Loud Rattle Under Valve Cover

[andymoraitis]

Hey all,

It seems that when I fix one noise the motor's making (yes the pinhole airleak noise is banished), I come up against another one.

In any event, I'm getting a loud rattle under the valve cover near #1 cylinder (closest to the T-belt). I can make the noise occur by free revving the motor to about 2500 RPM or so and if I go past that point, the noise also diminishes. I would compare it to a loud clatter. It will happen under load in gear and also out of gear. I've checked the following:

1. Compression: 160-160-160-160 (sounds right for Comp 200's)
2. T-belt is not obstructed or hitting anything
3. Spark plugs are intact (no missing tips or electrode)
4. Performance under high revs feels fine (no power loss).
5. Oil levels are good
6. Coolant temps are perfect.
7. Knock counts have not changed under WOT
8. No cracks on the crank pulley/balancer.

This started immediately after I pulled my injectors to re-check the seals and fix my air leak that I was having on the lowers (again). The car fired up fine and on the first test drive, this started almost immediately.

I'm going to pull the valve cover late tonight and see what I can find. I'm betting something's up with one of the lifters on the intake cam, but I would welcome any suggestions as to any other problems I should be looking for.

Thanks!

Andy

 

[cfisher]

Let me know what you find out. I'm having a similiar issue and it sounds like a lifter could be failing. It's not lifter tick at all and sounds like a valve could be off.

 

[TimG]

This happened to a car I worked on a few years ago. Collapsed exhaust lifter. 3G lifters installed and everything went well on the install.

 

[1993eclipseGS]

It sounds like a lifter, But the only way to be sure is if you pull the valve cover.

 

[andymoraitis]

I pulled the valve cover last night and removed the lifters from Cylnder 1 on the intake side. Both of them compress properly when depressed with a paperclip and they appear to have full travel. A re-test reveals that the sound is still there.

I did take the time to call my older bropther who is an ASE Mitsu Master Tech. If I understood him correctly, with the car making the noise, pull the plug to cylinder one and if the noise continues, it's likely a bearing issue, but if it stops it's most like lifter related. Happily, I can report that the sounds stops, but I'm not sure if I understood him correctly on this.

Anyway, I'm off to have a few more things checked out:

1. Autio tensioner on the T-belt
2. Balance shaft belts
3. Pull the pan and check for trashed rod bearings.

I'll let you know what I find.

 

[andymoraitis]

Number one road bearing is toast and it's time for a rebuild. I'll post pics when I have a chance...

 

[ddavisaf]

Ouch. Sorry to hear that Andy.

 

[steve]

I did take the time to call my older bropther who is an ASE Mitsu Master Tech. If I understood him correctly, with the car making the noise, pull the plug to cylinder one and if the noise continues, it's likely a bearing issue, but if it stops it's most like lifter related. Happily, I can report that the sounds stops, but I'm not sure if I understood him correctly on this.

As I'm sure you now know it's the other way around. If the noise goes away the problem was the bearing. The lash adjusters will continue to make noise when the cylinder isn't under load.

Steve

 

[gurmanator]

anytime a bearing failes the oil pressure will drop...how was the oil pressure?I have been building motors since 1987...if #1 rod is knocking it is a bad rod bearing which means low oil preasure..nothing was said about low oil preassure...if you have good oil preassure than it is something else...number one rule...you must have good oil preassure...good oil preassure=good bearings.I have a motor with bad oil preassure but still runs but means bad bearings...its days are numbered...to sum it up...no blood preassure,you die...no oil preassure,the motor dies.hope this helps

 

[andymoraitis]

As I'm sure you now know it's the other way around. If the noise goes away the problem was the bearing. The lash adjusters will continue to make noise when the cylinder isn't under load.

Steve

Steve,

Yes indeed, although I wish it was the other way!

The issue appears to have been oil pressure related. Over the last couple of months, I would see different oil pressures on different days at the same RPM/gear. Sometimes, she'd run at 50psi at 70 and sometimes she'd run at 65psi.

While pressure didn't drop to "danger" levels, this is likely the cause. When the new motor goes in or the old one is rebuilt, a new oil pump will be installed to make sure that everything's the way it should be. I'm just thankful that I caught this before it punted a rod through the block. As it stands, the crank can be micropolished and everything else is in good shape, but I may throw an SBR stage II block in there just to have some future growth potential.

I'll keep you guys posted on what I decide.

Andy

 

[LilRedRocket]

Sorry to hear that steve, cause I've posted about a noise fom my waterpump tht rattled around those RPM's, It sounds just like mine so I guess I will pull the plug and try the same test. Just woundering though... Did the noise seem to go away after the engine warmed up cause Mine does.

Mike