Less than .0015" valve clearance on #6 exhaust and only #38 lbs in that cylinder. Any chance I might get lucky and installing a .010"-.012" thinner shim may restore the compression or not a chance and the valve is already gone? That's my question.....or read on for some history.....

Decided to get my 4Runner going again, last inspection was June '14 and I haven't even put 100 miles on it since. Before that I think I went 4 yrs without inspection...I just don't use this poor old truck.

So after sitting 17 months it started right up but was running like crap! Old gas for sure....so drained the 10 gallons from the tank (thank you Toyota for the gas tank drain!) and with fresh gas it runs much better but still no good.

So after checking some things ended up doing a compression test and found cylinder #6 to have 38lbs. Imagine that....cylinder #6....hmmmm.

Oil is clean and not losing coolant so I put a little oil in the spark plug hole and compression is still #38.....yup.....valves.

I did the compression test cold, just didn't feel like burning myself on a hot engine and was expecting to find a dead cylinder not one with slightly lower compression. The other 5 cylinders showed 118-120lbs, but this is a rental from O'reilly so I don't consider that an accurate reading.....was just wanting to compare across the 6 cylinders.

Pulled the drivers side valve cover to find 5 of the 6 valves on that side to be at or under min clearance with cylinder #6 being the worst. #6 intake is at .005" and exhaust is less than my thinnest feeler gauge at .0015" but not zero because I can turn the shim/bucket when lobe is nose up. But I can tell the cam has been riding the shim all the way around the base circle from the wear on the cam. Not bad wear....just can see the color difference. This does fit with the way it runs better when cold but like poo poo when warm. The way I understand it valve clearances tighten up when at operating temp. Engine has 178K so if the valves were checked/adjusted at 120K like they should have been it wouldn't be due for another check yet.....hard to believe it was checked at 120K.....probably wasn't even checked at 60K. Arrgghhh.

The truck passed emission in June '14 and it's barely ran since then (under 100 miles).....hard to believe it could have passed emissions with a dead cylinder but maybe it did if the cat was doing a really good job???

But it has been running bad for a very long time....probably since 2010 or so was my first thread trying to figure out why it was running so bad. I have probably only put 500 miles on it since way back then so that's the good news.

So, if because of no clearance the exhaust valve was not fully seating...is there any chance the valve is ok or do they start to get eaten away immediately?

My plan is to install a thinner shim and recheck compression (while it's still apart) to see if I get lucky. If so I'll change the other 4 shims that need it and be happy happy happy.....if not I dunno. What does it usually cost to have a head done on these trucks? I'll pull and install the head myself, just have to decide if the truck is worth the $$$ for the work plus all the gaskets, head bolts and such that will need to be replaced if the head is pulled.

 

Hope springs eternal in the human heart.

But Carnac sees a valve job in your future.

You gotta know that the clearances on the other head need attention too.

 

No question, but just pulled the valve cover on the "easy" side for now.....but yes....even if changing the shim restores compression the other side needs attention ASAP.

Problem is the city is hassling me about it and I have no time to do anything. We have an overzealous code enforcement lady and because of a miss-typed word in the statute ("or" instead of "and") she considers ANY vehicle, operative or not, a junker if it doesn't have a current inspection. So a 2015 Ferrari without an inspection sticker would be considered a nuisance vehicle and subject to removal. You don't get the normal 30 days either. No current inspection sticker....its a junker....running or not.

I have nowhere to put it while I work on it.

I am considering pulling the injector plug on cylinder 6 and going and getting it inspected. I have a feeling it will pass even if it's only running on 5 cylinders as long as the dead cylinder isn't getting any gas to be spit out the tail pipe unburned.

 

Good luck in your quest to evade the Man, or in this case, the Woman.

 

I went to 6 auto repair shops today looking for a valve shim, no luck. Only 2 of the places even knew what I was talking about. One of those was a shop that only does headwork, but even he didn't have any shims. None of the shops I went to even do valve check/adjustments!

Even the local Toyota stealership told me they don't check/adjust valves on these!

I have no clue what an owner that couldn't do the work themselves would do. Maybe what the PO's of my truck did.....just never do it!

I was able to order the shim I need from the Toyota dealer.....for $20! For comparison it's $9.45 from toyotapartscheap, but I need the shim ASAP and the dealer will have it at 9am tomorrow morning.

If by some miracle installing the thinner shim raises compression in that cylinder to an acceptable level I'll order the rest of the shims I need from online......After getting an inspection sticker on it to keep the crazy code lady off my back for another year. That will buy me the time to do valve clearances on both sides, install a new rad, new knock sensor/wire, fix the leaking power steering box, fix the leaking windshield.......the list goes on and on.....

I'll report back tomorrow after I get the thinner shim installed....fingers crossed for me please!

If this doesn't work I'm probably going to try disconnecting the injector plug on cylinder #6 and see if it will pass running on the remaining 5......5 outta 6 aint bad huh? Ha! I really do have a feeling it was running on 5 last time it passed, with the dead cylinder being fed by the injector. If it'll pass like that it should pass without gas going into that cylinder. That's gotta be hard on the cat trying to eat up all that unburnt fuel.

One way or another I've got to get a sticker on it to keep the city off my back so I have time to fix it right.....which will probably be having the heads redone. On the bright side I bet it will run better than it has since I've owned it.

 

Might be talking to myself but incase anyone is following....

Got the MUCH thinner shim installed and no difference in compression......still holding out some hope I put it all back together and ran it about 15 mins hoping maybe there was a chance the valve would re-seat......nah. Still no change in the compression.

So the valve must be toast.

Strange thing is that while it was warming up pulling the #6 wire off the dist cap was making a difference in how it ran, it would make it bog down and roughen up quite a bit, but after fully warmed up no difference. Pull the plug wire, nothing, unplug the injector, no change. So that cylinder is dead dead dead.

It is running MUCH better than before however. I found and fixed a few vacuum leaks, flushed out the IAC valve in the TB and got it moving again.....but most important......found the distributor was a tooth off!!! It was off the scale advanced, probably 30 deg at least....I'm not sure how it was running like that or for how long. No idea how it got like that either. The drive gear on the distributor is fine. Hopefully it's not a stripped gear on the crank.....that would really ruin my day.

I was able to get idle to a steady 800, set timing to 10 deg and call it a day.

So at this point I feel confident that other than the burnt valve it's in pretty good shape. Setting the timing correctly, fixing vacuum leaks and getting the IAC working seems to have really helped out a lot. Gonna have to see how much having the heads done is gonna set me back.

Water pump seems to be leaking off and on also.....hmmmm, and the power steering box is leaking. Things that can be fixed while the heads are at the shop.

 

Decided to go for a quick test ride. Funny, it seems to be running better than I remember it running in a LONG time. I bet the valves were almost too tight when I got the truck. It seemed to run great for the first few yrs I had it and then one day it didn't run the same and MPG made a big drop.

This was before I owned motorcycles and didn't realize the importance of properly adjusted valves!

Like yesterday, when the engine was cold pulling the plug wire or injector wire on cylinder #6 made a difference in how it ran, but after warm no difference.

The intake on that cylinder is still too tight at .005" = min is .007", so could be when warm and the lash tightens up clearance is going to nil. I knew it was tight but was thinking .005" would still be enough for the valve to seat, heck lots of engines .004" is the min...but not this one.

But then again....why would it make a difference if the intake valve is not seating when I'm about 95% sure the exhaust valve is leaking by anyways.

I'm also still suspect of the distributor. When setting timing it's bouncing around a few deg, so I just to set it in the middle of where it's bouncing. I had it jumpered in the diag box when I set timing. Still moving around. It's been doing the shaky timing thing since I have owned it from what I can remember.

The dist bearings for sure don't don't feel fresh either. Betting it's time for a new one. Add that to the list.....

 

Passed emissions test today. HC, CO and NOx were all lower than last inspection I had in June '14. NOx was much lower actually.

But my goodness it's barely drivable, just has NO power. Was running "ok" until guess what popped up on the way home.....code 52. Then wow....top speed was maybe 60 mph, no kidding....it wouldn't rev past 4K rpm's, at 4K it was like the fuel was cut, very abrupt. That's when the engine light came on, when it cut out at 4K.

Guessing this is the ECM retarding timing?

It was running much better until it got warmed up, then once warm it just took a turn for the worse.

Water pump decided to start leaking a lot, can fix that when I have it apart to pull the heads. When I got home I checked timing, before clearing code 52, it was bouncing around from 5-12 deg....will not hold still jumpered or not.

But I now have a sticker so the city will leave me alone for another year, plenty of time to either fix it or just get rid of it.

 

Hi David, Did you pass smog with the injector connected or disconnected for burned cylinder 6? Thanks!