Cracked Valves - New Engine or Rebuild?

Hello everyone, I have an 03 double cab SR5 with the 3.4L V6 and 270k miles on it. I got it in 2015 and I'm not sure I could ever bring myself to sell it. That being said, about two years ago the engine was running rough, compression tests showed low compression on cylinders 5 (80psi), 4 (80 psi), and 3 (115 psi). My mechanic believed it was likely cracked valves and recommended it would be cheaper to put in a new (used) engine, but we didnt spend the time or money to confirm the theory.

I need a truck for work, and I also need to be able to drive up to 5 hours away from home on any given day, so I bought a 2020 TRD Offroad and stopped driving the old truck. Just recently I took a borescope and was able to get the following pictures out of cylinder 5 and cylinder 4, confirming the cracked valve theory. I stopped there to assess my options moving forward.

With these cracked valves and this high mileage what is the groups feeling about a new (used) engine vs. rebuilding the heads with new valves from a cost and future use standpoint? And on that note, does anyone have a mechanic who knows the ins and outs of this sort of work on these trucks in New England? southern Maine, New Hampshire, and northern Mass. would be ideal locations. Thanks everyone!

 

Looks like you can get rebuilt heads for about a grand (~500 ea).

One example: https://www.headsonly.com/product/toyota-tacoma-5vzfe-3-4-rebuilt-cylinder-head

 

There was another recent thread where an owner with about the same mileage was faced with the same decision. His had some coolant in a cylinder, so not exactly the same, but there was some discussion that would still apply to you.

I had one cracked valve (I thought burnt valve) that required repair at 190k miles. When the heads were pulled multiple cracks were found in the heads as well. Between valves and valve to spark plug holes. I would anticipate you finding the same. So then you have to decide if head replacement or a complete new engine makes more sense. Future plans and budget might play into the decision.

The cost to use OEM Toyota castings and associated parts was ridiculous, so I decided on reman heads from a reputable
source....but I was at 190k, not 270k. Tough decision. My concern with a used engine would be the potential for revisiting this same problem in the near future.

Here's what mine looked like.

 

How were able to get a photo of the valves when the camera comes in from the plug hole?

 

@Gen1andDone thanks for the info, that’s about the sum of it for me. At 270k the mechanic who did the compression tests advised that he didn’t think the bottom half of the engine would be able to take a rebuild of the upper half.

 

@1997tacomav6 I rigged up a bore scope with some hanger wire, the plastic straw off some brake clean, and some fishing line. I got this idea from this guy on YouTube, worked like a charm.

https://youtu.be/KLyy8ZCNYv4?si=Sc7pLVfYTgG-LOy4

 

pull the head buy and replace 2 valves and lap them in with VGC

 

I've heard techs say that about engines with half that mileage. It's like their release of liability whenever doing only top end work.

 

My 2.7L had a shot valve some years ago. I went with valve job which included machining the head. $1900 all in. Truck had 130k now has 178k and fine. So I think a good move. But sounds like you've not used the truck in a couple years so ask your self if you'll use it if you sink the money in. If you have the cash laying around and it will bring joy to drive, go for it. If you let it go maybe find something else for a second vehicle. good luck~

 

Im the other guy on here going through this right now. I have ~290k miles and a crack between the valve seats in cylinder 3.

Because of my compression readings of 170-180 on all good cylinders and 150 on the cracked cylinder I’m going with new heads from Clear Water Heads. I would’ve gone with headsonly (linked above), they’re cheaper and the guy there I talked to seemed to know a lot. They are out of passenger side cores for rebuilds at the moment though and I want to get the truck back together soon.

A lot depends on if you’re doing the labor or a shop. If you’re doing it yourself, rebuilding may be a better option to save money.

I also don’t know anything about just replacing the valves, because most I’ve learned has been related to a crack in the casting.

If my compression looked like yours though I’d probably lean towards a new engine.
Maybe a leak down test would help to see if your rings or the heads are the reason for the lower compression and new heads would bring it back up.
I’ll throw the spreadsheet I made on head and rebuilt options. I don’t include labor, but I’d expect it to be a fair bit less on an engine swap vs disassembly and head rebuild.


Freight was calculated as residential delivery to AZ, likely cheaper if shipping to a mechanic with a forklift. Or local pickup if you are local to any of the listed options.
I think I fairly underestimated the 'misc' category of the rebuilt long block options, that would probably be closer to 1k by the end of it.

 

150 psi is not really a deal breaker for a new head, was it leaking coolant or something else.
I have one cylinder that’s at 150 psi too passenger side but the engine runs fine with no problems.
Rebuilding my heads is on my list but not worrying about it

 

When I had the heads replaced on my truck the shop told me an engine swap would be the same or more in labor. I wish I could remember exactly what he said but I do know it wasn't less. An engine swap does involve quite a bit of parts removal and swapping of old parts to the new engine. Not sure what book time on an engine swap is but book time for the heads was 12 or 13 hours (tech said it's possible to actually get them done in as little as 6 hours).

 

Reputable Machine Shop would be my next step

if your pix shows all the dmg, that valve done. But machine shop will RR not only valve but the valve seat as well
The head itself appears not to be cracked
That is great news

time623 has a good/recent thread worth checking out
GL

 

Cracked between valves leaking coolant into cylinder
https://www.tacomaworld.com/threads/compression-test-white-smoke-cracked-head.824933/

 

Thanks 623!^^^^^

 

The cracks can be difficult to see until the head is cleaned up. Even after machine shop clean up they can be hard to spot. I would be surprised if at 270k miles they don't find numerous cracks. At 190k only 1 cylinder didn't have cracks in the heads on my 5vz. In other words, 5 out of 6 did have cracks.

 

True. From what I’ve seen these 5vz heads all crack, and it’s just a matter of time before one of the cracks grows big enough to become a problem. Cylinder 3 seems to be the most common, so much so that it’s much easier and cheaper to find a drivers side head over a passenger side.

 

If you decide to repair as opposed to replace... as a preventative measure I would have the machinist look at the cam lobes, all of the cam lobes, especially those with the burned valves. Have him measure taper across the face of the lobe. As the cam lobe contacts the shim and bucket it should rotate the shim bucket and the valve slightly. Did the valve burn due to tight clearances and not allow the valve to seat and cool or did the valve burn due to not rotating.

 

I'm not sure if it cracked due to tight clearances or not rotating, but I can say for certain that the valves were not adjusted as toyota requires. I bought the truck from its first owner at around 150k in 2015. He maintained the truck well and kept religous maintenance records, however he wasn't a dealership guy (neither am I) so I think he missed out the need to adjust the valves. I never did the valves either, and wasn't even aware of this becoming an issue until I started running into the compression which lead to where I am today. Lesson learned!

I have a lot of research and considering left to do, but the costs seem to be pointing towards a new (used) engine being the most economic solution. I'll keep the thread updated.

 

In any case the engine needs removed ! Pull things apart and inspect then decide your course of action. Depends on your budget and luck . Full rebuild on the engine you have compared to a used long block. Unless your lucky enough to find a running engine . You would still need a new Timing belt and most hoses and Belts etc. My luck with used engines has not been good.