Ebin

(4Runner)Driver side camshaft wont turn. Crankshaft cogs eating up timing belt. Could this be a stuck valve or maybe something else. How easy/hard should it be to turn the camshaft (either side). Please help, only vehicle I have. If it is a stuck valve, what is/are solution(s)? Repair shop not an option. Has to be a do-it-your-selfer.

BRossman

Sounds like a seized cam. Remove the belt and hand turn each cam (when I say hand turn I mean wth a wrench). They should feel similar to each other. A seized cam is not uncommon I worked on a 3vz the other week that kept jumping time due to a sticky cam.

DudeBud

most of the time its caused by a warped head or a head that was surfaced and the cam journals weren't taken car of

Ganoid

Did some one put the cam caps on backward? They will fit both ways but only one way works correctly.

Could also be a broken spring wedged against its own coils?

Ebin

No internal engine work has ever been done. Everything as is from factory. Has 242,000 miles. I was tempted to crank down on camshaft sprocket bolt but I was afraid of damaging something. I wont hurt anything by turning cam as long as I get notch pointing up strait when I'm done? If it is a sticking cam what's the fix?

ChickenLover

Did this problem just occur out of the blue? Or where you doing some type of work on the engine prior?

toyota_mdt_tech

Seized camshaft, journals wil be galled from lack of lubrication. Why was there no lube? Screen plugged up? I have seen this exact scenario before.

Ebin

I had been having a miss prblem for a couple of years, had done all the obvious things. Even (recently) changed TPS and mass air flo sensor. Couple of weeks prior to this problem I had been tweaking on the fast idle air flow screw. "mdt_tech", forgive my ignorance, but where is this screen you refer to? Looks like I have to look at my Haynes manual a little closer.

leiniesred

bent/broken valve.

The screen in question is the oil pickup screen down in the pan. If you had decent oil pressure, I don't think seized camshaft is going to be it.

I think you are about to pull the head. Siezed cam = pull head. bent/broken valve = pull head. About the best you can hope for is broken valve spring. Even then, the engine will still turn over 99% of the time. (until you bend the valve!)

Ebin

Update: I think I have this prob figgered out(correct me on anything I get wrong please). I do believe my hydraulic belt tensioner has gone bad (isn't extended out against idler). This was causing my oil pump cogs(crankshaft) to jump a notch every so often, til finally after jumping so many time it wore the ribs off the timing belt. Also, with the oil pump not pumping oil when it needed to on the heads it caused the cams to stick, making the miss even worse and grinding at the belt even worse. I took my timing belt off and it completely worn smooth down at the crankshaft. Please let me know what I got right and what I got wrong on this theory. I have everything (well, everything needed for the timing belt) put together and I'm ready to install my new tensioner today. I've got my fingers crossed. (I have followed my Haynes manual step by step). Thanx for the help fellas.

Ganoid

The good news is that you got the oil pump part wrong. Everything else sounds good.

If the crank turns the oil pump turns. You are probably looking at the water pump as you may not recognize the oil pump being right behind the crank pulley it looks like part of the block at first glance.

Elvota

Does the "bad" camshaft you originally mention turn freely with a socket? Just wondering if you should make sure things that should spin are spinning before you fire it up.

As Ganoid mantioned, your oil pump should have still been working even with the belt problems, so your camshaft should be okay. There may be options to repair if siezed before the new belt starts tugging.

Bumpin' Yota

yeah as ganoid said, if your crank physically turns your oil pump pumps oil....

With the timing belt of does the cam shaft turn? If not you have issues with either the bearings, a broken spring, or a broken valve. This is a non interference engine so there is nothing to worry about with concern to piston contact with the valve....unless the valve actually snapped off and is loose in the cylinder...

toyota_mdt_tech

Agreed. Toyota oil pumps will even chew up gravel if you ran rocks through it, tough as nails and not driven by a cheezy little spindly shaft. (Ford)

Ebin

Update - Seems original prob was timing belt tensioner (hydraulic). Caused belt to slip and eventually get worn. Now I am replacing head gasket (myself). Have everything cleaned up and just about ready to re-install. Heads not warped (checked with straight edge and gauge), valves have good edges, no visible spring damage or bent valves, lifters look good and camshaft and journals look good will post pix soon.