Valvetrain Noise issue on 2nd Gen

[skatermillar]

I have a 1992 SHO. I am getting some weird valvetrain noise only at certain RPMS. I will hear the noise which in my experience would sound like a bad rocker or bad phaser (but obviously this motor doesn't have rockers or phasers). When I go full throttle the noise drops even before the RPMs go up. Tested it out last night multiple times. Also under heavy load (5th gear at 20mph) there was no noise valvetrain noise. Any experience with this issue or maybe a possible idea of what the issue could be. I am reaching out to the forum gods on this because I am lost and can't figure it out. Its been going on for awhile and doesn't seem to affect performance.

 

[Irish Pride]

Possibly a worn or bad chain tensioner. How many miles on the engine? Try changing the oil and going to a thicker weight and see if that does anything. 10w40.

-Chad

 

[skatermillar]

Possibly a worn or bad chain tensioner. How many miles on the engine? Try changing the oil and going to a thicker weight and see if that does anything. 10w40.

-Chad

Thats actually a good thought. The motor has 173k and I am already putting 10w40 in it to help reduce the small leak I am getting from the rear main seal.

 

[Irish Pride]

Thats actually a good thought. The motor has 173k and I am already putting 10w40 in it to help reduce the small leak I am getting from the rear main seal.

The rear mains virtually never leak on these engines. You more than likely need to reseal the oil pan. Do rod bearings while in there.

-Chad

 

[skatermillar]

The rear mains virtually never leak on these engines. You more than likely need to reseal the oil pan. Do rod bearings while in there.

-Chad

So far I have done valve cover gaskets, intake manifold gasket, new oil pan RTV. I misspoke and I believe the leak is coming from the front main seal not the rear main seal. Can we still get ahold of the parts to do this or just ebay love?

 

[Irish Pride]

Front seal #710220

Various brands. Timken, National, etc.. Rockauto or any parts house.

-Chad

 

[luigisho]

If you are doing front main might as well get everything in the front. Waterpump, timing belt + that main seal. Don't want to duplicate work and go back in there twice

 

[zoomlater]

shosource has decent prices for a crank sensor and has parts for a 60K

 

[rubydist]

Crank sensors are available again?

 

[zoomlater]

I think Shosoure bought a bunch of them from Brian when he got those made awhile back

 

[Irish Pride]

Crank sensors are available again?

Readily. They pop up on Rockauto for $18 per a couple times a month. I bought 5 just because earlier this year. I have several NOS ones in my stash already. The ones on Rockauto are an exact copy of the ones Brian had made. Me thinks the company that he contracted is now screwing him.

-Chad

 

[skatermillar]

I have dug a little deeper into troubleshooting this issue. The car has 173k miles on it. The timing belt seems really tight. The cam tensioners seemed really tight. The back side definitely had more slack then the front side but still no signs of metal to metal contact on the chain guide. I have also attached photos of the cylinder heads. Was looking for maybe some possible valve slap but the heads don’t look terrible. I’m at a loss here. Have no idea what could be causing my issue. The noise has gotten louder and doesn’t go away under full throttle and I’m also noticing power loss in the higher RPMs. Thoughts?

 

[ScotSHO]

Power loss at higher RPMs typically means the secondaries are not opening. You should hear a noticeable difference in engine tone at ~4000 rpm. You can also check the secondaries while parked & running in neutral - grab the throttle and get it to go above 4000 rpm. You should see the secondary actuator open at 4k.

As for the engine sounds - not sure what you're experiencing.

 

[luigisho]

Metal to metal is one way to look at cam tensioners. Sometimes they aren't fully extended. Not sure if you can see it while it's on the car. Never had to address these myself.

 

[Irish Pride]

I have dug a little deeper into troubleshooting this issue. The car has 173k miles on it. The timing belt seems really tight. The cam tensioners seemed really tight. The back side definitely had more slack then the front side but still no signs of metal to metal contact on the chain guide.

The chains should have plenty of play/slack with the engine off. You should be able to compress the tensioners with your hands. It's the oil pressure that tightens them when running. If one had more slack than the other then you might be dealing with a stuck tensioner or tensioners. If you still have the covers off play with the tensioners and see if you have any movement in them. It might be best to remove the cam caps and take the tensioner out to inspect them better.

-Chad

 

[skatermillar]

The chains should have plenty of play/slack with the engine off. You should be able to compress the tensioners with your hands. It's the oil pressure that tightens them when running. If one had more slack than the other then you might be dealing with a stuck tensioner or tensioners. If you still have the covers off play with the tensioners and see if you have any movement in them. It might be best to remove the cam caps and take the tensioner out to inspect them better.

-Chad

One of the tensioners I have out already and can move it easily by hand. The other one is still in the car. I can’t compress it by hand with it in the car. Should I try and take it out and see if can compress it?

 

[Irish Pride]

Yes. It should have a spongy squish to it in your hand.

-Chad