trying to fix broken timing belt
saturn vue 3.0 which is opel motor not honda
have heads off. this motor uses hydraulic valve buckets
i bolt down cams and i see the valves are being slightly pushed open off valve seat
i checked the 24 followers and more than 1/2 have no spring plunger type movement
do these cam buckets crud up over time? and turn into solid lifters?
the followers do not have shims. inside or out.
Z
What is the deal with the valve crud on rmiddle combustion chamber? Tops of pistons look identical. Cylinder walls look good. Man, I think I should dig up a used head. At least it wil have “good” followers. 12 per head @$24 each. Did I mention former owner replaced cats? Due to Major oil fouling issue? Springs have been removed from extended valves.
My guess is the center cylinder has been misfiring or has been running overly rich for some reason, and those are carbon deposits due to incomplete combustion of the gasoline. re the hydraulic lifter buckets, no experience with it myself, but I’ve seen articles in magazines on how to revive a stuck lifter, usually involves soaking it in something to dissolve traces of solid oil deposits, until al the orifices are free, and the part inside slides freely in the outer part. I think it is hard to tell if a newly installed hydraulic lifter is working to the proper clearances or not until it has been run for a few minutes to allow the hydraulics to equilibrate. I notice in the photos above some of the valve pairs, one valve of the exhaust pair is open, and the other isn’t. Was the cam installed when those photos were taken?
Cams are not installed as I am trying to figure out the deal with the lifters. The pics show the side by side combustion chambers and vastly different amounts of carbon crud. The other head looks much better. The exhaust valves on other head are very clean. Almost no crud. The head in pic is nasty. Even exhaust ports are coated in crud.
My guess is that the center cylinder is drawing oil past a tired valve stem seal and that’s resulting in the crud.
I think, because of the design, that these lifters have far less travel than the old pushrod motors. The travel is enough to take up the valve lash but not enough to allow all the valves to seat on the high part of the cam lobe. notice they are very short. Where could you get the travel in that short a space?
I had these type lifers on a Saturn 4 cylinder - the actual Saturn engine, not an Opel - that I rebuilt and I think I remember them doing this. But that was a long time ago…
Cam bearing surface is odd, funny, small rib.
Head Journal bore to lifter face is .140
Cam journal to lobe base is .180
So, base dia will compress lifter at least .030
So, if lifter is solid than valve will be pushed open .030
A tech I know says that’s the way cams install. Some lobes may be pushing the valves down upon install and make it seem odd. This is a v6. 3 sets of lobes per cam. So they are 120 deg apart? You can install cam so all 3 lobes are not pushing/opening valves. Till you than align the cams with the timing belt. But ALL the base journals ARE pushing down on lifters ALL the time.
Removed the worst exhaust valves to clean them. Plan was to replace all intake valves. I might even figure out the lifter issue someday.
Here’s an alternate theory about why the crud is caking only one cylinder: That cylinder is actually the normal one, the other ones would look like that too, except they had coolant leaking into the cylinder, which steam cleaned them. I don’t expect that’s the case here, but it’s something to consider at least.
did a little digging. you can take them apart. i did and now you can compress the plunger because there is no oil inside.
obviously there is no oil pressure when the lifter is sitting on bench. there are 2 springs but I only show 1. that is the preload spring. the 2nd spring is for the check ball assy which traps oil inside when the motor is off. so, the lifter wont collapse when motor is sitting for awhile? so should I be able to compress the plunger when it is out of car? which makes my diagnosis of lifter issue sort of wrong?
No, they are hydro-locked due to the check valve as you found out. Just one of many reasons you keep track of which hole they came from if you’re not going to replace or disassemble and clean them before re-installing. Most of the time, it makes most sense just to put in new lifters but there are situations where it also makes sense not to. BTW- that cam looks questionable as well…
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Never tried that experiment myself, and it probably varies by design, but I concur with TT above, you won’t be able to press the assembled lifter down when there is oil inside, even on bench. At least not very easily. You could probably set it up in a vice and exert a little pressure and leave it overnight to get it to deflate.
plunger/piston is slip fit with tiny snap ring. you smack down lifter on wood block and plunger will pop out. than you can drain any oil from body and clean plunger/check ball if you wish. reinstall lifter with no oil in main body. than cam lobe will push plunger down and valve will be seated so you can crank motor to start where the motor oil pressure will refill lifter.
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I haven’t worked on valves since that old Farmall tractor back in the 50’s. And, it was a lot simpler.