost always pretty low mileage. I would just buy an engine from a reputable supplier. The only JDM engines I wouldn’t bother with are rotary.

 

I'd be skeptical of it not starting from low compression. To not even run would be extremely bad compression. Also not sure how low compression relates to replacing the heads. Compression is a bottom end thing unless valves are messed up but idk how you could manage that.

 

Yea I’m gonna get a second opinion after the long weekend.

It’s possible it overheated and warped the heads if the fan came off.

 

Unless it's really fubar I'd doubt it'd be soo bad it wouldn't run. My guess would be the timing is off. It had enough compression out of time to run so compression really doesn't make sense.

 

Yea, my only other thought was maybe I washed down the cylinders or rings when I limped it over there with the severe misfire, or maybe burnt a few valves from running so rich?

The mechanic was also trying to tell me it was an interference engine if the belt jumped enough. I’m pretty positive the 3.4 is non interference though.

 

Washed rings will go away though if you let it sit. Burned valves I'd usually poor valve adjustment. The 3.4 is non interference UNLESS the head had been machined.