Why do I always seem to get the difficult problems?

A couple of weeks ago I was on the highway and had to pull a stomp on the pedal maneuver to avoid being hit. When I slowed and got off the highway I noticed the engine was running rough. Got home and hooked up the scanner, got code P0306 misfire #6. Swapped the plug, no change, put a compression tester on it...zero PSI. I figured great, bent a valve when the engine over-reved.

So I ordered valves, gaskets, etc. pulled the head, checked to top of the piston which had some carbon build up but there were no marks on it like you would expect from a valve hitting it. So I ground the new valves and seats and put it all back together...still zero PSI on #6.

Now I'm wondering if a lifter is stuck fully expanded and is preventing a valve from closing all the way. Anyone ever run into something like this before?

 

ya, some guys have all the luck eh?

Do you think that a leak down test will/or would have helped provide you more info before tearing into it? You know I'm just a rookie guy so not provoking, you have helped a lot of people... I'm only asking and hoping you will figure it out

 

I did, just didn't want to bore everyone and write a book explaining every little step I took. I don't think it provided any more information. All it did was confirmed is that the cylinder wasn't holding compression at all and was passing air into the exhaust system (hence my bent valve theory).

 

I don't think anyone would mind hearing how you are and have been working through this... not much support here but interested and
what you've done so far, any updates?

 

I've got it stripped down to the block, all the new parts came in including the heads. It was a real bear trying to get the driver's side exhaust manifold off. On that side the thicker portion of the manifold is towards the front and the body gets in the way. I ended up removing the front left tire and going in with 2 feet of extension just to even think about getting them out. The forward most bolt I had to cut into the bolt head with my cutoff wheel and then blast if off with my air chisel. The next one back I was able to get out after trying various sockets and hammering it onto the bolt head.

When I took the timing chain cover off yesterday I was surprised to see a chain tensioner in there. (I thought they only used them in the pick-up trucks). Anyways, as I was trying to pull the tension back so I could insert a holding pin in order to get the chain off, the "flexible" plastic guide snapped. So I called it a night and went out and got an new tensioner. I'll start today by changing the tensioner and timing set, but first I've got to cut the grass because it's supposed to rain on and off here for the next several days. A few days like that and it'll be a foot tall if I don't get to it today.

 

I imagine that was a bear of a job, I've found even getting to those two front spark plugs can take nearly as long to replace as the other 6 plugs combined for the lack of room and how they set back alittle!

Thanks for that update and sorry to hear it wasn't a more simple fix for you but sounds like in the end you'll have a nearly new motor, top end anyway.

Mine's just shy of 300k now and not running too bad other than little things that pop up but know my day is coming...

 

A few years ago I did a video on YouTube on how to get that manifold out. I believe I lifted the engine off the mounts and also went in from the wheel well.

How did you do the compression test? I tried that once and there was gasoline flying all over the cab of the van so I gave up.

Steve

 

I loosened all the rocker arm to make sure the valve were closed, then I pumped compressed air through each spark plug hole to hear where the air would escape from. There was little to no leakage from the intake valves, but oh boy, the exhaust valves in every cylinder on the driver's side (cylinders 1, 3, 5) was leaking bad. This brings me back to thinking one of the lifters for #6 was holding a valve open and causing the compression loss right from the get go. So hear is hoping the new lifters I just installed will solve the issue.

 

New timing chain and tensioner in place.




New roller lifters all the way around.




Reconditioned heads are in place.

 

Raining here today so I'll be taking a break, but here is where I'm at now.



Timing cover, damper, and water pump are all back on.



New pushrods installed, rockers installed, intake installed.



Passenger side valvetrain and exhaust back together.



Driver's side valvetrain and exhaust back together.