Hello all. Kinda new to the posting though ive been a member for a while. My issue is my Intake valves keep sucking into the head causing low compression. just built the motor, has about 20k on it and this is the second time its done this. My plugs show no sign of running lean either. Had the heads completely redone with new valves and springs, re-seated, the works. Spendy bill right there. Now i gotta pull the heads again this week and i still have no idea why its doing this. Ive read a few posts on here but none of them seem to have a solution or a fix. Theres not many parts under my hood that arent new. If anyone could shed some light here that would be great.

 

I am assuming that you have a 3.0 v6 because you said heads. it sounds to me like the valve keepers are coming loose. which begs the question of why??? the ring on the valve going bad? or the keepers cracked or not seated properly?? best of luck in your search. bad valve seals???


here isa factory service manual link. I used it A LOT when I did my head gaskets and valve seals.
http://ether3al.physic.al/93fsm-mobile/

 

Yes, sorry. Its the 3.0. It has new seals, valves, and springs, and been re-seated. Plus all 6 intake valves at the same time is what i dont get. I could see one or 2. And since its not running lean, or showing it anyway. Im clueless. I did see a post on here that the new valves they put in were not strong enough. Could be the case here i guess. Will know more when i get the heads off. I've already got one motor torn apart in my garage so it might be a bit.

 

Wow all 6??? did you get the wrong valves?

 

Were your new valves genuine Toyota parts?
The conditions that valves endure are horrendous, especially exhaust valves.
Any lean burning condition would likely affect the exhaust valves most.
If the intake valves or intake valve seats are other than factory OEM, and the valve and seat angles were correctly ground, I would look to inferior materials for the fault.

 

Im not sure what valves were put in. The machine shop did all that. The exhaust valves were done new also and they are fine. Havent moved.

 

If you dropped all 6 intake valves I would say they are the wrong size. My guess is the diameter of the shaft is too small and the keepers couldn't hold them. I would contact the machine shop immediately. Good luck

 

If I understand the OP correctly, you have got the wrong idea about what happened.
The valves did not drop, but rather, they did the opposite. pulling up ever deeper into their seats, effectively making the stems longer until there was no valve lash remaining.

 

Yes, thats exactly it. I know what its doing, just dont know why. Ive seen posts here of the same issue but none ever posted what the initial problem was. Was hoping somebody might know. If and when i figure it out i will post feedback.

 

i assume that 3.0's have adjustable valve lash? no hydraulic lifters? i'm a 22re guy.

it's normal behavior for valves to tighten up, and lose lash, you should never see the lash increase... but they shouldn't tighten up to the point that there is no lash, unless they were adjusted wrong from the beginning, or the motor was overheated.

did you do any valve adjustments on this motor? if it has adjustable valve lash, that should have been checked not long after the heads were rebuilt, it's routine, any lash problems should have shown up then.

 

No hydraulics on 3vz-e.
Lash is adjusted by installing different thicknesses of shim pucks under the cams.
Giant PITA. Ordinarily though, they stay in decent adjustment for a long time.

 

Yes, the valves were all to spec when the heads were installed. Then a couple thousand miles later they were pinned to the cam, no lash. So i re-shimmed them and a couple miles again. I think the original shims were 2.85 if i remember right and after the first job i had to put 2.40-2.60 shims in. And it appears they only go down to a 2.20.

 

that sounds pretty extreme... basically somewhere around .25-.45 loss of lash in 20k miles.

i used to do a lot of work on aircooled vw's, both stock and seriously built... acvw's are a valve nightmare, but i don't think that any of my cars ever had that much loss, at least not on the intake side anyway.

vw valves are designed to rotate every time that they come off of the seat, which promotes even wear in the seat and the valve... i wonder if the 3.0 has anything similar, and if something went wrong with that.

another possibility might be keeper wear, on the stem end... on vw's it's a two-piece keeper, that snaps rather tightly on the stem, and keeps the valve spring held captive onto the valve... on the 22re, you can't pull the valve spring/keeper without unbolting the entire valve train, which means that the head gasket has to be replaced... a really crappy design; if the 3.0 allows you to pull the valve spring without having to remove the head, you could at least see if the keepers have gotten sloppy on the stem.

if they are grinding around on there, metal particles will be going into the oil... it's a real long shot, somebody like millball needs to weigh in here and give an opinion, i'm just shooting in the dark.

another longshot, based on vw design, is that the end of the valve stem is pounding out... or, what about cam wear on the intake lobes? did you see anything weird when you did the shims?

 

Loose keepers could not cause this problem.
Worn cam lobes or pounded valve stem ends would increase clearance, not decrease it.
Either the valve stems are stretching, ( not so likely on intake valves as on exhaust valves), or there is excessive wear occuring at the valve seat- valve face contact area, causing valve recession into the head and closing up the lash clearance.
I have heard before that certain mismatched seat material and valve face material combinations can cause this type of problem, but as I recall, that was again, an exhaust side issue.
I would still try to determine whether or not OEM parts were installed and try to verify that correct angles were ground on the seats and faces when the machine work was done.

If you take it apart, I would like to see some good pics of the seat contact areas and the valve faces.

 

that makes sense millball, even if the keeper rides higher on the stem, it doesn't change the length of the valve itself.

sounds like the heads are going to have to come off no matter what :-(

 

Yep. The heads are definitely coming off. Ill post pics (if i can figure out how) whenever i get this speed 6 out of my shop, broken valve on that car also. What are the odds.

 

Sdoolin posted a while ago about the same issue although it was a 22r.
Not sure how to post the thread so here's the URL.
https://www.yotatech.com/forums/f116...estion-276483/

 

Well its been a while. Havent been able to get to it. But here it is. Every intake valve was pulling into the heads. Not sure how to post pics from my phone. But they are horrible.

 

Are you running heavy duty valve springs?
Are these the original heads?
Valves will sometimes do this if HD springs are used or if the valve seat on the head was ground through the hardened area

Once you get it apart might want to look at getting some hardened seats installed

 

Original valve springs. Just had new valves put in. It doesnt appear to be a valve seat issue. Just ordered a set of OEM's to put in.