Compression test - White smoke *Cracked head*

I took long to type
I’m responding to #17 post
(About rad fluid test)

 

Oh yeah time623
Those new closeup pix of #3 vs #1 plugs

the electrodes on #3 has more corrosion (from water/coolant) than #1 plug electrodes
Really sure about that

 

Got the borescope down cyl 3..
I don’t think I’ll be able to turn it to see the heads with the one I’ve got unfortunately.

 

Ended up getting the scope turned around in there, not liking what I found. Is this a crack in the head?

 

Ugh
Good find though
(Better than throwing parts at her)

im not positive that machine shop could fix…..thru sleeve and head…
I can ask my contacts on Monday

 

Yeah doesn’t seem like something that can be machined out..
So options going forward seem to be reman heads or a new (used) motor?
Is there a reason I should lean towards one or the other? Looks like I can get the fresh rebuilt heads for ~1/2 of an unknown ebay motor. Just the heads seems like a less daunting job as well.

 

So did you find cracks on both heads or just one?

Do you have any other vehicles to drive, if you were to have this one down for a prolonged time?

How much do you love this truck?

Thankfully you can just keep adding coolant (as needed), and this thing will probably run pretty decent for a while still, while you figure this out.

I'd be leaning towards a junkyard engine if you need a quicker fix. Or if you can drive something else for a while, an engine rebuild (or boutique rebuilt engine like Yota1).

How good of shape is the rest of the truck in? That would weigh heavily on my decision personally as to how much "love" you want to show this truck.

 

IMO
That crack is the compression leak

Very good chance bottom end good
Hence that stupid listen test I talked about to confirm

if you get a used head(s)
Get them to reputable machine shop

eager to see what others say….

 

I’ve only checked the one cylinder. Compression was good everywhere else and that one crack seems to explain all the problems. Definitely would replace both heads though.

This is my weekend driver so prolonged downtime isn’t a huge issue.

I do have a bit of a connection to the truck, been in the family since ‘99 and mine since ‘16.
My preferred route would be the cheapest option while still doing it ‘right’ (so no snake oil head sealer), which led me to the reman heads. Definitely don’t want to drop 5k+ or whatever it is for a nice fully rebuilt engine, hoping to keep it under 2k if possible, which it seems to be with just heads. Not to say I can’t be convinced for a full rebuild if that is really the only way to do it right.

Truck is in decent shape overall, definitely not perfect. Front end suspension needs a refresh and leafs as well but overall decent. I’ve been working through most the other issues the last few months (with a lot of help from @ControlCar !) didn’t expect to have to deal with this though.

 

Cracking between the valves is common on large diesels, and it normally isn't a problem. But that seems to be the most likely cause. The question is why? Are these heads not what they're cracked up to be? At least you'll be able to replace the head gasket too.

It appears to have cracked to the valve seat too. If it's a small amount of coolant, I'd say it isn't a super urgent problem, fix it when your ready. I don't think any damage can be done as long as coolant isn't mixing with any other fluid.

Edit: aparently this isn't rare on the 5vz once it gets miles. Yours probably has many cracks, this is the first one that hit coolant.

This shows a 5vz head with the same problem. You should watch the whole video, but this 18:10 (linking to specific time doesn't work for some reason)

 

General consensus seems to be that it is at least drivable for some time, which makes sense because I have been driving it with some of these symptoms for a few months. Though obviously this is a significant failure that will need to be addressed sooner rather than later.

Does that recommendation change if I want to do new heads instead of a new engine? Am I putting the bottom end at risk every time I start it?

I imagine it won’t do damage to the bottom end unless a large amount of coolant collects in the cylinder but I don’t know how I’ll ever know if or when that happens.

Still not sure if heads is the right answer, looking at past threads seems like there’s a general attitude that with high mileage you shouldn’t just rebuild the top and leave the old bottom alone.

Also, is there still value in performing a compression leak down test? Could that provide more information about the bottom end health that would guide toward the best solution? Only hesitant because it looks like a pita and I’ll have to buy a compressor and the gauge.

 

The best time to get an idea of the bottom end would be when you remove the head. Inspect the cross hatching on the cylinder wall, look up photos of new engines to get an idea. There will be some scratches from wear, but nothing should be super deep. Your compression at 180 is a good sign. There isn't much you can do besides removing the oil pan, and if it's anything like it is on a 4wd 3rz 4runner, that means removing the diff, which will cost you $1000 if you don't DIY.

The next level of disassembly would be removing the engine to get at the crank shaft and cylinders, which is a significant increase in difficulty and required tools. I don't think you need to do that.

If the bottom end isn't broken don't fix it. If you watched the video they recommended replacing both heads if 1 fails, and that makes more sense to me. Put your money towards replacing the heads since you've already had 1 fail.

The block is cast iron, and people go much further with it. If you didn't run it low on oil, there is no reason to suspect it needs anything. But I'm sure there will be a lot of differing opinions.

 

that’s the typical crack location. Usually see this happen around 250k. OEM castings are best, but many used ones are cracked, so if you can’t see it in person then dont buy a used one.

 

At about 190k miles I was getting a misfire code. No smoke and didn't appear to be eating coolant. Did some basic checks before taking it to a shop for diagnosis. The diag found compression was 90 and leak down 85% on #5. It was pointing to intake valve(s). That was the worst cylinder but there was some excessive leak down on another cylinder too. So I agreed to have the heads pulled. Found that #5 had a burnt intake valve (hole in it) and after the machine shop cleaned the heads they pointed out 8 cracks in one head and 6 in the other. A pair of reman heads from Yota1 took their place.

I have owned the truck since new and it had never been over heated. I don't know what caused the hole in the intake valve, but I do wonder if never adjusting the valves contributed to the cracks.

 

I would fix this sooner rather than later, my understanding is: You are essentially stripping the oil in that cylinder. Each time you turn the truck off, coolant sits on top of piston, fire truck up again, it now steams that cylinder, the oil starts to thin significantly. Rinse and repeat a dozens of times and you now need a new motor, instead of a head.

I just replaced my cylinder head, the linked timmy the toolman video made it pretty simple.

From everything i researched, the bottom end on these motors are bullet proof, its the head castings that often fail. I would reach out to yota 1
https://209yota1.com/products/5vz-3-4l-reconditioned-cylinder-head-new-95-5-04/

They have quite the following and reputation. They were 7+ months out for a 3rz head so I went with https://www.toyotatruckengine.com/

I was really happy with the set up they sent me. After I tightened the cylinder head down, the valve lashings were set 100% perfect from them. That is often not the case with other heads people purchase.

 

Now let me be annoying and play devils advocate and give you option #2. Your truck nearly has 300,000 miles with one cylinder head toast. Lets price together a package?

Cheapest way? Purchase a new cylinder head, head gasket kit and new head bolts? you are around 1300-1600$ to do it yourself.

Expensive way? If one head went, your next is probably around the corner, so two new cylinder heads, head gasket kit, head bolts. ( $3000 ish). People generally inspect or replace at this time the oil pump, water pump, timing belt (not chain my bad haha) etc. $300 ish?

That's $3,500 and you still have 300,000 miles on the rest of the bottom end, another $1,000 buys you a complete rebuild motor from a very reputable motor shop. https://209yota1.com/products/5vz-3-4l-rebuilt-toyota-engine-complete/

 

Yeah that’s the math I’ve been doing as well. Damn gasket sets are so expensive it throws it all off… yotashop wants $600 just for the full gasket kit. Plus a couple hundred for timing belt kit and I’m getting uncomfortably close to a rebuilt 5vz and already surpassed a jdm 5vz…

 

You have a very tough decision! My 3rz head went at 190,000. I opted to just replace the head, with oem head gasket kit, water pump, oil pump and oem head bolts, with a few other little things like fuel filter, manifold studs, toyota fipg. The 300,000 mile mark has got me scratching my head for you.

I did legitimately have fun with the project, this forum saved me a few times. Im anxious to see what you route you go.

 

Just to clarify @woad4, OP has the 5vz V6. It's a timing belt motor, no timing chain. So that should save some cost on that expensive route.

 

Derp! I got a decent grasp on the 3rz and 2rz, I forget the 5vz is different there.