I recently completed a timing chain replacement on my '94 22RE. The guide broke while going down the road and it started running awful. Got it back together and it runs the same and now there is a whirring noise coming from the cam gear area. Compression test reveals 170-180 in #3 & #4, very low in #1 & #2 (10-15). OK, maybe I bent a valve or two, I mean, I was driving when the guide broke. So, I read about leakdown tests, and tested 1 & 2 with a little portable compressor. Not a lot of HP, but perhaps good for diagnostics. An open intake, and it comes out the plenum. However, when I close the valves on #1, I'm getting the flow out through #2 and the other way around.

I'm not sure whats going on here. Did the HG breach? Could I have breached it with this little compressor? I figure I have to pull the head anyway since its not running right and there probably is a valve problem somewhere, so its probably no longer a big deal. (spraying down exhaust bolts now)

Just trying to get a handle on whats going on. Thanks!

 

If the cylinders are sharing air, the HG probably blew between them. I wouldn't think that little compressor could do that, probably happened some other way. Just the first thing that comes to mind.

 

For what it is worth if you pull the head check for cracks and straightness clean it and put it back on.

Depending on your mileage almost every body I know with one of these engines that did a valve job ends up spinning a bearing in the bottom end within a few weeks of getting it all running again.

 

Is that because the older bottom end has hard time working with the new top end? I'll research that issue. Does anyone else have experience with this?

Looks like the head needs to be pulled no matter what now, so I'll have it checked while its off.

 

FWIW, I thought I would update this thread.

It took a while, but I finally jumped back into this project. I pulled the head and took it to a machine shop. There was some damage to the head and block surfaces at the #1 cylinder. There was a slight warp in the head near this area and the HG breached between the #1 and #2 cylinder (see pic below). The machinist later called to tell me that the #1 intake valve was bent and the guide had broken in half (see pic below). Apparently the missing piece(s) probably detonated during combustion causing the damage to the head and block surfaces.

The head was milled to the minimum tolerance (it had been done once before), the bent valve and broken guide were replaced, and the remaining valves and guides cleaned up. I had to let things sit around until I had the time and initiative to start reassembly. Parts always look so nice and new when they come back from the machine shop. Well, back into the rusty truck it goes. I followed procedures in the FSM and engnbldr's torque procedure for the head bolts. Its nearly back together.. just some wires and vacuum hoses to put back together.

Because of the damage to the valve, I was a bit nervous about getting the crank and cam back in sync with each other. I had already completed the TC, so during this project, I just left the chain wire-tied to the cam pulley. It seems in sync.. I've rotated the engine several times and encounter some resistance in places, but I'm guessing its air getting forced back through various oil passages.

On another note, ever since I had this truck, I've had problems with the EGR. Sometimes it would work, but most of the time the OBD I would flash a code 71 (EGR). As it turns out, some of the ports on the back of the head where that crossover piece bolts up, were completely plugged with carbon. Hopefully it will work now.

 

Its alive.. and idling nicely, but there is a strange noise coming from the top front. I e-mailed with Ted at EB and he suggested I check the tension on the chain. Or, it could be the chain wearing into the metal-backed guide, in which case the noise should go away soon.

I shot a quick video of the noise. What do you think?

http://www.youtube.com/watch?v=JIvCacSOKN4[/URL]

 

Hmmm that doesn't sound very healthy, hopefully Ted is right about the noise. Looks like one of your intake hose clamps needs some tightening, incase you didn't notice

 

When I started it this morning to move it, the noise wasn't as bad.. maybe its just me. I pulled the valve cover and there was some slack in the driver side part of the chain. I cranked it by hand back to TDC and now the slack is gone. The crank pulley and cam gear relationships appear normal/unchanged at TDC.

??

Going to try examining the tensioner, but it appears to be functioning.

edit: Oh, I tightened up the hose clamp!