Shims/Buckets slow to come back up

[loneshepherd]

So... I decided to put my knocking 4runner on hold in favor of finishing up another project thats occupying my garage space.

Long post sorry:

I have a 97 5VZ-FE, it had no compression, I had the cylinder heads done at Vegas Machine for a whopping $1500 and I redid the headgasket with all oem parts, it ran! then it got stuck in limbo at a friends house because I moved. They ghosted me, for over a year. I just got it back and tried to start it, and it has no compression again. I took it apart past the valve covers and found several of the buckets are sticking. They aren't seized, but some take several seconds to pop back into their "up" position.

When I called the Machine Shop they claimed I used bad gas, yet the tank and pump were also new and the gas was fresh. I've seen plenty of cars start and run fine after sitting for a year with the same gas, including my daily driver 3rd gen.

They said they would reevaluate the heads for me, but 1) I really don't want to take them off again and have to buy another head gasket kit as well as just doing all that again would kind of suck. and 2) I am sure they will find something to charge me even more for, which seems ridiculous after the huge price tag I already paid them, but I know it will happen.

Any ideas or methods to.. "clean" or "ungunk" the buckets without removing the cylinder heads? if I could do it without removing the cams would be awesome too. Maybe there's something I can spray them with? I tried MMO and it did nothing. They still come up slowly.

Vid of it turning over.

 

[rdruss]

Kind of odd. Hopefully the buckets/bores were all lubed before they were reinstalled in the head. It's possible there was some "debris" left in some of the bores from other work the machine shop did. If it were mine I would continue rolling the engine over with starter and pour some oil over all the buckets as doing so hoping they will all "free up". If not then I would pull the cams and inspect each bucket that is causing a problem before pulling the heads. If you find scoring on the problem buckets you will have to deal with that as best you can.

 

[loneshepherd]

Kind of odd. Hopefully the buckets/bores were all lubed before they were reinstalled in the head. It's possible there was some "debris" left in some of the bores from other work the machine shop did. If it were mine I would continue rolling the engine over with starter and pour some oil over all the buckets as doing so hoping they will all "free up". If not then I would pull the cams and inspect each bucket that is causing a problem before pulling the heads. If you find scoring on the problem buckets you will have to deal with that as best you can.

So I did as you said and spent an hour turning it over and dousing it in MMO and spraying the buckets with WD40 while it was turning over ( wd40 probably isnt the best goto but eh ).

Anyway after ages it started sounding a bit more normal, so I did a compression test and this was the outcome. For the life of me I can't get the buckets to spring back up any faster on #4. They take like 4-8 seconds.

Should I reassemble and start it like this? kind of wondering if the oil + heat with the engine running might take care of #4...

 

[Pyral]

You should definitely not reassemble, those valves springs need to be strong enough to snap the valve closed thousands of times a minute without floating, so they should be more than strong enough to overcome friction even without lubrication.

To me it sounds like a slightly bent valve stem, 0 psi means a valve isn't closing, all the valves were equally dry when you started so why is only 1 cylinder having 0 PSI. Or a valve keeper isn't installed correctly, or you have a weak valve spring. I've replaced a shim bucket before, this was never a problem.

If the shim buckets aren't coming up fast, it is possible for the shim to be swiped right out of the bucket by the cam lobe.

The variation in PSI in all the cylinders is also concerning, unless you're breaking in new rings the PSI variation shouldn't be more than 15 psi between the highest and lowest cylinder.

 

[brillo_76]

Can you take the spark plug out of number for and get a inspection camera down the spark plug to look the the valves , head and cylinder wall?

 

[loneshepherd]

Sadly no dice, I tried with my boroscope but its a cheapy that doesn't have the cool twist functions, and no mirror attachment. All I could get were some not great shots of the piston head, and some springs. Probably not worth posting but Ill show some anyway. After sitting a for a few more days, I turned it over again and all the other cylinders are still fine ( didnt get restuck ) and the culprit is coming back up WAY faster but still extremely slow. Like 5-6? seconds vs the 15 or so it was before. I'm unsure what to think about the variation in the PSI. I did douse everything in mmo before that compression test and its very possible some of it got into the cylinders, so I'm not sure. Tons of buckets were sticking at first, several of the cylinders had zero compression when I tried to start it the first time. Compare the first video to the one below.

Current video of the bucket

Edit: Its currenly taking about 3/4th sec to come back up now. Obviously this is still way too slow, as Pyral said above they need to open and close thousands of times per minute. So its progress but at the same time its not fixing the root of the problem. I am not good with cylinder heads which is why I paid that machine shop to refurbish the head. Can the spring be replaced by removing the cams or does the entire head have to come off?

Also redid compression on #5 and it came out to 170 today, the others were the same.

 

[subzjc]

I am not convinced it is the spring or the bucket.

What if the valve and the valve guide are the problems?

You may as well pull your timing belt and get the cams out,

that will allow you to pull the bucket for inspection and then manually

work the valve. Don't forget to lockout the spring-loaded cam with a bolt.