Engine/Transmission (1994 - 1998) Need help, found problem while adj valves

[1tuffram]

I've been tring to track down what sounds like a valve train clatter noise on my '95 12 valve. Several months ago I checked the valve lash and found one or two a little loose, so I re-adjusted all of them to the 0. 010 / 0. 020 spec. On test drive the rattle/clatter continued so I re-checked and all ok. Rattle still persisted on second test drive so for a third time I went through and re-adjusted the valves a little on the tight side (0. 009 intake, 0. 019 exhaust) and inspected valve train components for signs of problems. Still nothing changed, Fast forward to today. The clatter is starting to get worse so once again I checked the valve lash, all still where I last set them. This time around I noticed when at TDC (I always use the timing pin to find tdc) and going thru things #5 intake rocker arm is loose. According to the service manual only cylinder 1, 2 and 3 intake valves should be loose for adjustment. Rotate engine 360 deg and #5 intake continues to be loose along with cylinder 2 and 6 intake valves as they should be. Not sure why #5 intake is loose (0. 09 lash) when #1 cylinder at TDC but I don't think this is right. Could this be the cause of the rattle/clatter noise? Any thoughts would help greatly

 

[Forrest Nearing]

that's not your noise



if you're going by the timing pin, you're FAR from exact TDC, so #5 could very well be on the base circle

 

[RHestand]

Forrest,

I read and appreciate most all of your posts, but I'm curious about your comment on the TDC plug.

In your experience, how far have you seen them off?

Is it pretty much standard procedure to find TDC with a degree wheel, before for example, adj. valves?

I know I would only have to normally do this once (true TDC), but from what I've seen doing this with the eng. in truck would be a real pain.

Thanks for any reply on this, Ray

PS. I'll be adj. the valves on my 98 in the next 10K miles or so.

 

[Joe G.]

First of all, watch #5 as you rotate the engine and see what it does.

As far as adjusting valves is concerned, you don't need to use the timing pin. Rotate the engine until both valves on #1 are loose and both on #6 are tight or barely loose. Set the valves according to the service manual. Then rotate the engine until both valves on #6 are loose and both on #1 are tight or barely loose. Adjust the rest of the valves.

 

[champspa]

are you sure it's not the old fuel pump rod making a clatter ?

 

[BigPapa]

I also will RESPECTFULLY take issue with you on that statement Forrest.



Anyway, what about a push rod?



Scott

 

[Vaughn MacKenzie]

This time around I noticed when at TDC (I always use the timing pin to find tdc) and going thru things #5 intake rocker arm is loose. According to the service manual only cylinder 1, 2 and 3 intake valves should be loose for adjustment. Rotate engine 360 deg and #5 intake continues to be loose along with cylinder 2 and 6 intake valves as they should be. Not sure why #5 intake is loose (0. 09 lash) when #1 cylinder at TDC but I don't think this is right. Could this be the cause of the rattle/clatter noise? Any thoughts would help greatly

While the valves you are adjusting at both stages of valve adjustment should be loose, there will be a few others that are "loose" as well. There isn't usually more than 3-5 of the 12 rockers that are tight (open) at any given moment. .

When at TDC on #1, #5 Intake should be loose. . . #5 is 120 degrees away from its firing TDC, meaning the crank is almost 60 degrees past the closing point of #5's intake valve.

The reason the specific valves are chosen for adjustment at each step of the procedure is because they are all far away from their opening point in both directions. . . plenty of "room for error" so to speak. That's way it's not important at all to be at TDC. . . as long as you're within about 1/4 of a crank turn from TDC you're good.

Vaughn

 

[1tuffram]

are you sure it's not the old fuel pump rod making a clatter ?

I thought the same and replaced the lift pump with the latest version a few months ago and still the rattle/clatter noise is present. I noticed today it seems to be getting a little worse.



When I replaced the fuel pump I noticed the tappet cover was looking like it needs to be replaced. I wonder if that has anything to do with my current problem. I posted a post about it back then, but did not get much feedback.



If it's not the upper valve train causing this noise, then what else could be a possibility... . bad injector, tappet or pushrod??? What makes this hard to trace is at idle or even slowly reving the engine while parked will not reproduce the sound. It only occurs with the engine under load, I notice it's most pronounced when lightly accelerating from a stop and RPM around 1800-2000. Dosn't seem to matter if engine is cold or at operating temp. I sent an oil sample off to see if that possible will help pick something up.

 

[1tuffram]

First of all, watch #5 as you rotate the engine and see what it does.



What should I be looking for?

 

[Joe G.]

Make sure it is opening and closing about the same as other intake valves. If not you probably have a push rod problem.

 

[Vaughn MacKenzie]

If you put the engine at TDC then rotate it backwards using the alternator pulley you won't have to go far before #5 intake opens.