DIY Headgasket advice for '02 5VZ-FE

Cylinder 4 is failing compression test, I'm loosing a bit of coolant and the oil cap is milky. A rough idle on startup spurred the check. Adding oil to the cylinder only gave me [edit] an extra [/edit] 10psi. It seems all signs lead to head gasket. Just over 250k on the truck

I've made it in far enough to replace the valve cover gaskets two years ago but no further. This will be my first go at a head gasket. Any thoughts, tips, warnings, advice? Things to look for when it's apart?

What else should I replace while I'm there? I'm buying the full gasket kit from Toyota. The timing belt only has 40k on it. Is it still worth replacing? Water pump? I've read the headbolts should be replaced, but I didn't see that indicate in the service manual.

 

If 1st time tearing down, refer to this to make it easier https://www.youtube.com/watch?v=ynolAwrRTmo

 

Thanks. I've seen the Timmy videos and worsethanchiggers but I hadn't come across this one.

 

Yes do water pump and Knock sensor.(maybe injectors) It might help to get a service manual I found a free one online. This video series helped me a lot he is pretty detailed and has a few tricks to take the pulleys off a little easier. https://youtu.be/voLBRDZL9fE

don’t forget to put the bolt in the cam before removing. And the timing belt skips around every revolution shit had me confused for hours.

 

I almost wonder if you don't have two issues; definitely sounds like your head gasket has gone south, but having virtually zero compression makes me wonder if there isn't another issue as well. Specifically, rings and/or valves which is causing the low compression.

 

Sorry, I should have been more clear on the failed test. I've got 190+ on the other cylinders. Cylinder 4 is at 150, ~160 after adding a bit of oil.

 

Ahhh... got'cha'. Okay, that makes sense.

 

Remember, when removing the exhaust cam, make sure the service bolt is in-place before removal. Otherwise, you'll launch a cam across your garage...

 

Good luck!!

 

Sounds like there's a story there. Oof. I'll be sure to double check that box when I get there.

 

Thanks!

 

Indeed, this seems like a head gasket issue.

Over time the camshaft lobes wear down the shims over the valve buckets. This puts valve lash out of spec and can affect compression. Just something to be mindful of if you're going to go through the trouble of digging into your head. Shims can be bought from the dealership or online and come in sizes incrementing by 0.05mm or ~0.002".

Don't forget the Allen head bolt after the eight "regular" head bolts come out. It's torque spec is also less than the regular head bolts.

I have a 0.040" MLS cometic head gasket if you want it.

 

The above is very important. Also get the head checked over by a good machine shop. Mine had a small crack when I took it in for inspection.

 

A big thanks for the gasket offer. Unfortunately I already ordered the OEM kit.
Good call on the valves. I hadn't given them much thought, but last time I checked a couple were barely within spec and I let them go.

 

hmm. I was hoping to avoid the machine shop as long as things looked flat and copasetic. Admittedly a bit of a pipe dream, but it's a couple hours drive to the headshop. Was the crack visible at all before you took it in? It sounds like I may have to rethink that one.

 

You don't have to machine it, but its best practice to do so.

My tips are, clean flush, but not mirror finish. Basically if its clean you wont be able to feel the old material with a finger nail. Resist the urge to clean it until it shines.

Blow out the head bolt holes, they can trap fluid and hydrolock when reinstalling.

Replace Valve seals while the head is off. Old toyotas are known for them leaking slowly, and its way easier with the head off. This also lets you inspect the valves and clean them off gently.

Take pictures. Sort stuff out carefully.

The exhaust is the hardest part depending on how rusty it is. I typically leave the manifolds on the heads and remove the pipes from the manifolds.

 

As long as you have a good machinist's rule, you can check the head for true easily enough, but if you're going to all this trouble, I would go the extra mile and get the head pressure-tested and magnafluxed. It would suck balls to get it all back together and find out you had a crack between passages or something like that. Chances are, you're fine, but that's a LOT of time, effort and money on a chance.... YMMV.

 

sub'd for outcome, GL OP

 

It's worth a trip to the machine shop. My crack was not visible, they saved me from doing the job twice.

It was around 3-500 I don't remember. I know they fixed the crack and cut the head a little with my permission. It runs fantastic on 91, and adequate on 87. I also have a long tube header, high flow cat and straight shot intake.

 

I also had a crack they tend to happen between valves I didn’t need a shop to point it out. But my gasket also was fine