sethn

I replaced my h/g, just fired it up, and now I have blowby (didn't before). I also detect a little more clacking sound than before, but I'm not sure if its related.

Right before tearing the engine apart, I checked for blowby by opening the oil cap and putting my hand over it, and didn't detect even a little bit, now its up to oil spitting territory.

As part of the H/G job, I had the head milled and a valve job done by a machine shop (one bent valve, which checks out since I had low compression in one cylinder, unfortunately they didn't track which cylinder the bent valve had been in).

When I first assembled the intake, I had a leak, and coolant got into the cylinders for 24 hrs. I blew the coolant out of the cylinders (cranking without spark plugs in blew it all out), and poured a couple tbs of oil into them to make up for the coolant. I don't think the piston rings could have possibly rusted this badly in 24 hrs???

Alternatively, maybe one of the new valve seals didn't get installed right? But could that cause this much leakage?

Anyone have other ideas what could be going on? I'm at my whits end, and I feel like I'm out of my depth. :-( I just need to get this running so I can get home for christmas. If anyone in Austin felt really kind, I'd love a second opinion, its so hard to explain sounds and the like over the internet ;-)

sethn

I made a video of the clacking sound. I don't /think/ its the valve cover being too tight, I've got it on pretty loose to check that out, but its pretty hard to figure out how tight the valve cover bolts should be.

http://www.youtube.com/watch?v=K8luOo_GBDU

sethn

Anyone recognize that sound?

toyota4x4907

adjust valve lash.

sethn

I thought that might be the issue when I first heard it, but this video is after I went and rechecked the valve lash (it was /way/ off on a couple exhaust valves, weird because I adjusted it very carefully the first time).

So I don't think its the valve lash, but I could check again. Do you adjust the lash with the engine hot or cold?

toyota4x4907

FSM calls for hot. I have always adjusted when hot. Try a little tighter lash this time. Say .007 in, .010 ex.

sethn

Just tried .07 and .10 with the engine cold, no appreciable change, maybe its something else? I'm avoiding getting the engine up to heat again until I have more guesses what the sound is (don't want to wear something out).

sam333

Blow by is caused by only one thing , bad compression ring seal. You have probably disturbed the carbon that was in the combustion chamber, piston tops and around the rings and ring groves, causing your rings not to seal well any more.
Boy thats hammering away.

muddpigg

iTrader: (1)

Was thinking it sounded like a leak in EGR system. But hard to tell.

X3 on valve lash, I do mine cold but I have an aftermarket cam.

sethn

hmmm, mudpig I think you might be on to something. I've had a hard time localizing the noise using my poor man's "wood dowel or vacuum hose" stethoscope (I'll probably get a real one tomorrow), but I kept gravitating toward the EGR corner, and wondering sometimes if the sound wasn't coming from over there. EGR will basically be an exhaust leak, right?

xxxtreme22r

not true, valve seals and seats can give blowby too. And some blowby is normal. I have blowby on mine and I get 170psi on all cyls with 6500 miles on my rebuild.

And considering he didn't have any blowby before he had the head redone, well, you can see where I am going with this.

How much did you have the head milled?

Excessive blowby can also be caused my an ill running PCV valve as well.

sethn

I wish I knew how much they milled the head. They weren't very informative on the whole, but I'm 2000 miles from home so I didn't know the shop. I have a photo of the milled head, I don't know if anyone is familiar enough with these to judge from that?


(click to enlarge)

I checked the PCV valve by blowing through it. It blows really easy in the head to intake direction, but it does seem to stutter a little before it "catches" blowing the other way. It always catches if you blow hard, but if you blow soft it doesn't. Is that normal?

sam333

Your right even a brand new engine has some blow by. No rings seal perfectly. But we are talking about excessive blow by. I have never heard the term used in reference to valves or valve seals.

muddpigg

iTrader: (1)

You can measure from the bottom of the front half moon to the base of the head. A little searching should reveal what the factory spec is, sorry I'm tired and not going to search it right now. You might be limited in accuracy if the head is mounted and by the still caliper. Seems like a PITA that the machine shop wasn't more forthcoming with information like that. If timing is an issue of course there is and adjustable timing/cam gear.

muddpigg

iTrader: (1)

Yes an EGR leak is basicly an exhausr leak. There is a vacuum line that is about halfway between intake manifold and head. Easy to knock it off and not notice.

sam333

If your valves were not sealing well before the valve job, your going to have higher cylinder pressures now that they are, also if compression was raised by the milling.

As far as the blow by ,have you ever tried to put oil in a running engine( it goes every where).

Like xxxtream22 said a bad PCV valve can cause high crankcase pressure.

Unless oil is blowing out your seals( causing leaks ) dont worry about it to much.

sethn

wow, I went and redid the valve job with 0.007 / 0.011 cold, and it made a *huge* difference. Everyone was right: that sound was rattle from the clearance, crazy. Its still there, but now the "engine sound" is much louder relative to the rattle.

Still haven't figured out exactly how I'm going to time this... don't want to buy a another timing light, but maybe I'll just guess-n-check it until it feels right.

Thanks so much everyone. /SO/ much.

The blow-by seems to be reducing a little too, maybe the piston seals found their seat again. Its been a hard two weeks, but I'm finally in the club party at my place!

sethn

Does this sound reasonable/normal, or should I keep tweaking it?

http://www.youtube.com/watch?v=fpAGId6UEA8

sam333

you have just made your valve train so noisy( loose) , that it has drowned out the original clacking/exhaust noise. You should set them at factory spec and while the engine is hot.
The valve clearances will lossen as the engine heats up ,so if you adjust them cold your cleareces will be excessive when the engine is hot. You will loose power and cause faster wear on your valve train. Did you check your EGR valve like muddpigg suggested? Put your hand back there and feel for an exhaust leak.

sethn

hi sam333, I went based on a number of yotatech posts that say toyota cold adjusts them in the factory to 0.007 / 0.011. Not sure if this is true, but I think the camera is causing tricks volume-wise (maybe it has auto-gain on the volume), they're definitely tighter than they used to be, and it feels much quieter to me....

I'm still looking for an EGR leak, I wonder if the leak is the cover that bolts to the back of the head? Does that have exhaust running through it? When I use a hose and listen, I feel like the exhaust-y sound is coming from back there.