legacycentral bbs

So I have acquired a knock in my 91 turbo. It does it when I first start it up. It stops after about 3 miles or so of driving. It does not matter if the car is hot or cold and does it after about 15 minutes of sitting. I pulled the passenger side valve cover off and the HLAs do not appear to be collapsed. I plan on switching out the rocker assm tomorrow with a spare I have.

So what do you guys think? wrist pin knock, rod knock, or HLA?

http://www.youtube.com/watch?v=MclvcS04hes


Edit: my oil is clean also. I also checked the power steering pump, A/C ect. I pulled the spark plug wires one by one and it made no difference in sound.

It's hard to tell from the video, but it kind of sounds a little more than lifter noise, however if it goes away after a while, it very well may be a lifter.

When you pulled the lifters off, did you try and bleed them? Were you able to compress any of them? I'd suggest checking the driver's side as well.

The intermittant sound of the knocking is kind of what leads me to believe it's something more than just the lifters.

Josh,


I am fairly certain it's a rod. Its so bad now that I am afraid to start it. I had to trailer it home last night because I was afraid of damaging the block. I guess I am in a for a rebuild lol. I'll post the process in my build thread. It might be a while since I am fairly busy ATM with college.

Ok, thanks for the update.

UPDATE:


The knock has disappeared again and I cannot get it to knock again. I pulled both rocker assembly off and checked them. Everything seemed to be in good working order, no excessive clearance or play. I still plan on pulling the engine and tearing it down to find the exact cause of the knock. I have also been toying with the idea of just swapping in a EJ20G full drive train out of a WRX/STi. The cost would be cheaper than to rebuild the engine, buy forged internals, TD05-16G, heaver clutch, and still have a weak transmission (N/A 5 speed). There are a number of engine importers in the Seattle area. They seem to be going for around 1k-1500k for the transmission and engine. If I do this I will most likely sell my EJ22T block, head and whatever else that is still useable.

I'm just guessing, possibly timing belt idler, the big one on top the tensioner pulley. The sound seamed to get louder when directly in front of the engine. With the abnormal beat of the tick I would look there. When that bearing goes it hits the crankshaft sprocket and also comes and goes.

Yeah I checked all those out when I took the rocker assembly apart. They appeared to be in good shape.


After about 300 miles the knock has yet to return. I changed the oil and filter. There was a little tiny bit of brass in it but that is most likely from when the turbo blew about 2k miles ago; other than that it looked pretty nice. I guess I will keep driving it until it takes a dump. It's time to move back onto my VW bus rust repair project lol.


P.S My uncle owned a GL wagon years ago and it did the same thing my car did with the knock disappearing.

Okay so the knock had been gone for around 3k km.... until today. So I connected the green connectors and drove the car, and it finally through some codes, 41, and 23. My idle is all over the place, very very hesitant. Sounds like its not running on all 4. When I rev out to past 3k (ish) RPMS it stops hesitating and goes to full boost. Also my vac is at around -2 to -3 which is way too low (normally at -8 to -9). It s so low that my brake booster is not functioning properly.

Another thing is the knock is gone again but this time it sounded more like an exhaust leak.

Are those vacuum readings at idle? If so, you've got some serious problems, either a MASSIVE vacuum leak or something is broken internally.

Those readings are at idle. The strange thing is I have full power after 3k rpm. I drove the car yesterday morning with no problems, than I went to move it later that night and upon start up it started running funky again. I'll take some readings and check everything over. At a glance all the hoses looked good and not lose. It is running lean, to the point is causing the cat to become extremely hot, too hot.

It sounds like you have a massive vacuum leak somewhere. It will cause you to run lean under vacuum and rich under boost. The rich under boost is what's causing the cat to become too hot.

Okay so I pulled the intake off and started the car. I then put my hand over the throttle body to block air flow..... it didn't kill the engine, it really didn't even struggle. Also, my up pipe gasket is blown, I have more exhaust in the engine bay than exhaust coming out of the tail pipe. I also rewired the knock sensor since the wiring was toast, made no difference.


So I guess I need to pull the intake off and change the gasket and also the up pipe gaskets. I mostly likely wont be able to get to until I have my VW bus back together, so like a week or 2.

Something isn't adding up. Are you still using the stock ECU? If so, the engine really shouldn't run without the MAF sensor hooked up. I think if you unplug it the engine may run, but in a fail-safe mode.

Regarding your test at blocking the throttle body, at idle the engine gets it's air from the IAC valve, so you'd need to block that tube.

Yeah I blocked all the vacuum lines. The stock ECU is still in. This car's problem has been elusive lately, it's rather annoying. My uncle has a spare MAF that is the same one as mine so I'll try that and see if that helps. I also have spare sensors for everything else that I will try, If that that doesn't work I'll drill for the intake air-sensor and plug the stand alone in, to see if I can get get it to run with just the base map. I need to get that in anyway, I dropped to much money to have it just sit around.

Well after 3 months of sitting I have finally found the problem.







The center bolt on the sprocket was by no means loose. This would explain the random computer codes since the cam angle sensor is on the drivers side (This cam is from the passenger head). I tore the engine completely down and found no major wear. This was the only problem I found and it is in correlation to the area the knock was coming from. I could rebuild my engine or I could go with a EJ20G STI drive train swap, which is what I will most likely do.

Well that sucks about the cam, but glad you found the problem!