3vze Top End Knocking and Cylinder Compression (3 Viewers)

[mattyice]

Recently as in, in the last year, the top end on my 3vze was taken to a machine shop and surfaced by the PO's. Not to say they did a s***ty job but I have had to redo every single other fix theyve done since buying this 4runner in april/may. It was pretty clear when buying it but mostly a miracle that it made it the hour+ back home on the freeway. They also LOVED rtv, this grey s*** is everywhere. Especially places it has no business being, wiring harnesses, inside vacuum lines, inside the coolant, inside the oil passages. This all kinda leads me to believe they could not have done the cylinder heads correctly right? Its also dumping oil from passenger rear cylinder head gasket just like it never had a surfacing in the first place.

New loud knocking coming from the drivers side rear end of the engine made me finally run a compression test and decide to see what is really going on in there. Ill post the specific values below but for starters, I got low compression from two cylinders, 1 and 6. They both came out to 165 and 160. This isnt too concerning given they still have pretty decent compression for an engine with unknown history and 230k on the odo all other cylinders were 170 and up. Cylinder one had nasty oil fouling on the spark plug; 6 was fine. No coolant seepage in either.

On to the valve clearances; only one cylinder was alarmingly out of spec which leads me to think it is causing my clattering noise. No scoring or anything else otherwise upsetting in the upper valvetrain, just the one interesting cylinder and all numbers generally all over the place.
All in inches,
5- Intake: .011 Exhaust: .012 6- Intake: .009 Exhaust: .011
3- Intake: .011 Exhaust: .011 4- Intake: .006 Exhaust: .014
1- Intake: .008 Exhaust: .009 2- Intake: .008 Exhaust: .011

Is it safe to assume a valve adjustment would fix either issue Im having? Is the lower compression in any way aided by a valve adjustment or am I going to pull my hair out doing this for nothing? Would tearing down the cylinder heads to the block be worthwhile to make sure that my issue isn't with cylinder head gaskets? It seems like something I may have to end up redoing anyways so I am leaning towards a might as well on the cylinder head gasket. If I go that route I'll also do the front and back camshaft seals/plugs because unknown quality and oil sealing capbilities.

Is all of this futile because to hell with the 3vze or should I just let it die for now and start saving up for the 5vze swap? Maybe in the future it is, but for now what do I gotta do to make this engine live.

 

[aztoyman]

A tight valve that doesn't close all the way will give you low compression. A loose valve will give you noise or more noise than a properly set one anyway.

If they let it get too tight and burned a valve, then tried to adjust after the fact can give you lower compression.

A leak down test would give you better information. Worn rings can give low numbers too. You can try a dry and wet compression test comparison for rings.

Adjust your valves properly and see how it runs. Hopefully this is the source of your noise.

If you have good oil pressure and no metal in the filter or oil, no coolant in the oil or compression in the radiator, run it. If it all seems to being doing ok (relatively) then decide if you want to start fixing all the leaks and such.

Good luck with whatever you decide. I hope you can get some more life out of it.

 

[mattyice]

A tight valve that doesn't close all the way will give you low compression. A loose valve will give you noise or more noise than a properly set one anyway.

If they let it get too tight and burned a valve, then tried to adjust after the fact can give you lower compression.

A leak down test would give you better information. Worn rings can give low numbers too. You can try a dry and wet compression test comparison for rings.

Adjust your valves properly and see how it runs. Hopefully this is the source of your noise.

So far I have priced out my rebuild and have removed everything from the heads in order to make removing more easily possible (pic attached). I want to doubt my abilities to kill this 3vze but you never really know. I've put less than 500 miles on it since its heads were done so smoking a valve is hopefully not the case; a lot can happen in 500 miles though. I will be doing valve reshimming once I get the tool in the mail. Hoping I can swap some around to get the correct tolerances but I live close enough to a dealership to get shims directly if need be.

I almost cant believe the 500 dollar price tag on this job but given I am including the ARP studs and peace of mind that the cylinder heads will be done correctly I will be going for it and updating on the rebuild here. Does anybody have info on numbers to shoot for in doing these valves? Im assuming for intake anything in the middle should be okay but am I looking for closer to .009 or .013 on the exhaust valves. Are they going to increase their gap over time going tighter on me?

 

[aztoyman]

I would follow the FSM if you have one. I have zero experience working on a 3.0 but generally speaking on engines, I'd make sure you have a good flat deck surface and head surface. Hopefully the cylinders look ok. My experience is valves "typically" get tighter as the seats and or valve faces wear more than cam surfaces. But like I said I have never worked on the 3.0. Maybe someone that has will chime in.

 

[mattyice]

I would follow the FSM if you have one. I have zero experience working on a 3.0 but generally speaking on engines, I'd make sure you have a good flat deck surface and head surface. Hopefully the cylinders look ok. My experience is valves "typically" get tighter as the seats and or valve faces wear more than cam surfaces. But like I said I have never worked on the 3.0. Maybe someone that has will chime in.

Way late on my follow up to this post but my new years resolution is to finish this rebuild. I tore the heads all the way down and am now in progress cleaning up valvetrain and cylinder heads. Found some damage to the inside surface of the cam caps which I'm not super happy with. There aren't any deep gouges or high spots but I will be doing a plastigage test to ensure they're in spec. Can just barely feel the scratches with a fingernail. In terms of toyota engines, as long as this type of scratching isn't interfering with the cam bearing oil clearances can I still run it?

Otherwise to put the rebuild into context, I am replacing exhaust studs (PO's didn't even have enough in there to fully install the exhaust manifolds) and exhaust nuts, replacing the head bolts with new head studs, and to triple checking my valve clearances. Just let me know what kind of damage is acceptable on a 200k mile 3.slow or if I need to look to a 3.4 swap.

 

[aztoyman]

I'm still going by you saying for now you gotta make this engine live. If it were mine and it was in spec, I'd run it. (The scratched cap) Definitely make sure whatever caused it is cleaned out of the oil passages. Make sure the cam surfaces aren't causing it and they are in spec. Basically eliminate the cause of the scoring.

How does the cylinder walls look? If you think this is all that's wrong it might be worth it to try to save this engine. I wouldn't spend money on ARP studs for this engine myself. I can see getting new studs though.

If a 3.4 is what you really want, look for a running donor. If you're worried this engine is a money pit, maybe find a running 3.0.

Whatever you decide I wish you luck with your truck. Post up how it all works out.

 

[mattyice]

Basically eliminate the cause of the scoring.

This is what I’m leaning towards. Plastigage comes in the mail tomorrow, praise Bezos. I finally have some form of shop air so I’m gonna blow all the oil and coolant passages from the cylinder heads out.

I think dropping my oil pan is unavoidable at this point to attempt to chase down the spec that scored my caps. I’m dreading doing so for the sake of my independent front suspension but what’s one more job when half the truck is already disassembled.

Cylinder walls weren’t noticeably scored, only damage seemed to be the goopy coolant sticking up two pistons and rings. Seafoam should hopefully clear that up once all back together.

Ultimately I think all of us would rather have a 3.4 over the 3.0 but I simply can’t afford that at the moment. Months ago when I started this whole thing I bought the studs and gaskets for the 3.0 so those are already sitting in a box in the backseat.

Might as well see it through.
Godspeed.

 

[mattyice]

So, pics attached, not sure where to go from here. These cylinder heads already dont have the best shot at life given the circumstances. If this kind of test is an acceptable way to test how warped/plane the heads are I may be out of luck (for context this is sitting on a piece of granite I found on the street, I dont know for certain it is truly flat). The haynes reports up to .10mm warpage is alowed, my first of 2 heads shows about .10 of warpage through the center. It's a tight fit on the .10, really doesnt move through much of the heads, and my next size up, a .13 does not fit whatsoever, but I can pretty clearly get a .10mm under the middle. If .10 is my limit, I know these are at the end of their life, but how would I fare running these?

Im leaning towards just finding out what happens, given the rest of the work I'm doing eliminates most other problems these heads could have; these are gonna have a fighting chance if I just go for it.

 

[aztoyman]

Can you borrow a straight edge?

 

[mattyice]

I'll ask around. After posting I let brake cleaner sit in exhaust and intake ports to test valve seats and found a leaky intake on cylinder 6. That would explain losing 20psi there when I ran compression testing.

Second cylinder head passed flatness test with flying colors, at least on the outside portions of the head. Found one more minor leaky valve but funny enough that cylinder gave perfect compression values early on so I might ignore. They both sat with the cleaner for like minimum 5 mins and only had minor leaks, nothing profusely out of spec imo.

 

[mattyice]

Good news and bad news,

Good news is that all the cam caps seem to be in spec after doing plastigage.

Bad news is that I stripped the hell out of the first cam cap. I know everywhere its said to be careful on that specific set of bolts, but I guess I wasnt enough. I will be chasing the threads and replacing with studs as soon as they arrive. If that doesnt work I have access to helicoils and will still replace with studs.

What a day