Well, it didn't take long before I was elbow deep into my V10 again. For the history on this motor, see my other thread "Fixed: no compression on #1 cylinder". I am choosing to start a new thread as for right now I am dealing with a specific question;

How can I identify a weak valve spring, a bad follower bearing or a bad/weak lash adjuster?

Here's the (recent) history; Since resolving the no compression issue a few weeks ago, the van has was running perfectly. No misses, no codes, lots of power and everything seemed fine. A few days ago, I went to start it, and, as the engine started to run and I let off of the key, I heard/felt a "thump" and it stopped. I tried the key again, and it would not turn over. I tried several times, and it simply felt like the engine had siezed. After the previous issues, I feared the worst and assumed that whatever had caused the follower on the #1 cylinder to fall out had reared its ugly head. I was expecting to find that I had dropped a valve and siezed the #1 piston.

A few days later, I went back and tried it again, to demonstrate the problem to another weekend wrencher friend of mine. This time, it turned over and started right up! But, with a rather loud tap in the engine. We shut it off immediately, not wanting to destroy the engine, in case it was a head issue that could be solved without having to replace the entire motor.

So yesterday, I loaded it up on the rollback and brought it home to tear into it. First, we ran it a bit to try to isolate the noise. It was hard to figure out where the tap was coming from, but it seems louder on the passenger side, which of course, is where the #1 cylinder that had issues before, is. So, we dug in and opened up the cam cover on that side (can't just remove it, as there isn't enough room because it is in an E350 van) .

To my surprise, the #1 intake valve assembly looked ok...I was expecting a broken spring. So, we dug in deeper. Here's where I'm at;

After removing all of the COPs on that side along with the fuel rail and injectors, and with about a 1" lift of the body off of the frame on the front right corner, I was able to completely remove the cam cover. And again, everything looks in order. We cranked the engine over and watched every assembly, and they all appear to be ok. I then pulled all the plugs and checked compression on that side and all have compression. Being a cold engine, the readings are all low, but with the exception of the #1 cylinder, they were all the same (about 75 PSI). #1 was about 55. But, the fact that I have compression in all tells me that I'm not dealing with a catastrophic failure...at least not on that bank.

I can't run the engine with the cam cover off without reassembling the fuel rail and reinstalling the COPs. And, the noise is not evident when turning the engine over with the starter, not letting it run. I have read a few other threads that described a similar engine tap that were caused by a bad follower or a broken spring, including a couple that had video/audio clips of the sounds, and I think we are dealing with a similar issue.

How can I identify a bad follower bearing, a broken spring or a bad/weak lash adjuster from this point. Getting the cam cover off was a royal PITA. I do NOT want to have to do it again, and I do NOT want to put it all back together until I am confident that my problem is NOT under it!

I have wiggled and felt for play in the followers on that bank and they all seem fine. All of the springs appear to be o.k., but will a broken spring be visually evident? And, the biggie, if I have a bad bearing in a follower, how can I tell without the engine running...or can I?

If necessary, I will put the fuel rail back together and reinstall the plugs and COPs and run the thing with that cam cover off. But, if there is some other way to diagnose this thing without doing all of that, I'd love to hear some suggestions.

I have not ruled out a problem with the driver's side bank, but before I put the passenger's side back together, I want to be as close to 100% sure that my problem is not there as I can.

 

Some follow up:

I have been reading a variety of posts regarding valve lash adjusters, one that even described a "pop" similar to what I experienced when this started, which I assume was a catestrophic failure of a lash adjuster. But, how can one tell from looking at them, in the engine, if one is bad?

Since my earlier post, I have taken a close look at the springs...at least as close as I can given the lack of access. I have used a small mirror and I have felt every accessable surface along the sides of the springs, and I can not see or feel anything that indicates a broken spring.

So, I think I am looking for either a weak spring, a bad follower bearing, or a bad lash adjuster. What I need to know is if there is any visual or other indicator that one is bad? Nothing feels loose. Is there a way to test them?

I am one step away from putting the fuel rail and COPs back in and firing the thing up with the cam cover off. But before I do, I'd love to hear from some of the experts and/or those that have had first hand experience with trouble like this.

Also BTW, I have verified that there are no broken exhaust studs (or at least there aren't any that APPEAR broken or missing) and all of the spark plugs were tight when I removed them, so I don't think either of those issues are the source of my noise.

 

The only thing I've ever seen make a roller follower fall off is a bent valve.

Your compression is quite low I would expect about 150-170 psi.

Im wondering if the cam timing is off causing the low compression and maybe a bent valve.

 

Ironhand, in this case, we beleive that it was a stuck valve from this van sitting for an extended time. When we got it, a '97 with only 49k miles, it had tires on it that the date code indicated were 10 years old that were cracked on the sidewalls, but still had new tire tread depth on them. It was obvious that the van had sat for a long time without being run, but we don't know how long. The thought is that the #1 cylinder intake valve was in the open (or at least partially open) position when the engine was shut down, and that the valve stuck in that postion when they started it up, which allowed the follower to fall out. It continued to be stuck in that position until the follower was put back in and started moving the valve again, as #1 had zero compression until the follower was re-installed. That is the basis for thinking that the #1 intake valve could be weak from being held in a compressed position for an extended time. But, I'm sure that some of the other 19 valve springs would have been in the same situation, so any number of them could be weak.

With that premise, I guess I could rotate the engine to that position and see which valves are open, and replace all of the springs and lash adjusters that might have been open during storage. But, if I'm going that far, I might as well do all 20 of the springs and lash adjusters. But, that's a big job with the motor/heads in, especially in an E-series...

Given the lower compression on #1, I'm leaning toward just replacing that spring and lash adjuster and see if that makes a difference in the noise and/or the compression...could be that the #1 intake valve isn't closing all the way because of a weak spring.

So, if I'm going to start just throwing parts at it, that's where I'll start. But, I'd rather have someone tell me how to detect a weak spring, a failed lash adjuster or a bad follower bearing when it isn't readilly evident. If that is possible, that is.

Anyone??

 

Oh also, the engine is still running smoothly and cleanly with no codes and no smoke, just a fairly loud noise. If the timing was off, I don't think it would run, or at least not well, and I'd expect that bent valves would cause zero compression, not low compression on the affected cylinders. Again, those compression figures were on a cold engine, so I don't think they are valid pressures, but they tell me that I have compression, so we haven't dropped or bent a valve, right?

 

A couple things.

If the motor sat that long then it is possible for something to get stuck between the two(rust) and not allow the valve to seat fully. Following your logic if that is the case then how do you have compression to begin with?

There are two ways to check for a weak valve spring. 1 is a high RPM dyno pull but since that is out of the question that leaves option number 2 which is to pull that valve spring out and have it checked for seat pressure at installed height and seat pressure when the valve is fully open.

But lets dig into this alittle further.

You say you have compression but its low. That to me sounds like 1 or two problems.

1) The valve guides are worn and allowing the valve to ''rock'' in the seat and leak alittle bit. Pull the roller follower off and see if you can rock the valve side to side or feel any play in the valves. Also look for leakage on the valves themselves.

2) The motor was sitting without oil for a long time. I would inspect the piston rings to make sure they are gapped correctly and are in good shape since some form of leakage is taken place in the cylinder.

I thought cam timing was an issue because of your compression test. You either didnt do it right or something is really wrong. My calculations follow.

This is for the motor at 9:1 compression and the intake valve closing 33 degrees ABDC.
dynamic compression ratio is 8.55:1 .
dynamic cranking pressure is 173.24 PSI.

173 psi is what you should see on the gauge when you crank the engine. If you take the static compression ratio up then the dynamic C/R and cranking pressure will also rise if everything else remains the same. Your dynamic C/R however will change depending on how the cams are timed.

If we were to raise the static compression ratio with everything remaining the same to 9.5:1.

dynamic compression ratio is 9.02:1 .
dynamic cranking pressure is 185.57 PSI.


On another note. Most modular motors that come from the factory have their cam timing incorrect. That's be documented countless times by engine builders. Regardless of that though your compression should be alot higher. At 70 PSI that would indicate that something is terribly wrong.

 

Side note:

I see you might be at elevation so here are the corrected numbers for 5,000 FT above Sea Level & 9.5:1 Static C/R.

dynamic compression ratio is 8.02:1 .
dynamic cranking pressure is 159.49 PSI.

 

Well, I'm not sure why my values would be so low, other than I'm not doing the test correctly, i.e. I'm testing a cold engine. But, the results on four of the five cylinders on the right bank were exactly the same, and #1 was a bit low.

That indicates to me that the problem is likely in from #1, and the noise is what I'm trying to address right now. And, logic dictates that if the lash adjuster or spring is weak on #1, that I might not be getting a good seal on that valve as a result, right? Perhaps resolving the noise will in turn resolve the compression?

Ironhand, you have answered one of my questions. That is that you can't easily identify a weak valve spring other than to remove it and test it or compare it to a new one. What about the lash adjusters? Is there some way to figure out if one (or more) of them is bad without removing them from the engine?

I'm going to try to cover the timing chain so that I can run this thing without throwing oil everywhere, and see if a stethoscope will reveal anything specific to one valve or cylinder. And, I may try pulling the follower on #1 intake (the one that fell out before) and run it to see if the noise goes away.

Before I re-installed the follower on the #1 intake a few weeks ago, I had felt the bearing and it seemed fine to me then, so I don't think that is the problem. I'd guess it is either a weak spring, a bad lash adjuster, or both, on that cylinder, so I'm probably going to replace them both and see what I get.

To do the spring, I'll use the rope in the combustion chamber technique to keep the valve from dropping. Maybe at that point, I can back the piston down just enough to move the valve and feel for play in the guide with the spring off.

But at this point, I'm still looking for a way to verify proper valve lash adjuster operation without removing them. Is that possilbe?

 

Well, since no one could tell me how to identify a bad follower, weak valve spring or bad lash adjuster, I decided that removing them one by one and running the engine would allow me to determine which one was making the noise. I have now done just that with all 10 followers on that bank, and guess what...it was none of them.

I had used a stethoscope to listen for the noise, and it sounded like it was in or near the 3rd cylinder back from the passenger side...basically right in the middle...go figure, the hardest spot to get to on an E350, so I started there.

After trying each one, I've determined that my problem is not in the top end, at least not on that bank. So now what??

I guess I'll get that cam cover back on so that I can run the engine without making any more of a mess, and see if I can better isolate the sound with the stethoscope. I might also take a peak under the driver's side cam cover just to make sure that everything looks right there.

But, I'm thinking bottom end right now. I might have to get a scope and take a peak down into the cylinders where it sounds like the noise is coming from. But, if the problem is with a rod or a wrist pin, that probably won't help.

Any thoughts on this are appreciated!

 

When you did the compression check, did you do it with the throttle plates wide open?

 

Krewat, no, I did not. Does that make a difference? Either way, I was not testing so much as to determine if I had good or bad compression, just trying to determine if valves were opening and closing properly to be able to create ANY compression. Is it correct to think that a weak intake valve spring might cause lower compression on the #1 cylinder? If I figure out the noise and the engine is able to be saved, then I'm thinking that I should replace the #1 intake (the one that the follower fell off of) lash adjuster and spring, just to be safe.

 

Yes, opening the throttle plates does make a difference in the final compression reading.

I don't think a weak spring would keep pressure from building though. As the piston comes up, it would push the valve against the seat anyway.

If you pulled all the followers off, and the noise didn't go away, sounds like bottom-end.

It's hard without HEARING the noise...

 

Makes sense. I started a new thread, now that I'm off of the valve train school of thought. I'm thinking the bottom end too, but just can't make it make sense. What could go wrong on the bottom end from a cold start that would lock up the engine at first, but then a week later allow it to turn but making a noise. Perhaps a hydrolock? But, I don't think that was the case. If it was a hydrolock, it would be with either oil or coolant. Either way, once it started, I'd have a crapload of smoke, which I don't. If I broke a rod or a wrist pin or something, then I wouldn't have any compression. And, a rod bearing or wrist pin slap would have been a bit more of a progressively developing problem. That wouldn't happen all at once from a cold start, right?

As far as the noise, there are a couple of other threads that have video/audio with them that I've listened to that sound just like it. I think they were dealing with a lash adjuster problem. That's why I was on that path...when I heard those audios, I said "that's it!", mine sounds just like theirs (sorry, I don't remember who's threads those were, but I'll be that you do!).